The burning of fossil fuels results in the production of environmental emissions as well as useful forms of energy. Some of these gaseous pollutants, of which carbon dioxide is the most prolific, congregate in the upper atmosphere. These gases are termed greenhouse gases because although they allow the sunlight to penetrate the earth's atmosphere they reflect some of the retransmitted energy back towards the ground thus inducing global warming.

Such temperature changes are always uneven with some countries experiencing higher changes than others. When people were few in numbers, they were able to migrate to reduce the influence of changing temperatures. However, this is no longer an option as the earth's population has expanded enormously since the last ice age 10,000 years ago. Temperature changes induce associated changes in rainfall patterns; these in turn impact on vegetation and animal life. Whereas in the past the process of change was gradual and therefore eco-systems had time to adapt, the ever increasing amount of pollution associated with current energy usage is causing much faster rates of change.

Observations of global temperatures dating back over the past 100 years or more indicate that the rise in global temperature of 1º C can be associated with a rise in carbon dioxide concentrations in the atmosphere. The difference with previous rises in carbon dioxide concentrations is that these changes are being induced by mankind and at a rate faster than in previous periods of climate change.

At the first 'Earth' summit held in Rio de Janeiro in 1992, this impact of man was recognised and the participants agreed to sign the United Nations Framework Convention on Climate Change.

Subsequently at a meeting of the parties in Kyoto in 1997, it was agreed to begin the task of reducing greenhouse gas emissions. The EU and its member states have already taken action to meet their commitments under the Kyoto treaty to reduce greenhouse gas emissions by 8 by 2012. Only 2 Member States are currently likely to meet this target.

The EU has now set an upper limit in the global temperature rise of 2º C above the pre industrial level in order to prevent irreversible changes in climate like melting of the ice caps or the permafrost.

A rise of 0.7º - 0.9 C has already been incurred as the figure below shows so immediate action is required by everyone if this limit is not to be breached.

The EU has now set a further reduction target of 20% (or 30% if a new post Kyoto agreement can be reached) with further reductions up to 60% or more by 2050.

Temperature variation (ºC) since 1860 (baseline pre industrial)

Economics of sustainable energy use

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