CLIMATE AND CLIMATE CHANGE

CLIMATE AND CLIMATE CHANGE

Climate is simply the weather that is dominant or normal in a particular region; the term climate includes temperature, rainfall and wind patterns. Geography, global air and sea currents, tree cover, global temperatures and other factors influence the climate of an area, which causes the local weather.

(A schematic illustration of the climate system)

The earth's climate has always varied naturally, in the past cooler cycles due to variations in the earths orbit round the sun, sunspot activity or volcanic eruptions, have altered the climate. However, large changes have been very gradual over huge time  periods;  nevertheless they are still  blamed for the extinction of the dinosaurs.

What is new is that humans are now, due to pollution from industrial processes and wasteful lifestyles  directly  influencing the climate of the earth. Human influence is now believed to be changing the climate  much faster than occurring in the past under natural processes.

Scientific evidence that humans were changing the climate first emerged in the international public arena in 1979 at the First World Climate Conference. At this time when the first effects of human induced  climate change were discovered, the changes were so small it didn't seem like a big issue. But by 1988 when the Intergovernmental Panel on Climate Change (IPCC) was formed the dangerous consequences of climate change became clearer. 

FUTURE CLIMATE CHANGE PREDICTIONS

Temperature

Latest IPCC predictions from their Fourth Assessment Report reveal that for the next twenty years warming at a rate of 0.2˚ C per decade is expected. While by the year 2100 best estimates predict between a 1.8˚ C and 4 ˚C rise in average global temperature, although it could possibly be as high as 6.4˚ C.

Agriculture

Food production will be particularly sensitive to climate change, because crop yields depend directly on climatic conditions (temperature and rainfall patterns). In tropical regions, even small amounts of warming will lead to declines in the amount of crops harvested. In cold areas, crop harvests may increase at first for moderate increases in temperature but then fall. Higher temperatures will lead to large declines in cereal (e.g. rice, wheat) production around the world.

Drought

Water is an essential resource for all life and a requirement for good health and sanitation. It is a critical input for industry and essential for sustainable growth and poverty reduction. Climate change will alter patterns of water availability by intensifying the water cycle. Droughts and floods will become more severe in many areas. There will be more rain at high latitudes, and less rain in the dry subtropics. Hotter land surface temperatures cause more powerful evaporation and hence more intense rainfall, with increased risk of flash flooding. Differences in water availability between regions will become increasingly pronounced and areas that are already relatively dry are likely to become drier.

Heavy Rainfall

Warming may induce sudden shifts in regional weather patterns such as the monsoon rains in South Asia or the El Niño phenomenon - changes that would have severe consequences for water availability and flooding in tropical regions and threaten the livelihoods of millions of people.

Winds

According to the IPCC future tropical cyclones will become stronger, with faster wind speeds. Also known as hurricanes and typhoons, these massive storm systems combine the effects of heavy rainfall,high winds, and storm surge and sea-level rise. Warmer ocean temperatures will increase the frequency and intensity of such storms. Storm routes are also predicted to move pole ward, which will mean changes in wind, precipitation and temperature patterns.

Glacier / snow melt

Snow cover and glaciers will continue to melt more rapidly, reducing in size. Widespread increases in thaw depth are projected over most permafrost (frozen ground) regions. Mountain regions are already under considerable stress from human activities. The declines in mountain glaciers, permafrost, and snow cover will reduce soil stability and damage hydro-logical (river) systems.

Sea Level Rise

Global warming has raised and will continue to raise sea level due to thermal expansion (warmer water takes up more space) of the oceans and the melting of ice stored in glaciers or ice sheets (floating sea ice being lighter than water sits on the sea surface and when it melts it increases the seas volume causing sea level rise). The consequences of sea level rise include more frequent and 

more devastating flooding and loss of coastal land. For in coastal situations, a 50cm rise normally results in a 50m loss of land.

Biodiversity

Biological diversity the source of enormous environmental, economic, and cultural value will be threatened by climate change. The composition and geographic distribution of ecosystems will change as individual species respond to new conditions created by climate change. At the same time, habitats will degrade and fragment in response to other human pressures. Species that cannot adapt quickly enough will become extinct an irreversible loss.

Economic cost

The monetary cost of climate change is expected to be very high; this means it will reduce economic output measured in Gross Domestic Product (GDP). With 2˚ C to 3˚ C warming which is expected by 2100 there could be a loss of global GDP as high as 3%, but with 5-6 ˚ C of global warming into the next century global GDP could be reduced by 5-10%.

Health & disease

Climate change is expected to have wide-ranging consequences for human health. For the health of communities depends on sufficient food, safe drinking water, comfortable homes, good social conditions, and a suitable environmental and social setting for controlling infectious diseases. All of these factors can be affected by climate change.