Glossary A–Z.

A

AdaptationAdjusting to the effects of climate change, for example by building sea walls or growing drought-resistant crops.Air Quality IndexIndia’s scale for reporting air pollution, from 0 to 500, in six bands from “good” to “severe”. It is based on up to eight pollutants, including PM2.5, PM10 and ozone.

B

BiodiversityThe variety of life — species, the genes within them and the ecosystems they form.

C

Carbon dioxide removalTaking carbon dioxide out of the atmosphere and storing it — through forests and soils, or with technologies such as direct air capture.Carbon footprintThe total greenhouse gases caused by a person, product, company or country, usually given in tonnes of carbon dioxide equivalent.Carbon marketA system for trading permits or credits that each represent one tonne of carbon dioxide (or equivalent) not emitted or removed. India notified its own Carbon Credit…Climate changeLong-term change in temperatures and weather patterns. Since the 1800s the main driver has been human activity, above all burning coal, oil and gas.COPConference of the Parties: the annual summit of the countries that have joined the UN Framework Convention on Climate Change.CycloneA large storm system rotating around an area of low pressure. In the north Indian Ocean, storms are named from a list contributed by the countries of the region.

E

El NiñoA periodic warming of surface waters in the central and eastern tropical Pacific that shifts weather around the world. It is often linked to weaker monsoon rains in…Electric vehicleA vehicle driven by an electric motor running on a battery, which produces no exhaust fumes on the road.Emissions gapThe difference between where greenhouse gas emissions are heading and where they need to be to meet the Paris Agreement’s temperature goals. The UN Environment Programme…

G

Glacier mass balanceThe difference between the snow and ice a glacier gains in a year and the ice it loses. A negative balance means the glacier is shrinking; see the chart in our data hub.Global warmingThe rise in the Earth’s average surface temperature since pre-industrial times, caused mainly by greenhouse gases from human activity.Green hydrogenHydrogen made by splitting water with electricity from renewable sources, so that producing it releases almost no carbon dioxide.Greenhouse gasA gas that traps heat in the atmosphere, such as carbon dioxide, methane and nitrous oxide. Burning coal, oil and gas is the biggest source of the increase since the…

H

HeatwaveA spell of abnormally hot weather. In the plains the India Meteorological Department declares one when the maximum temperature is at least 40°C and well above normal, or…

L

Loss and damageHarm from climate change that cannot be avoided by adaptation. A fund to help vulnerable countries was agreed at COP27 in 2022 and set up at COP28 in 2023.

M

MitigationCutting the greenhouse gas emissions that cause climate change, or removing gases from the air.MonsoonThe seasonal reversal of winds that brings most of India’s rain. The south-west monsoon normally runs from June to September; parts of the south-east also get rain from…

N

NDCNationally determined contribution: each country’s climate plan under the Paris Agreement, setting out how it will cut emissions and adapt. Countries are expected to…Net zeroThe point at which the greenhouse gases a country or company emits are balanced by those it removes from the atmosphere. India’s target year is 2070.

O

OvershootTemporarily exceeding a temperature limit such as 1.5°C and then bringing warming back below it by removing carbon dioxide from the atmosphere.Ozone layerThe layer of the upper atmosphere that absorbs most of the Sun’s harmful ultraviolet rays. The Montreal Protocol of 1987 phased out the chemicals damaging it.

P

Paris AgreementThe 2015 climate treaty under which countries agreed to hold global warming well below 2°C above pre-industrial levels and to pursue efforts to limit it to 1.5°C.Parts per millionA measure of concentration: the number of molecules of a gas in every million molecules of air. It is the usual unit for carbon dioxide in the atmosphere.PM2.5Particulate matter 2.5 micrometres across or smaller — about thirty times thinner than a human hair — which can travel deep into the lungs and the bloodstream.

R

Renewable energyEnergy from sources that are naturally replenished, such as sunlight, wind, flowing water and biomass.

S

Stubble burningSetting fire to crop residue left in fields after harvest, a major source of autumn smoke over north India.

U

Urban heat islandA city that is noticeably hotter than the countryside around it, because concrete and asphalt store heat and there is less greenery.

W

Western disturbanceA weather system that travels east from the Mediterranean region and brings winter rain and snow to north India.Wet-bulb temperatureA measure of heat and humidity together. The higher it is, the harder it is for the body to cool itself by sweating.