Abstract: The bioavailable iron could control the marine productivity by regulating the phytoplankton growth, which influences the carbon exchanges between sea and air, and ultimately regulates the marine ecosystem and global climate change. The terrestrial bioavailable iron is deposited into the cryosphere (including glaciers, ice sheets, permafrost, sea ice and icebergs) by the atmospheric dry and wet depositions, and then stored on the earth surface as solid state. As a result of global warming, the retreat of main components of the cryosphere will release bioavailable iron into the surface system of earth at a global scale. Preliminary studies on the iron biogeochemical cycle have been made in the cryosphere area of the three poles (Antarctica, Arctic and Qinghai-Tibet Plateau) since 2000. Recent studies in the Greenland and Antarctica ice sheets have demonstrated that the bioavailable iron released by ice sheet melting could regulate the marine productivity. We introduce the historical progress of the iron hypothesis, and summarize its research achievements in cryosphere science, and propose research directions that may be broken through in the future.

Key words: three poles, iron hypothesis, cryospheric component, Asian desert, Southern Ocean