Summer in the northern hemisphere has not even officially started, but already the season has brought wildfires, floods, droughts and heatwaves.
ut that kind of extreme weather is now par for the course when it comes to the climate crisis – and the Union of Concerned Scientists (UCS), a non-profit group, has come up with a new name for the hottest months of the year.
“Because of climate change, the months of May through October amount to Danger Season in the US and around the world,” wrote Kristy Dahl, a climate scientist at UCS.
Summer is when many climate-related disasters strike in the US, she explained – from the heatwaves that peak in the hotter months to the Atlantic Hurricane season that runs from June through to the autumn. Hotter temperatures also bring a higher risk of wildfires, and can worsen the impact of drought conditions.
Sometimes, these events can occur at the same time – such as this week, as flooding rocks Yellowstone National Park while extreme heat stifles the midwest and wildfires rage across the southwest.
These threats can also make each other worse, Dr Dahl pointed out. For example, the decades-long “megadrought” in the southwest has made wildfires worse. And the aftermath of last year’s Hurricane Ida in Louisiana could have exacerbated the impact of a heatwave that followed the storm, she noted.
This new “danger season” nomenclature was initially reported by Grist.
In the past few years, scientists have been able to do more and more “attribution studies”, calculating just how much the climate crisis has worsened specific extreme weather events.
For example, scientists determined that last year’s Pacific Northwest heatwave that lead to dozens of deaths would have been “virtually impossible” without human-driven climate change – and that warming made 2017’s Hurricane Harvey, which walloped the Texas coast, three times more likely and 15pc more intense.
Not all extreme weather is necessarily caused by the climate crisis, Dr Dahl noted in her post. But trends have been tilting toward stronger storms, more fires and more heatwaves overall.
According to the most recent report from the Intergovernmental Panel on Climate Change (IPCC), things like heatwaves, droughts and intense storms will get stronger and more common as the planet warms.
Of course, climate impacts are not solely limited to the summer – a study last year found that climatic changes in the Arctic could be leading to more extreme cold events in other parts of the northern hemisphere due to disruptions to the “polar vortex”, for example.
But summertime is when many of these challenges start to pile up on each other.
“The current approach of treating climate extremes as one-off disasters instead of part of a bigger, dangerous trend is leaving communities, policymakers and emergency responders reactive and ill-prepared,” wrote UCS’s Rachel Cleetus in a separate post.
“The physical and mental toll on communities being repeatedly hit, and on first responders, is immense.”