Extreme heat days where high temperature and humidity become dangerously sweltering will be a lot more common across California and on the Central Coast, according to a report released Tuesday morning by the Union of Concerned Scientists.
By the end of the century, more than one-third of the United States will experience heat conditions once a year, on average, that are so extreme they exceed the current National Weather Service heat index range — if we don’t take action, the scientists said. That’s literally off of the charts.
Historically, fewer than 2,000 people nationwide have experienced such conditions in an average year.
Scientists expect that by the end of the century, as many as 5.1 million Californians could experience “off-the-charts” weather.
The number of days in the state that feel hotter than 100 degrees is expected to increase from an average of nine days a year to an average of 26 days a year by midcentury, or as soon as 2036, the report says.
“To limit future extreme heat, the United States must contribute to global efforts to constrain climate change and invest in solutions that get us to net-zero carbon emissions by midcentury,” says the report, which suggests an economy-wide price on carbon, low-carbon electricity generation and policies to reduce transportation emissions.
The Union of Concerned Scientists is a national nonprofit science advocacy organization. The results of the research were published in a peer-reviewed article in Environmental Research Communications.
Deadly heat on the Central Coast
Most of the Central Coast won’t likely experience super-high heat, but heat waves are expected to become hotter and longer, data show.
Paso Robles, Simi Valley and Thousand Oaks are expected to experience more than 100 days a year of dangerously hot days after 2070 if no action is taken to reduce heat-trapped emissions, the report says.
Each of those cities will also experience weather with an off-the-charts heat index at least once a year by the end of the century if no action is taken to combat climate change.
Those kinds of temperatures have proven to be deadly in the Golden State.
Heat-related deaths and illnesses both increased dramatically in 2006 following a record-breaking heat-wave, according to the California Office of Environmental Health Hazard Assessment. At least 140 people died between July 15 and August 1 and emergency room visits by 16,000, the office says.
Outdoor workers such as construction workers, farmworkers, landscapers, military personnel, police officers, postal workers, road crews and others will face increasingly dangerous conditions, the Union of Concerned Scientists report says.
“With the number and intensity of hot days projected to climb steeply, millions of workers already at elevated risk of heat stress would face greater challenges,” the report says. “Many of these outdoor jobs require being in direct sun, often for extended periods of time.”
That’s an example of why the Union of Concerned Scientists calls its report “Killer Heat in the United States: The Future of Dangerously Hot Days.”
The analysis considered three global climate scenarios with different levels of potential emissions and warming, tracking projections of hot days that will increase with no action on climate change, with slow action on climate change and with rapid action on climate change.
Rising temperatures in Monterey, San Luis Obispo, Santa Barbara and Ventura counties
Some California regions will unsurprisingly experience more extreme heat days than others, the report says.
The Central Valley like Kings County and southernmost California counties will likely see a greater increase in dangerously hot days than say, Alpine or Lassen counties.
The Central Coast will see an increase in dangerously hot days, even if some slow action is taken to reduce heat-trapping emissions, according to the scientists’ research.
Santa Barbara County, for example, could experience two days a year — up from zero — with a heat index above 100 degrees by midcentury (2036 to 2065), data show.
According to the report, here’s how county averages may change by midcentury if we fail to reduce heat-trapped emissions:
- Monterey County could see an increase from one day a year with a heat index above 100 degrees to an average of nine days a year, and two days above 105 degrees.
- San Luis Obispo County could see an increase from one day a year with a heat index above 100 degrees to an average of 11 days a year, and three days above 105 degrees.
- Santa Barbara County could see an increase from no days with a heat index above 100 degrees to an average of four days a year.
- Ventura County could see an increase from no days with a heat index above 100 degrees to an average of five days a year and one day above 105 degrees.