How much do direct livestock emissions actually contribute to global warming?

Area of Science:

• Climate Science
• Agricultural Science
• Environmental Science

Background:

• Traditional estimates of agriculture's contribution to global warming (10-12%) rely on global warming potentials (GWPs), which may not accurately reflect actual warming from methane.
• Methane's atmospheric accumulation differs from carbon dioxide (CO2), necessitating alternative assessment methods.

Purpose of the Study:

• To quantify the actual warming caused by direct livestock emissions (non-CO2 and CO2 from pasture conversion) without using GWPs.
• To project the future contribution of livestock emissions to global warming under different global emission reduction scenarios.

Main Methods:

• Utilized a simple carbon cycle-climate model.
• Incorporated historical and projected livestock emission data.
• Calculated the fraction of actual warming attributable to livestock emissions.

Main Results:

• Direct livestock non-CO2 emissions accounted for 19% of total modeled warming (0.81°C) in 2010.
• CO2 from pasture conversion added at least 0.03°C, bringing livestock's total warming contribution to 23% in 2010.
• Livestock's future warming impact is highly dependent on global emission reduction efforts in other sectors.

Conclusions:

• Livestock emissions are a significant driver of current global warming.
• Reducing livestock emissions is vital for achieving Paris Agreement targets, particularly the 1.5°C goal.
• Mitigation strategies for livestock emissions can substantially increase the global carbon budget for climate targets.