Quantifying Methane Emissions from Aquaculture Ponds in China

Area of Science:

• Environmental Science
• Climate Change Research
• Aquaculture Science

Background:

• Small ponds are recognized as crucial sources of methane (CH4).
• Estimates of CH4 emissions from aquaculture ponds, particularly in China, suffer from significant uncertainty due to limited data.
• China is the world's largest producer of aquaculture products.

Purpose of the Study:

• To conduct a nationwide metadata analysis of CH4 emissions from aquaculture ponds in China.
• To quantify the total CH4 emissions and their growth rate from Chinese aquaculture ponds.
• To compare the CH4 emission intensity of aquaculture with global major protein-producing livestock.

Main Methods:

• A nationwide metadata analysis was performed.
• A database comprising 55 field observations of CH4 fluxes from aquaculture ponds was compiled.
• CH4 emission intensity was calculated per unit of animal protein produced.

Main Results:

• Annual CH4 fluxes from aquaculture ponds in China were found to be substantially higher than those from reservoirs and lakes.
• Total CH4 emissions from Chinese aquaculture ponds were estimated at 1.60 ± 0.62 Tg CH4 yr-1.
• A consistent average growth rate of approximately 0.03 Tg CH4 yr-2 was observed from 2008 to 2019.
• Aquaculture species exhibited a 63% lower CH4 emission intensity compared to global major livestock protein sources.

Conclusions:

• China's aquaculture ponds represent a significant contributor to national CH4 emissions.
• The aquaculture sector presents a lower environmental cost for future animal protein production.
• Further field measurements and multi-scale observations are essential to reduce uncertainties in CH4 emission estimates from aquaculture ponds.