Glossary

Anthropocene: The current geological epoch, characterized by human activity having a significant global impact on the Earth's environment and climate. This includes changes to the atmosphere, land use, oceans, and biodiversity. The Anthropocene is often marked as beginning with the Industrial Revolution in the 18th century, although some scientists argue that it began earlier.

Atmosphere: The layer of gases surrounding the Earth that is held in place by the planet's gravitational pull. The atmosphere is made up of 78% nitrogen, 21% oxygen, trace amounts of other gases, and a small but important concentration of GHGs, such as CO2 and methane.

BECCs (bioenergy with carbon capture and storage): A form of negative emissions technology that involves using biomass to generate energy and capturing and storing the resulting GHG emissions. BECCs have the potential to reduce GHG emissions while also providing a source of renewable energy. However, the feasibility and sustainability of large-scale BECCs systems is still the subject of scientific debate.

Biodiversity: The variety of plant and animal life in a particular ecosystem. High levels of biodiversity are important for the functioning and resilience of ecosystems, as well as for the health and well-being of humans. Climate change is a major threat to biodiversity, as it can alter the conditions that species need to survive and thrive.

Carbon offset: A reduction in GHG emissions made in one location to compensate for emissions made in another location. Carbon offsets are often used as a means of reducing the overall GHG emissions of a company or individual through investments in projects that reduce, remove, or sequester GHGs, such as reforestation, clean energy, or carbon capture and storage.

Carbon sequestration: The capture and storage of GHG emissions, typically in forests, soils, oceans, or geologic formations. Carbon sequestration can help offset GHG emissions and mitigate climate change, but the effectiveness and permanence of different sequestration methods vary.

Climate adaptation: The actions taken to prepare for or reduce the negative impacts of climate change. This can include measures such as strengthening infrastructure, developing drought-resistant crops, or enhancing natural systems that provide protection from extreme weather events. Climate adaptation is important because some of the impacts of climate change, such as sea level rise and more frequent heatwaves, are already inevitable due to past GHG emissions.

Climate change: The long-term alteration of the Earth's climate, including changes in temperature, precipitation, and wind patterns. Climate change is primarily driven by human activities that release GHGs into the atmosphere, such as the burning of fossil fuels and deforestation. The Earth's climate is naturally variable, but the current rate of warming is unprecedented in modern times and is largely caused by human actions.

Climate equity: The fair distribution of the benefits and burdens of climate change and climate action. Climate equity recognizes that the impacts of climate change are not evenly distributed and that disadvantaged and marginalized communities often bear a disproportionate burden. It also acknowledges that those who have contributed the least to the problem of climate change should not bear the greatest burden of addressing it.

Climate justice: The fair treatment and involvement of all people in the efforts to address climate change. This includes ensuring that disadvantaged and marginalized communities have a voice in decision-making and that the burden of climate action is shared fairly. Climate justice also involves holding those who have contributed the most to the problem of climate change accountable for their actions and ensuring that they contribute a fair share to the solution.

Climate mitigation: The actions taken to reduce GHG emissions and prevent or slow the pace of climate change. This can include measures such as transitioning to clean energy, improving energy efficiency, and reducing deforestation. Climate mitigation is important because the more GHGs that are emitted, the more the Earth's average temperature will rise, leading to more severe and irreversible impacts of climate change.

Climate sensitivity: The measure of how much the Earth's average surface temperature will increase in response to a doubling of atmospheric CO2 concentrations. Climate sensitivity is an important factor in predicting the future trajectory of climate change and is used in Earth System Models to project future warming. The current best estimate of climate sensitivity is that a doubling of CO2 concentrations will result in a temperature increase of 1.5-4.5°C.

CO2 equivalent (CO2e): A measure of the global warming potential of different GHGs, expressed in terms of the equivalent amount of CO2. The CO2e of a gas is calculated by multiplying the gas's global warming potential by its mass. The CO2e is used to compare the warming effect of different GHGs and to track emissions reductions in CO2e terms.

