A child looks on as water floods through a fence in Wessem, Netherlands, July 16, 2021. REUTERS聽
As scientists gather online to finalize 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 rains 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 U.S. wildfires, along with record drought across the U.S. West and parts of Brazil.
鈥淕lobal warming was well projected, but now you see it with your own eyes,鈥� said Corinne Le Quere, a climate scientist at the University of East Anglia.
A man holding a baby wades through a flooded road following heavy rainfall in Zhengzhou, Henan province, China July 22, 2021. REUTERS
Scientists had long predicted such extremes were likely. But many are surprised by so many happening so fast 鈥� 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.
鈥淚t鈥檚 not so much that climate change itself is proceeding faster than expected 鈥� the warming is right in line with model predictions from decades ago,鈥� said climate scientist Michael Mann of Pennsylvania State University. 鈥淩ather, it鈥檚 the fact that some of the impacts are greater than scientists predicted.鈥�
That suggests that climate modeling may have been underestimating the 鈥渢he potential for the dramatic rise in persistent weather extremes,鈥� 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.
聽A lone boat sits perched on a mound near Hensley Lake as soaring temperatures and drought continue to affect livestock and water supplies in Madera, California, U.S. July 14, 2021. Picture taken with a drone. REUTERS
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鈥檚 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 鈥� 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 鈥渧irtually impossible鈥� without human-caused climate change, scientists from the World Weather Attribution network determined.
But those temperatures 鈥� as much as 4.6 degrees Celsius higher than the previous record in some places 鈥� might also have resulted from new atmospheric changes that are not yet captured by climate models.
鈥淚n the climate models, this does look like a freak event,鈥� said the study鈥檚 co-author Friederike Otto, a climate scientist at the University of Oxford. 鈥淭he climate models do simulate such rare events and don鈥檛 suggest there is something else going on, but of course that could mean the models are just not correct. This is really something we and the scientific community need to look into.鈥�
Residents are silhouetted as they watch the Blue Ridge Fire burning in Yorba Linda, California, U.S. October 26, 2020. REUTERS FILE PHOTO
One area of mystery is how the Earth鈥檚 four main jet streams respond to shifting temperatures. The jet streams are fast-flowing air currents that circle the globe 鈥� near the poles and the tropics 鈥� driving many weather patterns. They are fueled by temperature variations. Some studies have suggested climate change may be slowing down parts of the northern polar jet stream, especially during the summer.
That can cause heat waves by trapping heat under high-pressure air, as seen in Canada in June, or it can stall storms for longer in one place, potentially causing flooding.
A key research challenge is the fact that extreme events are, by definition, rare events so there is less data.
There is 鈥渢antalizing evidence鈥� that the warming has introduced new, unexpected factors that have amplified climate change impacts even further than previously understood, but more research is needed, said Ken Caldeira, an atmospheric scientist at the Carnegie Institution for Science鈥檚 Department of Global Ecology.
鈥淔rom my perspective, the jury is still out on that,鈥� he said. 鈥淲hichever the answer is, the policy prescription is the same. We need to get ourselves off of CO2 emissions as soon as is practical.鈥�
More immediately, though, countries need to realize that extreme events are here to stay, even if the world can rapidly reduce emissions, scientists say.
鈥淭here鈥檚 almost no strategy for adapting to a changing climate,鈥� Le Quere said. 鈥淕overnments are not prepared.鈥