Climate change is a long-term shift in Earth’s average temperatures and weather patterns. It is caused by human activities, such as burning fossil fuels (oil, coal and natural gas), which produce greenhouse gases that blanket the Earth and trap the sun’s heat.
Warmer temperatures alter natural cycles and disrupt the normal balance of nature, leading to a wide range of impacts that threaten people and other living things. These include extreme heat, drought, wildfires, flooding and rising sea levels. Climate change also affects health, for example as mosquitoes and ticks move to new habitats, they carry dangerous diseases.
Scientists have found that we can avoid some of the most harmful impacts by limiting warming to a level that is safe for people and other species, known as 1.5°C above pre-industrial levels. This limit would reduce the risks from melting ice sheets and glaciers, as well as sea-level rise, which is caused by thermal expansion of warmer water.
It is important to understand that the changes we are seeing are much faster than shown in geological records. This is due to the interconnected nature of the climate system, where a disturbance in one part may cause a series of ‘feedbacks’ that amplify or dampen the effects.
It is essential to realise that the climate crisis exacerbates existing inequalities between rich and poor nations, between those who can afford to take action and those who cannot. For example, wealthier nations are responsible for the lion’s share of historical greenhouse gas emissions, but it is low-lying countries that will be most at risk from climate disaster.