Mid-Ohio Valley Climate Corner: Let that sink in
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The best time to plant a tree was 20 years ago. The second-best time is now. -- Chinese Proverb
Carbon is an essential element to all life on Earth. Like DNA and protein, it is one of the molecules that make up our bodies. Carbon, in the form of carbon dioxide, or CO2, is part of the air we breathe in every day. It can also be found in plants, rocks, oceans and fossil fuels. However, in the form of carbon dioxide gas, it can be very dangerous, and since industries emit a lot of CO2, it causes the planet to get warmer. Fortunately, there are natural ecosystems that store this carbon dioxide in what are called "carbon sinks."
A carbon sink is any natural or artificial reservoir that absorbs more atmospheric carbon dioxide than it releases. By removing greenhouse gases from the air, these systems play a critical role in the natural carbon cycle and mitigating global climate change. The most effective, important carbon sinks on Earth are oceans, forests, and soil. Just like a kitchen sink holds water, a carbon sink holds carbon. In nature, things that release carbon into the air (like burning fuels or human breathing) are called sources. Things that suck that carbon out of the air and store it are called sinks. CO2, is a greenhouse gas, which means it traps heat from the sun and warms up the planet. If we didn't have carbon sinks like oceans and forests soaking up huge amounts of this gas, Earth would get much too hot.
When we burn too many fossil fuels, we release excess carbon into the air. The carbon sinks try to soak it all up, but climate change is making it harder for them to do their job in several ways:
Ocean Acidification: As oceans absorb too much CO2 the water becomes more acidic. This makes it very difficult for marine animals like corals and shellfish to build their shells.
Wildfires: Warmer, drier weather leads to intense forest fires. When trees burn, they release all their stored carbon right back into the air.
Warming Waters: Water, especially the ocean, also acts as a carbon sink. A warmer ocean is less able to dissolve and hold onto carbon dioxide.
Trees are nature's carbon storage units. As they grow, trees pull CO2 out of the air through photosynthesis and use the carbon to build their trunks, branches, roots and leaves. Because that carbon is stored in the wood and other plant tissues, the tree acts as a "carbon sink" -- it takes in more carbon than it releases and keeps it out of the atmosphere for years, or even centuries, depending on the life of trees -- while releasing oxygen back into the air.
In one year, a mature tree can absorb the equivalent of a half a metric ton of carbon dioxide. Altogether, forests in the U.S. offset about 16% of greenhouse gas emissions from cars, trucks, power plants and other sources. In fact, forest ecosystems are the largest land-based carbon sink on Earth.
Forests have been quietly cooling the planet for decades, but their role is increasingly under threat. Historically, by removing CO2, forests have acted as a reliable planetary thermostat. They regulate Earth's temperature, drawing CO2 from the atmosphere, and lock it in trees, roots and soil -- carbon that is emitted if trees are cut down. In a typical year, forests and other vegetation absorb roughly 30% of the carbon that humans emit from burning fossil fuels -- a vital climate service performed at virtually no cost by trees around the world, from tropical rainforests to temperate and boreal forests. Deforestation reverses this absorption, releasing stored carbon and turning these areas into carbon sources
The past several years have not been typical. Recent research reveals that extreme fires have caused forests to absorb far less carbon than usual in 2023 and 2024, weakening their cooling effect. During those years, forests absorbed only a quarter of the carbon dioxide they do in an average year. 2023 marked the lowest "forest carbon sink" in over two decades when considering the loss of trees' stored carbon and greenhouse gases caused by burning.
This recent sharp drop is also part of a longer-term decline, where the margin between forest emissions and carbon removals appears to be narrowing. With emissions from deforestation and other forest disturbances rising, the world's forests risk shifting from a carbon sink to a carbon source.
Losing the world's forest carbon sink will have catastrophic consequences for people and the planet. Without urgent intervention, a continued decline in forests' ability to absorb carbon could accelerate climate change, increasing the frequency of deadly extreme weather events, and disrupting rainfall patterns that underpin water and food security.
Until next time, be kind to your mother Earth.
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Linda Eve Seth, SLP, M.Ed., is a mother, grandmother, concerned citizen and member of MOVCA.