Does sprawl make the urban heat island effect worse?

urban heat island effect by city
urban heat island effect by city

Cleveland experiences the fourth strongest urban heat island effect in the United States. Could our sprawling development patterns be to blame? (courtesy of Debbage and Shepherd, 2015).

A few weeks ago, NASA officially announced that the record-breaking, “Godzilla” El Niño event that dominated much of our weather over the past year plus had finally come to an end.

But while the monster has returned to its hibernation deep below the surface of the Pacific Ocean, its impacts have already been and will continue to be felt across the United States. Around the same time that it made this announcement, NASA also revealed that April and May were the warmest such months on record in the US, meaning that every month since October 2015 has broken the existing record for that month. This eight-month streak of heat is, obviously, unprecedented. To date, the average temperature in 2016 is 1.9°F (1.08°C) above the average for the 20th century, making it a full 0.43°F (0.24°C) above the mark for the first five months of 2015.

You remember 2015, right? The warmest year on record? Well, not for long. NASA scientists are already more than 99% certain that 2016 will break that record, just as 2015 had claimed the mantle from 2014.

The impacts of 2016’s extreme heat

The extreme heat is having clear effects. It is contributing to wildfires consuming wide swathes of the West. Ozone levels are higher than normal across the country, as high temperatures foster the development of harmful, ground-level ozone more readily. So far, Greater Cleveland has already experienced six days when ozone levels exceed 70 parts per billion (ppb), the most at this point since 2012.

But the most acute impact of high temperatures heat-related mortality, a subject that I’ve written about considerably. Extreme heat is the deadliest type of disaster in the US, killing more people than hurricanes, floods, tornadoes, and lightning strikes combined each year. As I’ve discussed in the past, climate change is only exacerbating this issue; the World Meteorological Organization (WMO) noted that the global death toll from extreme heat rose by around 2,300% from 2000-2010, compared to the previous decade.

change in disaster deaths by decade

The change in the number of deaths, by disaster, from 1991-2000 to 2001-2010 (courtesy of WMO).

Nearly all regions have seen a spike in dangerous heat, but the risk of heat-related mortality is not distributed evenly. While an individual’s vulnerability to extreme heat is the function of a number of factors, one of these is where s/he lives. Generally speaking, those of us living in cities are at greater risk due to the so-called urban heat island (UHI) effect. I won’t go too far into the science behind the UHI effect; suffice it to say that the combination of dark surfaces, a lack of urban trees, and the production of waste heat from various sources like air conditioners increases the temperature of cities, relative to rural areas. According to the U.S. EPA, the temperature of a large city can be more than 20°F higher than surrounding rural areas under the right (or wrong?) conditions.

Last September, Forbes published an article examining the scale of the UHI in various cities throughout the US. Strikingly, it included a map (see above) stating that Cleveland has the fourth strongest UHI effect in the country. Now, if you’re one of the literally tens of people who has inexplicably read something I’ve posted on this site, you may be familiar with my general dislike of sprawl. I’ve discussed research linking it to population decline, limited social mobility, climate change, and poor air quality, among other things.

So, I wondered, could Cleveland’s strong UHI effect be the result of our development pattern? Given that sprawl affects so many important phenomena, it seems reasonable to assume it would have an effect on UHI, right? To the peer-reviewed literature! [Cue 1970s Batman transition music].

Is suburban sprawl actually linked to the urban heat island effect?

At first glance, it may seem odd to posit that suburban sprawl would play a role here; the phenomenon is called the urban heat island effect, after all. But a handful of studies strongly suggest that sprawling development patterns do, in fact, exacerbate the UHI effect.

Two of the most convincing papers come from Brian Stone, Jr., a professor at the Georgia Tech School of City and Regional Planning and an expert on urban environmental planning and climate change.

In a 2006 study (paywalled) that he coauthored with Jon Norman from the University of Wisconsin-Madison, Stone examined the link between land use patterns and the UHI effect in Atlanta. The researchers broke properties into groups based on four variables: extent of impervious surfaces, lawn and landscaping, tree canopy, and the number of bedrooms per residential structure. This categorization enabled them to study the magnitude of surface warming produced by property type.

Stone and Norman concluded that the size of residential lots – in other words, residential density – was closely tied to black body flux, a measure of surface warming. As one moves from the highest density lot type to the lowest density, the amount of surface heat released increased 6-fold. Other land use features closed tied to suburban and exurban development – namely large lawns – also exacerbate the UHI effect. A one unit increase in the area of a plot covered by lawn and landscaping increases the net black body flux by 0.51 units.

As the authors conclude,

The results of this analysis provide compelling evidence that the size and material composition of single-family residential parcels is significantly related to the magnitude of surface warming in the Atlanta study region. Specifically, smaller, higher density parcels were found to be associated with a lower net black body flux than larger, lower density parcels…

[The] results of this study support the hypothesis that lower density, dispersed patterns of urban residential development contribute more surface energy to regional heat island formation than do higher density, compact forms.

Connecting sprawl and the UHI across cities

On its own, one study does not prove the relationship. Fortunately, Stone followed up with a 2010 paper that he co-wrote with Jeremy Hess and Howard Frumkin of the University of Washington, which studied the connection between urban sprawl and the number of extreme heat events (EHEs) in 53 cities from 1956-2005.

To measure the relationship, they took the correlation between the mean annual change in the number of EHEs from 1956-2005 and the sprawl ranking for each of the cities in 2000. Whereas the most compact cities experienced 5.6 more extreme heat days in 2005 than in 1956, that number was 14.8 for the most sprawling cities. In other words,

The most sprawling cities experienced a rate of increase in EHEs that was more than double that of the most the most compact cities…These findings are consistent with the hypothesis that urban sprawl contributes to EHE frequency.

Exploring some competing research

Now, I should note that there is other research that does not jibe with Stone’s work. Last year, Neil Debbage and Marshall Shepherd of the University of Georgia took another look at urban form and the urban heat island effect. Using a different measure for UHI (the difference in average rural and urban temperatures) and a different measure for urban form (an index measuring various variables of city shape, contiguity, and land uses), Debbage and Shepherd studied the degree to which city configuration affected urban heat in the 50 largest US metro areas from 2001-2010.

Contrary to Stone, Debbage and Marshall found that both more compact and more sprawling cities experience a stronger UHI effect, provided they are highly contiguous. That is, the contiguity of urban form may matter more than its composition; designing cities so that they are made up of either cul-de-sacs or skyscrapers as far as the eye can see makes them more vulnerable to extreme heat. According to the authors,

A ten percentage point increase in the spatial contiguity of high-intensity urban development, the equivalent of shifting roughly from Orlando to Seattle, was predicted to enhance a city’s average UHI intensity by 0.4°C…[In turn] a ten percentage point increase [in low-intensity urban development] was predicted to enhance a city’s annual average UHI intensity by 0.3°C. Therefore, as suggested by the bivariate analysis, both low and high-density urban land uses appear to amplify the UHI effect if they are high contiguous.

Importantly, Debbage and Marshall note that, while compact development may not solve the UHI on its own, it does provide a litany of other benefits, from improved air quality to better public health. Accordingly, urban planners may want to promote less contiguous, higher density urban development by designing networks of smaller green spaces, expanding the urban tree canopy, and installing white and green roofs throughout cities. A 2014 study by Stone and colleagues found that implementing these types of policies can offset projected increases in heat-related mortality due to climate change by anywhere from 40-99%.

