World Meteorological Organization #AirQuality and #Climate bulletin highlights impact of #wildfires #ActOnClimate #KeepItInTheGround – Coyote Gulch

Growing risk of “climate penalty” due to pollution and climate change

A projected increase in the frequency, intensity and duration of heat waves and an associated increase in wildfires this century are likely to worsen air quality, harming human health and to ecosystems. The interaction between pollution and climate change will impose an additional “climate penalty” on hundreds of millions of people, according to a new report from the World Meteorological Organization (WMO).

The WMO Annual Bulletin on Air Quality and Climate reports on the state of air quality and its close links with climate change. The bulletin explores a range of possible air quality outcomes under high and low greenhouse gas emission scenarios.

The WMO Air Quality and Climate Bulletin 2022 focuses in particular on the impact of smoke from wildfires in 2021. As in 2020, hot and dry conditions exacerbated the spread of fires of forest in western North America and Siberia, leading to a general increase in fine particulate matter (PM2.5) levels harmful to health.

“As the globe warms, wildfires and associated air pollution are projected to increase, even under a low emissions scenario. In addition to impacts on human health, this will also affect ecosystems as air pollutants are deposited from the atmosphere to the Earth’s surface,” said WMO Secretary-General Professor Petteri Taalas.

“We’ve seen it during the heat waves in Europe and China this year, when stable high atmospheric conditions, sunlight and low wind speeds were conducive to high levels of pollution,” the professor said. Taalas.

“This is a taste of the future as we expect a further increase in the frequency, intensity and duration of heat waves, which could lead to even worse air quality. , a phenomenon known as the “climate malus,” he said.

The “climate penalty” specifically refers to the amplifying effect of climate change on ground-level ozone production, which negatively impacts the air people breathe. The regions with the highest predicted climate penalty – mainly in Asia – are home to about a quarter of the world’s population. Climate change could exacerbate surface ozone pollution episodes, leading to adverse health effects for hundreds of millions of people.

The Air Quality and Climate Bulletin, the second in an annual series, along with an animation on atmospheric deposition, was released ahead of the International Day of Clean Air for clear skies on September 7 . The theme of this year’s event, led by the United Nations Environment Programme, is The air we shareemphasizing the transboundary nature of air pollution and emphasizing the need for collective action.

The bulletin is based on the contributions of experts from the WMO Global Atmosphere Monitoring Network which monitors air quality and greenhouse gas concentrations and can thus quantify the effectiveness of the policies designed to limit climate change and improve air quality.

Air quality and climate are linked because the chemical species that cause air quality degradation are normally co-emitted with greenhouse gases. Thus, changes in one inevitably lead to changes in the other. The burning of fossil fuels (a major source of carbon dioxide (CO2)) also emits nitrogen oxide (NO), which can react with sunlight to form ozone and nitrate aerosols.

Air quality in turn affects ecosystem health via atmospheric deposition (when air pollutants are deposited from the atmosphere to the Earth’s surface). Nitrogen, sulfur and ozone deposition can negatively affect services provided by natural ecosystems such as clean water, biodiversity and carbon storage, and can impact crop yields in systems. agricultural.

Forest fires in 2021

The European Union’s Copernicus Atmosphere Monitoring Service measures particulate matter around the world. PM2.5 (i.e. particles with a diameter of 2.5 micrometers or less) is a serious health hazard by prolonged inhalation. Sources include emissions from burning fossil fuels, wildfires, and windblown desert dust.

Intense wildfires generated abnormally high PM2.5 concentrations in Siberia and Canada and the western United States in July and August 2021. PM2.5 concentrations in eastern Siberia have reached levels never seen before, mainly due to increasing high temperatures and dry soils.

Estimated total annual emissions in western North America ranked within the top five years of the 2003-2021 period, PM2.5 concentrations well above the limits recommended by the World Health Organization.

Globally, observations of annual total area burned show a downward trend over the past two decades due to fewer fires in savannas and grasslands (WMO Aerosol Bulletin 2021 ). However, on a continental scale, some regions are seeing increasing trends, including parts of western North America, the Amazon, and Australia.

Future scenarios

The Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC) includes scenarios of how air quality will change as temperatures rise in the 21st century. It assessed that the likelihood of catastrophic wildfires – such as those seen in central Chile in 2017, Australia in 2019 or the western United States in 2020 and 2021 – is likely to increase by 40 to 60% by the end of this century under high intensity. low-emission scenario, and 30-50% for a low-emission scenario.

If greenhouse gas emissions remain high such that global temperatures increase by 3°C above pre-industrial levels by the second half of the 21st century, surface ozone levels are projected to rise in the heavily polluted areas, especially in Asia. This includes a 20% increase in Pakistan, northern India and Bangladesh, and 10% in eastern China. Most of the increase in ozone will be due to an increase in emissions from the burning of fossil fuels, but about a fifth of this increase will be due to climate change, most likely achieved by increased heat waves , which amplify air pollution episodes. Therefore, heat waves, which are becoming more frequent due to climate change, are expected to continue to cause air quality degradation.

A global scenario of carbon neutral emissions would limit the future occurrence of extreme episodes of ozone air pollution. Indeed, efforts to mitigate climate change by eliminating fossil fuel (carbon-based) combustion will also eliminate most human-made emissions of ozone precursor gases (especially nitrogen oxides ( NOX), volatile organic compounds and methane).

Particulate matter, commonly referred to as aerosols, has complex characteristics that can cool or warm the atmosphere. Large amounts of aerosols – and therefore poor air quality – can cool the atmosphere by reflecting sunlight back into space or by absorbing sunlight back into the atmosphere so that it does not never reaches the ground.

The IPCC suggests that the low-carbon scenario will be associated with slight short-term warming before temperature drops. This is because the effects of reduced aerosol particles, i.e. less sunlight reflected back into space, will be felt first, while temperature stabilization in response to emission reductions carbon dioxide will take longer. However, emissions of natural aerosols (e.g. dust, smoke from forest fires) are likely to increase in a warmer and drier environment due to desertification and drought conditions, and may negate some of the aerosol reduction effects related to human activities.

A future world that follows a low-carbon scenario would also benefit from reduced deposition of nitrogen and sulfur compounds from the atmosphere to the Earth’s surface, where they can damage ecosystems. The response of air quality and ecosystem health to proposed future emission reductions will be monitored by WMO stations around the world, which can quantify the effectiveness of policies designed to limit climate change. and improve air quality. WMO will therefore continue to work with a wide range of partners, including the World Health Organization and the EU’s Copernicus atmospheric monitoring service to monitor and mitigate impacts.

The World Meteorological Organization is the authoritative voice of the United Nations system on weather, climate and water

For more information, contact: Clare Nullis, WMO Press Officer, [email protected] Tel 41-79-7091397

Aubrey L. Morgan