March 16, 2018, by Tim Radford
Heat and moisture together can speed up climate change. Image: By Mary Hollinger, NOAA, via Wikimedia Commons
While more rain normally cools a summer environment, a warmer and wetter world could face quite unfamiliar problems.
LONDON, 16 March, 2018 – Climate change may still cause surprises, if simultaneously it means a warmer and wetter world. More heat and moisture together can unbalance ecosystems.
Scientists have been warning for decades of shifts towards ever greater risks of flooding in some places, more intense and sustained droughts and potentially lethal heatwaves in others.
But new research suggests an unexpected twist: temperate and subtropical zones could become both hotter and wetter during future summers.
And this could create a whole suite of unexpected problems: farmers and city dwellers who have adapted to a pattern of cool wet summers or hot dry summers could face a new range of fungal or pest infections in crops, or pathogens in crowded communities, as insects and microbes seize a new set of opportunities.
“We found that where temperature and precipitation are increasing together, climates are changing faster than the temperature trend alone would suggest”
Canadian scientists report in Nature Communications that they considered what they call “departures from natural variability” that may follow as a consequence of continual rises in global average temperature, driven by ever greater combustion of fossil fuels that emit ever higher ratios of greenhouse gases into the atmosphere.
They studied historical records back to 1901, and climate projections as far as the year 2100. And they see a problem: creatures – people, crops, pathogens and pests – that have adapted to particular regional ecosystems could be jolted out of their comfort zone.
“Some of the disruptions of climate change stem from basic physics and are easily anticipated. Increases in sea level, forest fires, heat waves, and droughts fall into that category.
“But there is a whole other category of unexpected disruptions that stem from upsetting the complex balance of ecosystems,” said Colin Mahony, a forester and doctoral student at the University of British Columbia, who led the research.
A global increase in outbreaks of fungal needle blight in pine plantations could be linked to wetter and warmer conditions. Mosquito-borne pathogens could flourish in hot cities with once rare puddles of standing water.
“The mountain pine beetle epidemic that devastated the pine forests of western North America ten years ago is an example of this. This study digs into global climate model output for clues about what kinds of ecological disruptions might be just over the horizon,” he said.
The research points to the south-eastern US, central Canada, northern Australia, southern Africa, central Asia and the African Sahel as regions that could unexpectedly become warmer and wetter in ways that could disrupt normal patterns.
“We found that where temperature and precipitation are increasing together, climates are changing faster than the temperature trend alone would suggest,” he said.
The research was triggered, he told Climate News Network, by the Network’s report of a 2015 paper that predicted harder rainfall in a warmer world.
“The scientific literature on climate change is so vast that sites like the Climate News Network are an important way to bridge the barriers between researchers in different disciplines like ecology and atmospheric sciences.” – Climate News Network
Tim Radford, a founding editor of Climate News Network, worked for The Guardian for 32 years, for most of that time as science editor. He has been covering climate change since 1988.