Future increase in compound soil drought-heat extremes exacerbated by vegetation greening

Area of Science:

• Climate Science
• Ecology
• Earth System Science

Background:

• Compound soil drought and heat extremes are increasing due to global warming, with significant socio-ecological impacts.
• Vegetation influences local climate by altering temperature and soil moisture, but its role in future extreme events is uncertain.
• Global vegetation cover is projected to increase, raising questions about its net effect on drought-heat events.

Purpose of the Study:

• To investigate whether projected vegetation greening will alleviate or exacerbate future compound soil drought-heat events.
• To quantify the contribution of vegetation changes to the frequency of these extreme events.

Main Methods:

• Utilized a suite of state-of-the-art climate model simulations.
• Analyzed the biophysical impacts of increased vegetation cover, including changes in albedo and transpiration.
• Assessed the influence of these changes on soil moisture and temperature dynamics.

Main Results:

• Projected vegetation greening is found to increase the frequency of global compound soil drought-heat events.
• This increase is primarily driven by reduced surface albedo and enhanced transpiration due to increased leaf area.
• Greening-induced transpiration can lead to soil moisture deficits, amplifying drought-heat extremes, particularly in northern high latitudes.

Conclusions:

• Vegetation greening is projected to worsen compound soil drought-heat extremes, contrary to potential mitigation expectations.
• The study underscores the critical need to incorporate vegetation biophysical feedbacks into climate change mitigation and adaptation planning.
• Understanding these complex interactions is vital for addressing future compound climate risks effectively.