Wait, so does sprawl make the UHI effect worse?

So what can we take away from all of this?

First, yes – the evidence does suggest that sprawl exacerbates urban heat islands. Low-density, suburban-style development increases the amount of impervious surfaces, which raises lowers the surface albedo of urban areas. It also increases the amount of excess waste heat that cities produce, as larger houses require more energy. And sprawl typically leads to forest clearance for development, reducing the extent of the urban tree canopy. All told, these factors increase the amount of heat cities generate, and they prevent this additional heat from dissipating rapidly at the urban fringe.

Second, the fact that sprawling development patterns are not the only type urban form that increases the UHI effect may not be as relevant as it may seem. While dense urban areas may also promote UHIs, they also make it easier to address both the causes and effects of heat-related mortality risks. Residents of dense cities produce fewer carbon emissions per capita, mitigating climate change. And the economies of scale in these dense neighborhoods increases the efficacy of mitigating extreme heat; opening a cooling station or installing shade trees are more effective in these areas, for instance.

All told, we can add the urban heat island effect to the list of social problems that sprawl makes worse. Maybe we should rename it the (sub)urban heat island effect?

Go hug a tree. You just might live longer.

edgewater willow tree
edgewater willow tree

The iconic willow tree at Edgewater Park (courtesy of Francis Angelone).

Once upon a time, Cleveland was the Forest City. When Moses Cleaveland arrived to survey Connecticut’s Western Reserve in 1796, the area was heavily forested. It was said that a squirrel could travel from the Atlantic Ocean to the Mississippi River without ever touching the ground.

These days, only the moniker remains. We still have Forest City Enterprises, Forest City Brewery, Forest City Portage, etc. The trees? Not so much.

According to Cuyahoga County’s Urban Tree Canopy Assessment, just 19.2% of the city remains forested. Nearly all of the trees that existed during Cleaveland’s trip to the city that (largely) bears his name are gone today. In 1946, city officials identified 150 trees that likely existed in 1796. When the city updated this inventory in 1975, just 92 remained; of these, only 15 still had the plaques that were installed in 1946.

cuyahoga county tree canopy by community

The existing tree canopy, by community, in Cuyahoga County (courtesy of Cuyahoga County Planning Commission).

Only two of Cuyahoga County’s 59 communities have less tree cover than Cleveland, and the city lags behind comparable cities, including Cincinnati (38%) and Pittsburgh (40%). According to projections, unless Cleveland reverses this trend, its tree canopy will fall to just 14% by 2040. This would represent a loss of 97 acres of urban forest annually over the next 25 years.

When you consider some of Cleveland’s pressing challenges – a 56% child poverty rate, violent crime, population loss – the number of trees within city limits may not seem like a big deal. But we cannot consider the city’s environmental challenges as distinct from its general urban challenges; they are intrinsically connected. Our tremendous urban struggles exacerbate our environmental issues, including tree cover, and these environmental issues subsequently compound these broader issues.

Cleveland’s trees are terrific

When I think about trees, my mind immediately goes to that strangely catchy 1970s commercial from the National Arbor Day Foundation:

And it’s true, trees are terrific. In fact, they’re freaking incredible. But, as the singing cardinal in that commercial indicates, sometimes we take for granted the best things ever planted.

For many Clevelanders, trees may seem like more of a hassle than they’re worth. They produce tons of leaves, fruit, and sap that coats lawns and clogs gutters. They can damage sidewalks. Their roots may get into water and sewer pipes. They may fall in a storm and damage your property or that of a neighbor.

But the costs of trees only outweigh their benefits when we fail to account properly for the latter. Fortunately, the City of Cleveland and a number of partner organizations have placed  a price tag on the myriad benefits that our trees provide in The Cleveland Tree Plan (PDF), which was released last October.

Utilizing the U.S. Forest Service’s i-Tree model, the document estimates that the city’s trees provide more than $28 million in ecosystem services each year. Cleveland’s trees intercept 1.8 billion gallons of rainwater, which helps to mitigate our ongoing challenges with flash flooding. The trees shade homes, lowering energy costs by $3.5 million each year, as well as increase property values by $4.5 million. They also play an important role in mitigating climate change, as they remove 42,000 tons of carbon dioxide per year.

In the plan’s appendices (PDF), which you have to be a massive nerd like me to read, the Tree Plan actually lays out these ecosystem services by neighborhood. As the table below shows, there is a clear overlap between the extent of a neighborhood’s tree canopy and a host of other issues, including energy costs, asthma rates, and property values. The correlation between a neighborhood’s tree canopy and its urban heat island risk, for instance, is extremely strong (0.7609) and statistically significant (p < 0.0001).

cleveland tree benefits by neighborhood

The tree canopy and related statistics in each of Cleveland’s neighborhoods (courtesy of City of Cleveland).

Trees and mortality rates

On its surface, all of this makes sense. It’s fairly obviously that trees filter out air pollution, mitigate stormwater runoff, store carbon, beautify neighborhoods, and shade homes. But trees can do so much more, including extend your lifespan.

A recent study in the journal Environmental Health Perspectives examines the relationship between “greenness,” a measure of vegetation cover (including trees) and mortality rates among a cohort of female nurses in the U.S. The researchers, led by up Dr. Peter James from the Harvard School of Public Health, utilized satellite images to measure the amount of vegetation within 250 and 1,250 meters of each woman’s residence. The 250-meter diameter represented the vegetation directly accessible from each woman’s home, while the 1,250-meter buffer accounted for vegetation within a 10- to 15-minute walk.

The authors considered four main pathways through which exposure to vegetation can affect mortality rates: physical activity, air pollution, social engagement, and mental health. They also controlled for a range of potentially confounding factors, including race/ethnicity, smoking status, socioeconomic status, region, and whether the person lived in a urban area.

According to James et al., higher levels of “greenness” significantly lowered mortality rates among the women in the study cohort.

Analyses showed a consistent relationship between higher greenness and decreased mortality that was robust to adjustment for individual- and area-level covariates. In fully adjusted models, those living in the highest quintile of cumulative average greenness in the 250m area around their home had a 12% lower rate of mortality compared to those in the lowest quintile. Results were consistent for the 1,250m radius, although the relationship was slightly attenuated.

Greater exposure to vegetation significantly reduced mortality rates from cancer, respiratory disease, and kidney disease by 13%, 35%, and 41%, respectively. Of the four pathways studied, the effects were greatest for mental health and social engagement, though “greenness” also reduced mortality related to fine particulate matter and a lack of physical activity.

Based on their research, James et al. conclude,

[T]hese findings suggest that green vegetation has a protective effect, and that policies to increase vegetation in both urban and rural areas may provide opportunities for physical activity, reduce harmful exposures, increase social engagement, and improve mental health. While the recognized benefits of planting vegetation include reducing wastewater loads, sequestering carbon, and mitigating the effects of climate change, evidence of an association between vegetation and lower mortality rates suggests a potential co-benefit to improve health, presenting planners, landscape architects, and policy-makers with an actionable tool to grow healthier places.

Clearly, city officials should work to expand urban tree canopies in order to mitigate the myriad social, environmental, and health issues that plague cities like Cleveland. Fortunately, Cleveland has taken the first step on this road with the release and adoption of its tree plan. Hopefully we can work together to expand the city’s tree canopy in order to tap into the numerous benefits that trees provide.

