Climate and COP glossary

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Here are some terms that you might hear being used to discuss what is happening at COP climate conferences. Have a go at the COP climate quiz or have a look at the interactive Climate Action Timeline.

Blue carbon

Blue carbon is carbon that is captured in ocean and coastal habitats. Coastal habitats such as seagrass meadows, tidal marshes, and mangroves capture carbon through plant photosynthesis. This carbon is then stored in the sediment. This water-covered sediment stores a higher level of carbon per area than land-based habitats such as grasslands and forests. Blue carbon habitats can store this carbon for millennia, making their conservation, restoration and management an important part of nature-based solutions to climate change.

Carbon dioxide (CO2)

Carbon dioxide is a greenhouse gas commonly caused by the burning of hydrocarbons such as oil and gas, and the combustion of carbohydrates (sugars) through plant and animal respiration.

Carbon emissions

Carbon emissions are the release of carbon dioxide gas into the atmosphere from human activity such as burning fossil fuels like coal, oil and natural gas, and the manufacture of cement. There are also natural sources of carbon dioxide being released into the atmosphere from plant respiration to volcanic eruptions.

Carbon offsetting

Carbon offsetting is a way of making up for carbon dioxide emissions by doing something that helps to absorb carbon dioxide as well. A common example of this is to plant a certain number of trees to make up for the amount of carbon emitted by a flight. Carbon offsetting can be done by individuals, companies, and countries. There are controversies that some offsetting schemes do not absorb as much carbon dioxide as claimed, and that the use of offsetting schemes can distract from the important work of cutting carbon emissions in the first place.

Carbon sink

A carbon sink is anything that absorbs more carbon from the atmosphere than it releases, and stores this carbon for long periods of time, typically over 100 years. Carbon sinks include plants, soils, and the ocean. Carbon sinks are part of the carbon cycle and help to balance natural and human carbon emissions.

Mangroves australia c Matt Curnock Ocean Image Bank Matt Curnock / Ocean Image Bank
This mangrove forest in Australia acts as a carbon sink and is a form of blue carbon.
Carbon source

A carbon source is anything that releases more carbon than it absorbs. This includes the burning of fossil fuels, deforestation, and cattle farming.

Certified Emissions Reductions (CERs)

CER is a technical term to describe the amount of carbon dioxide that has been offset by a particular project. In short, these certificates are like the money of carbon offsetting. Organisations can purchase CERs to counterbalance their own emissions footprint. Most reputable CERs are verified under the Clean Development Mechanism program to prove their worth. The United Nations provides a way for countries to use CERs to to count towards their annual carbon emissions targets.

Clean Development Mechanism (CDM)

The Clean Development Mechanism (CDM) is a United Nations-run carbon offset scheme allowing countries to fund greenhouse gas emissions-reducing projects in other countries and claim the saved emissions as part of their own efforts to meet international emissions targets.

Climate change

Climate change describes the long-lasting changes in normal weather patterns across the entire world, and in individual regions. This includes rising temperatures, shifting rains and storms, floods, droughts, heatwaves, fires, melting ice, and sea level rise. Climate varies naturally, but today's climate change is caused by the rapid overall warming of the planet caused by increased levels of greenhouse gases in the atmosphere from human activities such as burning fossil fuels.

Climate change adaptation

Climate change adaptations are actions that individuals, communities, and countries make to deal with impacts caused by climate change. These include building sea defences to cope with sea level rise and increased storm surges, or reforestation and river management to cope with flooding. Some adaptations such as buying an air conditioner to cope with higher temperatures may also contribute to climate change.

Sea defences near the opening of Port Sultan Qaboos Oman c istock mtcurado
Sea defences near the entrance to Port Sultan Qaboos, Oman
Climate change mitigation

Climate change mitigations are actions that reduce carbon emissions. These include using clean energy, protecting forests, and eating less meat. Climate change mitigation aims to slow or stop global warming by limiting the amount of carbon emitted into the atmosphere.

Climate justice

Climate justice addresses the fact that countries that suffer most from climate change are not those that are most to blame for causing it. It also means that richer polluting countries should provide funding to developing regions to cover their costs relating to climate mitigation and adaptation, as well as compensating for the loss and damage caused by climate impacts such as storms and floods.

Conference of Parties (COP)

A Conference of Parties is a meeting of countries that have signed up to a United Nations treaty. Parties is just a legal term for those who have signed an agreement. The most well-known COPs are those addressing climate change. These are the annual summits for all those countries that have signed up to the United Nations Framework Convention on Climate Change, the international treaty to combat climate change. The first Climate COP was held in Berlin in 1995.

Fossil fuels

Fossil fuels include coal, oil, and natural gas and are formed from buried plants and animals under certain conditions over millions of years. Burning these fossil fuels releases captured and stored carbon back into the atmosphere.

