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Plastics In The Air | Earth Wise

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Plastic pollution is a big deal.  There are plastics clogging up landfills and waterways and accumulating in the oceans, choking turtles and seabirds.  Annual production of plastics has grown from 2 million tons a year in 1950 to more than 450 million tons today.

As if plastic problems weren’t already big enough, it is becoming increasingly clear that there are growing amounts of microplastic particles in the air. Bits of plastic are lofted into the sky from seafoam bubbles and from spinning tires on highways.  The particles are so light that they can travel for thousands of miles, far from where they originate.

Studies in recent years documented the presence of plastic particles even in places like the Pyrenees in Europe and in federally protected areas of the US.  Other studies have measured the quantity of plastic in the air of various locations and have looked at the origins of the particles.

In the western US, over 80% of microplastics came from roads where vehicles kick up particles from tires and brakes.   In remote areas of the Pacific, there is less than a single particle of plastic per cubic meter of air.  In cities like London and Beijing, on the other hand, there can be several thousand particles per cubic meter.

Microplastics can act as airborne aerosols, like dust, salt, soot, volcanic ash, and other particles.  Aerosols play an important role in the formation of clouds and in temperature regulation on the earth.  At low concentrations, such as exist in most places, microplastic aerosols don’t have much of an effect.  But there are more in the atmosphere all the time and, at this point, scientists don’t really know what effect they will have.

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Microplastics Are Filling the Skies. Will They Affect the Climate?

Photo, posted August 28, 2014, courtesy of Alan Levine via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Wildfire Smoke And Global Weather | Earth Wise

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In 2019 and 2020, wildfires burned 72,000 square miles in Australia, roughly the same area as the entire country of Syria. During the nine months when the fires raged, persistent and widespread plumes of smoke filled the atmosphere.

These aerosols brightened a vast area of clouds above the subtropical Pacific Ocean.  Beneath these clouds, the surface of the ocean and the atmosphere cooled.  The effect of this was an unexpected and long-lasting cool phase of the Pacific’s La Niña-El Niño cycle.

A new modeling study by the National Center for Atmospheric Research in Boulder, Colorado quantified the extent to which aerosols from the Australian wildfires made clouds over the tropical Pacific reflect more sunlight back towards space.  The resultant cooling shifted the cloud and rain belt known as the Intertropical Convergence Zone northward.  These effects may have helped trigger the unusual three-year-long La Niña, which lasted from late 2019 through 2022.

The impacts of that La Niña included intensifying drought and famine in Eastern Africa and priming the Atlantic Ocean for hurricanes.  2020 was the most active tropical storm season on record, with 31 storm systems, including 11 that made landfall in the U.S.

The study highlights widespread multi-year climate impacts caused by an unprecedented wildfire season.  The wildfires set off a chain of events that influenced weather far from where the fires occurred.  In the future, climate experts will need to include the potential effects of wildfires in their forecasts.

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How Wildfire Smoke from Australia Affected Climate Events Around the World

Photo, posted December 19, 2019, courtesy of Simon Rumi via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Understanding Geoengineering | Earth Wise

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The most recent report from the UN Intergovernmental Panel on Climate change includes discussion of a number of extreme and untested solutions to the climate crisis.  Among these are solar geoengineering – modifying clouds or spraying tiny reflective particles into the upper atmosphere in order to block some of the sun’s light and thereby cool the planet.  The underlying principles are relatively straightforward.

There have been various models that predict the extent to which solar geoengineering would lower the earth’s average temperature.  What hasn’t been modeled to any real extent is what other effects it would have.

The new report discusses the results of models that predict how temperatures would vary at different latitudes and how geoengineering would affect rainfall and snowfall.  According to the models, releasing sulfate aerosols into the upper atmosphere to block sunlight would lower average precipitation.  But every region would be affected differently.  Some regions would gain in an artificially cooler world, but others might, for example, suffer by no longer having suitable conditions to grow crops.

The drop in temperature would allow the planet’s carbon sinks (plants, soils, and oceans) to take up more carbon dioxide from the atmosphere.  However, as long as people continue to pollute, carbon dioxide would continue to make the oceans more acidic, causing significant harm to marine ecosystems.  Furthermore, solar geoengineering would have to be an ongoing process that would go on indefinitely and if it were to suddenly stop, it would lead to rapid warming.