Decarbonisation: The process of reducing the carbon intensity of an economy or sector. This can involve transitioning to clean energy, improving energy efficiency, and adopting low-carbon technologies and practices. Decarbonisation is an important part of climate mitigation efforts because the burning of fossil fuels is the largest source of GHG emissions.

Droughts: Prolonged periods of below-average precipitation that result in a shortage of water. Droughts can have significant impacts on agriculture, ecosystem health, and human health and well-being. Climate change is expected to increase the frequency and severity of droughts in some regions.

Deforestation: The removal of forests, either through natural processes or human activities. Deforestation is a major source of GHG emissions because forests sequester carbon and release it back into the atmosphere when they are cleared. Deforestation is also a significant threat to biodiversity and the many ecosystem services that forests provide.

Earth System Models: Complex computer models that simulate the Earth's climate system and are used to project future climate conditions. Earth System Models include representations of the atmosphere, oceans, land, and cryosphere (snow and ice) and take into account the interactions between these components. Earth System Models are used to inform climate policy and assess the effectiveness of different climate mitigation and adaptation strategies.

Ecosystem: A community of living organisms and their physical and chemical environment, functioning as a unit. Ecosystems provide a range of services, such as air and water purification, pollination, and soil formation, that are vital to human well-being. Climate change is having significant impacts on ecosystems, including alteration of species ranges, shifts in the timing of life cycle events, and changes in the structure and functioning of ecosystems.

Emissions: The release of GHGs into the atmosphere from human activities. Emissions from the burning of fossil fuels are the largest source of GHGs, but emissions also come from activities such as deforestation, agriculture, and waste management. Reducing GHG emissions is an important part of climate mitigation efforts.

Emission Reduction Plans (ERPs): Plans developed by countries, cities, or other entities to reduce GHG emissions over a specific time period. ERPs typically outline specific actions and targets that will be taken to reduce emissions.

Extreme weather events: Unusual or severe weather events that are outside the range of what is normally expected. Extreme weather events can include heatwaves, heavy rainfall and flooding, and severe storms. Climate change is expected to increase the frequency and intensity of some extreme weather events.

Fossil fuels: Fuels that are formed from the remains of ancient plants and animals and are composed primarily of hydrocarbons. Fossil fuels, including coal, oil, and natural gas, are a major source of energy but are also a major contributor to GHG emissions when they are burned. Transitioning to clean energy sources is an important part of climate mitigation efforts.

Food security: The availability, access, and stability of food supplies. Climate change is expected to have significant impacts on food security, including through the alteration of crop yields and the disruption of food supply chains.

Geoengineering: The deliberate modification of the Earth's climate system to counter the effects of climate change. Geoengineering approaches include solar radiation management, which involves reflecting sunlight back into space, and carbon dioxide removal, which involves removing CO2 from the atmosphere and storing it. Geoengineering is a controversial approach to addressing climate change and is not a substitute for reducing GHG emissions.

Greenhouse gas emissions (GHGs): Gases that trap heat in the Earth's atmosphere, causing the Earth's average surface temperature to rise. The main GHGs are water vapour, carbon dioxide, methane, and nitrous oxide. GHG emissions from human activities, such as the burning of fossil fuels and deforestation, are the primary driver of climate change.

Heatwave: A prolonged period of unusually hot weather. Heatwaves can have significant impacts on human health, agriculture, and infrastructure. Climate change is expected to increase the frequency and intensity of heatwaves in some regions.

Intergenerational justice: The principle that the actions of one generation should not compromise the ability of future generations to meet their own needs. Climate change poses significant challenges to intergenerational justice, as current GHG emissions will have long-lasting impacts on the Earth's climate and the ability of future generations to thrive.

IPCC: The Intergovernmental Panel on Climate Change, a United Nations body that assesses the science related to climate change. The IPCC produces periodic reports that summarize the latest scientific knowledge on climate change, including its causes, impacts, and potential mitigation and adaptation options.

Kyoto Protocol: An international agreement under the United Nations Framework Convention on Climate Change (UNFCCC) that sets binding GHG emission reduction targets for industrialized countries. The Protocol was adopted in 1997 and went into effect in 2005. It was superseded by the Paris Agreement in 2016.

