AUSTIN (KXAN) — The Fifth National Climate Assessment was released this week and found that Austin can expect 100-degree days to double by 2050, and perhaps even triple by the end of the century if global greenhouse gas emissions go unchecked.
The report is a broad scientific analysis of climate change-related impacts we are already experiencing, what we can expect in the future in our warming world as well as climate mitigation and emissions reductions strategies. The authors — a collaboration between government scientists — found that climate change-related impacts to the U.S. will continue increasing in the future. However, the report also illustrates that the amount of future warming we experience is in our hands.
Summer heat intensifies
Austin marked its second-hottest summer on record in 2023, and the hottest-ever at Austin-Bergstrom International Airport. Camp Mabry tallied 80 days of 100°+ temperatures, and an all-time record of 42 days with temperatures 105° or hotter.
Austin’s long-term average triple-digit heat day count is 15 100° days per year. But as the climate has warmed, Austin now averages 29 100° days per year (between 1991-2020).
The Fifth National Climate Assessment laid out specific impacts projected for the southern Plains and Texas, including different scenarios for the future of 100° heat in Central Texas based on future greenhouse gas emission pathways.
In an “intermediate” emissions scenario, planet-warming gas emissions continue to decrease over the coming decades as countries transition toward clean, renewable energy and forms of transportation and electricity production that pollute less.
Because of the long residence time of planet-warming gases in Earth’s atmosphere, however, even in this scenario, temperatures will warm further for some time.
In 20 years from now, under an intermediate emissions scenario, the report found that Central Texas can expect an increase of 20 to 30 100° days per summer. This would mean Austin would average 54 100° days per year and the hottest summers could have over 100 days of triple-digit heat. Under this scenario, Austin could see an average of 74 100° days per year and a maximum of 130 100° days in the hottest summers by the end of the 21st century.
Here’s where the outlooks get grim.
In a higher-greenhouse gas emissions scenario, where the world continues polluting without drastic cuts, Austin is expected to average 104 100° days per year at the end of the 21st century. Under this scenario, Austin’s hottest summers would bring 100° temperatures nearly half of the entire year.
Socioeconomic inequities in a hotter world
Summer heat does not affect people equally. The report stated that local neighborhood factors like pavement, trees and park space have a big impact on the temperatures people experience every day — and that the heat hits lower-income areas harder.
The plots above from the assessment show land surface temperatures in Atlanta, Houston and Minneapolis neighborhoods. Red highlights the hottest surface temperatures, while blue areas are cooler.
The assessment finds that wealthier neighborhoods are cooler, while lower income areas get hotter. Households in Houston with lower incomes experience land surface temperatures as hot as 112°, while wealthier neighborhoods only get as hot as 107°.
In Minneapolis, lower income parts of the city experience ground temperatures over 100°, while wealthier neighborhoods remain under 90°.
Worst impacts of climate change can still be avoided
How much the U.S. warms up in the future is highly dependent on how rapidly the world reduces emissions. U.S. carbon dioxide emissions peaked in 2007 and have been declining since. By further cleaning up industry, how electricity is produced, and how transport is powered, the worst effects of climate change can be reduced or even avoided.