1.2 Polar Marine Ecosystems and Climate 



YURIY A. IZRAEL* , ALLA V. TSYBAN' , TERRY E. WHITLEDGE", C. PETER McROY", and 



VIKTOR V. SHIGAEV* 



'USSR State Committee for Hydrometeoroloiiy and Natural Environmental Control, Moscow, USSR 



institute of Global Climate and Ecology, State Committee for Hydrometeorohgy and Academy of 



Sciences, Moscow, USSR 



'Marine Science Institute, University of Texas at Austin, Port Aransas, Texas, USA 



' Institute of Marine Science, University of Alaska, Fairbanks, Alaska. USA 



Introduction 



The warming of the global climate predicted to have 

 occurred by the middle of the next century will have a profound 

 effect on the state of the World Ocean and, therefore, on the 

 entire realm of relations between it and man. The magnitude 

 and thrust of this effect may vary widely from one geographic 

 zone to another. Possible physicochemical, ecological, or 

 socioeconomic consequences will be detemiined by the specific 

 characterofmarine ecosystems functioning, by regional factors, 

 and by the roles played by particular regions in world and 

 national economies. 



According to present predictions, the regions that will be 

 most significantly impacted by global warming are those in 

 higher latitudes (Roots, 1989), where most marked changes in 

 the functioning of marine ecosystems may occur. This fact 

 makes it a matter of urgency that we generalize the findings of 

 ongoing environmental observations with a view to diagnosing 

 the possible effects of global warming as early as is feasible. 

 The assessment of these effects on circumpolar and polar 

 marine ecosystems calls for the mobilization of a broad 

 assortment of scientific methods and approaches. 



To this end, the present paper relies upon predictive 

 assessments made available by global circulation models 

 (GCM's) of the coupled ocean-atmosphere systems when 

 applied to high-latitude regions; upon results obtained by 

 modeling of the oceanic branch of carbon circulation in the 

 marine environment; upon analyses of long-term environmental 

 observations; and finally upon economic projections. 



The concluding section of the paper draws on these methods 

 for an analysis of possible changes in the physicochemical 

 parameters of the Bering Sea ecosystem that are expected to 

 ensue as a result of the presumed warming of the world's 

 climate. 



Effect on Physicochemical Processes 



Effect of Global Warming on the Temperature Regime and 

 Water Circulation in the High-latitude Ocean 



Given all of its diverse ramifications, evaluation of the 

 effect of global warming on the temperature regime and water 

 circulation in the World Ocean is tantamount to the task of 

 predicting possible changes in all fundamental natural processes 

 as a result of new climatic conditions. 



Since changes in the composition of the atmosphere and its 

 circulation affect processes occurring in the ocean and vice 

 versa, dealing with the this problem requires consideration of 

 the operation of the ocean-atmosphere system in conditions of 

 a developing "greenhouse effect." In this connection, one of 

 the most promising methods of investigating the sensitivity of 

 the climatic system to the mix of gases constituting the 

 atmosphere involves performing numerical experiments using 

 models of global circulation in the unitary ocean-atmosphere 

 system (Manabe&Stouffer, 1980;Schlesinger, 1986). Results 

 obtained from such calculations make it possible to predict 

 changes in temperature over the entire air column and in the 

 surface layer of the ocean as a function of a given atmospheric 

 composition and more especially as a function of CO, levels in 

 the atmosphere. 



Of the numerous GCM ' s presently available for describing 

 the behavior of the ocean-atmosphere system, we would 

 suggest that the models that are most carefully developed and 

 take into account the maximum number of factors affecting 

 circulation processes are those developed by Oregon State 

 University (Ghan, 1982; Schlesinger & Mitchell, 1987); 

 Goddard Institute for Space Studies (Hansen et al., 1983, 

 1988); and by the NOAA Fluid Dynamics Geophysical 

 Laboratory at Princeton (Manabe & Wetherald, 1980, 1987). 



Considerable quantitative differences notwithstanding, 

 results obtained from numerical experiments run on the basis 

 of the above models have shown close qualitative agreement of 

 predicted trends in the behavior of the ocean-atmosphere 

 thermal balance in high-latitude regions in the event of a 

 doubling of the CO, content of the atmosphere. A constant 

 problem with such models is the extremely widespread ice 

 cover and the very weak thermohaline circulation in the northern 

 part of the North Atlantic and Arctic Oceans (Bryan et al., 

 1988). According to calculations, the temperature of the lower 

 layers of the atmosphere may be expected to rise by from 1 .3° 

 to 4.2°C, with greater warming occurring over land than over 

 water; the surface waters of the ocean would become 0.2° to 

 2.5°C warmer. Analysis of the seasonal dynamics of the 

 temperature field with all three models indicate that maximum 

 warming would occur in the Arctic and Antarctic regions 

 during the winter period. 



The particular importance of the latter factor for the 

 system of water circulation in the World Ocean should be 

 noted. Thus, significant warming in the polar latitudes would 



