ESS terms in Atmosphere and climate change

A suspension of fine solid particles or liquid droplets in the air, such as dust, sea salt, sulfate droplets or soot, which affects climate by scattering or absorbing radiation and by changing clouds.

The planting of trees on land that has not been forested for a long time, or never was, creating a new forest that stores carbon.

Caused or produced by human activities, such as the carbon dioxide released by burning fossil fuels, as opposed to arising from natural processes.

The layer of gases held around the Earth by gravity, forming the boundary between the Earth and space and the outer limit of the biosphere.

A for-profit company certified by the non-profit B Lab as meeting verified standards of social and environmental performance, accountability and transparency.

A carbon removal method in which crops or trees are burned for energy and the carbon dioxide released is captured and stored underground, giving net removal from the atmosphere.

Dark, light-absorbing particles of carbon (soot) from incomplete burning of fossil fuels and biomass, which warm the atmosphere and darken snow and ice when deposited on them.

The total amount of carbon dioxide that can still be emitted while keeping global warming below a chosen limit, such as 1.5 °C, with a stated probability.

A technology that captures carbon dioxide from power stations or industrial sources and stores it permanently, usually deep underground in rock formations, so that it does not reach the atmosphere.

The movement of production and its emissions from a country with strict climate policies to one with weaker policies, which can cancel out the original emission cuts.

A state in which the carbon dioxide released by a country, organisation or activity is balanced by an equal amount removed from the atmosphere or offset, giving zero net emissions.

A reduction or removal of greenhouse gas emissions in one place, such as tree planting or avoided deforestation, that is paid for to compensate for emissions released elsewhere.

Any policy that makes emitters pay for each tonne of carbon dioxide they release, either through a carbon tax or through an emissions trading scheme.

A tax charged on each tonne of carbon dioxide emitted, or on the carbon content of fuels, which raises the price of high-carbon activities so that emitters have an incentive to cut emissions.

A clouding of the lens of the eye that blurs vision and can lead to blindness; exposure to ultraviolet radiation, especially UVB, increases the risk.

The set of natural reactions in which ultraviolet radiation splits oxygen molecules into atoms that form ozone, and ozone is broken down again, keeping stratospheric ozone in a steady state.

Stable, non-toxic compounds of carbon, chlorine and fluorine once widely used as refrigerants, aerosol propellants, foam-blowing agents and solvents; they release chlorine that destroys stratospheric ozone.

Long-term changes in the Earth’s climate, including global warming and the wider changes it causes in rainfall, extreme weather, ice cover, sea level and ocean conditions.

Adjustment of human or natural systems to actual or expected climate change, reducing its harmful effects and making the most of any beneficial ones.

Action that reduces the causes of climate change by cutting greenhouse gas emissions, removing greenhouse gases from the atmosphere or reducing the warming process itself.

An approach to climate change that treats it as an ethical and political issue, asking that responsibility, costs and help be shared fairly given that those least responsible are often most vulnerable.

A computer simulation that uses mathematical equations for the physical, chemical and biological processes of the atmosphere, ocean, land and ice to reproduce past climate and project future climate.

Doubt or denial that climate change is happening, that it is caused mainly by human activity, or that it is serious enough to justify action.

The degree to which a community, country or ecosystem is likely to be harmed by climate change, depending on its exposure, sensitivity and capacity to adapt.

The annual meeting of all the countries that are party to the UNFCCC, where climate agreements are negotiated and progress is reviewed.

A charge on imported goods according to the carbon dioxide emitted in making them, so that producers in countries without a carbon price cannot undercut those that pay one.

The total amount of a greenhouse gas, usually carbon dioxide, emitted by a country or the world over a long period, typically since the Industrial Revolution.

The process of reducing or ending the use of energy sources that emit carbon dioxide, such as fossil fuels, and replacing them with low-carbon or renewable sources.

The dating of past events and the reconstruction of past climate from the pattern of annual growth rings in trees, which are wider in favourable years and narrower in poor ones.

The unequal heating of the Earth’s surface and atmosphere, mainly because the angle and path length of sunlight vary with latitude, giving an energy surplus in the tropics and a deficit near the poles.

