Climate politics

The earth has a fever

The earth’s climate has always varied. Many factors influence our climate, such as solar radiation, weather systems, greenhouse gases, particles, the earth’s rotation around the sun, snow coverage and sea currents. Greenhouse gases have also always influenced our climate; without them, the earth would be uninhabitable, with an average temperature of -19 °C.

With every year that passes, the scientific evidence becomes clearer that mankind’s emissions of greenhouse gases – mainly carbon dioxide, nitrous oxide and methane – are strengthening the greenhouse effect. This has caused the earth’s average temperature to increase by about 0.6 °C during the 20th century. Such rapid changes affect the conditions for all life on earth. There are signs that we could, for example, suffer sudden changes in the earth’s climate system and the collapse of whole ecosystems. In recent times a number of positive feedback systems have been discovered which can lead to acceleration in the temperature increase; one such system is reduced albedo due to melting glaciers. It is one of mankind’s biggest challenges to prevent continued increases in the earth’s average temperature.

Figur: Utsläpp av växthusgaser fördelat på olika sektorer, direkt översatt från IPCC:s klimatrapport från 2007

Emissions of carbon dioxide are the most significant cause of the climate change problem. Each year, around 25 billion tonnes of carbon dioxide are emitted, just by burning fossil fuels. A further 6 billion tonnes are released by deforestation. This has lead to a rise in the atmospheric concentration of carbon dioxide from preindustrial levels of 280 ppm (parts per million) to 380 ppm. Concentrations would have increased much more were it not the case that over half of the extra carbon dioxide has been absorbed by the oceans and the biosphere. Whilst this concentration is still low, studies from ice cores show that the concentration of carbon dioxide in the atmosphere is a steering factor in climate and temperature. In order to avoid any unpleasant surprises we move away from the use of fossil fuels and take measures to prevent continued deforestation. Read more about this on the UN’s Climate Panel IPCC website.

IPCC recommends that a political goal should be set whereby carbon dioxide concentrations should not exceed 450 ppm (from the current concentration is about 380 ppm). New research shows that there are many risks associated with allowing the concentration to rise to 450 ppm. Many scientists therefore recommend a goal of returning to preindustrial concentrations in the atmosphere, 350 ppm.