Recent extreme weather occurrences around the world emphasize the need for greater research on how it will play out, especially locally, as experts assemble online to conclude a long-awaited report on global climate research.
In the previous two weeks, the list of extremes has been startling: Unprecedented rainfall in Central China and Europe were followed by devastating flooding. In Canada, temperatures reached 120 degrees Fahrenheit (49 degrees Celsius), while Finland and Ireland experienced tropical heat. The Siberian tundra has been set ablaze. Massive wildfires in the United States, as well as record drought in regions of the United States and Brazil.
“Global warming was predicted, but now you can see it,” said Corinne Le Quere, a climate scientist at the University of East Anglia.
Such extremes had been expected by scientists for a long time. However, many people are startled that so many things are happening so quickly – especially because the global environment is now 1.2 degrees Celsius warmer than it was before the Industrial Revolution. The Paris Climate Agreement calls for limiting global warming to 1.5 degrees Celsius.
“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.
The first installment of the IPCC’s sixth Assessment Report, which will update the established science around greenhouse gas emissions and projections for future warming and its impacts, will be completed in the next two weeks by top scientists with the Intergovernmental Panel on Climate Change (IPCC). The virtual two-week summit also includes government representatives.
The report will build on the latest IPCC report, which was released in 2013, by focusing more on extreme weather and regional effects.
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 advanced to the point where scientists have high confidence in their estimates, there are still unknowns about how climate change will manifest, particularly at the local level. It’s possible that answering these questions will take many more years.
Scientists from the World Weather Attribution network assessed that the June heat wave that killed hundreds in Canada would have been “almost impossible” without human-caused climate change.
However, those temperatures, which were up to 4.6 degrees Celsius higher than the previous record in certain spots, could possibly be the consequence of new air shifts that climate models have yet to account for.
“In the climate models, this does look like a freak event,” said the study’s co-author Friederike Otto, a climate scientist at the University of Oxford. “The climate models do simulate such rare events and don’t 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.”
One area of mystery is how the Earth’s four main jet streams respond to shifting temperatures. The jet streams are fast-flowing air currents that circle the globe — near the poles and the tropics — 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 “tantalizing evidence” 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’s Department of Global Ecology.
“From my perspective, the jury is still out on that,” he said. “Whichever the answer is, the policy prescription is the same. We need to get ourselves off of CO2 emissions as soon as is practical.”
More immediately, though, countries need to realize that extreme events are here to stay, even if the world can rapidly reduce emissions, scientists say.
“There’s almost no strategy for adapting to a changing climate,” Le Quere said. “Governments are not prepared.”
