Robust increases in severe thunderstorm environments in response to greenhouse forcing

Area of Science:

• Atmospheric science
• Climate modeling
• Extreme weather events

Background:

• Severe thunderstorms cause significant damage in the US.
• The impact of greenhouse gas emissions on severe thunderstorms is uncertain.
• Climate models are crucial for predicting future climate impacts.

Purpose of the Study:

• To assess the response of severe thunderstorm environments to elevated greenhouse gas forcing.
• To investigate projected changes in atmospheric conditions conducive to severe thunderstorms.
• To evaluate the influence of global warming on the frequency and intensity of severe thunderstorms.

Main Methods:

• Analysis of the Coupled Model Intercomparison Project, Phase 5 (CMIP5) global climate model ensemble.
• Examination of changes in convective available potential energy (CAPE) and wind shear.
• Assessment of the emergence of severe thunderstorm environments under different global warming levels.

Main Results:

• CMIP5 ensemble projects robust increases in severe thunderstorm environments over the eastern US with global warming.
• Increases in conducive environments emerge before 2 °C of warming for spring and autumn.
• Higher CAPE and strong low-level wind shear days increase, indicating greater tornado potential.
• Decreases in wind shear are concentrated on low CAPE days, not reducing overall severe environments.
• Shift towards high CAPE is linked to low convective inhibition, increasing severe event likelihood.

Conclusions:

• Projected increases in severe thunderstorm environments are robust across models and emerge with moderate warming.
• Physical changes indicate a higher likelihood of severe thunderstorms due to continued greenhouse gas forcing.
• Increased severe thunderstorm occurrence will likely elevate the risk of thunderstorm-related damage.