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Clean Air, Clean Planet: Climate Pollutant Science - A Dialogue with Scientists and Journalists

by Aleksander Esmann

HAF Intern

As part of the Climate and Clean Air Conference 2023 in Bangkok, a dialogue with scientists and journalists covering the nexus of climate change and air pollution took place on May 31.

While a couple of years ago air pollution was a relevant topic in politics and media, the attention has recently shifted entirely towards climate change. While climate change action definitely helps improve air quality and thus protect public health as well as agricultural and ecosystems, more direct steps must be taken soon.

Air pollution is not an issue that we will have to deal with in the future - it is here now and its impact can be felt all over the world already. According to the World Health Organization (WHO) air pollution is responsible for 7 million premature deaths every year.

Michael Brauer from the University of British Columbia presented the effects of climate pollution on health. Together with a team of scientists he gathered information from 750 communities from all over the world and they found several strong correlations between air pollution and health.

First, on days with stronger air pollution, more people die. Second, people in more polluted cities die earlier than people living in less polluted ones and in the most polluted areas of cities there is an even greater risk of dying prematurely. However, these deaths do not just occur in heavily affected areas but basically everywhere because there is no such thing as a “safe level of air pollution”.

This makes it very difficult to impose standards as even the WHO´s air quality guideline for fine particles (PM 2.5), which proposes a maximum average of 5 μg/m3 in a calendar year, shows a 5% increase in relative risk. For comparison, the annual average in New York City is 12 μg/m3, which already poses a 10% increase in risk.

Air pollution can be linked to the top 9 global causes of death. It is estimated to be responsible for about 7% of all deaths, lowering the mean global life expectancy by about a year, and to cause $5 trillion of welfare losses every year.

Especially elderly people are vulnerable to diseases caused by air pollution, which means that with an ever-increasing life expectancy all across the world this issue will become more and more relevant in the future. In general, improving air quality offers even bigger health benefits than reducing global warming.

While measures to improve air quality are very helpful, there is one thing which could undo

all of the progress made in the last 50 years: Wildfires have become more frequent and more devastating in the last couple of years due to climate change. Not only do these fires destroy the forests, which act like filters to clean the air, but they also produce smoke, which severely pollutes the air.

The dangerous component of these smokes is black carbon, one of the most harmful air pollutants. Black carbon is a component of PM 2.5 and it consists of pure carbon in several linked forms. It is produced when fossil fuels, biomass or biofuels are not fully combusted. Black carbon has two main effects. First, it is very harmful to the lungs and can lead to various respiratory diseases. Second, it is about 1000 times more warming than CO2 as it absorbs sunlight and thus accelerates global warming.

One of the main consequences of global warming are heatwaves and droughts. After analyzing the 2015 heatwave in India, scientists found that air pollution and in particular warming aerosols (black carbon) worsen heat waves. The scientists observed a direct correlation. Whenever black carbon levels increased, the daily maximum temperature increased by 0.2 - 2 °C as well.

On top of that aerosols prevent moisture from rising upwards from the oceans, which leads to disturbed weather cycles and decreases in rainfall. In India regions with higher aerosol levels experienced more monsoon breaks which in turn worsens water availability. In Europe on the other hand, where black carbon levels have been decreased already, rainfalls went up again.

Many developed countries have already passed and continue to improve laws regarding black carbon emissions. Today, the majority of them are produced in East and South-East Asia, South America and Central Africa. While much of the climate action focuses on formal sectors such as fossil fuels and heavy industry, a bigger emphasis must be put on informal sectors such as households and agriculture as these emit big amounts of pollutants, which have a strong impact on the climate in the short term. Simple steps such as providing access to clean cooking stoves or installing filters to prevent black carbon from reaching the air can already make a big impact.

Coupling these efforts with the mitigation of other short-lived climate pollutants (SLCPs) such as methane or ozone, which stay in the atmosphere for a much shorter period of time than CO2, can give societies and nature more time to adapt to climate change and develop strategies to counteract it.

Ozone and methane are two closely connected greenhouse gasses, which also have a big impact on air quality. While ozone in the stratosphere plays an important role in protecting the surface of the Earth from dangerous UV rays, it can damage the tissues of the respiratory tract when inhaled, thus causing various health issues. On top of that it is toxic to plants and can endanger food security.

Methane on the other hand can reduce the amount of oxygen breathed from the air and cause health conditions, but that is not the only danger it poses. Because methane and ozone levels are closely connected, increases in methane can lead to higher ozone levels, which are very dangerous for humans.

