Climate change to significantly alter urban climates


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Climate Central and the World Meteorological Organization’s list of top ten fastest warming cities. (Climate Central)
Jenna Ladd| August 28, 2017

Climate Central in partnership with the World Meteorological Organization have created an interactive tool detailing how average summer temperatures in cities around the globe are likely to change by 2100.

The effects of global warming are often compounded in cities by the urban heat island effect, which can make cities up to 14°F hotter than rural areas. On average, land temperatures are expected rise by 8.6°F by 2100, but some cities will warm much more. For example, the analysis found that if emissions are not curbed, Ottawa, Canada is projected to have a climate comparable to Belize City by 2100. In the same scenario, residents of Chicago can expect to have a climate more similar to Juarez, Mexico.

At present, more than 54 percent of the world’s population call cities home. Given that rising global temperatures will felt more acutely in urban areas, it is no surprise that many U.S. mayors have pledged their continued support of the Paris Climate Accord, despite President Trump’s decision to withdraw.

Check out the interactive tool here to see how climate change is projected to change the climate in your city.

On The Radio – Urban areas to suffer economic costs of climate change


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According to a recent study, the world’s larger cities, such as New York City, will be hit hardest by global warming. (Chris Goldberg/flickr)
Jenna Ladd| July 24, 2017

This week’s On The Radio segment describes how climate change will have a disproportionate economic impact on urban areas.

Transcript: A recent study by an international group of economists found that climate change will likely cost cities twice as much as rural areas.

This is the Iowa Environmental Focus.

The study, published in the journal Nature Climate Change, found that the largest quarter of the world’s cities could see more intense temperature spikes by 2050 due to the combined effect of global warming and urban heat island effects. Urban heat islands are formed when naturally cooling surfaces like vegetation and bodies of water are replaced by surfaces that trap heat like concrete and asphalt.

Higher temperatures in cities have negative economic impacts including less productive workers, higher cooling costs for buildings and poorer water and air quality. On average, the global gross domestic product (GDP) is expected to drop by 5.6 percent by 2100 due to climate change. The combined climate change and heat island effect means that the most-impacted cities are expected to lose about 11 percent of their GDP in the same period.

The economists noted that some actions can be taken to mitigate these effects including installing cooling pavements and green roofs and reintroducing vegetation in urban areas.

To read the full story and for more information, visit iowa-environmental-focus-dot-org.

From the UI Center for Global and Regional Environmental Research, I’m Betsy Stone.

Urban heat islands compound economic impact of climate change


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A 2011 heatwave in New York City produces an orange sunset. (Chris Goldberg/flickr)
Jenna Ladd | May 30, 2017

A recent study published in Nature Climate Change revealed that the climate change is likely to be twice as costly in cities than in rural areas.

An international group of economists found that the world’s largest cities could see temperature spikes of 46 degrees Fahrenheit by 2100 if greenhouse gases continue to rise at the current rate. The top 25% largest cities could are likely to see temperatures rise by about 45 degrees Fahrenheit in the same period of time.

The report explains that about 41 degrees Fahrenheit of warming can be explained by global climate change, but the additional four to five degrees of warming will be the result of the urban heat island effect. Urban heat islands are formed when naturally cooling surfaces like vegetation and bodies of water are replaced by surfaces that trap heat like concrete and asphalt.

Based on their analysis of 1,692 cities, the economists expect the combined heating affect to have negative economic consequences for urban areas. Higher temperatures cause workers to be less productive, raise cooling costs for buildings, and deteriorate water and air quality.

On average, the global gross domestic product (GDP) is expected to drop by 5.6 percent by 2100 due to climate change. In contrast, the most-impacted cities are expected to lose 10.9 percent of their GDP. The researchers provided cost-benefit analyses of several cooling measures in the report, including cooling pavements, green roofs and the reintroduction of vegetation in urban areas. For example, transforming 20 percent of a city’s pavement and rooftops to cooling surfaces could save a city up to 12 times what the structures cost to maintain and install, providing a bump to the local GDP.

The researchers conclude that local efforts to mitigate the effects of climate change can play an important role in global efforts. One of the study’s authors, Professor Richard S.J. Tol, Professor of Economics at the University of Sussex, said, “Any hard-won victories over climate change on a global scale could be wiped out by the effects of uncontrolled urban heat islands.” Tol added, “It is clear that we have until now underestimated the dramatic impact that local policies could make in reducing urban warming.”