The science of climate change

The CCC has assessed in detail the very extensive scientific evidence behind climate change.

There is a vast body of research undertaken by scientists over many years showing that global climate change is already happening. The last decade showed the highest global average surface temperatures since records began, about 0.8°C above pre-industrial levels. Global sea level has risen by around 20cm with significant contributions now coming from the melting ice sheets over Greenland and Antarctica. Sea ice is also decreasing.

Human activity is playing a key role. The greenhouse gas effect, whereby CO2 and other gases warm the atmosphere, has been understood for over a hundred years. We have been burning increasing amounts of fossil fuels since the industrial revolution; and as a result CO2 concentrations in the atmosphere have broken out of the natural cycle seen over the last million years. There is a high degree of confidence that human emissions have caused most of the observed warming since the mid-20th Century.

If we make no efforts to cut global use of fossil fuels, global warming is likely to reach between 2-7°C this century with further warming beyond. This will have significant consequences for human welfare and ecological systems.

It is not possible to precisely predict these long-term impacts, but it is sensible to take action now as insurance against risks of dangerous climate change.

Click on the boxes below to see more about the science behind climate change.

Measuring a warming world

lobal average surface temperatures since 1880 as calculated

Observations of global temperature, sea level and ice

How a changing climate affects us

risks and benefits adapted from IPCC

Climate change will become more pronounced in the future as emissions continue. But exact predictions of how this will affect us are difficult to make.

Climate variations: natural and human factors

Trends in stratospheric temperature since systematic measurements began, from eight different datasets

How Earth’s climate has changed over the years and the part humans are playing

Setting a target for emission reduction

global average temperature above pre-industrial level thermometer

How climate science has guided CCC advice on emission targets

Many leading science organisations around the world have summarised the evidence for climate change in further detail. Some of these are listed below.