Maybe the next time you look out your window at your tree lawn, you will see the tree standing there in a different light. It’s time we appreciate and better care for our trees in Cleveland. They just might extend your life.

Karachi’s Heat Wave a Sign of Future Challenges to Pakistan’s Fragile Democracy

A man (R) cools off under a public tap, while others wait to fill their bottles, during intense hot weather in Karachi, Pakistan, June 23, 2015. A devastating heat wave has killed more than 400 people in Pakistan's southern city of Karachi over the past three days, health officials said on Tuesday, as paramilitaries set up emergency medical camps in the streets. REUTERS/Akhtar Soomro - RTX1HPUL

A man (R) cools off under a public tap, while others wait to fill their bottles, during intense hot weather in Karachi, Pakistan, June 23, 2015. A devastating heat wave has killed more than 400 people in Pakistan’s southern city of Karachi over the past three days, health officials said on Tuesday, as paramilitaries set up emergency medical camps in the streets (courtesy of Reuters).

Karachi, the world’s second largest city by population, is emerging from the grips of a deadly heatwave. A persistent low pressure system camped over the Arabian Sea stifled ocean breezes and brought temperatures in excess of 113°F (45°C) to the city of 23 million people in June. The searing heat disrupted electricity and water service, making life nearly unbearable. All told, officials estimate the heatwave killed at least 1,200 Pakistanis, more than twice as many as have died in terrorist attacks this year.

But meteorology alone cannot explain this turn of events. Rather, as with all disasters, Karachi’s heatwave is rooted in a complex web of natural and man-made factors. “The emergency is the product of a perfect storm of meteorological, political, and religious factors,” notes The New York Times.

Karachi’s rapid growth has heightened people’s exposure and vulnerability to heat. Since 2000, Karachi’s population has doubled, making it the fastest growing megacity in the world. This population explosion has overwhelmed the capacity of local government. At least half of all Karachiites live in informal settlements, with little access to infrastructure and vital services. Unplanned expansion has also led to widespread environmental degradation. Karachi’s annual concentration of fine particulate matter is 11.7 timesWorld Health Organization standards (and more than double that of Beijing), making it the fifth most air-polluted city in the world. Karachi also faces an acute water crisis. Some of its poorest residents survive on just 10 liters per day, one-fifth of daily drinking requirements, while some estimates suggest more than 30,000 people die from water-related diseases every year.

Wide swathes of trees and other vegetation have been cleared for roads and buildings, limiting shade and exacerbating the urban heat island effect (the process by which urbanized areas absorb and retain solar radiation, significantly increasing local temperatures). Add to this the city’s construction boom which creates a major demand for manual labor and the onset of the holy month of Ramadan – during which Muslims can neither eat nor drink before sundown – and you have a recipe for disaster.

To read the rest, head over to the original post at New Security Beat.

It’s time to include climate change in the immigration debate

hanna lake dried up
hanna lake dried up

A man walks through the desiccated remains of Hanna Lake in Balochistan, which dried up during a decade-long drought in the region (courtesy of Al Jazeera).

Last month, The New York Times released the results of a poll, showing that Hispanics are far more likely to view climate change as a pressing issue that directly affects them. Fifty-four percent of Hispanics rated global warming as a extremely or very important, compared to just 37% of non-Hispanic whites. Moreover, nearly two-thirds (63%) of Hispanics said that the federal government should do a lot or a great deal to tackle climate change.

There are a number of reasons to explain this high level of concern, such as the fact that Hispanic households are far more likely to live in neighborhoods adversely affected by pollution. Minority communities are also more acutely vulnerable to the impacts of climate change, such as heat-related mortality.

This increasing awareness about climate change among Hispanics may appear odd to some, at first glance. As Coral Davenport put it, “the findings of the poll run contrary to a longstanding view in politics that the environment is largely a concern of affluent, white liberals.” Timothy Matovina, executive director of the Institute for Latino Studies at the University of Notre Dame, voiced this conventional wisdom in January, arguing,

Many Spanish-speaking immigrants are worried about surviving from one week to the next. Going to the latest rally on climate change or writing letters to their local chamber of commerce about some environmental issue that sounds to me more like something a middle-class person would do with time on their hands.

Climate change and drought in the American Southwest & Central America

What this argument misses, however, is the myriad ways that climate change is intertwined with other key issues, like immigration. Recently, NASA scientists released a study examining how climate change will affect drought conditions throughout the American Southwest and Central Plains. The study also investigated the impacts on Central America, particularly Mexico. As the map below illustrates, under a business as usual emissions scenario, there is a greater than 80% likelihood that the region will experience a megadrought of at least 30 years between 2050-2099. The historical risk of this type of megadrought is less than 12%.

This study was the first of its kind to compare projected drought trends to the historical record for the past millennium. While droughts of this type did occur during the Medieval Climate Anomaly, a warmer-than-average period lasting from 1100-1300 CE, future droughts will be exceptional. Even if the world takes steps to dramatically curb carbon emissions by mid-century,  climate change will lead to drought conditions that are “unprecedented” in at least the last 1,000 years.

nasa drought projection 2095

The portions of the continental US and Mexico that will be affected by extreme drought this century under a business as usual scenario (courtesy of NASA).

This latest study supplements earlier research showing the looming specter of drought for the region in question. A 2012 Nature Climate Change study by Aiguo Dai, for instance, concluded there would be “severe and widespread droughts in the next 30–90 years” through much of the world, particularly the US and Central America. And a 2011 study from Michael Wehner et al. found that an ensemble analysis “exhibits moderate drought conditions over most of the western United States and severe drought over southern Mexico as the mean climatological state.”

Climate change, drought, and immigration

So what does this research have to do with immigration and Hispanic Americans? Well, we have considerable evidence that droughts are a major driver of migration. As I wrote last January, high temperatures and declining rainfall significantly increase rates of migration in Pakistan. Males living in rural parts of the country, for instance, are 11 times more likely to migrate during periods of extremely high temperatures, while both men and women are more likely to leave their villages under drought conditions.

But the evidence linking climate-induced droughts and migration is not just contained to Pakistan. Because declining rainfall and elevated temperatures combine to lower crop yields in arid and semi-arid areas around the world, drought is likely to be a driver of out-migration in a number of regions. A 2010 study in PNAS found just such a link in Mexico. Declining yields of corn due to drought could increase rates of immigration from Mexico to the US by up to 9.6% through 2080.

Last week, Joe Romm connected the NASA drought study toUS immigration policy. In a post, which is somewhat inartfully titled “If We Dust-Bowlify Mexico And Central America, Immigration Policy Will Have To Change,” Romm writes:

But what are the implications for our poorer neighbors to the south? There will be virtually no part of their countries that are not in near-permanent Dust Bowl or severe drought. And of course their coastal areas (and ours) will be trying to “adapt” to sea level rise of perhaps 3 to 6 feet by 2100 (and likely faster rise after that). Again for all but the wealthiest coastal areas, the primary adaptation strategy will probably be abandonment.

Much of the population of Mexico and Central America — likely over 100 million people (Mexico alone is projected to have a population of 150 million in 2050!) — will be trying to find a place to live that isn’t anywhere near as hot and dry, that has enough fresh water and food to go around. They aren’t going to be looking south.

