Protect biodiversity to fight climate change - The Washington Post - 0 views
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Giant kelp is among the best organisms on the planet for taking planet-warming gases out of the atmosphere. Buoyed by small, gas-filled bulbs called “bladders,” these huge algae grow toward the ocean surface at a pace of up to two feet per day. Their flexible stems and leafy blades form a dense underwater canopy that can store 20 times as much carbon as an equivalent expanse of terrestrial trees.
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Yet this powerful force for planetary protection is under siege. Warming waters and worsening storms caused by climate change have weakened the kelp forests.
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Most significantly, the demise of important predators such as otters and sea stars has led to an explosion in the population of sea urchins, which eat kelp.
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The Earth itself is our greatest ally in this effort. Ecosystems like California’s kelp forests absorb about half of the greenhouse gases humans emit, studies show. Without them, warming would be even worse. Nature shields us from the worst consequences of our own actions, forgiving the sins we refuse to repent.
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If we hope to solve climate change, humanity must also address this biodiversity crisis — restoring ecosystems and the creatures that inhabit them.
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One way to revitalize ecosystems: protect the ground they grow from.Think of the soft, spongy soil of an old-growth woodland. Here, a towering oak tree draws up water and nutrients via threadlike fungi attached to its roots. In exchange, the fungi take sugar from the oak, funneling carbon from the air into the ground.Now imagine a leaf from that oak drifting slowly to the forest floor. Perhaps it becomes food for an earthworm. Then microbes attack the earthworm’s droppings, breaking down the residue further still.Eventually, the carbon that was once a leaf can become trapped in clods of earth. Other atoms may form strong chemical bonds with minerals like iron, which prevents them from reacting with oxygen and returning to the air. Under the right conditions, carbon might stay locked away in dense, dark earth for centuries. Soils contain more carbon than the entire atmosphere and all the world’s plants combined.
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“And because soil is such an important reservoir,” Berhe said, “a small change in the release of that carbon can lead to a big change in the concentrations of greenhouse gases in the atmosphere.”
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A 2020 analysis in the journal Nature Sustainability found that better soil stewardship could reduce emissions by at least 5.5 gigatons of carbon dioxide each year — about 15 percent of current annual emissions.
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“Once that happens,” Berhe said, “it’s not just the carbon status of the soil that’s improved. The soil literally becomes softer. It holds more water and nutrients. It’s easier for plants to grow in … and serve as a home for the most abundant and diverse group of organisms that we know of.
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Enhancing carbon in soils is just the beginning. In 2017, an international team of scientists set out to determine how much carbon the planet could pull out of the atmosphere, if humans would only give it a chance. In a study in the Proceedings of the National Academy of Sciences (PNAS), they concluded natural climate systems are capable of storing almost 24 gigatons of carbon dioxide per year — roughly two thirds of what people emit.
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About half of that sequestration would be cost-effective, meaning enacting the necessary protections would cost less than the consequences of keeping that carbon in the air.
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Of the climate solutions they studied, few delivered more carbon bang per buck than mangroves — lush systems of salt-tolerant shrubs and trees that thrive where freshwater rivers spill into the sea. Though these forests occupy just 0.5 percent of the Earth’s shorelines, they account for 10 percent of the coast’s carbon storage capacity.
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But the unique ecosystems are too often dismissed as unproductive swamps, good for no one but the mosquitoes. In the past half-century, more than a quarter of the world’s mangroves have been destroyed — drained for development, converted for shrimp farms, poisoned by fertilizer and drowned by dammed-up streams.
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Yet the Earth cannot compensate for all of humanity’s pollution, said William Schlesinger, former dean of Duke University’s School of the Environment and a co-author on the 2017 PNAS study. Unless people also reduce the amount of greenhouse gases we emit, no amount of ecological restoration will save us.
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“The bottom line is we’ve got to get off of using fossil fuels in transportation and heating and lighting and everything else,”
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In public talks, he puts it this way: “It’s easier to patch a hole in a bag than to pick up the marbles that fall out.”
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Since the end of the last ice age, the frozen expanse at the top of the world has acted as a protective shield. During the summer, when the sun shines 24 hours a day, Arctic sea ice reflects about two-thirds of the light that hits it back into space. By contrast, the dark open ocean absorbs the majority of the sun’s heat.
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If the Arctic loses its perpetual ice cover, it would add half a degree Celsius of warming to the global average temperature, studies suggest. The world is hurtling toward that milestone. Since 1979, the volume of ice left at the end of the summer has shrunk about 75 percent.
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There is just one way to save it, she said: by stopping global warming. Only by ending the use of fossil fuels and eliminating greenhouse gas emissions can people prevent the Arctic from heating further and give the ice a chance to recover.
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If we do nothing, models indicate, it will be a matter of decades before the summertime Arctic is ice-free for the first time in human history. Sea levels will surge, coastal communities will be deluged, and we will no longer have the planet’s air conditioning unit to help us cool our world down.
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Our species evolved and our civilization was built under fairly stable climate conditions. When things changed, they changed slowly, giving us time to adapt.
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The rapid transformation of our planet doesn’t just endanger ecosystems; humanity will suffer. People have never lived on a planet without mangroves, or peatlands, or summertime ice. We’ve never had to go without the benefits the Earth provides.