(Source: www.climatechange.gc.ca, Prepared by: The Environmental Education and Information Division Environmental Management Bureau-DENR)
A lot of people think that the atmosphere is just air. But it is more complex than that. It is actually a mixture of gases that surrounds the earth, performing many functions and helping to support life on our planet.
The earth is a huge greenhouse.
As you know, greenhouse uses glass to keep the heat in. And just as the glass in a greenhouse holds the sun’s warmth inside, so the atmosphere traps the sun’s heat near the Earth’s surface. This keeps the Earth warm using what are called “greenhouse gases”. Without these gases, the sun’s heat would escape and the average temperature of the Earth would drop from 15 C – 18 C!
For thousands of years, the Earth’s atmosphere has changed very little. The temperature and the careful balance of greenhouse gases have stayed just right for humans, animals and plants to survive. But today, we are having problems keeping this balance. Why? Because we burn fossil fuels to heat our homes, run our cars, produce electricity, and manufacture all sorts of products, we are adding more greenhouse gases to the atmosphere. These activities are changing the atmosphere at a greater rate than humans have ever experienced.
By increasing the amount of “heat-trapping” gases, we are adding to the warming effect of the natural atmospheric greenhouse. This could warm the planet and have a huge effect on all forms of life. The global sea level could rise due to several factors including melting ice and glaciers. Rising sea levels could damage coastal regions through flooding and erosion. The climate of various regions could change too quickly for many plant and animal species to adjust. Harsh weather conditions, such as heat waves and droughts, could also happen more often and more severely.
There are several greenhouse gases that are contributory to climate change. Some occur naturally while some come from human activity.
Carbon dioxide or CO2 is the most significant greenhouse gas released by human activities, mostly through burning of fossil fuels. It is the main contributor to climate change.
Methane is produced when vegetation is burned, digested or rotted with no oxygen present. Garbage dumps, rice paddies, and grazing cows and other livestock release lots of methane.
Nitrous oxygen can be found naturally in the environment but human activities are increasing the amounts. Nitrous oxide is released when chemical fertilizers and manure are used in agriculture.
Halocarbons are a family of chemicals that include chlorofluorocarbons (which also damage the ozone layer), and other human-made chemicals that contain chlorine and fluorine.
Scientists may not agree exactly how much global warming will occur, or exactly how much the climate will change, but they do agree that global warming has already occurred and there will likely be much more. The 12 warmest years in the past 140 years have all been since 1980, with eight of them since 1990. The Inter-governmental Panel on Climate Change noted that 1990 was the warmest decade and 1998 was the warmest year.
For many in the temperate countries, warmer temperature might not seem like such a bad thing. But in tropical countries, this would be significant. Scientists warn us of the possible consequences like: more severe weather events like droughts, more powerful hurricanes, winter storms and tornadoes; flooding and erosion in the coastal regions; our forests and farms would be at greater risk from pests, diseases and fires; damage to our water sources
Climate change could also affect the health and well-being of people. Many larger cities could experience a significant rise in the number of very hot days. Air pollution problems would increase, placing children, the elderly and people suffering from respiratory problems at greater risk of health effects. Increases in molds and pollens due to warmer temperatures could also cause respiratory problems such as asthma for some people.
As climate change affects the entire globe, developed and developing countries are working together to find solutions to this problem. In June 1992, the United Nations Framework Convention on Climate Change was signed by 154 countries that agreed to stabilize the amount of greenhouse gases in the atmosphere at levels that won’t cause harm. In December 1997, Kyoto, Japan, 161 industrialized nations committed to reduce their greenhouse gas emissions, as part of an international agreement on climate change called the Kyoto Protocol.#