Physical variation in the Barents Sea is likely to affect seabirds both directly and indirectly. Direct influence works primarily through the effects of temperature, wind and precipitation during the breeding season, and through extreme weather outside the breeding season. Temperature and wind affect the birds’ energy budget, and changes in these factors can impose great energy costs on the birds. Air temperature is partly responsible for determining the onset of breeding for several species.
Severe precipitation during the breeding season may lead to increased chick mortality, and thus a reduction in breeding success, especially for species breeding in flat ground. Long-lasting autumn and winter storms may lead a great number of seabirds to stray off course, most of which succumb after a while. Extended periods with extreme weather can also prevent the birds’ foraging activities, resulting in starvation. Seabirds dependent on sea ice may be affected directly by climate changes. Ivory gull Pagophila eburnea, for example, which is sea ice dependent through the entire annual cycle, is expected to change distribution, decrease in abundance or the species may disappear totally from the Barents Sea in the complete absence of sea ice in the summer season. However, the most important climatic effects are by far indirect, when sea temperature, ocean currents and wind directions affect the availability of the seabirds’ prey.