'Heat island' effect could double climate change costs for world's cities

The downtown Dallas, Texas (USA) skyline from a levee along the Trinity River. Facing southeast. Credit: drumguy8800/Wikipedia

Overheated cities face climate change costs at least twice as big as the rest of the world because of the 'urban heat island' effect, new research shows.

The study by an international team of economists of all the world's major cities is the first to quantify the potentially devastating combined impact of global and local climate change on urban economies.

The analysis of 1,692 cities, published today (Monday 29 May 2017) in the journal Nature Climate Change, shows that the total economic costs of climate change for cities this century could be 2.6 times higher when island effects are taken into account than when they are not.

For the worst-off , losses could reach 10.9 per cent of GDP by the end of the century, compared with a global average of 5.6 per cent.

The occurs when natural surfaces, such as vegetation and water, are replaced by heat-trapping concrete and asphalt, and is exacerbated by heat from cars, air conditioners and so on. This effect is expected to add a further two degrees to global warming estimates for the most populated cities by 2050.

Higher temperatures damage the economy in a number of ways - more energy is used for cooling, air is more polluted, water quality decreases and workers are less productive, to name a few.

The authors - from the University of Sussex in the UK, Universidad Nacional Autónoma de México and Vrije University Amsterdam - say their new research is significant because so much emphasis is placed on tackling , while they show that local interventions are as, if not more, important.

Professor Richard S.J. Tol MAE, 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.

"We show that city-level adaptation strategies to limit local warming have important economic net benefits for almost all cities around the world."

Although cities cover only around one per cent of the Earth's surface, they produce about 80 per cent of Gross World Product, consume about 78 per cent of the world's energy and are home to over half of the world's population.

Measures that could limit the high economic and health costs of rising urban temperatures are therefore a major priority for policy makers.

The research team carried out a cost-benefit analysis of different local policies for combating the urban , such as cool pavements - designed to reflect more sunlight and absorb less heat - cool and green roofs and expanding vegetation in cities.

The cheapest measure, according to this modelling, is a moderate-scale installation of cool pavements and roofs. Changing 20 per cent of a city's roofs and half of its pavements to 'cool' forms could save up to 12 times what they cost to install and maintain, and reduce air temperatures by about 0.8 degrees.

Doing this on a larger scale would produce even bigger benefits but the vastly increased costs mean that the cost-benefit ratio is smaller.

The research has important implications for future climate policy decisions - the positive impacts of such local interventions are amplified when global efforts are also having an effect, the study shows. Professor Tol said: "It is clear that we have until now underestimated the dramatic impact that local policies could make in reducing urban warming.

"However, this doesn't have to be an either/or scenario.

"In fact, the largest benefits for reducing the impacts of are attained when both global and local measures are implemented together.

"And even when global efforts fail, we show that local policies can still have a positive impact, making them at least a useful insurance for bad outcomes on the international stage."

Explore further

Not all cool pavements are created equal

More information: A global economic assessment of city policies to reduce climate change impacts, Nature Climate Change (2017). nature.com/articles/doi:10.1038/nclimate3301
Journal information: Nature Climate Change

Citation: 'Heat island' effect could double climate change costs for world's cities (2017, May 29) retrieved 16 October 2019 from https://phys.org/news/2017-05-island-effect-climate-world-cities.html
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May 29, 2017
The fact is, though, as I've warned about repeatedly, solar farms can create massive flows of heat into the environment. It's already been established that solar farms produce "heat island" effects on their surroundings,. Just as , as I've also warned, windmill farms prevent wind acting as effectively as it should. It's reported that air is abnormally warm in the lee of windmill farms because the farms are absorbing some of the energy of the moving air, making it move less and so not distribute temperatures as it should. In fact. "alternative energy" systems cause massive damage to the environment. If it wasn't for "fossil fuels' being used as a supposed threat, "alternative energy" systems would be prohibited! That's why no one want to admit that chemtrails cause climate change, not "fossil fuels"!

May 29, 2017
What you and most deniers miss is that earth can only rejects heat at night by nighttime radiant cooling. Under clear skies with 25% relative humidity a 120oF aluminum disk will drop to freezing in just 6 hours. Winds move heat but only radiation can reject heat off the planet. Your false and misleading statements may be from ignorance, but more likely stems from some irresponsible hidden agenda. Clearing skies from excess CO2 will allow another 2 W m-2, also reduce heat trapping particulates associated with fossil fuel burning, which also adds an uncompensated heat load, unlike renewables. Cloud seeding in the afternoon reducing cloud cover and humidity could provide up to 50 W m-2 improvement in thermal control.

May 29, 2017
Just so much gobbledygook.
Among other things, an aluminum disk will not freeze, as such, it will only cool to ambient temperature. And, depending on the size, it could take longer than six hours.
And, frankly, nothing of what I said has anything to do with this. I pointed out that winds disperse temperature less effectively due to wind farms, and that is verified. In fact, there are no false or misleading statements in what I said. Freerovingbovine cannot provide evidence disproving anything I said. And, as for "particulates" in the air, I pointed out that reflections from solar farms can superheat ordinary dust particles in the air.

May 29, 2017
In fact, there are no false or misleading statements in what I said.

Actually, there are several. You claimed that alternative energy systems cause "massive" damage to the environment, but you gave no evidence. You indicated that they cause some damage, but no evidence that the damage is "massive". You claimed the threat from fossil fuels "supposed". But the evidence refuting that claim is very large (e.g., https://www.acs.o...ing.html ). You claimed that "chemtrails" cause climate change, but you can never give evidence for the existence of "chemtrails" and the massive conspiracy that would be required for such a thing make your claims unbelievable.

To be fair, you are probably correct about the additional heat from solar and wind farms. But you provide no evidence that this additional heat is a factor in anything.


May 29, 2017
To make your claims, you'd have to show that the additional heat was significant. But consider that urban heat islands have been shown to have little effect on global temperature. You'd also have to show that sources of alternative energy produce more heat than fossil fuel. Given the low efficiency for fossil fuel plants, this may be hard to do. If it isn't true, then by your reasoning alternative energy plants are superior.

There's also the claim of the "chemtrails". To claim that they're responsible for climate change, you'd need to take the additional energy added to the climate from "chemtrails" and show that it is larger than the measured increase in energy from greenhouse gases. You need actual numbers. If you don't have them, then you're at the very least misleading people with your claims.

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