Arctic and sub-Arctic climate system and ecological response to the early 20th century warming

This proposal will examine the climate changes, and the causes and ecological impacts of these changes in the Arctic and sub-Arctic regions in the 20th century with focus on the early warming and cooling event (1920-1960). Time series of various climate parameters (i.e. surface air temperature, ocean temperature and salinity, sea ice extent) and biological data including previously unpublished Russian data will be extended and compiled. New, reconstructed atmospheric forcing data (surface atmospheric temperature and surface atmospheric pressure) and 400000 quality controlled oceanographic stations extending back to the beginning of the 20th century will be available and used in model simulations. The natural variability of climate over several centuries will be studied using the fully coupled Bergen Climate Model (BCM). The BCM simulations in combination with observational data will be used to reconstruct the 20th century climate system including CO2 and primary production, focusing on the Norwegian and Barents seas. Regional ecosystem changes during the warm period of the 1920s ¬ 1940s and the cooling period 1940 ¬ 1960 will be examined using newly available Russian data. These studies will focus on changes in condition, growth, and spawning sites as well as distribution and migration within the Norwegian Sea and the Barents Sea of (1) zooplankton, in particular Calanus finmarchicus, a key prey for young cod and herring; (2) planktivorous fish, including Norwegian Spring-spawning (NSS) herring in both seas, young North-East Arctic (NEA) cod (age 0-3), and Barents Sea capelin; and (3) top predators (harp seal, minke whale, and cod older than 3 years). Model simulations will be performed to study how the zooplankton populations respond to climate fluctuations and to test the linkage between plankton distribution and fluctuations in populations of fish and marine mammals. The proposal will lead to increased knowledge of the mechanisms causing the early 20th century warming as compared to the present warming, and to the response of ecosystems to these warming events. ARCWARM will be a significant contribution to the Management Plan for the Barents Sea ("Helhetlig forvaltningsplan for Barentshavet") and the Norwegian participation in IPY.