Climate Change
Climate change is a phenomena of changes in climate caused by increased greenhouse gas (GHG) concentration in the atmosphere. There is scientific consensus that the significant increases in GHG concentrations observed in recent history are caused by human action and have lead to an increase in the Earth’s near surface air and ocean temperatures. These temperature changes will become more pronounced overtime unless significant action is taken soon. To avert the worst, experts say that concentrations must get back to 350 parts per million (we are currently at about 387 parts per million) and global emissions must peak by 2015. This is no small task.
Greenhouse gases are not all bad as they are necessary for life on earth to survive. These gases which include water vapour, CO2, methane, ozone and many others, which occur naturally in the atmosphere, trap the sun’s heat causing the earth to warm. The average temperature on earth’s surface is 15°C however without these gases the average temperature on the surface of the earth would be approximately -18°C. The reason that global warming is now a concern is the concentrations of many of these greenhouses gases in the atmosphere are increasing at an alarming rate. This has been shown to cause an increase in the air and ocean temperatures on earth. Over the last century we have seen a temperature rise of approximately 0.74°C. Scientists believe that by the end of this century we could see a global average temperature rise of more than 4°C.
4°C may not seem like a huge change when you think of our day to day temperature fluctuations but this increase is a global average temperature is extremely significant and is likely to cause catastrophic effects throughout the world. For example, the arctic regions are expected to experience the greatest warming leading to the melting of polar ice caps and glaciers. This in turn will lead to a global average rise in sea levels which will affect all coastal areas. It will also lead to a loss of habitat for many species, likely leading to extinctions. A change in the distribution and intensity of extreme weather events, such as hurricanes and severe storms, is also anticipated. Increased water scarcity is likely as fresh water glaciers recede and fail to provide populations with water upon which they have depended for centuries and as some locations experience less precipitation. This will lead to more frequent and severe droughts as well as a change in agricultural yields.
The rate of change is alarming. The six most important greenhouse gases causing global warming are carbon dioxide, nitrous oxide, methane, perfluorocarbons, hydrofluorocarbons, and sulphur hexafluoride. These gases are emitted from many human activities such as use of combustion engines, coal and wood burning, farming, deforestation and land use change. Concentrations of CO2 and methane have increased 36% and 148% respectively since the industrial revolution. Geological data suggests that CO2 levels have not been this high in the last 2 million years.
The fact that global warming is occurring is now widely accepted and the debate now concerns what we do about it.
More information coming soon… |