Mae Moh Coal Power Station Thailand
Mae Moh coal-fired power station in Thailand
Global warming

Global warming describes the overall heating of the planet caused by increased levels of greenhouse gases in the atmosphere. The main cause of climate change is carbon emissions created by burning of fossil fuels.

Greenhouse gases

Greenhouse gases are gases like carbon dioxide that stay in the atmosphere and trap heat from the sun, causing global temperatures to rise. Other greenhouse gases include methane and water vapour.

Intergovernmental Panel on Climate Change (IPCC)

The IPCC is an important research group that studies climate change and provides information for leaders around the world so they can make better decisions. The IPCC is made up of thousands of scientists from universities and labs all over the globe. They review and summarise all the latest research about climate change to show where scientific findings agree and where there's uncertainty. Every few years, these scientists put together reports that talk about what is causing climate change (like burning fossil fuels), the impacts from rising temperatures like more extreme weather, and what could happen in the future based on different actions taken. Many governments and leaders look to their reports when making policies around greenhouse gas emissions and preparing communities for the changes ahead.

Methane (CH4)

Methane is a simple hydrocarbon gas. It occurs as the fossil fuel, natural gas, as well as being created by decomposing plants in swamps and by cow burps. It is a powerful greenhouse gas, with an effect 25 times greater than carbon dioxide. The main human-induced sources of methane emissions into the atmosphere come from fossil fuel extraction and cattle farming.

Nature-based solutions

Nature-based solutions can help stop climate change by protecting forests, wetlands, and other natural habitats. These lands absorb and store carbon dioxide so it does not stay in the atmosphere and trap heat. Planting new trees and plants is one way we can do this. However, it is important to be thoughtful in how nature is restored. If we use only one type of fast-growing tree, it would not support as much wildlife as a natural, diverse forest. The goal is to grow healthy lands that absorb carbon dioxide in balanced ways.

Amazon rainforest yasuni national park ecuador c i Stock Maris Maskalans
Nature-based solutions include the conservation and management of ecosystems such as the tropical rainforest
NDCs (Nationally Determined Contributions)

Every country in the world creates plans called Nationally Determined Contributions or NDCs. NDCs are national climate action plans that are part of the Paris Agreement to tackle climate change. In these plans, governments promise how much they will cut their greenhouse gas emissions by certain years like 2030 or 2050. All the NDCs together contribute to slowing down rising temperatures worldwide. With each nation promising to pollute less through efforts such as using cleaner energy, the overall goal of keeping global temperature rises to 1.5° Celsius comes closer.

Paris Agreement

In 2015 at the Paris COP climate summit, nearly all countries around the world agreed to try to limit future climate change effects from becoming too extreme. They promised to cut their greenhouse gas emissions to help keep global warming under 2° Celsius above pre-industrial temperatures if possible, and if possible to the safer limit of 1.5° Celsius. This deal is called the Paris Agreement. It united countries across the world into acting on climate. Before the Paris Agreement, plans to slow down climate change did not include formal promises from every nation. Now almost every country has said it will reduce emissions to limit global warming.

14 COP21 Paris agreement public domain US State Dept US State Department
French Foreign Minister Laurent Fabius, President of the COP21 climate change conference, bangs down the gavel on 12 December 2015, after representatives of 196 countries approved a sweeping environmental agreement.

The stocktake is a regular check-up to see how the world is doing on addressing climate change. Every five years, starting in 2023 at COP28 in Dubai, all countries have to provide an update on their work to cut carbon emissions. Together this forms a global stocktake on climate action and support, and means that gaps can be identified. This can then inform the next round of commitments to limit warming.

Ratchet mechanism

The Paris Agreement created something called a ratchet mechanism. This is designed to keep moving forward on tackling climate change. Like a ratchet tool that tightens when you crank it one way, the climate rules are designed so countries keep promising stronger and stronger cuts in carbon emissions over time. The point is to stop backsliding and instead scale up action to meet global climate goals. Every five years when the global stocktake happens, the ratchet requires countries to increase their efforts.

Rio Earth Summit

In 1992, leaders from countries around the world met in Rio de Janeiro, Brazil for a major United Nations Earth Summit. They came together to discuss major environmental problems, such as climate change. Several major international agreements were started here, addressing both climate change and biodiversity. This laid the foundation for global agreements to coordinate action to tackle climate change. It led to rules that all nations had to start helping fix the issue fairly, based on who polluted more over time. The 1992 Rio Summit marked the first time that there was a global acknowledgement of global warming and the need for international action.


UNFCCC stands for the United Nations Framework Convention on Climate Change. This is the technical name for the international climate change convention that was started at the Rio Earth Summit in 1992. The UNFCCC came into effect in 1994 and organises the annual COP climate summits that bring together nations to agree international action to tackle climate change.