Air pollution and fires, threats to clean water

The World Meteorological Organization published its annual report on air quality and climate, which on this occasion has highlighted how the growing forest fires will influence the air we breathe, in our health, in ecosystems and in resources such as water.

The annual report on air quality of the World Meteorological Organization focuses on how the growing forest fires will affect the quality of the air we breathe and the problems they will cause in ecosystems and bodies of water.

Air pollution and fires

The report notes that, as in 2020, high temperatures and dry weather conditions exacerbated the spread of wildfires in western North America and Siberia, resulting in widespread increases in small particulate matter levels in suspension (PM 2.5), which constitute a health hazard.

“As the planet warms, wildfires and air pollution are projected to increase, even in a low emissions scenario. In addition to the consequences for human health, this situation will also affect ecosystems and water quality, since air pollutants are deposited from the atmosphere on the earth's surface”, explained Professor Petteri Taalas, WMO Secretary General.

The organization also refers to how heat waves, with stable conditions in the upper atmosphere, high solar radiation and low wind speed, have given rise to serious pollution episodes, such as those that occurred this summer in Spain and throughout Europe.

“This is a preview of the future, as a further increase in the frequency, intensity and duration of heat waves is expected, which could further worsen air quality, a phenomenon that is called a 'climate penalty' added the teacher.

The “climate penalty” refers specifically to the amplifying effect of climate change on tropospheric ozone production, which has a negative effect on the air we breathe. The regions with the largest predicted climate penalty, primarily Asia, are home to about a quarter of the world's population. Climate change could exacerbate episodes of surface ozone pollution, leading to detrimental health effects for hundreds of millions of people.

Air and water pollution

Air quality affects the health of ecosystems through atmospheric deposition, as air pollutants are deposited from the atmosphere on land, bodies of liquid water, and ice masses. Nitrogen, sulfur and ozone deposition can have a negative effect on the services provided by natural ecosystems, for example, clean water, biodiversity and carbon storage, as well as affect crop yields in agricultural systems.

Particles and ashes from pollution and fires contribute to the contamination of water bodies, reducing their quality. In addition, fire erodes the soil, causing water management problems when heavy rains occur that can lead to flooding. If these precipitations also carry ashes, they pose a serious problem for water purification systems, as is happening, for example, in the city of Las Vegas, New Mexico, where work is being done against the clock to find a solution to the problem, since only water to supply the population for 20 days.

When these particles are on snow or ice, they cause a decrease in its reflectivity and an increase in its absorption of heat. As a result, there is an acceleration of the melting processes, mainly in the lower and intermediate zones of the glaciers.

They can also modify rain cycles. The clouds, with a high amount of black carbon, are less reflective than normal, rise to different atmospheric levels and alter their location. A high accumulation of toxic vapors and gases in the clouds produces what is known as 'acid rain', which returns contaminated water to the ground. A water that reaches rivers and seas and contributes to contaminate their surface. These precipitations also seriously affect the soil, since the acids increase erosion, damaging land and crops.

Spain and France have recorded the highest carbon emissions of the last 20 years between June and August, driven in large part by the devastating forest fires that have occurred in the southwest of France and the Iberian Peninsula in recent months. This follows from a report by the Copernicus Atmospheric Monitoring Service, according to which the total accumulated area burned in the European Union from the beginning of the year to September 3 amounts to more than 750,000 hectares, compared to an average of just over 260,000 hectares between 2006 and 2021.

According to data from the CAMS Global Fire Assimilation System (GFAS), the total emissions from wildfires in the EU and the UK between June 1 and August 31, 2022, are estimated at 6.4 megatonnes of carbon, the highest level high since 2007. GFAS is based on satellite observations of active fires and fires radioactive energy (FRP), which uses remote sensing data to estimate the amount of biomass burned, to estimate emissions of smoke pollutants.

Fires in 2021

The European Union's Copernicus Atmospheric Monitoring Service measures global concentrations of particulate matter. Inhalation of PM 2.5 (ie, particles with a diameter of 2.5 micrometres or less) over prolonged periods is a serious health hazard. Sources of such particles include emissions from burning fossil fuels, forest fires, and windblown desert dust.

The WMO report highlights that severe wildfires generated exceptionally high concentrations of PM 2.5 in Siberia, Canada and the western United States in July and August 2021. PM 2.5 concentrations in eastern Siberia reached levels never before seen and were primarily driven by rising high temperatures and dry ground conditions.

Estimated total annual emissions in western North America were in the first five years of the 2003-2021 period, with PM 2.5 concentrations far exceeding World Health Organization recommended limits.

On a global scale, observations of the total annual area burned show a downward trend in the last two decades, as a result of fewer fires in savannahs and grasslands. However, on a continental scale, upward trends have been observed in some regions, for example parts of western North America, the Amazon and Australia.

Reducing emissions would help

The WMO renewed calls to respect the Paris climate agreement saying that as well as halting global temperature rise, it will also help halt contributions to air quality degradation.

"A future world following 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 WMO said.

“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 from air".

Carbon neutrality can limit ozone air pollution

The bulletin indicated that a carbon-neutral global emissions scenario would limit the future occurrence of extreme ozone air pollution episodes.

This is because efforts to mitigate climate change by eliminating the burning of (carbon-based) fossil fuels will also eliminate most human-caused emissions of ozone precursor gases, particularly nitrogen oxides (NOx), volatile organic compounds and methane.

The particles, commonly called aerosols, have complex characteristics that can cool or heat the atmosphere. High amounts of aerosols, and thus poor air quality, can cool the atmosphere by reflecting sunlight back into space or by absorbing sunlight in the atmosphere so it never reaches the ground.

The Intergovernmental Panel on Climate Change suggests that the low-carbon scenario will be associated with little short-term warming before the temperature declines.

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 reduced carbon dioxide emissions will take more time.

However, natural aerosol emissions (eg, dust, wildfire smoke) are likely to increase in a warmer, drier environment due to desertification and drought conditions. This may cancel out some of the effects of reductions in aerosols related to human activities.

A future world following a low-carbon scenario would benefit from reduced deposition of nitrogen and sulfur compounds from the atmosphere to the Earth's surface, where ecosystems could be damaged.

WMO stations around the world would monitor the response of air quality and the health of ecosystems to propose future emission reductions, and this could quantify the effectiveness of policies designed to limit climate change and improve the quality of the environment.

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