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Evidence of climate change

In just 200 years, the amount of carbon dioxide in the atmosphere - the major gas that causes climate change - has increased by around 35 per cent.

Changes in the atmosphere

Concentrations of greenhouse gases are now higher than at any point in the past 800,000 years³. This change has happened very quickly and although the full impact is not completely known, it is possible to predict with some certainty what this change will lead to.

Global temperature warming

Greenhouse gases like carbon dioxide (CO₂) trap heat in the atmosphere which would otherwise escape into space. Of course, as more heat gets trapped in the atmosphere, the earth below heats up too. Over the past century, average global temperatures have risen by 0.74°C and computer modelling suggests that at least half of the increase since 1900 and most of the warming over the past 50 years has been caused by human activities³.

According to the Intergovernmental Panel on Climate Change, global temperatures are predicted to rise by between 1.1 and 6.4°C over the next century².

Since 1990, global temperatures have risen by 0.2°C and atmospheric carbon dioxide concentrations have increased from 354 parts per million (ppm) to 380 ppm¹. The ten warmest years on record have all been since 1990. Six of the ten warmest years on record in the UK were between 1995 and 2004.

Over the last century global temperatures have risen by 0.7oC

During August 2003, the hottest temperature ever recorded in the UK was taken in Brogdale in Kent. It was 38.5°C and between 4th and 13th August 2003, over 2,000 people in the UK died as a result of the heat³. Studies show that summers of such exceptional warmth are twice as likely to occur due to the presence of increased greenhouse gases and by 2050 may occur every two to three years¹.

Rising temperatures also cause flooding, as weather becomes more extreme. The number of people affected by floods worldwide has already risen from 7 million in the 1960s to 150 million todayª. The autumn and winter floods in 2000 in the UK were the worst for 270 years and flooding on farmland cost the farming industry nearly £500 million³.

Sea levels will continue to rise for several centuries after greenhouses gas concentrations in the atmosphere are stabilised because of the very large thermal inertia of the oceans. A noticeable effect of higher sea levels is the use of the Thames Barrier, which has increased from a few times a year when it was constructed to an average thirteen times a year now§.