Climate Change - The Science Bit

The Greenhouse Effect

The climate is warming faster than at any time during the past 10,000 years and much of the warming can be attributed to the activities of humans, which have enhanced the greenhouse effect.

The greenhouse effect is a natural process that warms Earth’s atmosphere. Without it much of the Earth would be covered in ice! Heat from the sun penetrates the atmosphere and arrives at the Earth’s surface. Some of this heat is absorbed, causing the land temperature to increase, which in turn leads to the radiation of heat back towards space.. This heat can become trapped in the atmosphere before it escapes into space by greenhouse gases such as carbon dioxide and methane. This causes a warming of the atmosphere.

Enhancement of the Greenhouse Effect

It is widely accepted that the burning of fossil fuels (oil, gas and coal) since the industrial revolution for our energy and transport requirements, global deforestation for valuable timber resources, and intensive farming to feed as many people as cheaply as possible have increased the concentration of atmospheric greenhouse gases.

Trees absorb carbon dioxide during photosynthesis which reduces the amount of carbon dioxide in the atmosphere available to contribute to climate change but when forests are cut down this process no longer happens.

Agriculture is the second largest source of UK greenhouse gases, contributing 7% of total emissions. However, of that only 1% is from carbon dioxide, for example from the use of diesel fuel, but 36% of the UK’s methane emissions, a greenhouse gas 21 times more potent than carbon dioxide, come from livestock and livestock manures and  67% of the UK’s nitrous oxide emissions, a greenhouse gas 310 times more potent than carbon dioxide comes mainly from the use of artificial fertiliser.

Today, the atmospheric concentration of carbon dioxide is 30% higher than it was 200 years ago and by 2050 could be 100% higher. This has caused an average rise in temperature of 0.6°C over the past century. The 10 hottest years on record have all occurred since 1995.

Present Effects of Climate Change

The effects of climate change are already being seen across the globe.

• Ice caps are retreating from many mountain peaks like Kilimanjaro
• Global mean sea level rose by 1-2mm a year during the 20th century
• In September 2007 Arctic sea ice extent was 39% below the long-term average from 1979 to 2000
• Global snow cover has decreased by 10% since the 1960s
• El Niño events have become more frequent and intense during the last 20-30 years
• Weather-related economic losses to communities and businesses have increased ten-fold over the last 40 years
• Deserts are spreading up into southern Europe
• Barn owls, robins and hornets are arriving in the Arctic for the first time

You can use the Energy Saving Trust’s interactive Climate Change Explained tool to learn more about the science behind climate change.

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