It is believed that an 80% reduction in carbon dioxide emissions by the year 2050 is the way to avoid catastrophic climate change.

It is also believed that in the next century a three-fold rise in energy demand will bring about an increase of 2 to 4oC in the average global temperature. These are quite dire predictions as to our planet's future. One method that has been devised to reduce climate change in the short term is carbon offsetting. Here I will define carbon offsetting and give some details on how it is achieved and the benefits of choosing this method of reducing greenhouse gas emissions.

A carbon offset as defined by the Environment Protection Authority of Victoria (Australia) gives the most detail. It states that a carbon offset is "a monetary investment in a project or activity elsewhere that abates greenhouse gas emissions or sequesters carbon from the atmosphere that is used to compensate for greenhouse gas emissions from your own activities." An example of a carbon offset would be replacing kerosene with solar energy as a fuel source in a community in India. Therefore the money used to buy the carbon offset is used to purchase these panels. So although as a business or country one may not be able to reduce the amount of carbon dioxide it emits in the short term, but by purchasing carbon offsets, they are funding a project in another country or area which can do so easily in the short term.

Carbon offsets are measured as metric tonnes. So that one carbon offset equals one metric tonne of CO2e that is carbon dioxide or its equivalent in other greenhouse gases. So if a company or country buys two tonnes of carbon offsets, then there will be two tonnes less of carbon dioxide or its equivalent in other greenhouse gases like methane, in the atmosphere.

But why chose carbon offsetting? Well, this is often the fastest way to get dramatic decreases in carbon dioxide emissions. In addition to preserving the environment, buying carbon offsets gives added benefits such as, employment opportunities, training education and community development programmes.

Carbon offsets have been sanctioned by the Kyoto Protocol as a way of governments and companies to earn carbon credits which in turn can be traded on a marketplace. This protocol also established the Clean Development Mechanism (CDM) which is in charge of validating and measuring the amount of reductions these projects produce, therefore ensuring that they are authentic. Also in order to be credible, there must be proof that the effects of the project are permanent, that is, it produces the reductions it claims to, so that the reduction done in one area does not increase somewhere else.

There are broad categories which projects suitable for generating carbon offsets fall into, for instance, renewable energy, energy efficiency, reforestation and methane abatement. In terms of renewable energy, I will not go into detail as there is much literature available on the various types, like solar, wind and hydroelectric.

Energy efficiency projects include funding cogeneration plants, that is, ones that generate both electricity and heat from the same sources, compared to typical plants where the energy generated as heat is not harnessed. Also, there are fuel efficiency projects where the combustion device is replaced with one that uses less fuel to generate energy. However, this will remain efficient only if the demand for energy does not change. There are also projects that make existing buildings energy efficient, which can be as simple as making adjustments to the heating and cooling systems, for example, replacing incandescent light bulbs with compact fluorescent lamps.

New buildings can also be constructed using materials that do not emit much carbon dioxide in their production.

When it comes to land use and forestry, there are quite a few ways of acquiring carbon offsets. The most obvious way is to fund reforestation programmes; however, it takes many years for trees to grow and mature and in turn for the environmental impact to be substantial.

However, programs can be funded to protect existing forests from deforestation, create forest on land that was previously unforested – known as afforestation. Also funding can be used towards soil management projects which attempt to increase or maintain the amount of carbon sequestered in the soil.

Finally, some projects use methane gas generated by livestock and landfills or other industrial waste can be used as a fuel source. But, purchasing carbon offsets should not be viewed as the entire solution for businesses wishing to conserve the environment. In order to achieve the maximum amount of carbon offsetting, one should critically assess the amount of internal reductions that can be made, those are the processes that emit carbon dioxide in the company and take action to reduce them, referred to as "internal reductions".

An example of an "internal reduction" in a company would be changing a fleet of vehicles to use another type or model that uses less fuel, or a hotel that uses solar energy to provide hot water to the guests.

Then the remainder of the amount that needs to be reduced or your unavoidable emission, for example, flights to other countries or states to attend meetings or workshops, can be done by purchasing carbon offsets.

However, it should be noted that purchasing carbon offsets are not limited to countries and companies, individuals can purchase offsets to compensate for their contribution to the emission of greenhouse gases, for example, caused by personal air travel.

Therefore it can be seen that although direct reduction of greenhouse gas emissions may not be possible by a country, company or individual, through carbon offsetting it can be achieved in the short term.