Climate change is caused by a build-up of carbon dioxide and other greenhouse gases in our atmosphere.
The gases trap heat by forming a blanket around the Earth – like the glass of a greenhouse.
These gases stay in the atmosphere for many years. And as they build up, the planet’s temperature rises.
Greenhouse gases are largely released by burning fossil fuels – coal, oil and gas – and by cutting down forests.
As the Earth warms up, other things – like the disappearance of ice – are helping push temperatures even higher.
Climate science explained
The most recent comprehensive assessment of climate science is from November 2014 by the Intergovernmental Panel on Climate Change (IPCC). We have distilled this assessment into ten key findings.
It says there is over 95% certainty that human influence is the dominant factor in warming since the mid 20th century.
That is as certain as scientists are that smoking causes cancer.
Did you know:
194 states have signed the 1994 United Nations Framework Convention on Climate Change, whose aim is the “stabilisation of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system”.
There are masses of other bodies endorsing of the need for urgent action, from the Ministry of Defence, the British Medical Association and the CBI (Confederation for British Industry) to the World Economic Forum, the International Energy Agency and the World Bank.
The IPCC in March 2014 said current global warming has already increased the occurrence of some types of extreme weather, and will get worse without action. The poorest people in the world with suffer the most, they said.
What is a safe temperature increase?
Even with just 0.8 degrees of warming so far, climate change impacts are already happening and are increasing in severity and likelihood – from floods in Europe and Australia to droughts in the USA.
Over 100 developing countries have called for global temperature rise to be limited to 1.5 degrees.
The European Union (EU) and G8 group of countries have set a 2 degree target.
But even to stay within this higher target, global carbon pollution has to peak well before 2020, and fall steeply afterwards.
We not only need to get off fossil fuels, but do it very fast.
What needs to happen?
Global carbon pollution has to peak before 2020, and fall steeply afterwards. We must reduce fossil fuel use by two-thirds by 2050. The world needs to be zero carbon by 2100.
And the wealthy countries, which have largely caused the climate change problem, need to support developing countries develop their economies in a low carbon way. This is a fair and equitable approach.