The more we learn about geoengineering, the more it becomes clear that there would be many side effects as well as serious moral, political, and practical issues.  Society has to consider if all these things represent too much danger to allow us to seriously consider such a strategy.

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In the New UN Climate Report, a Better Understanding of Solar Geoengineering

Photo, posted September 9, 2012, courtesy of Kelly Nighan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Should We Block The Sun? | Earth Wise

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There is growing concern that greenhouse gas emissions are not falling quickly enough to avoid dangerous levels of global warming.  As a result, there is the impetus to examine other options.  Among these are geoengineering, which is one of the most contentious issues in climate policy.  Geoengineering embodies many risks that make even seriously considering it seem risky in itself.

Despite this, the National Academies of Science, Engineering, and Medicine has issued a report saying that governments urgently need to know whether solar geoengineering could work and what its side effects might be.

Solar geoengineering is also called solar radiation modification, which entails reflecting more of the sun’s energy back into space.  This would likely be accomplished by injecting aerosols into the atmosphere, much like what happens after large volcanic eruptions.

Schemes for solar geoengineering raise numerous issues.  Although solar geoengineering might cool the earth’s surface to a global temperature target, the cooling may not be evenly distributed, affecting many ecosystem functions and biodiversity.   It would likely upset regional weather patterns in potentially devastating ways, for example by changing the behavior of the monsoon in South Asia.  It might dangerously relax public commitments to reduce greenhouse emissions. 

Despite these concerns, or perhaps because of them, the committee that produced the report believes that technology to reflect sunlight deserves substantial funding and should be researched as rapidly and effectively as possible.  Once any geoengineering projects get into the hands of policymakers, they may gather momentum that bypasses the advice of scientists.  So, it important to make progress on the science while geoengineering is still only theoretical.

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Should We Block the Sun? Scientists Say the Time Has Come to Study It.

To intervene or not to intervene? That is the future climate question

Photo, posted August 3, 2018, courtesy of Tomasz Baranowski via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Pandemic And Global Temperatures | Earth Wise

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The early months of the Covid-19 pandemic last year saw dramatic reductions in travel and many forms of commerce.  With much of human activity greatly curtailed, greenhouse gas emissions were greatly reduced.   And yet, all of that did not slow down global warming: 2020 ended up tied with 2016 as the warmest year on record and atmospheric greenhouse gas levels reached a new high.

In order to understand how this came about, it is necessary to understand the complex climate influences of different types of emissions from power plants, motor vehicles, industrial facilities, and other sources.  The fact is that some types of pollution actually have a cooling effect rather than contributing to global warming.

Tiny industrial pollution particles called aerosols actually make clouds brighter, causing them to reflect away more solar heat from the surface of the planet.   During the drastic shutdown last year, the biggest emissions decline was from the most polluting industries.  The reduction of aerosols had immediate, short-term effects on temperatures.  These types of pollutants are very bad for human health, but when they are present, they do have the effect of reducing temperatures.

It is important to keep in mind that carbon dioxide spreads through the Earth’s atmosphere and stays there for a century or more, trapping heat on a global scale.  Industrial aerosols stay relatively concentrated in the region where they are emitted and are often removed by rain and winds within a few weeks.  So, their cooling effect doesn’t spread very far or last very long.

Overall, the initial pandemic slowdown probably didn’t have any real long-term impact on the climate but over the short term, the effects were not as simple as one might expect.

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Covid-19 Cut Gases That Warm the Globe But a Drop in Other Pollution Boosted Regional Temperatures

Photo, posted July 7, 2020, courtesy of Joey Zanotti via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Side Effects Of Geoengineering | Earth Wise

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As the world struggles to reduce the greenhouse gas emissions that are warming the global climate, some researchers are exploring proposals to deliberately engineer climate changes to counteract the warming trend.  One of the most widely discussed approaches is to shade the Earth from a portion of the sun’s heat by injecting the stratosphere with reflective aerosol particles.  Proponents of this idea point out that volcanoes do essentially the same thing, although generally for only a limited amount of time.  Particularly large eruptions, such as the Krakatowa eruption of 1883, wreaked havoc with weather around the world for an entire year.

Schemes to launch reflective aerosols – using planes, balloons, and even blimps – appear to be quite feasible from the standpoint of physically accomplishing them. But this says nothing about the political, ethical, and societal issues involved.  The point is that such an approach could indeed lower global temperatures and thereby potentially offset the warming effects of greenhouse gases.

