Climate change. Take a deep breath. Even if the air looks clear, it’s nearly certain that you’ll inhale tens of millions of solid particles and liquid droplets. These ubiquitous specks of matter are known as aerosols, and they can be found in the air over oceans, deserts, mountains, forests, ice, and every ecosystem in between. And aerosols can change the climate!
Climate change, Aerosols And The Coronavirus
They drift in Earth’s atmosphere from the stratosphere to the surface and range in size from a few nanometers - less than the width of the smallest (corona)viruses - to several tens of micrometers, about the diameter of human hair. Despite their small size, they have major impacts on our climate and our health.
The coronavirus starts to effect life on a global scale. This also means that production of goods and transportation are slowing down rapidly.
Less production, less transport, less pollution and less aerosols!
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Global Temperature Rise: How Do Aerosols Affect Climate?
Aerosols affect the climate as strongly as greenhouse gases, but in a completely different way. They are able to scatter sunlight, meaning they actually cool the planet by reflecting about 1/4 of the sun’s rays back to space, with the IPCC concluding that industrial aerosols have acted to significantly slow the increase in global temperature over the last thirty years.
Coronavirus & Climate Change
Global Cooling: Mount Pinatubo
In 1991, the eruption of Mount Pinatubo in the Philippines ejected more than 20 million tons of sulfur dioxide—a gas that reacts with other substances to produce sulfate aerosol—as high as 60 kilometers (37 miles) above the surface, creating particles in the stratosphere. Those bright particles remained above the clouds and didn’t get washed from the sky by rain; they settled only after several years.
Climate change due large volcanic eruptions. The eruptions may lift sulfate aerosols into the stratosphere, which usually cools the global climate for the following year or two. (Graph by Robert Simmon, based on aerosol data from GISS and temperature data from the UAE CRU.)
Climatologists predicted global temperatures would drop as a result of that global sulfate infusion. They were right: Following the eruption, global temperatures abruptly dipped by about a half-degree (0.6°C) for about two years. And Pinatubo isn’t a unique event. Large, temperature-altering eruptions occur about once per decade. However other types of aerosol, particularly black carbon or brown carbon/organic matter (depending on the brightness of the underlying ground), will absorb light radiation, adding to warming the atmosphere.
Climate Change, Temperature, Aerosols And The Albedo Of The Planet
Bright surfaces reflect radiation, cooling the climate, while dark surfaces will absorb radiation and warm the climate. For example, white sheets of sea ice reflect a lot of radiation while dark surfaces, like the ocean, tend to absorb solar radiation and have a net warming effect. Aerosols, especially black carbon, can deposit a layer of dark residue on ice, which both speeds up melting and reduces the amount of radiation being reflected.
How does Earth’s Albedo effects the Global Warming?
Overall, scientists believe the cooling from sulfates and other reflective aerosols overwhelms the warming effect of black carbon and other absorbing aerosols on the planet. Estimates suggest that the cooling effects of aerosols has counteracted about half of the warming caused by the build-up of greenhouse gases since the 1880s. However, unlike many greenhouse gases, aerosols are not distributed evenly around the planet, so their impacts are most strongly felt on a regional scale.
This suggests that, beyond CO2 emissions, we need to reduce fossil fuel use in order to also avoid black carbon aerosols being released into the air, therefore reducing the amount of radiation that is being absorbed.
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Coronavirus, China And Industrial Pollution
As China battles one of the most serious virus epidemics of the century, the impacts on the country’s energy demand and emissions are only beginning to be felt. Electricity demand and industrial output remain far below their usual levels across a range of indicators, many of which are at their lowest two-week average in several years. These include:
- Coal use at power stations reporting daily data at a four-year low.
- Oil refinery operating rates in Shandong province at the lowest level since 2015.
- Output of key steel product lines at the lowest level for five years.
- Levels of NO2 air pollution over China down 36% on the same period last year.
- Domestic flights are down up to 70% compared to last month.
All told, the measures to contain coronavirus have resulted in reductions of 15% to 40% in output across key industrial sectors. This is likely to have wiped out a quarter or more of the country’s CO2 emissions over the past two weeks, the period when activity would normally have resumed after the Chinese new-year holiday. Over the same period in 2019, China released around 400m tonnes of CO2 (MtCO2), meaning the virus could have cut global emissions by 100MtCO2 to date.
China’s industrial activity in compare with the production globally is about 40%. Some figures give a decline of 60% industrial activity. That means a 24 % decline of global industrial activity and emissions and aerosols. Because of this we could see in a few weeks an average global temperature rise. This rise of 1 C in a couple of weeks could be in the ‘long term’ catastrophic.
Before you go!
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