SLCPs, or short-lived climate pollutants

 

What are SLCPs?

SLCPs, or short-lived climate pollutants, are chemicals that remain in the atmosphere

for only a few days or a few decades at the most. They include black carbon, methane and

tropospheric ozone.

Black carbon, present in the atmosphere as particles, has a warming impact on climate

460-1 500 times stronger than CO2. With a lifetime that varies from a few days to a few

weeks, black carbon is a major component of soot and is produced by incomplete

combustion of fossil fuel and biomass. When deposited on ice and snow, black carbon

causes both atmospheric warming and an increase in melting rate. It also influences cloud

formation and affects regional atmospheric circulation and rainfall patterns. In addition,

black carbon is a primary component of particulate matter in air pollution, the major

environmental cause of premature human death globally.

Methane (CH4), a greenhouse gas, is over 20 times more potent than CO2 in terms of its

climate-warming impact. With an atmospheric lifetime of about 12 years, it is produced

through natural processes (e.g. the decomposition of plant and animal waste) and is also

emitted from man-made sources, including coal mines, natural gas and oil systems, and

landfills. Methane directly influences the climate system and also has indirect impacts

on human health and ecosystems, in particular through its role as a precursor of

tropospheric ozone.

Tropospheric or ground-level ozone (O3) is present in the lowest portion of the

atmosphere (up to 10-15 kilometres above the ground) and is responsible for a large part of

the human enhancement of the global greenhouse effect. With a lifetime of a few days to

a few weeks, it is not directly emitted, but rather is produced through sunlight-driven

oxidation of other agents, called ozone precursors: primarily methane (CH4), but also

carbon monoxide (CO), non-methane volatile organic compounds (NMVOCs) and nitrogen

oxides (NOX). Tropospheric ozone is a harmful pollutant that has detrimental impacts on

human health and plants, causing important reductions in crop yields.