A technology that removes carbon dioxide directly from the surrounding air using chemical filters, after which the gas can be stored underground or used.

The unit for the total amount of ozone in a column of atmosphere; 1 DU equals a layer of pure ozone 0.01 mm thick at standard temperature and pressure.

The degree to which the Earth’s orbit around the Sun departs from a circle; one of the Milankovitch cycles, varying over periods of about 100,000 and 405,000 years.

The full range of electromagnetic radiation, from long-wavelength radio waves through microwaves, infrared, visible light and ultraviolet to short-wavelength X-rays and gamma rays.

A plausible description of how future greenhouse gas and aerosol emissions could develop, based on assumptions about population, economy, technology and policy, used as an input to climate models.

A scheme in which a government caps total emissions, issues permits up to the cap and lets emitters buy and sell them, so that emissions are cut where it is cheapest.

The strengthening of the natural greenhouse effect by greenhouse gases added to the atmosphere by human activities, such as burning fossil fuels and farming, which causes global warming.

The long-term rise in global mean surface temperature once the climate has fully adjusted to a doubling of atmospheric carbon dioxide; the IPCC's best estimate is 3 °C.

A weather event that is rare at a particular place and time of year, such as a heatwave, intense rainfall, drought or tropical cyclone, far outside the usual range of conditions.

A structure such as a levee, embankment, sea wall or storm surge barrier built to stop river or sea water from flooding land.

The large-scale death of trees across a forest, often from drought, heat, fire or pests, which can turn the forest from a carbon store into a carbon source and shift it towards savanna.

An atom or molecule with an unpaired electron, such as a chlorine atom released from a CFC, which makes it highly reactive.

A person or country that enjoys the benefits of a shared resource or collective action without paying its share of the cost, such as a country that lets others cut emissions.

Deliberate, large-scale intervention in the Earth's climate system to counter global warming, either by reflecting sunlight away from the Earth or by removing carbon dioxide from the atmosphere.

A cold interval within an ice age, lasting tens of thousands of years, when ice sheets expand, sea level falls and atmospheric carbon dioxide is low, about 180–200 ppm in recent cycles.

The balance between the solar energy Earth absorbs and the energy it returns to space as reflected sunlight and emitted infrared radiation, which sets the planet's mean temperature.

The increase in the mean global surface temperature of the Earth, caused mainly by the enhanced greenhouse effect; one part of climate change.

A measure of how much warming a given mass of a gas causes over a set period, usually 100 years, compared with the same mass of carbon dioxide, which has a value of 1.

The period beginning about 2.4 billion years ago when oxygen produced by photosynthesising cyanobacteria first built up in the Earth’s atmosphere and shallow oceans.

The natural process by which greenhouse gases absorb infrared radiation emitted by the Earth’s surface and re-emit it in all directions, keeping the surface about 33 °C warmer than it would otherwise be.

A gas in the atmosphere, such as water vapour, carbon dioxide, methane or nitrous oxide, that absorbs and re-emits infrared radiation emitted by the Earth’s surface, so less escapes directly to space.

One of a group of reactive elements (fluorine, chlorine, bromine and iodine); chlorine and bromine released from ozone-depleting substances destroy stratospheric ozone.

Testing a climate model by running it over a past period with the known inputs and comparing its output with the climate that was actually observed.

Compounds of hydrogen, chlorine, fluorine and carbon used as transitional replacements for CFCs; they release less chlorine into the stratosphere but still deplete ozone and are being phased out.

Compounds of hydrogen, fluorine and carbon that replaced CFCs and HCFCs in refrigeration, air conditioning, aerosols and foams; they do not deplete ozone but are powerful greenhouse gases.

A cylinder of ice drilled from an ice sheet or glacier whose layers and trapped air bubbles record past atmospheric composition and temperature, in Antarctica going back about 800,000 years.

A mass of glacial land ice larger than 50,000 km², such as the Greenland and Antarctic ice sheets, which together hold enough water to raise sea level by tens of metres.

