West Nile virus may have recently evolved in virulence, as it has not previously killed birds in such numbers. Early warnings of conditions conducive to disease outbreaks can give sufficient time for interventions, such as vaccination of livestock and treatment of mosquito breeding sites. In general, climate constrains the range of infectious diseases, while weather affects the timing and intensity of outbreaks. Uncovering these associations is aided by increased understanding of the Earth's climate system, in particular how land and sea surface temperatures and pressure gradients drive winds and weather. Changes in atmospheric chemistry may have so altered Earth's heat budget that natural climate modes such as ENSO have been modified.
Studies suggest that the ocean is becoming warmer at intermediate depths and around both poles.
If the world's oceans are a long-term heat sink for this century's global warming, then this has profound implications for marine life and terrestrial weather patterns. With disproportionate warming at high latitudes and high elevations, and winter and nighttime, most summit glaciers are in retreat. Seven of Antarctica's ice shelves are in retreat and polar researchers suspect that melting at the base of the Greenland ice sheet may be sculpting fault lines that could diminish its stability. High-resolution ice core records suggest that greater variance from climate norms may indicate greater climate instability, increasing the potential for rapid shifts between stable climate states. The impacts of warming and changing weather patterns on forests, agriculture, marine life, and water may hold the most profound consequences for global health.