NEW YORK – For several decades, scientists have gathered evidence that the global warming caused by greenhouse gas emissions is making some types of extreme weather more likely or more intense.
It’s a bigger challenge to connect climate change to a particular weather event at a specific time and place. But the science that enables researchers to do just that has advanced over the past 20 years to the point where individual heat spells, storms, floods, droughts and wildfires are now routinely tied to global warming. Here’s a look at how scientists are joining the dots.
A possible connection is assessed by using computer models to create two virtual worlds. One of them, the so-called counterfactual world, is built by keeping carbon concentrations constant at a level in the past before people began burning fossil fuels. In the other, actual concentrations are plugged in. Then researchers compare the weather event in the two scenarios. This methodology doesn’t determine whether global warming caused the event – but rather whether it made it more likely, more severe or both.
One of these three was the determination in 71 per cent of the more than 500 extreme weather events or trends reviewed by researchers since 2011, according to a count up to August 2022 maintained by CarbonBrief.org, a UK-based non-profit that covers developments in climate science.Heat waves are most directly linked to carbon pollution.