Land use change: Changes to the use of land, such as deforestation, agriculture, and urbanization, that can affect GHG emissions. Land use change is a significant source of GHGs, as well as other environmental impacts, such as biodiversity loss.

Methane: A GHG that is 28 times more effective at trapping heat in the atmosphere than CO2 over a 100-year period. Methane is emitted from a variety of sources, including livestock farming, rice cultivation, and landfills.

Nitrous oxide: A GHG that is 298 times more effective at trapping heat in the atmosphere than CO2 over a 100-year period. Nitrous oxide is emitted from a variety of sources, including agriculture and waste management.

Nationally Determined Contributions (NDCs): GHG emission reduction targets that countries submit as part of their participation in the Paris Agreement. NDCs are intended to reflect each country's unique circumstances and capabilities and are updated every five years.

Ocean acidification: The process by which the ocean becomes more acidic as it absorbs increasing amounts of CO2 from the atmosphere. Ocean acidification has significant impacts on marine ecosystems, including coral reefs and shellfish.

Paris Agreement: An international agreement under the United Nations Framework Convention on Climate Change (UNFCCC) that aims to limit global warming to well below 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5°C. The Paris Agreement was adopted in 2015 and went into effect in 2016.

Planetary boundaries: A set of nine environmental systems or processes that, if significantly disturbed, could lead to potentially irreversible and damaging changes to the Earth's climate, biosphere, and hydrosphere. The planetary boundaries include climate change, biodiversity loss, and land use change, among others.

Pollution: The presence of harmful substances in the environment, including GHGs, that can have negative impacts on human health and the environment.

Permafrost: Permanently frozen soil that is found in high-latitude regions, such as the Arctic. Permafrost stores large amounts of carbon, which is released into the atmosphere as GHGs when the permafrost thaws.

Resilience: The ability of a system, such as a community or ecosystem, to withstand and recover from stress or disturbance. In the context of climate change, resilience refers to the ability of communities and ecosystems to adapt to the impacts of a changing climate.

Sea level change: The rise or fall of sea levels, which can be caused by factors such as melting ice caps and thermal expansion of seawater. Sea level change has significant impacts on coastal communities and ecosystems.

Sustainability: The ability of a system, such as a community or ecosystem, to continue functioning over time without depleting its resources or causing significant harm to the environment.

Tipping point: A threshold at which a small change can have significant and possibly irreversible impacts on a system, such as the Earth's climate. In the context of climate change, tipping points could include the collapse of the West Antarctic ice sheet or the die-off of the Amazon rainforest.

UNFCCC: The United Nations Framework Convention on Climate Change, an international treaty adopted in 1992 that aims to stabilize GHG concentrations in the atmosphere at a level that would prevent dangerous human interference with the climate system. The UNFCCC is the parent treaty of the Paris Agreement.

Uncertainty: In the context of climate change, uncertainty refers to the lack of complete knowledge about the causes, impacts, and potential solutions to climate change. There is significant uncertainty in the field of climate science, particularly in terms of predicting the precise impacts of climate change and the effectiveness of various mitigation and adaptation measures.

Vulnerability: The susceptibility of a system, such as a community or ecosystem, to harm or damage from external factors, such as climate change.

Variability (climate): The natural fluctuations in the Earth's climate system, including variations in temperature, precipitation, and other atmospheric and oceanic conditions. Climate variability can have significant impacts on communities and ecosystems.

Water cycle: The movement of water from the Earth's surface to the atmosphere and back, including processes such as evaporation, transpiration, and precipitation. The water cycle is a critical component of the Earth's climate system and is impacted by climate change.

eXtinction Rebellion: A grassroots movement that uses non-violent civil disobedience to demand action on climate change and biodiversity loss. The movement, which originated in the United Kingdom, has spread to other countries and is known for organizing protests, blockades, and other acts of civil disobedience.

Net Zero Emissions: A state in which a company, country, or other entity is able to balance the amount of GHGs it emits with an equivalent amount of GHGs removed from the atmosphere. Net zero emissions can be achieved through a combination of reducing GHG emissions and implementing carbon sequestration or negative emissions technologies.