Aerosol climate change effects on land ecosystem services

Area of Science:

• Earth System Science
• Climate Science
• Ecology

Background:

• Anthropogenic aerosols influence climate and land ecosystem services.
• Understanding aerosol impacts is crucial for climate change assessments and policy targets like the Paris Agreement's 1.5°C limit.

Purpose of the Study:

• To assess the impacts of aerosol physical climate change on land ecosystem services, specifically gross primary productivity (GPP) and net primary productivity (NPP).
• To quantify aerosol impacts relative to an aerosol-free world and examine the roles of land and ocean feedbacks.

Main Methods:

• Utilized a coupled global aerosol-carbon-climate model.
• Quantified aerosol impacts on an annual mean basis for the 1996-2005 period.
• Examined separate and combined effects of fast land feedbacks and slow ocean feedbacks.

Main Results:

• Aerosols induce global cooling (-0.8°C) and drying (-0.08 mm/day), with effective radiative forcing of -2.08 W m^-2.
• Without aerosol pollution, the 1.5°C global warming limit would have been exceeded by 1996-2005.
• Regional impacts vary: Amazon NPP increased by 8% due to cooling, while North American Boreal GPP and NPP decreased by 35% due to cooling and drying.

Conclusions:

• Aerosol climate impacts on global average land ecosystem services are small due to opposing effects in tropical and boreal biomes.
• Oceanic slow feedbacks significantly influence impacts in the Amazon and North American Boreal regions.
• An 'eco-climate teleconnection' exists where Northern Hemisphere aerosol pollution cools the tropics, protecting Amazon NPP, while suppressing boreal NPP.