Global warming is likely to be far greater and faster than previous estimates, says the latest report of the Hadley Centre for Climate Prediction and Research. Merely planting more trees won't help
global warming over the next century could turn out to be much worse than previously estimated, says the latest report of the uk Met Office's Hadley Centre for Climate Prediction and Research. Even if greenhouse gas ( ghg ) emissions are stabilised (which would require an overnight cut of 60-70 per cent in global carbon dioxide emissions), there would be a 1 degree Celsius rise in atmospheric temperature and a seal level rise of about one metre. Based on the findings of the Intergovernmental Panel on Climate Change ( ipcc ), the centre projects that warming over land would be 80 per cent faster than over sea; the highest emission scenario could lead to a 6 degree Celsius rise in temperature over land by 2100, 2 degree Celsius C higher than previous estimates.
The Earth has a natural abalance of releasing the heat that it absorbs from sunlight.But in recent years there has been an enormous increase in ghg s like carbon dioxide, which trap heat, leading to alarming rise in temperatures. Global warming will also cause large-scale increase in rainfall over India's western coastline, says a joint study by Hadley Centre and the Indian Institute of Technology, New Delhi.
Temperatures were lower in 1999 than in 1998 the tropical Pacific changed from the warm El Nio phase to the colder La Nia phase. The past decade has been the warmest period in the 20th century, about 0.6 degree Celsius warmer than the late 19th century. Proxy measurements, involving measuring the change in tree rings and coral, indicate that temperatures over the past decade are higher than in the last 1,000 years. This has been accompanied by an increase in the number of heat waves and a reduction in the frequency of frost in many parts of the world. There are also indications of more days with heavy rainfall, the latest to be a victim of this is Britain, which has experienced the worst flooding in the past 50 years.
A range of potential causes of climate change were assessed by the scientists. They conclude that human activities since 1850 have upset this balance. Global warming due to sunlight is likely to have been offset by volcanic aerosols.
Sea level rise is directly related to climate change. As the temperatures rises, there will be an increase in the frequency of short-lived extreme high water events such as storms. Bigger waves and more storms could destroy coastal defences and increase flooding. These events that will present the greatest threat. According to the scientists, the global mean sea level will rise due to thermal expansion of the ocean, the melting of glaciers and ice sheets of Greenland and Antarctica. While sea level is predicted to rise almost everywhere, there is considerable spatial variation. In some regions the sea level rise may only be close to nil, while others might experience a rise of as much as twice the global average. The predicted patterns show large increases in sea level in parts of the north Pacific and to the west of Greenland.
While ocean and land ecosystems absorb about half the carbon emissions at present, this absorption is sensitive to changes in climate as well as to atmospheric carbon dioxide concentrations. Though a warmer climate would increase photosynthesis, leading to more absorption of carbon dioxide, it isn't that simple. A warmer atmosphere would also increase plant and soil respiration rates, leading to release of more carbon into the atmosphere. In some regions, the changes in climate can also reduce the rate of photosynthesis, thus reducing the ability of vegetation to absorb carbon. But the Hadley Centre claims it is the first to study how global warming might impact upon the carbon cycle itself. Therefore, it questions earlier predictions of climate change - even those that take the carbon cycle into account. The scientists say additional carbon resulting from human activity has raised levels of atmospheric carbon dioxide by 30 per cent over the past 150 years. Climate change will alter the much larger natural carbon cycle.
The World Meteorological Organisation says deaths from heat waves in big cities are expected to double worldwide over the next two decades if nothing is done to curb global warming. In the biggest cities of the us, an average of 1,500 deaths occur due to heat waves each year. This is anticipate to increase to 3,000-4,000 deaths by 2020. Other cities vulnerable to similar changes are Toronto, Shanghai, Athens and Madrid. The problem is expected to be more acute in cities of developing countries.
There may never be complete agreement among scientists on climate change, given the wide field of scientific enquiry. Yet it is likely to become a reality worse than a nightmare if no preventive action is taken. The reports from ipcc and the Hadley Centre reinforce this arguments.
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