Global temperatures are rising as a result of human activity.
People around the world are already experiencing the consequences, from more intense heatwaves to rising sea levels.
Things are likely to worsen in the coming decades, but scientists argue that urgent action can still avoid the most dangerous effects of climate change.
What is climate change?
Climate is the average weather in a place over many years. Climate change is a shift in those average conditions.
The climate has fluctuated naturally throughout the world's history.
But scientists say that there is no doubt that the particularly rapid climate change seen over the past century is caused by humans.
In particular they say it is due to the widespread use of fossil fuels - coal, oil and gas - in homes, factories and transport.
When fossil fuels burn, they release greenhouse gases - mostly carbon dioxide (CO2). These gases trap the Sun's heat in the atmosphere, causing the planet's temperature to rise.
Since the start of the Industrial Revolution - when humans started burning large amounts of these fuels - the amount of CO2 in the atmosphere has risen by over 50%, and is still growing.
As a result of the increase in CO2 and other greenhouse gases like methane, the world is now about 1.1C warmer than it was in the late 19th century.
What are the effects of climate change so far?
A global average temperature increase of 1.1C might not sound much, but it has already had a huge effect on the environment. Impacts so far include:
- more frequent and intense extreme weather, such as heatwaves, drought and floods
- rapid melting of glaciers and ice sheets, contributing to sea level rise
- huge declines in Arctic sea ice
- ocean warming and marine heatwaves.
What are governments doing about climate change?
In a landmark agreement signed in Paris in 2015, almost 200 countries pledged to try to keep global warming to 1.5C.
To achieve this, scientists said that countries should achieve net zero CO2 emissions by 2050. Net zero means reducing greenhouse gas emissions as much as possible, and removing any remaining emissions from the atmosphere.
Most countries have, or are considering, net zero targets, but many of these are dated after 2050.
What can individuals do?
Major changes need to come from governments and businesses, but scientists say small changes from individuals can also make a difference:
- take fewer flights
- use less energy
- improve home insulation and energy efficiency
- switch to electric vehicles or live car-free
- replace gas central heating with electric systems like heat pumps
- eat less red meat.
Source: bbc.com
