City of Houston Releases Climate Impact Assessment Projecting Future Houston Climate Trends

The City of Houston’s Mayor’s Office released the Houston Climate Impact Assessment, to better illustrate how climate change will impact Houston’s future based on lower and higher scenarios of future climate change. The assessment, conducted by Anne Stoner and Katharine Hayhoe of ATMOS Research & Consulting, studied 25 separate future climate indicators, including the number of days with temperatures above 100 degrees, the number of nights above 80 degrees, total annual precipitation, days with precipitation above 4 inches, and the annual number of dry days.

“As we keep our eyes on the gulf during another record-breaking hurricane season, we know the damage that a changing climate can cause,” said Mayor Sylvester Turner. “We need to be on offense, which includes being informed and taking immediate action to reduce emissions to ensure that Houston is prepared and resilient for generations to come.”

The assessment used historical and current climate data from 11 region- al weather stations from Columbus to Beaumont to Galveston using historical data from 1950 until now to project future climate data trends to 2100. Houston’s Climate Impact Assessment was made possible through generous funding from C40 Cities, a network for megacities committed to addressing climate change.

“Climate change is a global challenge,” said Katharine Hayhoe, who previously served as a lead author for several chapters of the U.S. Global Change Research Program’s Fourth National Climate Assessment released in 2017 and 2018. “But it impacts us locally, affecting our health and our safety, as well as the economy and the city’s infrastructure and public services.”

Houston’s climate trends and projections related to precipitation include:

• Little change in total annual precipitation but decrease in summer precipitation and increase in fall precipitation

• Greater variability in day-to-day precipitation

Houston’s climate trends and projections related to heat include:

• Increase in the number of hot days per year with temperature above 100 degrees and warm nights with temperature above 80 degrees

• Longer heatwaves, lengthening of summer

• Increases in the temperature of the hottest days experienced each year

“Houstonians know that our summers are already long and hot, said Marissa Aho, Chief Resilience Offi- cer for the City of Houston. “But this assessment shows that summer will be exponentially hotter by 2100 with 30- 90 nights with temperatures above 80 degrees compared with approximately 3 nights now.”

Each of the 25 indicators was evaluated under a higher scenario where emissions continue to rise (RCP8.5) and a lower scenario where emissions are significantly reduced (RCP4.5).