Romm calls this scenario “a humanitarian and security disaster of almost unimaginable dimensions.” Unfortunately, like all too many commentators before him, Romm makes broad statements about environmentally-induced migration, a topic that is incredibly complex and multi-layered. It’s exactly these types of sweeping generalizations that has led others to claim we would see up to 50 million “climate refugees” by the year 2010. Not quite.

Putting environmentally-induced migration in context

First of all, from a legal and academic sense, there’s no such thing as a climate refugee. But beyond that, it’s not helpful to reduce an issue as complex as migration to a string of simplified absolutes. Arguing that drought conditions will inevitably force people to abandon their villages, en masse, ignores a large collection of evidence to the contrary and effectively robs these people of their agency. We need to do better than that as a community of people who purport to care about the interests of individuals on the front lines of climate change.

Romm’s claim that abandonment will be the primary adaptation strategy has little support. Migration carries considerable costs and risks for individuals, so it is almost never the first choice people pursue. Environmental stress is one of many considerations that people have when deciding to migrate, but it is important to remember that this decision includes a number of social, economic, and political factors.

When examining migration patterns, we need to consider both the push and pull factors involved. Drought can be a major push factor that drives people from their homes, but there generally needs to be pull factors on the other end to attract people to destination communities. We have plenty of evidence of this from Mexico, where multiple studies from migration scholars at the University of Colorado have found that emigration to the US largely occurs among households that have previous experience with migration and/or have access to established migration networks. While declining rainfall does appear to drive households to migrate from Mexico to the US (especially for households living in dry portions of Mexico and during periods of extreme drought), the existence of social networks for potential migrants is “dominating” these flows. Whether or not households choose to migrate during dry spells is largely predicated on this factor.

None of this is to suggest that, as large portions of the Southwest and Central America enter persistent drought conditions, the number of people entering the US across the southern border (with or without legal approval) won’t increase. It almost certainly will. We have already seen spikes in migration from countries such as Guatemala, which is currently enduring an historic drought.

But, if we are proactive, things need not devolve into the worst case scenario Romm laid out. The US and our neighbors need to work together to both enhance the adaptive capacity of people living in Central America, so they can be better prepared to weather a changing climate in situ and to reform immigration policies to facilitate the movement of people throughout the region.

Migration has always been a vital adaptation in the face of external stress, and we should consider it through that lens. It is likely time for the international community to begin including migration and displacement in the broader discussion about climate change policy. Perhaps it can be couched under the national adaptation plans or the work program on loss and damage. But we need to be very careful not to let migration get subsumed within climate change. As I’ve noted, there could be significant unintended consequences of creating a special protected class for climate migrants. What about internally displaced persons who cannot access international assistance? What about the 40-80 million people who have been displaced by large dam projects worldwide?

We must also be careful about hyping waves of climate refugees. There is already enough backlash against immigrants worldwide, and pushing such doomsday scenarios may just serve to heighten that opposition. Rather than building figurative and literal barriers to immigration, we need to begin upgrading our domestic and foreign policy to support and protect potential migrants of all stripes. In a greenhouse world, we can no longer afford to consider immigration policy in a vacuum.

Sorry, Roger Pielke, climate change is causing more disasters

typhoon haiyan damage
typhoon haiyan damage

Damage in Tacloban from super Typhoon Haiyan (courtesy of The Daily Mail).

Back in March, controversial political scientist Roger Pielke, Jr. published his first post for FiveThirtyEight. The piece centered on the argument that climate change is not contributing to an increase in scale of disasters globally; rather, Pielke argued, “the numbers reflect more damage from catastrophes because the world is getting wealthier.”

The piece immediately drew consternation and criticism from a number of individuals and even prompted Nate Silver to commission a formal response from MIT climate scientists Kerry Emanuel. In particular, Emanuel and fellow climate scientist Michael Mann criticized Pielke’s decision to normalize GDP data. As Emanuel wrote,

To begin with, it’s not necessarily appropriate to normalize damages by gross domestic product (GDP) if the intent is to detect an underlying climate trend. GDP increase does not translate in any obvious way to damage increase; in fact, wealthier countries can better afford to build stronger structures and to protect assets (for example, build seawalls and pass and enforce building regulations). A grass hut will be completely destroyed by a hurricane, but a modern steel office building will only be partially damaged; damage does not scale linearly with the value of the asset.

Pielke’s critics also noted that he used an oddly brief time span for his investigation (1990-2013), that his use of global data tends to cover up significant differences in disaster damages among regions, and that he does not account for disaster damages that have been avoided due to investments in disaster mitigation and risk reduction. There’s also the fact that he includes geological disasters (i.e. earthquakes and volcanic eruptions) in an analysis that purportedly dismisses climate change as a factor; would it really have been that hard to get the original data on climate-related disasters directly from EM-DAT?

Not suprisingly, Pielke and a number of his friends, colleagues, and allies defended the piece, portraying Pielke as the victim of a coordinated witch hunt from climate activists and radical environmentalist bloggers. In an interview with Pielke, Keith Kloor, someone with whom I have disagreed on many occasions but respect, wrote that various commenters had “used slanderous language in an attempt to discredit” Pielke’s work. The basic argument is that few people had any real qualms with the research itself; instead, Pielke’s critics could not escape their personal feelings towards him and allowed those to color their critiques of his work.

Disaster frequency in the Asia-Pacific region

All of this is just an excessively long introduction to a new study published this week in the journal Climatic Change. In the article, researchers Vinod Thomas of the Asian Development Bank, Jose Ramon G. Albert of Philippine Institute for Development Studies, and Cameron Hepburn from Oxford University (herein known as TAH) “examine the importance of three principal factors, exposure, vulnerability and climate change, taken together, in the rising threat of natural disasters in Asia-Pacific” during the period from 1971-2010.

Now, there are three key reasons why this article piqued my interest and why its results are relevant to the topic at hand, particularly in contrast to Pielke’s research:

  1. The Asia-Pacific region typically accounts for at least a plurality of all disaster metrics – frequency, victims, and economic damages. From 2002-2011, according to EM-DAT (PDF, see page 27), Asia-Pacific was home to 39.6% of disaster events, 86.6% of disaster victims, and 47.9% of economic losses.
  2. The overwhelming majority of disaster events, losses, and victims in Asia result from climate-related disasters. For instance, the region accounts for 40% of all flood events (PDF, see page 6) over the last 30 years, and three-quarters of all flood-related mortality occurs in just three Asian countries – Bangladesh, China, and India.
  3. Both the size of the region’s populations and economies have grown dramatically over the past 40 years. As the figure below demonstrates, East and South Asia have seen GDP per capita growth rates of 8.4% and 5.6%, respectively, easily outpacing other regions. Asia-Pacific is also rapidly urbanizing. From 1950 to 2010, the number of Asians living in urban areas grew seven fold to 1.77 billion (PDF, see page 32). Many of these individuals live in areas highly exposed to disasters; for instance, 18% of all urbanized Asians live in low elevation coastal zones. Accordingly, if population growth and increased exposure to disaster risk were the ultimate drivers of increasing disaster occurrence, Asia would likely be the test case.

So, does this new research validate Pielke’s assertions that disasters are not becoming more frequent and, if they are (which they aren’t), it has nothing to do with manmade climate change?

In a word, no.

