Poor countries face 'unfair pattern' of temperature swings

A new study suggests temperature changes made worse by climate change will hit poor countries the hardest.

Study says tropics, where soil moisture helps control fluctuations, particularly at risk

The researchers' map shows the areas where they predict the greatest temperature fluctuations. (Sebastian Bathiany/Wageningen University)

Poor countries are expected to see the greatest swings in temperature as a result of climate change, a new study suggests.

Using models for the last report of the United Nations Intergovernmental Panel on Climate Change, European researchers analyzed 37 climate-model simulations to calculate which regions would likely experience the higher highs and lowest lows until the year 2100.

Their study, published in the journal Sciences Advances, suggests temperature fluctuations amplified by climate change will hit the world's poorest countries hardest.

The European study of 37 climate models revealed that most of the increased temperature fluctuations expected in the coming decades could be in the tropics, threatening food and water supplies. (Jayanta Shaw/Reuters)

The researchers said they discovered an "unfair pattern" as they tried to predict how weather extremes such as heat waves and cold snaps might change in the future. Co-author Tim Lenton, a professor from the University of Exeter, said the pattern emerges more and more clearly as the century progresses.

For every degree of global warming, the study suggests temperature variability will increase by up to 15 per cent in the Amazon and southern Africa, and up to 10 per cent in the Sahel region of western and north-central Africa, as well as India and Southeast Asia.

The exception is Australia — considered a wealthy country — which was included on the list of regions on track to see the greatest fluctuations.

Climate models consistently project increases in temperature variability in tropical countries, the researchers said.

However, developed countries that are typically outside the tropics and in the mid- and higher latitudes of the Northern Hemisphere are expected to not only escape the same increases in variability but should actually see a decrease on average.

"This is mostly because the arctic sea ice gets lost and the Arctic warms up faster than the lower latitudes. This reduces the temperature gradient between the equator and the poles, and it is that temperature gradient that drives weather and its extremes in the mid-latitudes," Lenton said.

He said there is currently some increase in mid-latitude variability because the arctic sea-ice is very variable from year to year as it is shrinking, but in the later part of the century, it is predicted to be gone every summer.

Drying soils

"The countries that have contributed least to climate change, and have the least economic potential to cope with the impacts are facing the largest increases in temperature variability," said lead author Sebastian Bathiany of Wageningen University.

One mechanism that plays a key role in the greater fluctuations is drying soils. The researchers said even a small increase in temperature can dry out a region's soil, curbing the cooling effect of the available moisture.

The buffering against heat is due to evapotranspiration, the process by which water is transferred from the land to the atmosphere by evaporation from the soil and by transpiration from plants.