Integrated Assessment of Short-lived Climate Pollutants in Latin America and the Caribbean

Key messages:

• Poor air quality and climate change have already affected vulnerable populations and ecosystems in LAC, resulting in premature deaths, crop yield losses and damage to ecosystems.
• Agriculture, transport, domestic and commercial refrigeration are the sectors that product the largest emissions of methane, particulate matter, black carbon, and HFCs.
• Without any action to reduce SLCP missions, the influence of LAC emissions on climate, human health and agriculture will increase significantly by 2050.
• A number of SLCP measures has been identified that, by 2050, has the potential to reduce warming in LAC by up to 0.9 degrees Celsius, premature mortality from PM2.5 by at least 26 per cent annually, and avoid the loss of 3–4 million tonnes of four staple crops each year.
• Efforts and experience on reducing some SLCPs are already in place across LAC and could be scaled up if identified barriers were overcome.
• The implementation of cleaner fuels, more efficient transport systems in LAC cities, will result in more accessibility of the population to jobs and less exposure to pollutants while commuting.

Methane (CH4): is a powerful greenhouse gas with a lifetime in the atmosphere of approximately 12 years. Increased methane emissions have caused the most significant warming of any greenhouse gas after CO2. It has a direct influence on the climate but is also notable for being an important precursor to tropospheric ozone (O3).

The LAC region is responsible for approximately 15% of global methane emissions. Virtually all of these emissions originate from three sectors: agriculture (approximately 50%) coal, oil and gas production and distribution (approximately 40%) and waste management (approximately 10%).

Ozone (O3): is a gas that exists in both the upper (stratosphere) and lower (troposphere) layers of the atmosphere. In the stratosphere ozone protects life on Earth from the sun’s harmful ultraviolet (UV) radiation. However, at ground level, it is an air pollutant, which is harmful to human and ecosystem health. It is also a major component of urban smog and the third most important contributor to global warming after methane and CO2. It stays in the atmosphere for a few hours to days. Recent studies have linked both short- and long-term ozone exposure to premature death, heart attacks, strokes, heart disease, congestive heart failure, and possible reproductive and developmental harm. It reduces crop yields and the quality and productivity of vegetation.

Ozone is considered a secondary pollutant because it is not emitted directly, but is formed when precursor gases such as methane, carbon monoxide, oxides of nitrogen (NOx) and non-methane volatile organic compounds (NMVOC) react in the presence of sunlight. It is a key reason why methane emissions must be reduced.

Black Carbon (BC): is a potent climate-warming particle that remains in the atmosphere for a few days or weeks. It is formed by the incomplete combustion of fossils fuels and biofuels. Black carbon and co-emitted pollutants contribute to the formation of fine air polluting particulate matter (PM2.5). PM2.5 has been linked to a number of health impacts including premature death in adults, heart and lung disease, strokes, heart attacks, chronic respiratory disease such as bronchitis, aggravated asthma and other cardio-respiratory symptoms.

The LAC region is responsible for less than 10 per cent of total global anthropogenic emissions of BC, excluding those from forest and savannah fires. Two major source sectors are responsible for about three quarters of BC emissions in LAC: transport and the residential burning of solid fuels for cooking and heating. More than 60 per cent of the region’s BC emissions originate in Brazil and Mexico.

Hydrofluorocarbons (HFCs): are a group of industrial chemicals primarily produced for use in refrigeration, air-conditioning, insulating foams and aerosol propellants, with minor uses as solvents and for fire protection. Many HFCs are very powerful greenhouse gases and a substantial number have a lifetime of between 15 and 29 years in the atmosphere. HFC consumption is projected to double by 2020, and their emissions could contribute substantially to global warming by the middle of the century.

The majority of the HFC emissions come from two sectors, mobile air conditioning, about 20 per cent, and commercial refrigeration, around 38 per cent. The third largest source of emissions, contributing around 15 per cent, is residential window- and split-unit air conditioners, listed as stationary air-conditioning. These three sectors offer a large opportunity for mitigation.