World leaders are under pressure to take action on climate change – but what exactly is it they are talking about? Here are some of the commonly used climate terms and what they mean.
– Greenhouse gases
These are gases that trap some of the heat from the sun in the atmosphere and keep the the planet warm enough for life to thrive.
Concentrations of these gases, which include carbon dioxide, methane and nitrous oxide, have increased at a rapid rate in recent years.
– Greenhouse gas or carbon emissions
This is the release of greenhouse gases, particularly carbon dioxide, into the atmosphere, mainly from burning fossil fuels – coal, gas and oil – in things such as power stations, vehicle engines and boilers for heating buildings.
Livestock and changes to how we use land, including cutting down or burning forests and draining peatland, industrial processes such as cement making and refrigerants are among other sources of greenhouse gas emissions caused by human activity.
– Global warming
Because of emissions from human activity, the overall level or concentration of carbon dioxide and other greenhouse gases in the atmosphere has increased.
The higher the concentrations in the atmosphere, the more they trap heat and warm the Earth, pushing up temperatures across the land and oceans, which is known as global warming.
In 2020 global temperatures were around 1.2C above what they were in the 19th century, before most of the industrial activity driving emissions got going.
– Climate change
This encompasses the rapid changes we are seeing to weather conditions and the natural world, driven by global warming and the human activities that cause it.
Impacts we are already seeing include more frequent and extreme heatwaves and wildfires, increased rainfall and storms which can cause floods, melting ice and rising sea levels, changes to crop yields and loss of wildlife.
As temperatures continue to rise, the impacts of climate change are projected to worsen, and the situation is increasingly being referred to as a climate crisis or emergency.
– Net zero
Cutting greenhouse gas emissions from human activity to zero overall, which is needed to halt the global temperature rises driven by the increase in levels of gases in the atmosphere.
Just as you need to turn off a tap completely to stop the level of water in a bath from continuing to rise, we need to cut emissions to zero to stop the greenhouse gas levels – and therefore temperatures – rising.
Completely stopping emissions is extremely difficult, but there are some measures, such as planting trees, which can absorb greenhouse gases from the atmosphere – the equivalent of bailing some water out of the bath to keep the water level steady even if the tap is still running slightly.
So emissions have to be cut as much as possible, and any remaining pollution, from hard-to-tackle sectors such as aviation, needs to be “offset” by action that absorbs carbon to have the net effect of cutting emissions to zero.
The process of removing the emissions associated with activities or sectors, for example decarbonising electricity generation by phasing out coal and gas plants that put out pollution, and building renewables such as offshore wind farms.
– Paris Agreement
The world’s first comprehensive treaty on climate change, agreed under the United Nations in the French capital in December 2015.
Under the deal, all countries commit to action to limit temperature rises to “well below” 2C above pre-industrial levels and pursue efforts to keep them to 1.5C, to reduce the risks and impacts of climate change.
– Nationally determined contributions (NDCs)
National plans for climate action submitted by countries under the Paris Agreement.
They outline post-2020 action to tackle climate change, with many plans running to 2030. Countries are under pressure to bring out new or updated plans because current action leaves the world way off track to meet the 2C or 1.5C goals.
This is a global climate summit held under the UN’s climate change convention, which is being hosted by the UK and is set to take place in Glasgow in the first two weeks of November.
Cop26, delayed from last year by the pandemic, is seen as the most important international climate meeting since Paris 2015, as it aims to drive urgent and significant action to halt rising temperatures.
There will also be negotiations to agree the final parts of the “rulebook” for implementing the Paris Agreement.
Cop stands for “conference of the parties” and it is the 26th meeting.