Unlike Pielke, who apparently believes that normalized economic losses represents an appropriate proxy for disaster occurrence, TAH actually examine the frequency of intense disasters over a four-decade period. And whereas Pielke considers damages from geological disasters, which, – given the fact that we have not suddenly entered an age of earthquakes – are a function of increasing physical and economic exposure, these authors focus exclusively on climatological (droughts, heat waves) and hydrometeorological (floods, tropical storms, etc.) disasters, which can be influenced by a changing climate.

Moreover, TAH only consider the occurrence of intense disasters, which they define “as those causing at least 100 deaths or affecting the survival needs of at least 1,000 people.” The use of this metric ensures that any increase in the number of observed disasters is unlikely to be the result of better reporting mechanisms alone, countering Pielke’s assertion that any perceived increase “is solely a function of perception.”

TAH explore the frequency of climate-related disasters in 43 Asian-Pacific countries, using both random and country-fixed effects*, which provides them with a greater sense of the validity of their results. They use the log of population density as a proxy for population exposure, the natural log of real income per capita as a proxy for socioeconomic vulnerability, and both average annual temperature and precipitation anomalies as proxies for climate hazards. Additionally, they break the data into 5 subregions and the timeframe into decade-long spans as sensitivity tests.

Climate change is increasing the frequency of disasters in Asia-Pacific

Results show that both population exposure and changes in climate hazards have a statistically significant influence on the frequency of hydrometeorological disasters. For each 1% increase in population density and the annual average precipitation anomaly, the frequency of such events increases by 1.2% and 0.6%, respectively. The authors then applied these results to historical trends in three Asia-Pacific states – Indonesia, the Philippines, and Thailand. As a result, a moderate increase in the precipitation anomaly of 8 millimeters per month (well within the observed changes for Southeast Asia over the past decade) leads to 1 additional hydrometerological disaster every 5-6 years for Indonesia, every 3 years for the Philippines, and every 9 years for Thailand.

In contrast, the models suggest that only changes in precipitation and temperature anomalies affect the frequency of climatological disasters. While a 1 unit increase in the average precipitation anomaly (logically) produces a 3% decrease in the number of droughts and heat waves, an equivalent jump in the annual average temperature anomaly leads to 72% increase.

It is not surprising that population exposure would play a role in determining the frequency of disaster events; if a tropical storm hits an uninhabited island, it doesn’t get recorded as a disaster. But what is surprising, if you take Pielke at his word, is the clear influence of our changing climate. As TAH conclude,

This study finds that anthropogenic climate change is associated with the frequency of intense natural disasters in Asia-Pacific countries. A major implication of this is that, in addition to dealing with exposure and vulnerability, disaster prevention would benefit from addressing climate change through reducing man made greenhouse gases in the atmosphere.

Ultimately, there can be no question that climate change will, is, and has changed the frequency and nature of disasters globally. That’s not to say that exposure and vulnerability are not playing an important role; we know they are. Bending over backwards to inject climate change into every event and subject, as some climate activists are prone to do, is misleading and irresponsible. But so is cherry picking data to downplay its role in shaping the nature and scope of disaster events, when the data tell us otherwise.

*Obviously I am, by no means, an economist or statistician of any repute. That said, here is how TAH define the difference between random and country-fixed effects: “In panel data analysis, while the random effects model assumes that individual (e.g. country) specific factors are uncorrelated with the independent variables, the fixed effects model recognizes that the individual specific factors are correlated with the independent variables.” Accordingly, because there is likely some correlation between the independent variables, it is impossible to assume that they are completely exogenous variables.

Climate hawks should focus more on the persuadable, less on the trolls

tea party global warming sign
tea party global warming sign

One of the more brilliant signs I saw at the fall 2010 Tea Party Rally at the Cuyahoga County Fairgrounds.

For years, climate hawks have devoted considerable time and energy to refuting arguments proffered by those who deny the basic tenets of climate change. This focus on countering climate deniers is evinced by the prevalence of handy lists of counter-arguments, including those from Skeptical Science, Grist, and Scientific American.

But, as I emphasized in a recent post, outright denial of the science is no longer the most potent weapon that “skeptics” have at their disposal. Instead, many of these actors have turned to denier 2.0 arguments, which frequently center on what Young and Coutinho term (paywall) the “acceptance-rejection approach.” This rhetorical acceptance that climate change is occurring opens up new pathways to forestall action on the issue by lulling the average observer into a false sense of security.

And, according to a recent article in the journal Global Environmental Change, this form of climate “skepticism” is exactly where we should be focusing our energies.

In the article, Drs. Stuart Capstick and Nick Pidgeon from the University of Cardiff develop a new taxonomy of climate change skepticism (or, as they British-ly spell it, “scepticism”). Using a mixture of quantitative and qualitative methods, the researchers define two basic types of climate skepticism – epistemic and response skepticism.

Epistemic skeptics turn their attention to the physical and scientific aspects of climate change. They challenge the fundamental nature of climate science, question whether whether it is man-made, and/or emphasize scientific uncertainty to cast doubt upon the topic. Epistemic skeptics seek to “construct climate change as an objectively uncertain phenomenon.”

Response skeptics, in contrast, don’t explicitly reject the science of anthropogenic climate change; in fact, many of them accept it. Despite this acceptance, however, response skeptics:

employ this type of skepticism to justify or explain lack of personal action on climate change, or as a way of distancing themselves from the need or requirement to do so.

Theses skeptics routinely question the effectiveness of potential responses to climate change, doubt that politicians can work together to address the issue, believe that the media exaggerates the risk, and are prone to fatalistic worldviews. Response skeptics are fare more likely to demonstrate a lack of concern over climate change as an issue than epistemic skeptics, perhaps due to the fact that many from the latter group may define themselves in opposition to climate “alarmists” and scientists engaged in the “greatest hoax ever perpetrated on the American people,” as Senator Inhofe has claimed.

As the research from Young and Coutinho demonstrated, smart climate deniers have begun to play more to such response skeptics by utilizing the acceptance-rejection approach. Accordingly, Capstick and Pidgeon argue that climate hawks should focus more directly on this audience as well. As they note:

whilst there are clear arguments that can be made concerning the level of scientific consensus and degree of confidence in an anthropogenic component to climate change, doubts concerning personal and societal responses to climate change are in essence more disputable.

Though it has become increasingly difficult to sway epistemic skeptics (who fall into either the “Doubtful” or “Dismissive” categories in the Yale “Six Americas” construction), response skeptics (the “Concerned,” “Cautious,” and “Disengaged”) are still persuadable. Moreover, these three groups accounted for 55% of Americans as of November 2013, far more than the 27% who identify as “Doubtful” or “Dismissive.”

six americas november 2013

Global Warming’s Six Americas breakdown, as of November 2013.

Most response skeptics view climate change as an issue that will largely affect people who are distant in both space and time. They fail to see it as an immediate, concrete issue that will affect them or the people they know and love. Accordingly, emphasizing the dire impacts that climate change is likely to have or is currently having in Bangladesh, the Philippines, or small Pacific island states will not only fail to motivate them to act, it may actually make them feel less engaged and more hopeless (PDF) about the issue, leading to greater inaction and division.

Accordingly, Capstick and Pidgeon discuss the need to focus on ways to localize climate change, as previous research has emphasized. As Lorenzoni et al noted (PDF) in a 2010 study,

Local environmental issues are not only more visible to the individual, but present more opportunities for effective individual action than climate change.

