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Forests And Climate Change | Earth Wise

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A carbon sink is anything that absorbs more carbon from the atmosphere than it releases.  Examples of carbon sinks include the ocean, soil, and plants.  In contrast, a carbon source is anything that releases more carbon into the atmosphere than it absorbs.  Volcanic eruptions and burning fossil fuels are two examples.

Forests are among the most important carbon sinks.  Trees remove carbon from the air and store it in their trunks, branches, and leaves, and transfer some of it into the soil.  But in many regions, deforestation, forest degradation, and the impacts of climate change are weakening these carbon sinks. As a result, some climate activists advocate for large-scale tree-planting campaigns as a way to remove heat-trapping CO2 from the atmosphere and help mitigate climate change. 

But according to a new study recently published in the journal Science, planting new trees as a substitute for the direct reduction of greenhouse gas emissions could be a pipe dream.  While planting trees is easy, inexpensive, and can help slow climate warming, the ongoing warming would be simultaneously causing the loss of other trees.  Instead, the research team says it makes more sense to focus on keeping existing forests healthy so they can continue to act as carbon sinks, and to reduce emissions as much as possible and as quickly as possible.        

But keeping forests healthy will require a paradigm shift in forest management.  Instead of trying to maintain forests as they were in the 20th century, the research team says forests need to be managed proactively for the changes that can be anticipated. 

One thing is clear: We cannot plant our way out of the climate crisis.

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Forests and climate change: ‘We can’t plant our way out of the climate crisis’

Photo, posted August 9, 2015, courtesy of Nicholas A. Tonelli via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Not All Trees Cool The Planet | Earth Wise

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A new study from Clark University has found that deforestation does not always contribute to planetary warming, as is generally assumed.  The researchers have found that there can be places where removing trees actually cools the planet.

Forests soak up carbon dioxide from the air and store it in the trees themselves and in the soil.   This process is important for slowing the accumulation of greenhouse gases in the atmosphere.

The new research focuses on a different effect that forests have on climate.  They are darker than other surfaces, which causes them to absorb more sunlight and retain heat.  This is known as the albedo effect.

In most places, the absorption of carbon outweighs the albedo effect and forests help cool the planet.  But there are some locations, including the Intermountain and Rocky Mountain West, where more forest actually leads to a hotter planet when both processes are taken into account.  State-of-the-art satellite remote sensing allowed the researchers to quantify the effects of forest loss in the United States.

The upshot of this research is that large-scale tree-planting initiatives, such as Canada’s 2Billion Trees Initiative and the Nature Conservancy’s Plant a Billion Trees campaign need to make sure to put the right trees in the right places.

Every year, about a million acres of forest are being converted to non-forest across the lower 48 states as a result of suburban and exurban expansion and development.   It is important to take into account the albedo effect in trying to replace the climate-cooling capabilities of these disappearing forests by planting more trees.

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Clark geographer Christopher Williams: More trees do not always create a cooler planet

Photo, posted June 5, 2017, courtesy of Todd Petrie via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Using CO2 To Convert Seawater Into Drinking Water | Earth Wise

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A chemist at the University of Copenhagen has invented a technology that uses carbon dioxide to convert seawater into drinking water within minutes.  This desalination technology has the potential to replace electricity with CO2 and be used in survival gear and in large-scale industrial plants in places where people don’t have clean drinking water.

Over 800 million people worldwide lack access to clean drinking water and that number is growing rapidly.  Seawater is a vital source of drinking water in many parts of the world, but desalination faces the major challenge of being highly energy intensive.  Desalination plants use huge amounts of fossil fuel-generated electricity and therefore contribute to climate change.

The Copenhagen technology is reminiscent of a SodaStream machine.  Carbon dioxide is added to water, initiating a chemical reaction.  But instead of using it for bubbly carbonation, it is used to separate salt from water.  It works by adding a chemical called CO2-responsive diamine to saltwater.  The diamine compound binds with the added CO2 and acts as a sponge to absorb the salt, which can then be separated.  The entire process takes one to ten minutes.  Once the CO2 is removed, the salt is released again, allowing the diamine to be reused for several more rounds of desalination.

In the laboratory, the method removed 99.6% of the salt in seawater.  The technology is still being developed to lower its price and optimize the recycling process.  It is also being tested on a small scale in the form of water bottles fitted with special filters that can be used in lifeboats or in other outdoor settings.  Ultimately, it could be used to greatly reduce the energy consumption of desalination plants.

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Chemist uses CO2 to convert seawater into drinking water

Photo, posted January 10, 2015, courtesy of Daniel Orth via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Carbon In The Ocean | Earth Wise

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New research from the University of Exeter in the UK reveals that the world’s oceans soak up more carbon than previously believed.  Previous estimates of the movement of carbon between the atmosphere and the oceans did not account for the temperature differences between the water’s surface and a few meters below.

The new model includes this factor and finds that there is a significantly higher flux of carbon into the oceans.

The study calculated carbon dioxide fluxes from 1992 to 2018 and found that at certain times and locations there was up to twice as much CO2 contained in the ocean as determined from previous models.

The temperature differences between the surface of the ocean and the water at a depth of a few meters is important because the amount of carbon dioxide that can be absorbed in water depends very strongly on the temperature of the water.   Anyone with a home soda maker knows this well as the devices always work much better with refrigerated water than room temperature water.

The difference in ocean carbon dioxide uptake measured from satellite data and calculated in the new modeling amounts to about 10% of global fossil fuel emissions, so it is a very significant revision.  The revised estimate for carbon dioxide uptake actually agrees much better with an independent method for calculating the amount of carbon dioxide in the oceans.  Those measurements came from a global ocean survey performed by research ships over decades.

Now that two so-called big data estimates of the ocean sink for CO2 agree pretty well, there is greater confidence that we understand this important aspect of the planet’s carbon cycle.

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Ocean carbon uptake widely underestimated

Photo, posted December 30, 2012, courtesy of Jerome Decq via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Ocean Acidification And Mass Extinction

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Since the industrial revolution, the concentration of carbon dioxide in the atmosphere has increased due to the burning of fossil fuels and land use changes.  The ocean absorbs about 30% of the CO2 that is released in the atmosphere.  As the levels of atmospheric CO2 increase, so do the levels in the ocean.

When CO2 is absorbed by the ocean, a series of chemical reactions occur, resulting in seawater becoming more acidic.  Ocean acidification threatens calcifying organisms, such as clams and corals, as well as other marine animals, like fish.  When these organisms are at risk, the entire marine ecosystem may also be at risk.

In fact, according to research recently published in the journal Proceedings of the National Academy of Sciences, fossil evidence from 66 million years ago has revealed that ocean acidification can cause the mass extinction of marine life.  Researchers analyzed seashells in sediment laid down shortly after a giant meteorite hit earth.  This strike wiped out the dinosaurs and 75% of marine species.  Chemical analysis of the shells revealed a sharp drop in the PH of the ocean over hundreds of years after the meteorite strike.  The meteorite impact vaporized rocks, causing carbonic acid and sulphuric acid to rain down, acidifying the ocean.  The strike also resulted in mass die-off of plants on land, increasing atmospheric CO2.  

Researchers found that the pH dropped by 0.25 pH units in the 100 to 1,000 years after the meteorite strike.  Alarmingly, scientists expect the pH of the ocean to drop by 0.4 pH units by 2100 if our carbon emissions continue as projected. 

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Ocean acidification can cause mass extinctions, fossils reveal

Photo, posted March 16, 2017, courtesy of Zachary Martin via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

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