Jeff Opperman, senior freshwater scientist, has been working to protect rivers and lakes for nearly 15 years. Much of Jeff’s focus is on improving the environmental sustainability of hydropower both by advancing sound policies and by supporting on-the-ground projects. You can follow Jeff on Twitter @jjopperman.
2010 was a tough year for Cleveland, my hometown. Forbes magazine ranked the city as having the most miserable weather and then piled on with a second poll claiming Cleveland was the most miserable city period (albeit in surprisingly hip company, with Miami and Chicago also making the miserable top 10). That latter poll included sports futility and, as if on cue, LeBron James left town in an audaciously miserable spectacle.
To me it all seemed a bit unfortunate and, in the case of Forbes, premised on suspect data. Pondering a rebuttal, I remembered that Sustainlane ranked Cleveland as the 16th most sustainable city among 50 major U.S. cities. Not top 5, but a lot higher than one might expect from a city famous for its river catching fire. The relatively high rank was based on some surprising categories (e.g., #2 for local food and agriculture) and some that were more expected (#1 for sustainability of water supply and #3 for risk of natural disasters). Those latter two categories got me wondering about how Cleveland will fare in the face of climate change; in other words, where the city would rank in terms of future challenges.
I decided to pursue this a bit more. In my spare time. After the kids were in bed.
Cities’ biggest concerns from climate change include problems with water supplies, increased risk of natural disasters (e.g., floods and hurricanes), and the heat itself: in addition to causing general discomfort, heat is already the biggest weather-related source of mortality.
Sustainlane’s rankings adequately covered the first two impacts, and a data set from Scott Sheridan (Geography Department, Kent State University) characterized “oppressive” heat that encompassed both dry and humid weather. (Though local, there’s no “home team” bias in Scott’s data; in fact, the National Wildlife Federation also used his data for a report on climate change and heat risk.)
My analysis did not attempt to predict future conditions. Remember, I was doing this is on my laptop while watching The Daily Show. Instead, I assumed that cities with low risk of heat stress, natural disaster and water supply disruption today would, all things being equal, be relatively less impacted by climate change than other cities under various climate-change scenarios.
Crunching the numbers, lo and behold, Cleveland was number one: the major city least vulnerable to climate-change impacts (in this ranking, #1 means least vulnerable or most resilient and #50 is most vulnerable; see the complete rankings at the bottom of this post along with a fuller explanation of my methods, particularly how I handled challenges with the natural disaster ranking).
So I decided to write an op-ed about the implications of the ranking for Cleveland.
I showed a draft to some of the Conservancy’s media people and they asked, “What’s your take-home message?”
I responded, “Um…buck up Cleveland?”
They then challenged me to explain why my rankings shouldn’t be construed by Clevelanders as a reason to root for climate change.
I was a bit surprised as that was not my intended take-home message. But, isn’t that what Cleveland would think, along with other highly ranked, but economically challenged, cities such as Detroit and Milwaukee? Particularly because the most vulnerable places (by this ranking) included rapidly growing Phoenix, Houston, Las Vegas and Miami—cities that were taking in the population that Cleveland and others was losing (I must admit there was some delicious irony in Cleveland being #1 and Miami, the destination for LeBron’s talents, being dead last. But perhaps only delicious irony for a conservation scientist who works on climate rankings in his spare time).
I suppose this concern hadn’t initially occurred to me because I’m fully convinced, and alarmed, by the forecasted impacts associated with climate change. It’s basically a reckless gamble with the kind of world we’ll leave our kids. Would anyone really be psyched to roll those die?
The op-ed was published in January. For the Cleveland audience, I hopefully communicated the positives of having relatively low vulnerability while still emphasizing the need to minimize climate change. But here I have a bit more space to make these points:
- Though some places may be better positioned to adjust, climate change could inflict immense misery on hundreds of millions of people: flooding, loss of coastlines, crop failures. These potential consequences are so devastating that responsible people everywhere should support efforts to minimize future changes.
- Beyond morality, disruption of global agriculture, economies and ecosystems is in no one’s best interest. The vitality of modern cities is intertwined with that of regions around the world. Having low vulnerability is like having a good immune system—reassuring, yes, but just because you’d get a mild flu compared to neighbors’ more severe cases, you’d still support prevention efforts to protect your community from illness.
- And even though Cleveland and other cities may be relatively less vulnerable, climate change will still have significant impacts on local people and quality of life. For example, warmer summers will promote algal blooms in Lake Erie, hurting the fishery. And although winter temperatures could become milder, Cleveland could actually receive more snow (which I love, but most don’t). The biggest snowfalls are generated by “lake effect” snow which stops as soon as Lake Erie freezes over. Milder temperatures means less ice cover and thus more snow.
So what can we take from these rankings?
The most vulnerable cities include many of the nation’s most rapidly growing regions, such as Houston, Phoenix, and Las Vegas. The fact that the country’s population is shifting toward the most vulnerable areas underscores the importance of limiting climate change as much as possible: the U.S. is exposed to major impacts and that exposure is growing rapidly. Additionally, these cities must continue to improve the sustainability of their water supplies and/or resilience to natural disasters (even though the Second City is ranked fourth here as among the most resilient, check out what Chicago is doing for climate adaptation.)
The flip side of the coin is that several of the least vulnerable cities actually lost population. People are moving away from the cities that may be better equipped to adapt to climate change. Interestingly, the cities with the lowest vulnerability are also well positioned to help halt climate change, and this effort could be key to their economic revitalization.
