Greenhouse Gases

PI: Eiji Watanabe (Japan Agency for Marine-Earth Science and Technology)

There are many sources and sinks of greenhouse gases (GHG) in the Arctic region. But response of these sources to climate change is still uncertain. The net emission of GHG from the land and sea surface to the atmosphere will further increase (including a decrease in absorption) due to global warming. The accurate detection of this change using strategic observations and numerical simulations is highly important for reducing the uncertainty of future climate predictions and for policy decisions regarding GHG emission regulations. The GHG program aims to comprehensively verify the impact of climate change on GHG emission and absorption through carbon and nitrogen cycles of frozen soil and the ocean surface layer. To serve as the basis for GHG emission policy and fishery resource management, our goal is generation of valuable knowledge such as reliability of the estimated GHG exchange, factors for corresponding environmental changes, and spatiotemporal hot spots that should be particularly monitored.

Sub-Theme 1 aims to precisely observe and analyze the concentrations and isotope ratios of major atmospheric GHG (CO₂, CH₄, and N₂O) and their related components (oxygen, etc.). The ground stations, aircraft, and ice core drilling are utilized to understand the spatiotemporal variations of atmospheric GHG in the Arctic. The key spots of GHG source and sink will be identified by incorporating newly acquired observation data into an atmospheric chemical transport model.

Sub-Theme 2 aims to clarify the impact of global warming and the associated environmental changes on terrestrial GHG dynamics in the Arctic. Continuous observations in Alaska boreal forests and glacier terminus will deepen our understanding of the emission and absorption processes of GHG (mainly CO₂ and CH₄). Satellite products, reanalysis data, and numerical simulations are also combined to obtain information covering wide areas on the scale of Alaska and eastern Siberia.

Sub-Theme 3 aims to quantify the effects of freshwater and biogeochemical inflow from sea ice melting, river water discharge, and coastal erosion into the ocean interior on the exchange of GHG (mainly CO₂) through the atmosphere, sea ice, and ocean. We will further investigate carbonate components (pH, dissolved inorganic carbon, alkalinity, calcium carbonate saturation rate, etc.) in the ocean surface layer. Marine carbon cycles consisting of biological production and vertical transport of organic matters to the deep ocean are also examined over the wide areas including the central Arctic.

Our program plans to detect the changes and uncertainties of GHG concentration and transport regulated by wild fires and sea ice loss in collaboration with the Aerosol, Climate Disaster, and Biodiversity programs. We will utilize research infrastructure such as ground observation bases in Ny-Ålesund and Fairbanks, as well as the research vessels Mirai and Mirai II.