Rising sea level:
At present, global sea level is gradually rising, and is projected to rise at an even greater rate in the future. The two main causes are thermal expansion of sea water at higher global temperature, and the additional water from the melting of land-based ice. The UN Intergovernmental Panel on Climate Change (IPCC) warned that thermal expansion will push sea levels up by 18 cm to 59 cm by 2100. It is enough to wipe out several small island nations.
Coastal areas are home to 20% of global population and the number is still rising. Coastal mega cities normally have their supporting infrastructure of port facilities and oil refineries along the coastlines. Sea-level rise will pose a serious threat to their socio-economy. The East coasts of China and India, the Caribbean region and Central America in particular, will be vulnerable.
Changing of precipitation pattern:
Global warming not only results in more frequent and more severe droughts,
it also results in more frequent and more severe floods.
More frequent and more severe droughts:
The higher temperature increases the water vapor retention power in the air, resulting in higher intensity when precipitations do finally occur. It thus increases the frequency and severity of droughts, as have happened in many areas. In the Sahelian region of African, warmer and drier conditions have led to a reduced length of growing season with detrimental effects on crops. .
Studies show that drought has become widespread in Africa, and now more common in the tropics and subtropics.
(Photo: More frequent forest fires
due to intense droughts)
Global warming also results in more frequent and more severe floods.
This may cause large scale population displacement; resulting in socio economic instability and resource insecurity.
Increase in tropical storm and hurricane intensity and duration. Thus storms are projected to be more destructive. Specifically, the number of category 4 and 5 hurricanes have increased by 75% by the year 2007.
Ice melting:
There is a shift of temperatures to higher values. It means the Earth experiences higher maximums and higher minimums. Equivalently there are more extremely warm days and nights; thus more incidences of heat waves.
In the colder latitudes, the equivalent change is the longer frost-free winter season and earlier spring with less number of very cold days and nights.
To name them are glacier-melting and sea-ice shrinking in the Arctic; diminished snow cover in the Northern Hemisphere, decreasing permafrost, frozen lakes and rivers. This would result in increasing number of potentially hazardous glacial lakes and enlarge glacial lakes. Settlements in mountain regions are at enhanced risk of glacier lake outburst floods.
This fresh water river can undermine the stability of the Greenland ice sheet while it makes its way to the sea. Global warming decrease coverage in snow/ice causing stress on fresh water resource.
More precipitation occurs in the form of rain rather than snow, especially in autumn and spring, at the beginning and end of the snow season. It would mean less water resources in summer, when they are most needed.
The warming and melting in the Arctic which is now occurring at an accelerating rate disrupts the region, its ecosystems and its people in many ways. Warming may improve fish stocks (for example cod and herring) but threaten cold water stocks (such as northern shrimp).
Arctic thaw due to global warming is opening up more passages of the Arctic to sea exploration and raising security concerns. Beneath the the frozen region north of the Arctic Circle lies a huge reserve of about 20% of untapped fossil fuels and 33% of untapped natural gas in the world. One of the most significant potential conflicts arises from intensified competition to control these new found Arctic and much needed energy resources, which will continue to create increasing military instability.