#DangerSeason Unleashed: Killer Heat Threatens 75 Million in US South, No End in Sight Through Next Week
Today climate change has broken a new Danger Season record: 76 million people in the US—or 23% of the total population—are currently under extreme weather alerts including heat, flooding, storms, or wildfire weather conditions. Almost all of those alerts—impacting 75 million—are for extreme heat covering most of Texas, Oklahoma, Missouri and Alabama, and all of Arkansas, Mississippi, and Louisiana. Several counties in California, Colorado, Florida, New Mexico, Illinois, Indiana, Kentucky, and Tennessee are also under extreme heat alerts. And notably, our tally does not include the millions of additional people across the Northeast and the Midwest are experiencing poor air quality due to wildfire smoke from Canada.
The cumulative number of people that have faced at least one alert since the start of Danger Season on May 1 today is 61%, up from 52% percent barely two weeks ago. And the footprint of climate change is all over this heat: as of June 28, 22% of heat alerts since the start of Danger Season would not have been possible without climate change, according to Climate Central’s Climate Shift Index (CSI).
Today’s CSI shows that high temperatures are between one and three times more likely due to climate change, with stronger climate attribution (that is, higher CSI values) along the Gulf Coast.
As climate change shifts global air and ocean temperatures get warmer, the likelihood of experiencing extreme heat events like this one increase. By midcentury, with no action to address global heat-trapping emissions, much of the region experiencing triple-digit temperature this week would see a tripling of the frequency of such heat.
The extreme heat that has affected the Gulf Coast and Southeast this week and last is attributed to what’s known as a “heat dome.” This phenomenon occurs when hot air gets trapped in an area by a zone of high pressure in the atmosphere. The high pressure system pushes air down toward Earth’s surface, which causes the air to heat up even more. In the case of the current heat dome, anomalously warm air coming from the Gulf of Mexico and direct heating from the sun are also contributing too.
As climate change shifts global air and ocean temperatures warmer, the likelihood of experiencing extreme heat events like this one increases. By midcentury, with no action to address global heat-trapping emissions, much of the region experiencing triple-digit temperatures this week would see a tripling of the frequency of such heat.
Today’s air quality alerts across the Midwest are also part of a troubling trend. While we usually associate the impacts of wildfires with states in the western US, where wildfires have grown increasingly large and severe in recent decades, data show that over the last 15 years or so, the Midwest and Eastern US have experienced increases in the frequency of “smoke days” like those their experiencing today.
An onslaught of seemingly unending extreme weather events threatens the US population, and there are still four months of Danger Season to go. We need action now to reduce climate change-causing emissions and also adaptation policies to protect people from the impacts we cannot avoid.
Danger Season is here and clearly demonstrating we are heading into uncharted climate disaster territory.
Originally published in Union of Concerned Scientists.
