TABLE 5-3 Examples of Possible Impacts of Climate Change Due to Changes in Extreme Weather and Climate Events, Based on Projections to the Mid- to Late 21st Century

Phenomenona and Direction of Trend

Likelihood of Future Trends Based on Projections for 21st Century Using SRES Scenarios

Examples of Major Projected Impacts by Sectors

Agriculture, Forestry, and Ecosystems (WGII 4.4, 5.4)

Over most land areas, warmer and fewer cold days and nights, warmer and more frequent hot days and nights

Virtually certainb

Increased yields in colder environments; decreased yields in warmer environments; increased insect outbreaks

Warm spells and heat waves; frequency increases over most land areas

Very likely

Reduced yields in warmer regions due to heat stress; increased danger of wildfire

Heavy precipitation events; frequency increases over most areas

Very likely

Damage to crops; soil erosion, inability to cultivate land due to waterlogging of soils

Area affected by drought increases


Land degradation; lower yields and crop damage and failure; increased livestock deaths; increased risk of wildfire

Intense tropical cyclone activity increases


Damage to crops; windthrow (uprooting) of trees; damage to coral reefs

Increased incidence of extremely high sea level (excludes tsunamisc


Salinization of irrigation water, estuaries, and freshwater systems

aSee WGI Table 3.7 for further details regarding definitions.

bWarming of the most extreme days and nights each year.

cExtreme high sea level depends on average sea level and on regional weather systems. It is defined as the highest 1% of hourly values of observed sea level at a station for a given reference period.

dIn all scenarios, the projected global average sea level at 2100 is higher than it is in the reference period. The effect of changes in regional weather systems on sea level extremes has not been assessed (WGI 10.6).

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