A study by scientists at MIT looked at what other effects such a solar geoengineering project might have on the climate.  Their modeling concluded that it would significantly change storm tracks in the middle and high latitudes.  These tracks give rise to cyclones, hurricanes, and many more ordinary weather phenomena.

According to the study, the northern hemisphere would have weakened storm tracks, leading to less powerful winter storms, but also stagnant conditions in summer and less wind to clear away air pollution.  In the southern hemisphere, there would be more powerful storm tracks.

Aside from turning the world’s weather patterns inside out, solar geoengineering would do nothing to address the serious issue of ocean acidification caused by increasing carbon dioxide levels.

As many have pointed out, playing the geoengineering game would have many unintended consequences.

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Study: Reflecting sunlight to cool the planet will cause other global changes

Photo courtesy of MIT.

Earth Wise is a production of WAMC Northeast Public Radio.

The Lockdown Cleans Up Indian Air | Earth Wise

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Our stories often discuss how human activities change the natural environment.  With most of us confined to our homes, the lack of human activities is having profound effects on the environment.  We are talking about some of these this week.

India suffers from some of the worst air pollution in the world.  Of the most polluted cities in the world, 21 out of 30 were in India in 2019.  According to World Health Organization standards, at least 140 million people in India breathe air containing 10 times or more greater levels than the safe limit for pollutants.  Air pollution contributes to the premature death of 2 million Indians every year.

Half of India’s air pollution comes from industry, 27% from vehicles, and 17% from crop burning.  Crop burning is prevalent because it is much cheaper than mechanical tilling after the harvest.

On March 25, the Indian government placed its 1.3 billion citizens under a strict lockdown to reduce the spread of COVID-19.   The country-wide mandate decreased activity at factories and drastically reduced car, bus, truck, and airplane traffic.

Within one week, NASA satellite sensor observed aerosol levels at a 20-year low for this time of year in northern India.  Aerosols are tiny solid and liquid particles suspended in the air that reduce visibility and can damage the human lungs and heart.  Some aerosols have natural sources, such as dust storms, volcanic eruptions, and forest fires.  But many come from human activities such as the burning of fossil fuels and croplands.  Scientists expected to see changes in atmospheric conditions during the Indian lockdown, but the current changes are dramatic.  They also present a unique opportunity to separate how natural and human sources of aerosols affect the atmosphere.

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Airborne Particle Levels Plummet in Northern India

Photo, posted April 29, 2020, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Fire-Driven Thunderstorms

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In 2016 and 2017, wildfires in western Canada spawned thunderstorms that ignited additional fires, in some cases tens of miles away from the original fire.  These fire-triggered thunderstorms are technically known as pyrocumulonimbus clouds, or “pyroCb’s”.

The physics of pyroCb’s is complex.  When super-heated updrafts from an intense fire suck smoke, ash, burning materials, and water vapor high into the air, these elements cool and form so-called fire clouds that look and act like the cumulonimbus clouds associated with classic thunderstorms.  What is different is that the heat and particulates in the smoke almost always arrest the ability of the cloud to produce rain.  Instead, what remains is a lightning storm that moves across the landscape, triggering more fires.

These PyroCb events appear to be happening far more often, producing more energy, and erupting in places where they have never been seen before.  As the world warms, wildfires themselves are becoming larger and hotter.  In the past decade, wildfires have been burning more than twice as many acres as they did before the turn of the 21st century.  Along with the growth in wildfire activity, there has been an increase in PyroCb events, and there are now an average of 25 per year in western North America.

Apart from starting new fires, pyroCb’s also have similar effects as moderate-sized volcanic eruptions.  Smoke and aerosols from wildfires can rise high into the stratosphere, where they can linger for months.  Eventually, the particles carried aloft in the atmosphere do come down, dumping dangerous chemicals on far flung regions of the earth.  But unlike volcanic eruptions, which are relatively rare events, pyroCb’s are happening more and more each year.

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Fire-Induced Storms: A New Danger from the Rise in Wildfires

Photo, posted July 31, 2013, courtesy of Loren Kerns via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Measuring Earth’s Outgoing Energy

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The earth’s energy imbalance is the difference between the amount of solar energy absorbed by the earth and the amount of energy the planet radiates back into space as heat.  If the imbalance is positive, that is, if more energy is coming in than going out, then the earth will get warmer over time.  If the imbalance is negative, then the planet will get cooler. 

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