ES7

Carbon dioxide (CO2) is released through natural processes such as respiration and volcano eruptions. Carbon dioxide along with other gases such as methane and water vapour solar energy to pass through to the planet surface from the sun but prevents much of this energy from radiating back out to space. The heat-trapping effect of carbon dioxide in the atmosphere called the greenhouse effect has been active on earth for millions of years and is responsible for the retention of heat on the earth allowing

the development of life.

On Earth, human activities are changing the natural greenhouse. Over the last century the burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO2). This happens because the coal or oil burning process combines carbon with oxygen in the air to make CO2. The industrial activities that our modern civilization depends upon have raised atmospheric carbon dioxide levels from 280 parts per million to 400 parts per million in the last 150 years. Deforestation has reduced the natural removal of carbon dioxide from the air due to photosynthesis. The earths

average surface temperature has risen about 1 degree Celsius since the late 19th century, a change driven largely by increased carbon dioxide and other human-made emissions into the atmosphere. More heat is being retained by the planet resulting in a trend towards global warming. Methane is a hydrocarbon gas produced both through natural sources and human activities, including the decomposition of wastes in landfills, agriculture, as well as cattle digestion and manure management associated with domestic livestock. Methane is a far more active greenhouse gas than carbon dioxide.

A stronger greenhouse effect will warm the oceans and partially melt glaciers and other ice, increasing sea level. Ocean water also will expand if it warms, contributing further to sea level rise. The Greenland and Antarctic ice sheets have measurably decreased in mass over the last 20 years almost

certainly due to global warming. Global warming will result in changes in atmospheric pressure, evaporation and precipitation rates across the planet leading to climate change and extreme weather events such as storms, flooding and drought.

Even if we stopped emitting greenhouse gases today, global warming would continue to happen for at least several more decades if not centuries. That’s because it takes a while for the planet (for example, the oceans) to respond, and because carbon dioxide – the predominant heat-trapping gas – lingers in

the atmosphere for hundreds of years. There is a time lag between what we do and when we feel it. But it may not be too late to avoid or limit some of the worst effects of climate change. Responding to climate change will involve reducing the flow of greenhouse gases into the atmosphere; and learning

to adapt to, the climate change that has already been set in motion.

The solution will require international policies and agreements between countries to reduce carbon emissions and to become more energy efficient. Recycling, heat insulation, alternative energy sources, driving more fuel-efficient cars and reforestation are examples of important steps that can be taken.