The most general definition of climate change is a change in the statistical properties of the climate system when considered over periods of decades or longer, regardless of cause. The term is sometimes used to refer specifically to climate change caused by human activity; for example, the United Nations Framework Convention on Climate Change in Article 1.2 defines climate change as "a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods." In the latter sense climate change is synonymous with global warming. Global warming is defined as the increase of the average temperature on Earth. As the Earth is getting hotter, disasters like hurricanes, droughts and floods are more frequent. According to scientists the average temperature of the air near the Earth’s surface has increased about 0.6 - 0.7 C° over the last century and that the level of CO2 or the greenhouse gas carbon dioxide has increased in the atmosphere by 25-30% from preindustrial values. Although it does not seem significant, some scientists say it is responsible for the noticeable increase in storms, floods and raging forest fires in the last ten years.
With many proponents and skeptics the dispute regarding the nature, causes, and consequences of global warming remains controversial. Currently there are two competing theories for the recent global warming trend:
- The first is based on a theory which followed the warming trend that occurred between 1975 and 1998. The first theory, which is the generally accepted one, is that the release of greenhouse gases from the burning of fossil fuels and from land use is responsible for the recent temperature increase.
- The second theory is based on highly correlated data going back thousands of years, that the sun's magnetic field and the solar wind modulate the amount of high energy cosmic radiation that the earth receives. This in turn affects low altitude cloud cover and how much water vapour there is in the atmosphere and thus regulates the climate.
This controversy poses world leaders with a dilemma. Climate change will drastically change the political, economic, and cultural landscape. According to the first theory the solution requires a restructuring of our entire economic system to eliminate carbon dioxide. If the second theory is correct, reducing the concentration of carbon dioxide will have very little impact.
The fact remains that we have to live with the practical consequences of global warming. One of the major anticipated consequences is rising sea levels. As the earth warms, glaciers and ice sheets melt, releasing water that had been locked up into the oceans. In addition as the water warms it expands which adds to the problem. Most of the world’s largest cities lie at or very close to sea level. The Greenland ice sheet contains enough freshwater to globally raise sea levels by 5 meters and is currently melting at an alarmingly rapid rate.
This graphic explains the causes of sea level change according to the Intergovernmental Panel on Climate Change (IPCC). It explains the IPCC's A1 scenario family, which consists of three scenarios on future use of fossil energy sources, including scenario A1F1, which involves the use of fossil-intensive energy sources. This resource also includes the graphic 'Components of Mean Sea Level Rise for the Scenario A1F1' which shows the projected sea level rise in metres by 2050 and by 2100 for Greenland, glaciers, expansion, the Antarctic, and the total sea level rise.
It seems likely that in the next 30 to 50 years, millions of people will become environmental refugees. Most likely the first countries to disappear due to global warming are Tuvalu and Kiribati, which lie at or barely above sea level.
But it is not all doom and gloom. Climate change can have a few positive effects too. It can “solve” territorial disputes as is demonstrated by the recent disappearance of a small uninhabited island in the Bay of Bengal at the mouth of the Hariabhanga river. The island, about 2 metres above sea level, was first detected on a remote sensing image taken by an American satellite in 1974. It probably emerged in the aftermath of the Bhola cyclone in 1970. Further remote sensing surveys showed that the island originally had an area of about 2,500 m2, which over the years gradually expanded to an area of about 10,000 m2. The island was named South Talpatti by Bangladesh and New Moore Island or Purbasha by India. Both Bangladesh and India claimed the island because there was speculation that there might be oil or natural gas reserves beneath it. In 1981 India sent a few gunboats and planted an Indian flag on the island, which soon afterwards was removed by the Bangladeshis. Since the 1990s the island began to erode gradually and was finally transformed into a shallow spot in the Bay of Bengal by the rising sea levels. The prediction is that a further rise of the sea level by approximately 1 metre will make Bangladesh 17% smaller by 2050 and displace about 20 million people.
New Moore Island in the Sunderbans has been completely submerged
Although the island has now disappeared the question of the delimitation of the maritime borders still remains. India is favouring a middle line solution.
Mary-Lou Considine: Sea-level Rise: Kiribati and Tuvalu view from Ground Zero. ECOS Magazine, 148 (2009, April/May), p.10-13.
Denis Culley: Global warming, sea level rise and tort. In: Ocean and Coastal Law Journal, Vol. 8 (2002), pp.91-125
Kiribati Sea Level Rise : Kiribati, an island-nation in the Central Pacific, is doomed to disappear because of sea level rise caused by global warming. Footage taken during a king tide shows waves crashing over the roads, domestic gardens and farmed animals.
Engr Khondkar A Saleque: Martime Boundary Disputes – Bay of Bengal.
Tuvalu threatened to disappear due to global warming and sea-level rise (BBC News - 22 Jan 2008)