Greenhouse gases (GHGs) drive the long-term warming trend. CO2 and methane trap heat in the troposphere, creating a steady upward climb over decades. This is the foundational cause of current climate change.
Sulfate aerosols act as a cooling shield by reflecting solar radiation back into space. Recent regulations, specifically the IMO 2020 mandate reducing sulfur in shipping fuels, slashed these particles. This removes the "mask," allowing more sunlight to reach the ocean surface. This shift likely triggered the sharp acceleration in sea surface temperatures seen since 2020.
Quantifying the exact split remains a challenge for climate scientists. Most models suggest GHGs are the main engine, but aerosol changes explain the suddenness of the recent jump. It is not an either-or scenario. The reduction of sulfur dioxide (SO2) simply stops a cooling process that had been offsetting some GHG warming for years.
The result is a compounded heating effect. We are now feeling the full force of accumulated GHGs without the aerosol buffer. The spike represents a convergence of long-term trapping and the loss of a temporary reflective screen.
