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Think Outside The Box

Renewal of extreme weather shifts focus to climate change as scientists update forecast

Global warming was well projected, but now you see it with your own eyes, says Corinne Le Quere, a climate scientist at the University of East Anglia

As scientists gather online to finalise a long-awaited update on global climate research, recent extreme weather events across the globe highlight the need for more research on how it will play out, especially locally.

The list of extremes in just the last few weeks has been startling: Unprecedented rain followed by deadly flooding in central China and Europe. Temperatures of 120 Fahrenheit (49 Celsius) in Canada, and tropical heat in Finland and Ireland. The Siberian tundra ablaze. Monstrous US wildfires, along with record drought across the US West and parts of Brazil.

“Global warming was well projected, but now you see it with your own eyes,” said Corinne Le Quere, a climate scientist at the University of East Anglia.

Scientists had long predicted such extremes were likely. But many are surprised by so many happening so fast – with the global atmosphere 1.2 degrees Celsius warmer than the preindustrial average. The Paris Agreement on climate change calls for keeping warming to within 1.5 degrees.

“It’s not so much that climate change itself is proceeding faster than expected — the warming is right in line with model predictions from decades ago,” said climate scientist Michael Mann of Pennsylvania State University. “Rather, it’s the fact that some of the impacts are greater than scientists predicted.” That suggests that climate modeling may have been underestimating the “the potential for the dramatic rise in persistent weather extremes,” Mann said.

Over the next two weeks, top scientists with the Intergovernmental Panel on Climate Change (IPCC) will finalize the first installment of its sixth Assessment Report, which will update the established science around greenhouse gas emissions and projections for future warming and its impacts. Government representatives are also taking part in the virtual two-week meeting.

The report will expand on the last such IPCC report in 2013 by focusing more on extreme weather and regional impacts.

When released on Aug. 9, the report will likely serve as a guide for governments in crafting policies around the environment, greenhouse gas emissions, infrastructure and public services. The report’s release was postponed several months due to the coronavirus pandemic.

LINGERING UNKNOWNS

While climate modeling has evolved over decades to where scientists have high confidence in their projections, there are still uncertainties in how climate change will manifest — particularly at a local scale. Answering these questions could take many more years.

The June heat wave that killed hundreds in Canada would have been “virtually impossible” without human-caused climate change, scientists from the World Weather Attribution network determined.

But those temperatures — as much as 4.6 degrees Celsius higher than the previous record in some places — might also have resulted from new atmospheric changes that are not yet captured by climate models.