The industrial revolution and increased use of fossil fuels like coal and oil that emit greenhouses gases, have increased in the earth’s mean surface temperature, During the twentieth century, an increase of around 0.60 C has been observed. In the past few decades, human activities have increased atmospheric concentrations of green house gases to their highest level in 420,000 years . A growing body of scientific research predicts rising temperatures and large scale alterations weather patterns that will continue through the 21st century, even if we manage to cultural green house gas emissions.
What are the causes of global climate change?
The causes of climate changes are mainly attributed to release of greenhouse gases such as carbon dioxide (CO2) methane (CH4) and nitrogen oxide (N2O). Carbon dioxide is the most important contributor in green house gases resulting in global warming. Not all the carbon dioxide generated on land due to burning of fuels remain in the atmosphere as some of it gets absorbed on land, for example by photosynthesis in growing plants and in oceans. Cuttings of trees or deforestation would therefore reduce the absorption of carbon dioxide on land increase the amount released to the atmosphere As a result the concentration of CO2 has increase from a 285 part. Per million in 2000 which means an increase of 30% in 150 years.
Similarly other gases like methane (CH4) and nitrogen oxide (N2 O) are estimated to have increased by 145% and 14% during some period.
What are the consequences of global climate changes?
It would result in raising not only the average global temperature and rise in sea levels but would also produce extremes of temperature, sea levels, rainfall, floods and other weather related phenomenon which would lead to natural disasters like loss of islands, coastal areas. Erratic rains would result.There would also be an increased cooling loads for air-conditioning . Melting of ice on mountain glaciers is another major consequence of global warming, resulting in floods.
How much should we limit?
Scientists warn that to avoid the worst effects of global warming, we must ensure that global average temperatures do not raise more than 2 degrees Celsius above pre-industrial levels. To have a good chance of remaining below this threshold, atmospheric concentrations of carbon dioxide equivalent must stabilize at 450 parts per million.