Rather than devoting so much of our time, resources, and energy to convincing people about whether Antarctic sea ice is waxing or waning, climate hawks should look to connect the issue to local environmental concerns. And one of the most effective ways of achieving this goal is to frame climate as a public health issue. According to research published in 2012, framing climate change as a human health issue “was the most likely [way] to generate feelings of hope.”

Making the link between health and local environmental challenges in a greenhouse world may represent the single most effective strategy for getting people from response skeptic to climate hawk. I have tried to do this by focusing on heat-related mortality in Cleveland, Great Lakes levels, and issues of microplastic pollution and algal blooms in Lake Erie. Fortunately, there now exist a number of excellent tools that allow people to bring climate models down to the local level, from these new interactive Google Maps from Berkeley Earth to “Your Warming World” from New Scientist.

Hearing and reading nonsensical rants from climate deniers gets my blood boiling just as much as any other climate hawk. But, given the amount of research available on this issue, perhaps we should all try to take a step back, realize the deniers are trolling us, and focus on more constructive efforts instead.

Could climate change actually increase winter mortality?

great lakes ice cover
great lakes ice cover

Ice engulfs much of the Great Lakes in this image from February 19 (courtesy of NASA Earth Observatory).

If you already thought that the impacts of climate change were incredibly complicated and, often, downright confusing, I’ve got bad news for you – things just got even more complex.

For years, researchers focusing on climate change concluded that increases in heat-related mortality would, by and large, be accompanied by decreasing cold-related mortality. As winter temperatures warm – which they have at an extremely fast rate – the health risk posed by extreme cold is assumed to decrease in a nearly inverse proportion. In its Fourth Assessment Report (AR4), for instance, the IPCC highlighted research that projected cold weather deaths would decrease by 25.3% in the United Kingdom from the 1990s to the 2050s.

But a new study in Nature Climate Change calls this assumption into question (paywall). As the study’s authors note:

An extensive literature attests to the fact that changes in daily temperature influence health outcomes at the local levels and that [excess winter deaths] are influenced by temperature. However, our data suggest that year-to-year variation in EWDs is no longer explained by the year-to-year variation in winter temperature: winter temperatures now contribute little to the yearly variation in excess winter mortality so that milder winters resulting from climate change are unlikely to offer a winter health dividend.

In order to explore the potential effects of climate change on winter mortality rates, the authors analyzed the factors which contributed the number of excess winter deaths (EWDs) in the UK from 1951-2011. They found that, across this entire span, housing quality, heating costs, the number of cold winter days, and influenza accounted for 77% of variation in annual EWDs.

cold weather death correlations

These charts depict the correlation between excess winter deaths and either the number of cold days (left) or influenza activity in the UK. As the charts suggest, the number of cold days drove excess mortality until around 1976, when the flu became the dominant factor.

But, when they further broke the data down into three 20-year timeframes (1951-1971, 1971-1991, and 1991-2011), they concluded that, while housing quality and the number of cold days were the primary drivers of winter mortality from 1951-1971, this effect disappeared after that point. Instead, flu activity became the only significant driver from 1976-2011. Accordingly, as they argue,

[W]e show unequivocally that the correlation between the number of cold winter days per year and EWDs, which was strong until the mid 1970s, no longer exists.

But, the authors don’t stop here. They continue by explaining that climate records actually suggest that “winter temperature volatility has increased in the UK over the past 20 years,” despite global warming. As I discussed in a previous post on heat-related mortality, the ability of people to acclimate to local weather patterns is a key determinant in temperature-related mortality rates.

As winters continue to warm, people will slowly see their comfort baseline shift; accordingly, when extreme cold snaps, like the Polar Vortex that hit the Eastern US in January, occur,

The nefarious effects on EWDs could be substantial, with especially the vulnerable being caught off-guard by abrupt changes in temperature.

Due to this increasing volatility in winter temperatures, population growth, and the continued graying of populations (people aged 65 and over are far more susceptible to influenza), it’s entirely possible that global warming could actually increase cold weather mortality rates.

A similar study from fall 2012 (paywall), also published in Nature Climate Change, lends further credence to this research. The article examined the influence of climate change on mortality rates from extreme temperatures in Stockholm; the authors compared mortality rates from 1900-1929 to those from 1980-2009.

mean winter temperatures stockholm

This chart depicts the distribution of the 26-day moving average for mean winter temperatures in Stockholm. The black bars, which show data from 1980-2009, suggest that baseline winter temperatures have increased over the last century.

The study, which examined changes in mortality rates from both extreme cold and extreme heat, found increases in both phenomena. The number of extreme cold events increased to 251 in 1980-2009 from 220 during 1900-1929. This change led to an additional 75 deaths.

Significantly, this study echoed two key findings from the UK article. First, cold weather extremes appear to have increased in frequency over the last century, likely as a result of global warming. Secondly, little evidence exists to suggest that people have adapted to the changing climate. According to the authors of the Stockholm article,

The stable and constant mortality impact of cold and heat over the past three decades, independent of the number of extreme events, shows the difficulties in adapting to changing temperatures…Future changes in the frequency and intensity of heat waves might be of a magnitude large enough to overwhelm the ability of individuals and communities to adapt. The expected increase in the number of elderly and other potentially vulnerable groups, in absolute numbers and as a proportion of the population, could make the impact of temperature extremes on human health even more severe.

And just when you thought it couldn’t get any more complicated, it can. Two studies published in 2009, one focusing on Sweden and one focusing on Italy (paywall), established an inverse relationship between weather-related mortality rates in the winter months and mortality rates during the following summer.

In other words, because the vulnerability factors for both cold- and heat-related mortality overlap to such a degree, any decrease in winter mortality due to global warming will likely be offset by a corresponding increase in excess mortality during the summer months. As the authors of the Italian study wrote,

Low-mortality winters may inflate the pool of the elderly susceptible population at risk for dying from high temperature the following summer.

So, to all of the climate deniers or “skeptics” who claim that global warming will somehow be beneficial – I’m looking at you, Congresswoman Blackburn – please take note: climate scientists keep discovering new ways that life is going to get drastically worse, unless we act now to slash carbon emissions and prepare for the warming that’s already locked in.

Extreme heat increases migration from rural areas

hanna lake dried up
hanna lake dried up

A man walks through the desiccated remains of Hanna Lake in Balochistan, which dried up during a decade-long drought in the region (courtesy of Al Jazeera).

The link between extreme weather and migration remains ambiguous, despite the hype surrounding so-called climate refugees, but new research appears to bolster the connection.

A new study published this week in Nature Climate Change (paywall) explores the effects of different disasters on human migration patterns in rural Pakistan. In light of the severe floods that have affected Pakistan in recent years, particularly the historic 2010 floods that affected 20 million people, the authors focused on the impact that extreme rainfall and temperatures have on patterns of migration in the country. The study examines the relationship over a 21-year period (1991-2012), relying on data from three longitudinal surveys.

The authors analyze several key weather variables, including rainfall during the monsoon season, average temperatures during the Rabi (winter wheat) season, flood intensity, and a 12-month moisture index measurement.

The various measures of rainfall have no significant effect on the mobility of men or women, either within or outside of the villages surveyed. In fact, the results suggest that periods of high rainfall actually decrease out-migration within the villages, perhaps due to the fact that farm and non-farm incomes increase significantly during these periods.

