When nature harms itself: Five scary climate feedback loops

The thing about climate change is, the worse it gets – the worse it gets. Feedback loops accelerate the warming process. Now, scientists looking at lakes have found yet another alarming vicious circle to add to the list.

Lakes make a tiny fraction of the world's water, but they're home to lots of plants and animals. They're often situated in the midst of still more biodiversity, in the form of forest. At least, they used to be.

Nature and Environment | 15.03.2018

Lately, forests have been vanishing, while aquatic plants continue to thrive. Due to this change, the lakes of the northern hemisphere could almost double their methane emissions over the next 50 years, new research has shown. Why? Climate change.

This increase of emissions will further contribute to global warming, in what scientists call a positive climate feedback loop.

And it's just the latest addition to a growing list of ways we're altering natural processes with spiraling impacts on the climate and carbon cycle. Here are some of the most alarming:

Nature and Environment | 06.02.2018

The 'ice-albedo' feedback loop acclerates polar ice melt

More and more methane 

Freshwater bodies are responsible for more than 15 percent of the Earth's natural emissions of methane, a greenhouse gas 25 times more potent than carbon dioxide.

Up to 77 percent of a lake's methane emissions come from the decomposition of aquatic plants. Microbes break down organic matter and generate methane that bubbles up to the surface.

Warming temperatures encourage the growth of aquatic plants, meaning there is more of this carbon-rich matter to break down, releasing still more climate-harmful methane into the atmosphere. 

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Researchers also found that debris from surrounding trees impedes methane production within the lake. But with fewer trees surrounding lakes that safety catch is also off.

Plants decomposing in lakes release methane, a greenhouse gas 25 times for powerful than CO2

A melting sun shield

The dazzling white of polar ice isn't just eye-catching, it also helps keep the planet cool, reflecting the sun's rays back to space.

As ice melts that reflective coating is lost, exposing darker bodies of water and land, which absorb more of the sun's heat, leading to greater warming and, in turn, to more ice melting... and so on. 

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This scary process is known as ice-albedo feedback.

Defrosting the permafrost

Permafrost is ground that has remained frozen for more than two consecutive years. It covers about 20 percent of the surface of the Earth — mostly in Canada, Russia and Alaska — and stores huge amounts of carbon, some of it for thousands or even millions of years.

As the planet warms up, permafrost is thawing. The IPCC estimates that permafrost in southern Alaska has become 4 millimeters thinner each year since 1992.

This thawing can put buildings and other infrastructure at risk, as a number of cities are built on permafrost. But it entails another and very worrying risk. Microbes in the newly defrosted soil become active, transforming once-frozen carbon into carbon dioxide and methane.

Scientists are very concerned about the impact of these greenhouse gases on the climate, but the true scale of the problem is still unknown. 

Ring of fire

Forest fires have had devastating consequences in countries like Indonesia, California or Spain over the last few years. Alongside other human activity — like unsustainable land use — warmer temperatures and drier land due to climate change increase the risk and scale of forest fires.

Various studies found that large forest fires in the western United States have become five times more frequent since the 1970s and 80s, scorching over six times as much land, and lasting almost five times as long.

Burning all that wood and other organic matter, forest fires release massive amounts of carbon dioxide back into the atmosphere, helping push the global temperature and further dying out the land...

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Palm Oil plantations threaten the rainforest

Cascading forest loss

Trees, of course, need water to survive. But they don't just consume this precious resource, they also help regulate it in the atmosphere. In the Amazon, the world's largest tropical rainforest, researchers are warning that a dangerous vicious circle might be taking place.

Rising temperatures close to the equator mean less rainfall, and even drought, which increases the risk of forest dieback. As drought takes its toll, there are fewer trees to absorb water and release it back, which in turns makes conditions still drier.

This "cascading dieback" is also worrying because forests are famously important carbon sinks, and forest loss a significant source of CO2 emissions. 

Bonus track: Look down, soils matter

Soils hold 70 percent of the planet's land-based carbon — four times as much as all the world's biomass and three times the amount of CO2 in the atmosphere. Carbon could remain locked into the soil for millennia if we just left it alone. But unsustainable agriculture means it often escapes as carbon dioxide. 

Since the start of the industrial revolution, a startling 50 to 70 percent of carbon once stored in soil has already been released into the atmosphere.

Loss of peatlands — which store huge amount of carbon — has a particularly terrifying impact, currently contributing 5 percent of global CO2 emissions and fueling forest fires.

While not a feedback loop, the example of CO2 from soils is a stark reminder of the delicate balance of our planetary system and the profound damage we do by upsetting it. 

The wondrous world of wetlands

What are wetlands?

Wetlands are hard to define since they are so complex and always changing. Merriam-Webster says that wetlands are "land or areas that are covered often intermittently with shallow water or have soil saturated with moisture." They are also distinct ecosystems and animal habitats with their own vegetation and are important for water purification, shoreline stability and flood control.

The wondrous world of wetlands

The mangroves in Sundarbans

The Sundarbans is the world's largest coastal mangrove ecosystem and spans an area between the Indian and Bangladeshi coasts. These forests are an important segue from the salty ocean to freshwater and earthy systems, and create habitats for many types of fish, crab and shrimp. The unique wetland is also home to endangered Bengal tigers, leopards, boars, spotted deer and protects against erosion.

The wondrous world of wetlands

Northern Europe's Wadden Sea

Nestled along the coast of Denmark, Germany and the Netherlands is a unique intertidal zone called the Wadden Sea. In a constant state of flux, it stretches nearly 500 kilometers and includes the tidal flats and wetlands between the mainland and the assorted North Sea islands. Though not as rich in fauna as it once was, the area still attracts hundreds of thousands of migrating birds each year.

The wondrous world of wetlands

Bogs are not only for fuel

Wetlands that gradually accumulate peat are called bogs. Peat is a deposit of dead plant material — usually moss — and can be several meters deep. Bogs, otherwise known as mires or quagmires, are usually found in the northern hemisphere in places like Canada, Russia and northern Europe. But recently scientists realized that a tropical peatland in the Congo Basin was "as big as England."

The wondrous world of wetlands

Seasons of change in Pantanal

Spread over Brazil, Bolivia and Paraguay, the Pantanal is one of the biggest tropical wetlands in the world. But it is only a seasonal wetland since it experiences periods of both flooding and desiccation. During the rainy seasons much of its area is under water only to later dry out. Not surprisingly the name has its roots in Portuguese: "pântano" means wetland, swamp or marsh.

The wondrous world of wetlands

Swamps are more than alligators

Wetlands come in all shapes and sizes. When they support forests they are called swamps. These natural phenomenon most often form next to large rivers or lakes and support diverse flora and fauna. In many cases water levels fluctuate and can include fresh, brackish or even salty water. Swamps are found all over the globe; some of the largest straddle the Amazon, Mississippi or Congo rivers.

The wondrous world of wetlands

The Volga delta

Covering the area where the Volga River enters the Caspian Sea, the Volga delta stretches from Russia to Kazakhstan. Over the last century the delta has grown enormously because of changing sea levels and is now nearly 160 kilometer wide. The landscape is full of reeds, cattails, sand dunes, islands and meadows. Shallow water provides home for fish, while plants offer nesting areas for birds.

The wondrous world of wetlands

Let's give wetlands a hand

Though wetlands can seem huge and indestructible, they are very susceptible to climate change and defenseless against human destruction. They are important cogs in the ecosystem and need to be better cared for. Once a bog dries out it is hard to restore since amassing peat takes decades. Planting mangroves in dry soil is pointless and revitalizing a drained swamp is nearly impossible.

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