Is human activity causing global warming?
Sixteen billion tons. This is the amount by which the volume of carbon dioxide, said to be one cause of global warming, is increasing every year. Why is it increasing so much? Because we humans have been extracting and burning vast quantities of fossil fuels: oil, coal and natural gas, discharging substances such as carbon dioxide and methane into the air. Gases like carbon dioxide and methane are heat-absorbing, so if they become too concentrated in the atmosphere, the Earth will rapidly heat up. This is the mechanism that many scientists now believe to be causing global warming. In other words, it is highly likely that we humans through our industrial activities are the direct cause of global warming.
Keeling curve (change in CO2 concentration)In 1957 American scientist Charles Keeling started measuring carbon dioxide concentration on the summit of Mauna Loa on the island of Hawaii. Forty years later these measurements are still being performed, and show only too clearly that carbon dioxide concentration is still rising.
Change in average temperature in the Northern Hemisphere in the past 1000 yearsChange in average temperature in the Northern Hemisphere in the past 1000 years This shows a dramatic rise in temperature since the second half of the 20th century. Many scientists believe this to be caused by human industrial activity.
Global warming is linked to climate change
So what will happen as the Earth gets warmer? If the temperature rises 1ºC for example, coral reefs may bleach and die off. At 2ºC warmer, more species may be driven to extinction, and crops will be severely affected. Other potential outcomes are an increase in infectious diseases such as malaria, and more frequent flooding and droughts. Some scientists say that if the Earth's temperature rises by 3ºC, destructive climatic phenomena will occur beyond the ability of mankind to control. The problem with global warming is not simply that the planet will become warmer, but that such rises in temperature will cause greater fluctuation in climatic conditions, changes that the world as it is may be unable to cope with.
The heatwave that swept over Europe in the summer of 2003 is said to have cost 30,000 lives. The typhoons that hit the Japanese archipelago in 2004 were the ten largest since records began, while Hurricane Katrina that swamped the city of New Orleans caused over 15 trillion yen worth of damage. We don't yet know if these natural disasters were caused by global warming, but many people were no doubt shocked by the inability of human societies to cope when confronted by nature's full fury.
Stopping global warming
Global warming is not a problem that any one nation can resolve. An international conference aimed at getting the countries of the world to act in unison to stop global warming was therefore convened in Kyoto in 1997. Under the Kyoto Protocol adopted at this conference, developed nations pledged to reduce their greenhouse gas emissions to 5-6 percent below 1990 levels by 2008 - 2012. If global warming is really to be prevented however, it is said higher targets will have to be met, and now a reduction of 50% by 2050 is being seriously discussed. We stand at a crossroads, and the path we choose will determine our future.