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Skip Navigation LinksDNREC : Climate Change : Climate Change Future Impacts 1

 
Climate Change

 

 

Future impacts: Freshwater resources, ecosystems, food production

Freshwater Resources

Global climate change is likely to affect freshwater resources by altering the availability of water. In some areas water levels may increase, while in others it may decrease. According to the IPCC, by mid-century, annual average river runoff and water availability are projected to increase by 10-40% at high latitudes and in some wet tropical areas, and decrease by 10-30% over some dry regions at mid-latitudes and the dry tropics. Water supplies stored in glaciers and snow cover also are projected to decline, further reducing water availability in regions supplied by meltwater from major mountain ranges. Reduced water availability means drought-affected areas will likely increase in extent; heavy precipitation events are likely to increase in frequency, thereby augmenting flood risk.

 

Ecosystems

According to the IPCC, climate change will harm many ecosystems as they face increasing stress “by an unprecedented combination of climate change, associated disturbances (e.g. flooding, drought, wildfires, insects, ocean acidification), and other global change drivers (e.g. land-use change, pollution, over-exploitation of resources).” Approximately 20-30% of plant and animal species assessed so far are likely to be at increased risk of extinction if global average temperature increases exceed 1.5-2.5oC. Also, net carbon uptake by terrestrial ecosystems is likely to peak around mid-century due to increased productivity. As temperatures increase further, however, uptake will weaken or even reverse, thus amplifying climate change.

 

Reduced water availability in the mid-latitudes and dry tropics means drought-affected areas will likely increase in extent worldwide.

Food and Agriculture

According to the IPCC, a warmer climate will result in long-term regional changes to precipitation, length of the growing season, and the growth range of certain crops. While some of these changes may be beneficial in the short-term (like increased global food production), these benefits will eventually diminish as global average temperatures continue to rise.

 

The IPCC predicts that crop productivity will increase slightly at mid- to high latitudes for local mean temperature increase of up to 1-3 oC, depending on the crop. At lower latitudes, though, especially seasonally dry and tropical regions, crop productivity is projected to decrease for even small local temperature increases, thereby increasing the risk of hunger in certain parts of the world. Globally, the potential for food production is projected to increases with increases in local average temperature over a range of 1-3 oC. Above this temperature range, however, global production is projected to decrease. Increases in the frequency of droughts and floods also are projected to affect local crop production negatively.

 

In addition to changes in agricultural production, changes in the distribution and production of particular fish and marine species are expected to continue, with adverse

effects projected for aquaculture and fisheries. As ocean temperatures continue to rise, the range of suitable habitat for many commercially important fish and shellfish species could change. In the U.S. northeast, for example, it is projected that warmer waters will shift cod and lobster distributions northward, further challenging the sustainability of the northeast’s cod fishery (NCIA, 2007).

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