Seasonal To Interannual Climate Fluctuations And Related Events

The climate of the Earth continually experiences natural fluctuations on seasonal to interannual time scales, as evidenced by the El Niño cycle (see figure). These naturally occurring fluctuations can lead to extreme climate events such as droughts, heat waves, and floods. Extended periods of drought and heat can increase the susceptibility of urban settlements and forest lands to fire, can disrupt food production and water supplies, and in developing regions, can occasionally lead to massive human migrations. Prolonged and excessive periods of precipitation can cause flooding, delay planting, contaminate water resources, and temporarily disrupt patterns of production and trade.

An improved ability to document and then forecast trends and patterns of change in ocean temperature, snow cover, sea ice, and other factors that contribute to changes in the global climate over seasonal to interannual scales could lead to a reduction of adverse impacts from potentially destructive climate events. Early warnings enable communities to develop strategies to better prepare for these events by, for example, implementing revised planting schedules, switching crops, and modifying water management, all of which have been demonstrated to lead to reduced costs and impacts.

Observations and analyses indicate that in some regions of the globe, seasonal to interannual variations of atmospheric conditions can be predicted up to two years in advance. These predictions are based on observed variations in parameters such as sea surface temperature, soil moisture, and snow and sea- ice cover. Significant changes in seasonal to interannual climate may be a key to the detection of longer-term climate changes.

Proposed Future Research on Seasonal and Interannual Climate

Highlights of USGCRP research in FY 1996 include programs to: