Rising temperatures and humidity will make the world's tropics increasingly unliveable by pushing more people to the thresholds of their physical tolerance and beyond, a new international study finds.
As of 2000, about 30 per cent of the world's population lived in regions where the climate exceeds deadly threshold levels – based on temperature and relatively humidity levels – for at least 20 days a year, researchers publishing in the Nature Climate Change journal estimate.
Earth's killer heat will get worse
A new global study says deadly heat waves will grow in frequency, intensity and duration, affecting 75 per cent of the world's population if greenhouse emissions are not reduced.
A new global study says deadly heat waves will grow in frequency, intensity and duration, affecting 75 per cent of the world's population if greenhouse emissions are not reduced.
"You are going to have all of those people in the tropics 'cooking' there because they are not going to have any possibility to cope with this [increase in heat and humidity]," said Camilo Mora, the paper's lead author and an associate professor in the Department of Geography at the University of Hawaii, Manoa.
The research examined studies of 783 cases of excessive human deaths from heatwaves between 1980 and 2014. These included the 70,000 deaths from a huge European heatwave in 2003 and more than 10,000 deaths in Russia in 2010.
Professor Mora noted that identifying heatwave mortality rates was difficult because the causes – such as heart attacks and other organ failure – may only surface some time after the event.
"I think there is a huge underestimate of that even in developed countries," such as in Europe, North America and Australia, he said. For developing nations with poorer record keeping, the deaths could be larger still.
Even though tropical areas, including northern Australia, were not projected to warm as much as regions further from the equator, conditions are already near tolerance levels with further warming forecast.
A family cools off in a stream during a heat wave last month in Islamabad, Pakistan. Photo: AP |
Air-conditioning offered some relief but would make people "prisoners of their own homes" – so long as electricity supplies didn't fail, Professor Mora said.
People cool off in a spray from a broken water pipe during a heat wave in Karachi, Pakistan last month. Photo: AP |
"If we're seeing an increase of 100 days a year that might be deadly in places that rely on subsistence agriculture, it's going to be pretty hard for people to be outside working," Dr Lewis said.
The paper provided an interactive graphic that estimated the populations most at risk under different emissions scenarios.
The chart [below] shows the risks under the most ambitious scenario of cuts out to 2100, based on the so-called 2.6 representative concentration pathway (RCP).
At the highest pollution scenario, the RCP8.5 pathway, most of the world's tropics face high risks by the end of the century.(See chart below.)
The heatwave report comes as much of south-western US faces a severe heatwave in coming days, particularly California and Arizona.
IMAGE |
Soils, for instance, are becoming drier in those regions, reducing the moisture available for evaporative cooling, Professor Mora said. The process works much like a human loses heat through sweating.
"Unfortunately the mid-latitudes are drying out so much, the energy is retained there like a rechargeable battery," he said.
Links
- Global risk of deadly heat
- 'Remarkable' high pressure shielding much of Australia from winter's wrath
- 'False sense of security': Scientists warn on pace of global warming
- Amazing drone footage captures never before seen areas of Antarctica
- Back-to-back bleaching covers two-thirds of the Great Barrier Reef
- The three-minute story of 800,000 years of climate change with a sting in the tail
- FactCheck Q&A: was it four degrees hotter 110,000 years ago?
- Climate change doubled the likelihood of the New South Wales heatwave
- Energy solutions but weak on climate – experts react to the Finkel Review
- Independent Review into the Future Security of the National Electricity Market
- Australia's Energy Future
- Full response from the Climate Council for an article on heatwaves and hot days in Australia
- On the Measurement of Heat Waves
No comments :
Post a Comment