Exploring geochemical cycle dynamics across atmosphere, land, and ocean: a key factor in global environmental change

In the atmosphere, land, and ocean, various geochemical materials, as well as water and energy, are cycled continuously, shaping the climate and environment of the Earth. Carbon dioxide (CO2), a representative greenhouse gas (GHG) released mainly by fossil fuel combustion (FFC) and cement production, is absorbed and sequestered by the land and ocean.

This process moderates the addition of CO2 to the atmosphere, reducing its increase by approximately half of the potential contribution from FFC emissions. Ocean and land ecosystems play an important role in geochemical cycle dynamics, such that the seasonal variation in atmospheric CO2 concentration is dominated by the seasonal variation in forest ecosystem CO2 cycling over high latitude regions in the Northern Hemisphere. Carbon dioxide is also absorbed by ocean surfaces and transported to deep sea depths within sinking particles produced by biogeochemical marine ecosystem processes. In addition to CO2, aerosols generated during wildfires and human activities, and methane (CH4) from paddy fields or wetlands strongly influence changes to the Earth’s climate and environment. A current challenge is to elucidate the dynamics of emission, transport, and accumulation (deposition), as well as the transformation of such geochemically active materials in the atmosphere, land, and ocean, based on field observations, satellite data, and numerical modeling.