These results correspond with previous studies examining the relationship between rainfall and migration. Afifi and Warner examined the influence of 13 different forms of environmental degradation on patterns of international migration. They found that only one of the 13 – flooding – failed to increase international migration flows. In addition, Raleigh, Jordan, and Salehyan (PDF) concluded in 2008 that Bangladeshis affected by flooding migrated just two miles from their homes, on average, and that the vast majority of those displaced returned home shortly after the flood waters receded.

In contrast to flooding, this study did find a robust relationship between extreme heat and out migration flows. The authors note that males in rural Pakistan are 11 times more likely to leave their villages when exposed to extremely high temperatures. These results hold for both land-owners and non-land owners, as well as asset-rich and asset-poor Pakistanis. This outcome likely stems from the fact that extreme heat decreases both farm and non-farm incomes by 36% and 16%, respectively.

The authors also find that both men and women appear far more likely to migrate during periods of both extreme high temperatures and low rainfall. This result indicates that out migration flows are likely to spike during extreme droughts.

While droughts often appear to develop due largely to below-average rainfall, they actually originate through a much more subtle interaction of precipitation and temperature. Less rainfall tends to lower soil moisture levels, which, in turn, increases heat transfer from the soil to the air and elevates surface albedo. These effects drive up temperature further, often creating a positive feedback cycle by which lower rainfall and higher temperatures work together to drive prolonged droughts.

The results of the study have important implications for governments, donor organizations, and NGOs operating in a greenhouse world. As global temperatures continue to rise, we already know that the likelihood of extreme heatwaves will spike dramatically. This outcome will likely increase rural out-migration in the developing world. Moreover, the authors suggest that their work will require donors and aid agencies to reconsider how they respond to and plan for disasters in the future.

Existing flood relief programs may potentially crowd out private coping mechanisms such as migration, particularly for the poor and risk-averse living in flood-prone areas. Our results also show the important role of heat stress — a climate shock which has attracted relatively less relief — in lowering farm and non-farm income and spurring migration. Sustainable development will require policies that enhance adaptation to weather-related risks for farmers and for enterprises tied to the rural economy. Shifting relief towards investments in heat-resistant varieties, producing and disseminating better weather forecasting data and weather insurance, and policies that encourage welfare-enhancing migratory responses might improve individual abilities to adapt to an array of weather-related risks.

Welcome to tropical Cleveland, part 3: Climate change in your backyard

If I’ve told you once, I’ve told you exactly three times that climate change is going to be a bigger deal for Cleveland than people seem to realize.

Well, thanks to the indispensable US Geological Survey, I now have even more data to back me up. With the help of NASA, the USGS has taken the data on temperature and precipitation from the various climate models used by the IPCC and broken it down to the county level. Thanks to this awesome new tool with a terrible name (NEX-DCP30), you can now find out what the mean temperature projections for April are in Charles Mix County in South Dakota from 2025-2049, if that’s your sort of thing.

NEX-DCP30 provides breakdowns for each county in the continental United States for three time periods (2025-2049, 2050-2074, and 2074-2099), compared to the averages from 1980-2004. You can even toggle between RCP (Representative Concentration Pathway; e.g. projected emissions scenario) 4.5, a mid-range scenario, or RCP 8.5, which is a worst-case scenario. Christmas came early for climate nerds like me.

Naturally I decided to check in on the projections for the state of Ohio and for Cuyahoga County. Here’s what I found.

Using the mid-range warming scenario (RCP 4.5), Ohio’s mean temperature will increase by 2.5°C (4.5°F) during the period 2050-2074. This puts it right in the middle of the pack – it’s average temperature change is tied for 16th of the contiguous 48 states, making it higher than 23 states, tied with 8, and lower than 15.

temperature increases mid-range emissions

Average temperature increases for the lower 48 states in 2050-2074, under RCP 4.5 (courtesy of USGS).

In the same scenario, Cuyahoga County warms at by 2.6°C (4.7°F), slightly more than the state as a whole. As you can see below, the state appears split along a diagonal line, that starts in Columbiana County and ends by cutting Hamilton in half. Those counties above the line warm at a higher rate than those below it. Overall, in the RCP 4.5 model, Ohio and Cuyahoga County warm at roughly the same rate as the country as a whole.

temperature increases ohio mid-range scenario

Average temperature increases for the 88 counties in Ohio in 2050-2074, under RCP 4.5 (courtesy of USGS).

These rates change under the RCP 8.5 model. Under this scenario, Ohio warms by an alarming 3.6°C (6.5°F) by 2050-2074, a rate of change above the national average. As the map below suggests, those states that are farthest North and/or are located in the interior of the country will experience the most warming. Ohio experiences warming greater than 26 states, the same as 4 states, and less than 18 states. While Alaska will likely see the greatest warming of all 50 states, Minnesota’s 4.0°C is the most among the lower 48.

temperature increases ohio worst case scenario in 2050-2074

Average temperature increases for Ohio’s counties in 2050-2074, under RCP 8.5 (courtesy of USGS).

Once again, under this scenario, Cuyahoga County outpaces the state as a whole. The county will see temperatures increase by 3.7°C (6.7°F). This number exceeds most of the state, though the greatest warming will take place in Northwest Ohio and in the counties along the Indiana border.

temperature increases worst case scenario 2050-2074

Average temperature increases for the lower 48 states in 2050-2074, under RCP 8.5 (courtesy of USGS).

Alarmingly, if you fast forward to the end of the century (2074-2099) using RCP 8.5, the picture becomes even bleaker. Ohio warms by a terrifying 5.3°C (9.5°F), while Cuyahoga County once again comes in higher at 5.4°C (9.72°F). The average July temperature in Ohio and Cuyahoga County would increase by 6.4°C, reaching 96.08°F and 93.74°F, respectively. Mid- to upper-90s would become the rule, not the exception.

change in monthly temperatures in worst case scenario

Mean monthly temperatures for the State of Ohio (left) and Cuyahoga County (right) in 2075-2099, under RCP 8.5 (courtesy of USGS)

Cleveland annual mean temperature currently stands at roughly 10°C (50°F), while the annual average maximum temperature of 15°C (59°F). Under a high-emissions scenario, Cleveland’s climate could became much closer to that of Oklahoma City than what we are used to experiencing now.

The current rate of climatic change – which The Geological Society now says is unprecedented in the history of the planet (PDF) – is far beyond what we are able to absorb. For a region that is not acclimatized to extreme heat and is highly vulnerable to heat-related mortality, climate change poses an immense public health risk to Northeast Ohio.

So, once again, I caution you that, while things may not become as bad in Cleveland as they may elsewhere, they’re still going to be crappy. To paraphrase The Lorax, unless we all start caring a whole awful lot, nothing’s going to get better. It’s not.

Welcome to tropical Cleveland, part 2: The social & political roots of heat-related mortality

children at water park
children at water park

Children attempt to escape from the heat during July 2012 in Louisville (courtesy of the AP).

In my last post, I explored some recent research that outlined projections of climate change in Cleveland and its potential to drive an increase in heat waves. But climate/weather is just one factor behind heat-related mortality; socioeconomic and political issues are, perhaps, just as, if not more important, determinants.

Just as Cleveland’s historic climate and the associated lack of acclimatization to heat waves will likely leave the region more vulnerable to extreme heat, so too do the region’s various socioeconomic and political pathologies leave it ripe for a public health crisis. (As I write this, it is 97° outside, and I just got an extreme heat advisory from the National Weather Service. On September 10.)

