Very high temperatures are set to affect some of the world’s least developed countries before touching the richer nations that are more responsible for climate change.

LONDON, 18 May, 2016 – Some of the world’s poorest people, who have contributed least to climate change, are likely to feel its effects sooner than most of their neighbours.

Research by an international team of scientists has found that many of the planet’s poorest countries are likely to experience daily heat extremes caused by climate change before wealthier nations do.

The research published in Environmental Research Letters shows that the poorest fifth of the global population will be the first to experience more frequent heat extremes, despite together emitting the smallest amounts of CO₂. Countries likely to be worst affected include those in the Horn of Africa and West Africa.

The scientists, who include researchers from the University of East Anglia (UEA), UK, say their study is the first to examine the link between cumulative CO₂ emissions and more frequent hot days.

Dr Manoj Joshi, senior lecturer in climate dynamics at UEA’s School of Environmental Sciences, says: “Most of the poorest people in the world live in tropical latitudes, while most of the world’s wealthiest people live in mid-latitude climates.

Extreme hot days

“We know that low-latitude regions have much less variability in day-to-day temperatures when compared with the mid-latitudes, which means the ‘signal’ of climate change emerges quite quickly, and because of this the frequency of extreme hot days increases rapidly too.”

The study’s lead author, Luke Harrington, a PhD student at the New Zealand Climate Change Research Institute, says: “Previous studies have shown a link between rising global temperatures and increases in the frequency of local heat extremes, while others have shown a clear relationship between the total amount of CO₂ emitted to the atmosphere and rising temperatures.

“This study is the first to use climate models to simulate the end-to-end link between cumulative CO₂ emissions and people experiencing more frequent hot days.”

“Much fewer cumulative emissions are required for the poorest fifth of the global population to experience a robust increase in the number of extreme hot days”

Earlier studies have already shown that more of the world can expect more frequent dangerous heatwaves unless greenhouse gas emissions are cut drastically, and that temperatures in parts of the Middle East and North Africa could rise so far as to make some regions uninhabitable.

Others have warned of the potential damage to harvests because of extremes of heat and of how climate-induced warming could rob from the poor to give to the rich.

In this latest study, the researchers used state-of-the-art climate models to estimate cumulative CO₂ emissions and subsequent changes to extreme local daily temperatures over the 20th and early 21st century.

They defined an extreme hot day as one that occurred 0.1% of the time in model simulations of the pre-industrial climate.

Wealthiest population

Dr Chris Jones, who leads the Terrestrial Carbon Cycle group at the UK Met Office Hadley Centre, says: “Our results show much fewer cumulative emissions are required for the poorest fifth of the global population to experience a robust increase in the number of extreme hot days, when compared with the wealthiest population quintile [fifth].”

“We also know the wealthiest countries will be able to cope with the impacts more easily than poorer nations,” says Dr Erich Fischer, lecturer in the department of environmental systems science at ETH Zurich.

“What our research shows is that heat extremes do not increase evenly everywhere, but are becoming much more frequent more quickly for countries nearer the equator. These happen to be disproportionately poorer nations, including those in the Horn of Africa and West Africa.

“In fact, this pattern was robust even when we considered future projections of population and income.”

Dr Ed Hawkins, a climate scientist at the University of Reading’s National Centre for Atmospheric Science,  says: “Most importantly, this disparity in exposure to more frequent temperature extremes between the global rich and poor only becomes more pronounced as cumulative CO₂ emissions continue to rise.

“This result is yet another piece of evidence demonstrating that limiting cumulative CO₂ emissions over the 21st century will help avoid these impacts.” – Climate News Network