A positive feedback in which warming melts reflective snow and ice, exposing darker ocean or land that absorbs more solar radiation, which causes further warming and melting.

The shift from hand production to machine-based manufacturing powered by coal, which began in Britain in the late 18th century and marks the start of large-scale human emissions of carbon dioxide.

Electromagnetic radiation with wavelengths longer than visible light; the Earth’s warmed surface emits long-wave infrared, part of which is absorbed and re-emitted by greenhouse gases.

A warmer interval between glacial periods, usually lasting about 10,000–30,000 years, when ice sheets retreat and atmospheric carbon dioxide is higher; the Holocene is the present interglacial.

The United Nations body, set up in 1988, that assesses the published science on climate change and reports on its causes, impacts and the options for mitigation and adaptation.

A graph of the concentration of carbon dioxide in the atmosphere measured continuously at Mauna Loa, Hawaii, since 1958, showing a steady rise with a yearly seasonal oscillation.

The 2016 amendment to the Montreal Protocol that commits countries to cut the production and use of hydrofluorocarbons by 80–85% over the following decades because they are powerful greenhouse gases.

An international agreement adopted in 1997 under the UNFCCC that set legally binding emissions targets for developed countries for 2008–2012.

Planning rules that control what land may be used for in each area, for example banning new homes on floodplains or in zones at risk of storm surges.

The rate at which air temperature falls with increasing altitude in the troposphere: about 1 °C per 100 m for rising dry air and on average about 0.65 °C per 100 m in the real atmosphere.

Harm from climate change that cannot be avoided by mitigation or adaptation, such as destroyed homes or land lost to the sea, and the finance provided to help vulnerable countries recover.

A period of days to months when sea surface temperatures in an area are unusually high for the time of year, a common trigger of mass coral bleaching.

A greenhouse gas (CH₄) released by wetlands, ruminant livestock, rice paddies, landfill and fossil fuel leaks; it lasts about 10 years in the atmosphere but traps far more heat per tonne than carbon dioxide.

Regular variations in the shape of the Earth’s orbit, the tilt of its axis and the direction of its axis, which change the distribution of solar radiation and pace glacial–interglacial cycles over tens of thousands of years.

The international treaty, signed in 1987 and in force from 1989, that controls the production, use and trade of CFCs and other ozone-depleting substances; it has been ratified by every UN member state.

The fund set up under the Montreal Protocol, financed by developed countries, that pays the extra costs developing countries face in phasing out ozone-depleting substances.

A plan prepared by a least developed country under the UNFCCC that identifies its most urgent climate adaptation needs and ranks priority projects for funding.

A country's own climate action plan under the Paris Agreement, setting out its emissions targets and policies, updated every five years.

A state in which human-caused greenhouse gas emissions are cut as far as possible and any that remain are balanced by an equal amount of greenhouse gas removed from the atmosphere.

A long-lived greenhouse gas (N₂O), released mainly from fertilised soils, manure and some industrial processes, with a 100-year global warming potential of about 273; it also depletes stratospheric ozone.

An adaptation to climate change that changes behaviour, rules, knowledge or practices rather than building infrastructure, such as early warnings, land zoning, building codes or drought-resistant crops.

The angle of tilt of the Earth’s axis, which varies between about 22.1° and 24.5° over a cycle of about 41,000 years; greater tilt gives stronger seasons.

A geoengineering method that adds nutrients, usually iron, to parts of the ocean where they limit phytoplankton growth, so that the extra phytoplankton absorb carbon dioxide.

The reduction in stratospheric ozone caused mainly by chlorine and bromine from human-made ozone-depleting substances, which allows more UVB radiation to reach the Earth’s surface.

A region of severe seasonal ozone depletion over a pole in spring, usually defined as the area where total ozone falls below 220 Dobson units.

A human-made chemical, such as a CFC, halon, carbon tetrachloride, methyl bromide or HCFC, that reaches the stratosphere and releases chlorine or bromine that destroys ozone.

The international climate agreement adopted at COP21 in 2015, in which almost every country agreed to keep warming well below 2 °C and to set its own emissions targets.

