.

Climate Change

Climate change is a shift in the "average weather" that a given region experiences. This is measured by changes in all the features we associate with weather, such as temperature, wind patterns, precipitation and storms. Global climate change means change in the climate of the Earth as a whole. Global climate change does occur naturally; the ice age is an example. The Earth's natural climate has always been, and still is, constantly changing. The climate change we are seeing today differs from previous climate change in both its rate and its magnitude.

The temperature on Earth is regulated by a system known as the "greenhouse effect". Greenhouse gases primarily water vapour, carbon dioxide, methane and nitrous oxide trap the heat of the sun, preventing radiation from dissipating into space. Without the effect of these naturally occurring gases, the average temperature on the Earth would be -18° C, instead of the current average of 15°C. Life as we know it, would be impossible.

Over the past 200 years, emissions of these gases due to human activities have accumulated in the atmosphere, where, because of their long life, they stay for anywhere from decades to centuries. As a result, since the Industrial Revolution, concentrations of carbon dioxide have increased by 30 per cent, methane by 145 per cent and nitrous oxide by 15 per cent.

The cause of these increases has been human activities related to our increasingly sophisticated and mechanised lifestyle, in particular the burning of fossil fuels such as coal, oil and natural gas in factories and cars and to generate electricity. Moreover we have cleared more land for human use in the past 100 years than in all of prior human history. This has resulted in the loss of forests and wetlands, which absorb and store greenhouse gases and naturally regulate the atmosphere.

In effect, by increasing the amount of these heat-trapping gases, we have "enhanced" the natural greenhouse effect to the point that it has the potential to warm the planet at a rate that has never been experienced in human history. Already, the average global temperature has increased by about 0.5° C in the past 100 years, and temperature increases over the next 100 years are expected to significantly surpass any such change of the past 10,000 years.

Trends in CO2 Concentrations (Past 1000 Years)

The rising global temperature may trigger a series of changes within the overall global climate system. For instance, global sea levels have risen 10-25 cm over the past 100 years, and are expected to continue rising due to increases in temperature. We are also seeing increases in severe weather events. Such impacts of climate change could have far-reaching and/or unpredictable environmental, social and economic consequences. Indeed, the climate change problem and the related changes it may bring about are among the most serious of the environmental issues that we face today.

.