Climate change

How climate change works

How climate change works

The climate change process

  • the sunlight warms the surface of the earth
  • the earth releases heat back out towards space
  • some of the heat is trapped by the layer of greenhouse gases surrounding the earth
  • this process keeps the earth warm enough for us to live on
  • humans have been producing way too much greenhouse gas
  • the more gas there is, the more heat it traps - this results in warmer climate

More information

CO2 emissions

Scientists are able to predict how the climate might change as a result of different levels of emissions of greenhouse gasses. These levels are classed as ‘low’, ‘medium’ and ‘high’ and depend on the action we take to reduce emissions.

We would achieve low emissions if we put in place clean and efficient technologies and reduced consumption.

Below are some of the key statistics for London on how the climate might change by 2050 if we continued on our high emissions path. The worst case scenarios are considered to be very unlikely to occur, meaning a less than a 10% chance.


  • 50% chance of a 2.5ºC rise in the average winter temperature - worst case scenario is 3.8ºC
  • 50% chance of an increase in average summer temperature of 3.1ºC - worst case scenario is 5.2ºC
  • 50% chance of an increase of 4.3ºC in the average maximum temperature on a summer’s day - worst case scenario is 7.4ºC
  • When we have a hot summer’s day of 25ºC, we could expect this to be more like 29.2ºC by 2050
  • The average daily minimum summer temperature has a 50% chance of increasing by 3.3ºC - worst case scenario is 5.6ºC
  • The annual average rainfall is not expected to change, which means that the total amount of water received should stay the same.
  • Rain will fall at different times of the year. The summer has a 50% chance of receiving 19% less rain. The winter is likely to have 16% more rain.

More information

To find out more about how these figures were calculated and to explore predictions for different global CO2 emission scenarios, visit

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