What could cause a sudden increase in atmospheric methane if the oceans continue to warm?

• A. Melting of clathrates on the ocean floor
• B. Increased volcanic activity at mid-ocean ridges
• C. Decreased ocean temperatures
• D. Reduced microbial production in sediments

Answer: (A)

Warming oceans can destabilize methane hydrates (clathrates) stored in sediments on the ocean floor. These hydrates are stable only under high pressure and low temperature. When ocean temperatures rise, the stability threshold shifts and the ice-like cages break, releasing methane gas into seawater and potentially into the atmosphere. Since methane is a much more potent greenhouse gas than CO2 on short timescales, a rapid release could accelerate warming, creating a positive feedback loop. This is why melting of clathrates on the ocean floor is the mechanism that could cause a sudden increase in atmospheric methane if the oceans keep warming.

The other scenarios don’t fit as well. Volcanic activity at mid-ocean ridges can emit gases, but it’s not directly linked to ocean warming in a way that would trigger a sudden, large methane spike. Decreasing ocean temperatures would reduce methane release, and reducing microbial production in sediments would curb methane production too, not cause an abrupt rise.