Many of the low-vulnerability cities are former industrial giants in need of new economic drivers and jobs. Arresting climate change will require developing and manufacturing innovative energy technologies. Policies that promote investment in these new industries would create tens of thousands of “green jobs” that could boost the economies of cities currently losing population. For example, studies by McKinsey and the Political Economy Research Institute forecast that aggressive transition to a “green economy” could produce 500,000 to 2 million Ohio jobs. For cities like Cleveland, despite their relatively low vulnerability, helping to prevent climate change could be the most promising way forward.
(Image: Sunset on Lake Erie and Cleveland. Image Credit: Robert Eardley.)
Rankings for cities’ vulnerability to climate change (low ranking = low vulnerability)
|Rank||City||Average||Water supply sustainability||Heat stress||Natural disaster risk|
Methods for ranking:
To develop a ranking of major US cities’ relative vulnerability to climate change, I focused on three primary impacts from climate change that could potentially negatively impact cities: an increase in the frequency or magnitude of natural disasters, disruptions to water supply, and heat stress. Note that this is a relatively simple ranking intended to promote awareness and generate discussion, and should not be considered a rigorous scientific exercise. However, this assessment did use very relevant and readily accessible data sources.
The ranking did not attempt to forecast vulnerability under future conditions but, instead, relies on the simplifying assumption that current vulnerability is a good predictor of vulnerability under future climate change. For example, should climate change result in an increased frequency of natural disasters, a city at high risk for natural disasters today will be more vulnerable to this future impact than a city that currently has a low risk of natural disasters. Relying on current vulnerability avoids the complexities of choosing between climate-change scenarios and the uncertainties associated with forecasts.
More scientifically rigorous approaches would no doubt produce somewhat different rankings, but it is quite likely that the broad trends would hold. In other words, the most and least vulnerable sets of cities would probably be fairly consistent across different methods. I hope that this simple analysis does inspire more rigorous exploration of this topic.
For vulnerability of water supply to climate change I used Sustainlane’s 2008 rankings of the relative sustainability of cities’ water-supply systems. These rankings were based on several factors that reflect climate-change risk, including drought vulnerability and the extent to which a water supply depends on snowpack, which is generally predicted to decline with climate change.
For vulnerability to natural disasters I used Sustainlane’s 2008 rankings of cities’ vulnerability to disasters such as hurricanes, major flooding, catastrophic hail, tornado super-outbreaks, and earthquakes. With the exception of earthquakes, climate change could increase the frequency or magnitude of all of these disaster events. Sustainlane’s public data do not provide information on cities’ vulnerability to specific types of natural disasters, but clearly several of the lowest ranking cities are primarily vulnerable to earthquakes. For example, San Francisco is ranked 47th out of 50 for natural-disaster risk and earthquakes are that city’s greatest concern. Under “overall ranking” I describe how I dealt with the problem that several cities’ rankings are strongly influenced by a type of disaster that will not be affected by climate change.
The experience of heat in New Orleans clearly differs from that in Phoenix, so I sought a data source that could identify heat stress across various types of climate. Scott Sheridan, a professor in the Department of Geography of Kent State University, developed a method that classifies each day’s weather into one of several categories, two of which are considered “oppressively hot”: moist tropical and dry tropical. Based on Professor Sheridan’s suggestion, I used a sub-set of the moist tropical days that identified the most intense days of that type of weather. For each city, I then found the average number of days per summer in an “oppressively hot” category over the past 25 years. To make the heat data consistent with the Sustainlane approach I then ranked the cities, with the city with the fewest oppressive heat days ranked #1 and the city with the most ranked as #50.
Each city had a ranking, from 1 to 50, for water supply, natural-disaster risk, and heat. I then took the average across these categories to derive the overall ranking.
As described above, the ranking for natural-disaster risk posed a challenge due to earthquakes. To deal with this, I dropped the natural disaster rank from cities with high vulnerability to earthquakes and thus these cities’ overall rankings reflected an average of water-supply sustainability and heat only. The “earthquake” cities included Seattle, San Francisco, Oakland, Long Beach, San Diego, Los Angeles, and San Jose.
Several of the earthquake cities are also at risk for climate-related disasters included in the Sustainlane ranking, such as flooding, and several of the cities are also at high risk for natural disasters not included in Sustainlane’s ranking, such as landslides and debris flows—both of which can be triggered by intense rainfall events and so their risk could increase with climate change—and wildfire. Both Oakland and San Diego have experienced recent major wildfires and the risk of wildfire is highly likely to increase due to climate change.
The lack of a natural-disaster score reduces the confidence in the overall rank for the earthquake cities. For example, Seattle is currently among the top ten for lowest vulnerability but if the city’s risk due to floods and landslides placed it in the lower half of disaster rankings then Seattle would fall out of the top ten. On the other hand, San Francisco has low risk of most natural disasters other than earthquake and a high ranking for climate-change disaster risk (meaning low vulnerability) would place that city in the top ten. For example, if San Francisco were ranked #1 for natural disaster risk (adjusted to not include earthquakes), then the city would rank as the 7th least vulnerable city for climate change. Clearly, a more rigorous assessment of climate-related natural disaster risk would improve this analysis. However, a more refined assessment of risk for the earthquake cities would likely not produce much change in the top and bottom ten of the overall rankings.