Air pollution has a cooling effect on the atmosphere, while greenhouse gases cause global warming. Discover why both emission types must be cut in combination to preserve our environment.
I get drawn into arguments more often than I probably should. Climate deniers, in particular, tend to raise my ire.
The science is settled. The climate crisis is real and caused by human activity. Yet, there are still a few people who cling to the notion that we have nothing to worry about from global warming.
One argument they often raise is that “carbon dioxide isn’t air pollution” They’re arguing about semantics when they bring this up, trying to make a point.
We Can Define Pollutants in Multiple Ways
We can define pollutants in multiple ways. The definition that matters comes from the legislation. In most jurisdictions, carbon dioxide is regulated as a pollutant. So, C02 emissions are pollutants for all practical purposes.
Even so, the argument over C02 versus pollution is becoming a distinction without a difference. We’ve learned that many substances that everyone thinks of as air pollution affect the climate.
Here in Canada, we call them short-lived climate pollutants. They include black carbon, methane, ground-level ozone and chlorofluorocarbons (CFCs).
Differentiate Air Pollution and Greenhouse Gases
A new study from Japan’s Kyushu University raises another issue with trying to differentiate between air pollution and greenhouse gases. They’ve shown that reducing conventional air pollution in the form of sulphate aerosols makes the climate crisis worse.
It’s a kind of Catch-22. Sulphate aerosols hover in the atmosphere and block sunlight. So, they have a cooling effect on the Earth’s climate.
That means that cutting emissions of pollutants like sulphur dioxide (S02) that turn into sulphate aerosols causes global warming. Ironically, cutting conventional air pollution makes climate change worse.
Doesn’t Meant that Sulphur Dioxide is a Good Thing
That doesn’t mean that S02 is a good thing to be spewing into the air. Professor Toshihiko Takemura of Kyushu University’s Research Institute for Applied Mechanics is the author of the study.
He explains the challenge this way, ““Air pollution causes an estimated seven million premature deaths per year worldwide, so action is essential, especially in emerging and developing countries, which tend to be most affected. However, reductions in air pollutants must come hand in hand with reductions in greenhouse gases to avoid accelerating global warming.”
In other words, if we don’t cut greenhouse gas emissions, cutting air pollution will aggravate the climate crisis. If we want to reduce S02 emissions, we have to eliminate greenhouse gas emissions in lockstep with those measures.
Minute Particles of Sulphur Compounds
Sulphate aerosols are minute particles made of sulphur compounds. They can be natural, but most of them come from human activity, like burning fossil fuels or biomass like wood.
Professor Takemura looked at data from two combined computer models called MIROC and SPRINTARS.
MIROC models the circulation of the atmosphere and the oceans which SPRINTARS provides air pollution forecasts for weather reports.
How Sulphate Aerosols Mix with the Atmosphere
The combined program calculates and makes predictions based on how sulphate aerosols mix with the atmosphere as they move around over time. Professor Takemura looked at both short and long-term effects of reducing air pollution in the form of sulphate aerosols.
In the short term, the model showed that reducing air pollution allows more of the sun’s energy to enter the Earth’s atmosphere. However, the immediate effects didn’t change much, even with twice our current carbon dioxide emissions.
“Eventually Leads to a Bigger Temperature Increase”
The issue arises in the longer term. At that point, the model shows the Earth’s surface temperature rising. Worse, the temperature increases faster when the model doubles the volume of C02 emissions.
As Professor Takemura put it, “Although the fast response is similar for both situations, long-term changes caused by more slowly responding factors related to interactions with the oceans and subsequent changes, such as in clouds and precipitation, eventually leads to a bigger temperature increase.”
So, there’s no point in making a distinction between C02 and more traditional air pollution. Assuming that we plan to keep reducing air pollution, that’s going to make our planet warmer.
Have to cut Pollution and Greenhouse Gases
That, in turn, means that we can’t afford to cut air pollution unless we cut greenhouse gas emissions enough to compensate for that warming effect. It’s not an either/or decision. We have no choice but to cut both in unison.
We tend to think of nature as a collection of unrelated objects. That’s been the folly of our industrial age.
More and more people are coming to understand our environment as a web of interrelated subjects. The way our atmosphere works is another example of that.
Misleading to Think About Implications in Isolation
It’s misleading to look at one type of emission and think about its implications in isolation. We need to take a systems approach where we recognize and respect the complexity of natural systems.
Distinguishing between air pollution and greenhouse gas emissions misses the point. We have to consider the combined effects of our emissions on the Earth’s overall geophysical systems.
Professor Takemura wrapped things up by saying, “Thus, global warming will accelerate unless increases in greenhouse gas concentrations are suppressed as air pollution control measures decrease aerosol sulphate concentrations, further emphasizing the urgency for reducing carbon dioxide in the atmosphere,”
“Urgency for Reducing C02 in the Atmosphere”
The upcoming research stage considers how local climates change when governments require industries to cut SO2 emissions, lowering aerosol sulphate concentrations in the air. Professor Takemura also plans to investigate the effects of other short-lived climate pollutants, like methane, ground-level ozone, organic aerosols, and hydrofluorocarbons (HFCs).
We always have more to learn if we dare to know.
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