THE EFFECTS OF GLOBAL WARMING

THE SOURCES OF CARBON DIOXIDE AND METHANA

The causes of the accumulation of heat- trapping gases are complex and less well defined than is commonly recognized. The primary cause is generally accepted to be the Industrial Revolution, with its heavy reliance on fossil fuels as a source of energy.

Deforestation has also, more recently been recognized as a contributing cause , with the potential for adding substantially to the total atmospheric burden of carbon dioxide adnd methane if the remaining forest are destroyed globally. A third source of additional carbon dioxide and methane for the atmosphere is the simulation of respiration including the respiration or organic matter in soils, by the warming itself.
The important of this latter effects is great enough to speed the warming appreciably. Its important is a function of the amount of carbon held in terrestrial ecosystem , especially forest and the effects of the climatic changes on those ecosystem.




EFFECTS ON THE WATER RESOURCES

Cities, hydro-power, irrigated, agriculture, shipping, the various, uses of waterways, fish and fisheries, dilution, and treatment of sewage and the circulation of coastal and oceanic water are all dependent on flows of fresh water from the land. The relationship are at once simple and complex like power production at Bonnevville Dam is obviously dependent on a continued flow in the Colombia River but the various rich fisheries of the Rio Negro and the Amazon are not as obviously dependent on the the massive seasonal pulse of water that flood the varzea forest to a depth of 10 metres for week.
Prediction of surface run-off are vulnerable to the same uncertainties that afflict other aspects of the effects of a continuous warming of the earth. Within narrow limits, perhaps within a warming of 1-2 C for the Earth as a whole , general patterns seem clear. Beyond that range uncertainly dominates. Meanwhile, long-term commitment to expensive projects that require current patterns of precipitation to continue become immediately questionable. Irrigation, or other water supply project, that might normally be expected to have useful lives of several decades to acentury or more, may well fall victim to changing patters of precipitation in years to adecade or so.

EFFECTS ON THE WORLD OCEAN AND COASTAL ZONES.

The scientists conclude, on the of climatic, that in the absence of efforts to cut greenhouse- gas emissions, sea level will rise by between 10 and 30 cm by the year 2030 and by to 100 cm by the end of next century.

aThis rise is the products of thermal expansion of sea water and the melting of glaciers, with the effects of the Greenland and Atlantic ice-sheets expected to be small over the next century. Other scientists take a less sanguine view of the prospects of a minimal contribution from the Antarctic over such a period and the stakes here are high .
The predicted increase in sea- level is 2 to 6 times more rapidly than historical rate over the last century which 10-15 cm rise. The directs effects are recession of shorelines and wetland, increase tidal range and estuarine salt-front intrusion, and an increase in salt water contamination of coastal fresh water acquifers , all have profound mplications for human society, especially in the many coastal areas that are densely populated.