Last month, the Graham Sustainability Institute at the University of Michigan released a new mapping tool that explores the social and economic factors underlying climate change vulnerability in the Great Lakes region. This great new tool allows you to zero in on any county around the Great Lakes to the extent to which its economy, infrastructure, and vulnerable citizens are likely to suffer in a greenhouse world. Unsurprisingly, Cuyahoga County (of which Cleveland is the seat) does not fare particularly well.

The Greater Cleveland area possesses a number of characteristics which, if they do not change, may create a perfect storm for heat-related mortality in a warmer world. I will explore four of these – the built environment, poverty, changing demographics, and racial segregation.

The Built Environment

Northeast Ohio has suffered from decades of sprawl and uncoordinated development patterns, leading to waves of suburbanization followed by exurbanization. In 1948, Cuyahoga County’s population stood at 1,389,532; just 26% of land in the county was developed at the time. Yet, by 2002, although the county’s population had grown by a mere .32% to 1,393,978, sprawl ensured that roughly 95% of the county’s land area had been developed.

cuyahoga county land use in 1948 & 2002

Changes in land use within Cuyahoga County from 1948 (left) to 2002 (right). Red shading indicates developed land, while the beige indicates land that is still undeveloped. The maps clearly demonstrate the waves of suburbanization in the county over the last six decades (courtesy of the Cuyahoga County Planning Commission).

According to data from the Cuyahoga County Planning Commission, 33.6% of the county (and 56.2% of Cleveland) is covered by impervious surfaces. These surfaces (e.g. asphalt) conduct heat, contributing to the urban heat island effect. The EPA notes that urban areas can experience annual mean temperatures of 1.8–5.4°F higher than their surroundings, while this difference can reach an astonishing 22° during the evening.

Cuyahoga County’s sprawl-based development structure presents a number of other challenges, as well. As people have spread out throughout the region, we have become increasingly car-dependent. Car use has come to dominate our policy discussions – transportation commentators like to note Ohio stands for Only Highways In Ohio” – despite its myriad of side effects.

According to the Northeast Ohio Sustainable Communities Consortium (NEOSCC), 86% of commuters in Northeast Ohio report driving alone to work. This car culture contributes to the development of chronic disease, which I discuss below. Additionally, combined with Cleveland’s industrial base and Ohio’s coal dependence, it significantly reduces air quality in the region. In its 2012 “State of the Air” report, the American Lung Association gave Cuyahoga County an F for ozone pollution and a failing grade for annual particle pollution.

Climate change will likely exacerbate this issue further. Last year, largely due to the abnormally warm summer, Northeast Ohio experienced 28 ozone action days – double the number from 2011. We know that high air temperatures increase concentrations of ground-level ozone, which can cause respiratory distress for vulnerable groups. Accordingly, Bell and colleagues have projected that ozone-related deaths will increase 0.11-0.27% in the eastern US by 2050. This issue adds to the risk of heat-related mortality in Greater Cleveland.

Changing Demographics

Like much of the Rust Belt, Cleveland has been shrinking and aging. From its peak in the 1950s, Cleveland’s population has plummeted. The city had 914,808 in 1950; by the 2010 census, the number had fallen to 396,815 – a 56.6% decrease in six decades.

This precipitous decrease in population has left large swaths of Cleveland abandoned and, increasingly hollowed out. Even before the Great Recession and the housing crisis that precipitated it began in 2007-2008, Cleveland had foreclosure rates on par with those in the Great Depression. From 2005-2009, Cuyahoga County average roughly 85,000 foreclosure filings per year, and parts of Cleveland saw nearly half of their homes enter foreclosure. The destruction of neighborhoods undermines social capital, a key coping mechanism for surviving extreme events.

foreclosures in Cuyahoga County 1995-2012

The number of annual foreclosure filings in Cuyahoga County from 1995-2012. As the chart indicates, the number of filings spiked in 2005, two years before the housing crisis began (courtesy of Policy Matters Ohio).

As people have fled the region, particularly young people and people of means, those who remain are increasingly poor and disconnected. Accordingly, the region’s population has aged significantly. Nationally, approximately 13% of the total population is age 65 or older. In Ohio, the number is 14.3%, while it sits at 15.8% in Cuyahoga County.

Older persons are far more vulnerable to the deleterious effects of extreme heat, particularly those suffering from chronic illnesses, like diabetes, and those living alone. Unfortunately, 20.6% of people 65 years and over (PDF) in the county suffer from diabetes; this number climbs to over 35% in Cleveland. Additionally, more than one-third of older persons in the county live alone, adding further to their vulnerability.

Poverty

Given the region’s challenges, it’s perhaps unsurprising that Greater Cleveland struggles with high levels of poverty. Cleveland was named the poorest city in the country in 2004; it has remained at or near the top since that point. Roughly one-third (32.7%) of Cleveland’s residents live below the poverty level. Even worse, more than half of Cleveland’s children are growing up in poverty.

map of poverty rates in Northeast Ohio

Poverty rates and changes in poverty rates within Northeast Ohio from 2005-2009 (courtesy of Rust Wire)

Much of this poverty is concentrated in highly depressed portions of the inner city and, increasingly, in the inner-ring suburbs. It creates regions where public health suffers dramatically; the Plain Dealer recently reported that portions of Cleveland had infant mortality rates higher than most of the developing world, including Bangladesh, Haiti, Pakistan, and Rwanda.

As one would expect, poor people suffer disproportionately in disasters. Roughly 95% of disaster deaths occur in the developing world, and the same principle applies within the developed world (see: Hurricane Katrina).

Racial Segregation

Lastly, Cleveland suffers from high levels of racial segregation. It was the 8th most segregated city in the US in 2011, which likely does not surprise Cleveland natives. For decades, the Cuyahoga River has been seen as something akin to the Berlin Wall – African-Americans stay to the East of the river, while whites and Hispanics live on the West Side.

Recently, the Atlantic Cities posted a map that showed the location of every person in the country (color-coded by race), based on Census data. The close-up shot of Cleveland is below. It quite clearly illustrates the racial divide within the city: African-Americans (green dots) to the east, whites (blue dots) and Hispanics (red dots) to the West. If you look closely, you can even see the small cluster of red dots that makes up Cleveland’s Asia Town.

map of Cleveland showing racial divide

The map, a closeup from the Racial Dot Map, shows the racial divide in the city of Cleveland.

Now, such spatial segregation creates a host of problems, but it also has a connection to heat-related mortality. A study published in Environmental Health Perspectives suggests that persons of color are far more likely to live in areas at risk of suffering extreme heat waves than whites. The study found that a high risk of suffering from the urban heat island effect is more closely correlated with race than class. Accordingly, severe spatial segregation, as we find in Cleveland, will ensure that poor minority neighborhoods have yet another risk factor to account for in a greenhouse world.

Taken together, Cleveland’s combination of heavy, sprawl-based development; an aging, sickly population; high rates of concentrated poverty; and racial segregation may create a perfect storm for heat-related mortality in the coming decades. The fact that sea level rise isn’t going to drown us, and it snows 6 months a year doesn’t mean we can get complacent as the climate changes. Like I said in my last post, just because it won’t suck as much as Bangladesh doesn’t mean it won’t still suck here.

Now that I’ve thoroughly depressed everyone, I will use my next post to look at some of the things Cleveland can do to mitigate the threat of heat-related mortality, including some of the initiatives the region is already undertaking.