A cloud of ice or nitric acid particles that forms in the polar stratosphere at about −80 °C or colder; reactions on its surfaces release chlorine that destroys ozone when sunlight returns in spring.

A large ring of strong winds that circles a pole in the stratosphere during winter, isolating very cold air inside it and allowing polar stratospheric clouds to form.

The slow change in the direction in which the Earth’s axis points, which shifts the season in which the Earth is closest to the Sun over a cycle of roughly 21,000–26,000 years.

Indirect evidence of past climate preserved in natural records, such as ice cores, tree rings, pollen and sediments, used to reconstruct conditions from before instrumental measurements began.

The current geological period, which began about 2.58 million years ago and is characterised by repeated cycles of glacial and interglacial periods.

The change in the Earth’s energy balance, in watts per square metre, caused by a change in a factor such as a greenhouse gas or aerosol since a reference time; positive values cause warming.

The replanting or natural regrowth of forest on land where forest has recently been cleared or degraded.

A fluid that absorbs heat as it evaporates and releases it as it condenses, used in refrigerators and air conditioners; CFCs, HCFCs and HFCs have all been used as refrigerants.

An increase in global mean sea level, caused mainly by thermal expansion of warming sea water and by meltwater from glaciers and ice sheets on land.

A set of five storylines describing how society, population and the economy might develop this century, combined by the IPCC with emissions levels to project future climate change.

Radiation of relatively short wavelength, mainly visible light, ultraviolet and near infrared, emitted by the very hot Sun; most passes through the atmosphere without being absorbed by greenhouse gases.

A city that uses sensors, data and digital networks to run services such as energy, transport, water and waste more efficiently, often with apps that help citizens choose low-carbon options.

The principle that each state has full authority over its own territory and affairs, so no outside body can force it to act without its consent, for example to cut its emissions.

The layer of the atmosphere from about 12 km to 50 km, in which temperature rises with height because ozone absorbs ultraviolet radiation; it contains the ozone layer.

A proposed geoengineering method that would release reflective particles such as sulfates into the stratosphere so that less sunlight reaches the Earth's surface.

Ozone in the stratosphere, mostly between about 15 km and 35 km (the ozone layer), which absorbs all incoming UVC and most UVB and so protects life at the surface.

An adaptation to climate change that involves building or changing physical infrastructure, such as flood defences, sea walls, cyclone shelters or desalination plants.

A payment or tax reduction from government that lowers the cost of a product or activity, used for example to encourage renewable energy, electric vehicles or insulation.

The difference between a measured temperature and the average for a reference period, such as 1850–1900, used to show how much warmer or cooler a year or place is than normal.

The increase in volume of a substance as its temperature rises; in the ocean it raises sea level because warmer water takes up more space.

A chain of events in which crossing the tipping point of one part of the Earth system makes it more likely that other parts cross their own tipping points, like falling dominoes.

The lowest layer of the atmosphere, from the surface to about 12 km, holding most of its mass and water vapour, where temperature usually falls with height and weather occurs.

Electromagnetic radiation with wavelengths of about 100–400 nm, shorter than visible light, divided into UVA, UVB and UVC; its high energy can damage DNA and living cells.

The international treaty agreed in 1992 whose aim is to stabilise greenhouse gas concentrations at a level that prevents dangerous human interference with the climate system.

Ultraviolet radiation with wavelengths of 315–400 nm; the lowest-energy ultraviolet band, most of which reaches the surface, where it causes skin ageing and contributes to skin cancer.

Ultraviolet radiation with wavelengths of 280–315 nm, mostly absorbed by stratospheric ozone; the part that reaches the surface causes sunburn, DNA damage, skin cancer and cataracts.

Ultraviolet radiation with wavelengths of 100–280 nm; the highest-energy and most damaging ultraviolet band, completely absorbed by ozone and oxygen in the upper atmosphere.

Water in its gaseous state in the atmosphere; the most abundant greenhouse gas, whose amount depends on temperature, so it amplifies warming caused by other gases rather than driving it.

Single-celled photosynthetic algae that live inside the tissues of reef-building corals in a mutualistic relationship, supplying most of the coral's food and its colour.