This together with the fact that methane is responsible for about 30% of global warming since pre-industrial times makes it imperative to mitigate methane emissions. Right now however, methane levels are increasing at a higher rate than ever as most of the climate action is focusing on reducing CO2 emissions. On top of that, the air-polluting qualities of methane are often dismissed as it spreads around the globe quickly, giving no big, quick local benefits from out-lawing it.

Achieving a reduction of methane emissions of 45% would mean avoiding a temperature increase of 0.3° C and is imperative to achieve the 1.5° C target. 0.3° C may not sound like a lot, but it would prevent an estimated 255,000 deaths from respiratory and cardiovascular diseases, 775,000 asthma-related hospital visits, 26 million tonnes of staple crop losses and 73 billion work hours lost to heat exposure.

The main methane-emitting sectors are fossil fuels, agriculture and waste. Methane emissions could be reduced relatively easily in the fossil fuel industry. There a lot of it is leaked from pipelines or produced as a byproduct of oil drilling. Controlling these leaks would be a very big step and much more effective than waiting for the energy transition because it could be done immediately.

Oil companies have the technology and the funds to capture the methane, which they could even sell for a profit, but actively choose not to do so as investing in additional fossil fuel production yields higher returns. Because of this companies must be forced to implement these measures, which would cost about $70 billion in total. By comparison, Aramco, the oil company with the biggest profit in 2022, had a net income of $161 billion in just one year.

One of the main challenges of preventing methane leaks is identifying them first. About 50% of total leakage stems from accidents and it can take a long time for companies to notice them. Using satellite data has the potential to change that. Up until now only very big methane leaks could be detected, but thanks to recent developments and improvements automated systems could be put in place to monitor and recognize smaller methane leaks and notify oil companies immediately.

The most effective way to reduce methane emissions in agriculture and waste is a change in lifestyle. While there are things such as more climate-friendly fertilizers and waste plants, reducing meat consumption and waste has a bigger impact and is much less complicated.

To achieve that, journalists and media have to communicate more effectively and compellingly to the population why and how they should change their way of living. This requires closer communication and cooperation between journalists and scientists to target regional issues that affect the people and to give them better insights as to how their actions can improve their situation.

This also offers various opportunities. For example, eating less meat has various health benefits and the methane from landfills could be used to produce electricity. The main challenge with the latter is often not a lack of technology or funding but bad waste management.

When it comes to methane emissions, reaching net zero emissions is not necessary to achieve a sustainable low level of warming because, other than CO2, methane dissolves relatively quickly and does not have a compounded warming effect.

As it can be seen, climate change and air pollution are closely related as many greenhouse gasses also lower air quality, which offers many opportunities to mitigate the health impacts of air pollution while taking climate action. One of the core ideas of the conference was implementing complementing measures with cumulative benefits instead of focusing on single measures or measures that interfere with each other. This would enable us to achieve much bigger improvements in several sectors while requiring lower investments. For instance, riding bicycles instead of driving cars not only reduces carbon emissions but also provides health benefits.

Tatsuya Hanaoka from the National Institute for Environmental Studies in Japan talked about these interdependencies in the context of the economic impacts of air pollution, a very complex field of research that takes into account several factors such as socio-economic drivers, emission projections and climate models.

The goal of his work is to estimate the cost of action and inaction regarding climate change and air pollution. The cost of action is the additional cost of climate measures such as changing from fossil fuels to renewable energy, whereas the cost of inaction could be health costs caused by polluted air.

While quantifying the cost of action is relatively straightforward, estimating the cost of inaction is very difficult as air pollution has impacts in many different areas of life, from health to agriculture, which are all closely interconnected.

Up until now, studies have only been conducted in regard to CO2. Nonetheless, the current scientific consensus is that the cost of inaction is much higher than the cost of action. That is without taking into account things such as lost human lives, destroyed ecosystems or animal species going extinct, which are all priceless. Considering that many other greenhouse gasses and air pollutants were also not considered, this difference is expected to be even bigger than calculated, meaning that it is much cheaper to invest in mitigation action now as this will avoid a lot of costs in the long run.

The overarching consensus was that while combating climate change is of big importance, reducing air pollution must not be overlooked. At the moment, it causes many premature deaths, droughts, heatwaves and food shortages which could easily be avoided. Fortunately, climate change and air pollution can be addressed simultaneously in various ways as the main air polluters are often greenhouse gasses. Action must be taken as soon as possible as any additional delay causes exponentially more lost lives, destroyed crops, losses of biodiversity and exorbitant costs that will affect our and future generations.

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