Thank you to the National Geographic website below for the information used in this blog.
Some of you may have seen the BBC programme on permafrost. It is basically consists of billions of years’ worth of organic carbon. The upper three metres storing enough methane, mercury, and carbon dioxide to overwhelm our ability to control climate temperatures. Should it escape? It will stay frozen underground if we can bring global warming under control. The summer thaws are purely temporary and last roughly three months. With global warming, the thaw could become longer, possibly permanent. This would have catastrophic effects globally lasting centuries.
Geologically as experts expected in the past, the permafrost is defrosting for longer and at a faster rate. But what they did not bank on was the permafrost thawing this fast. The climate has sped up to such extremes it has left scientists in a state of flux. As this ancient frozen soil thaws, it releases remnants of ancient history which comprise methane, mercury and carbon. As these chemicals enter the atmosphere, the methane, mercury and carbon accelerate temperatures and climate change even faster once more.
estimated 1,656 gigatons of carbon are frozen in Arctic permafrost, making it one of the world’s largest carbon sinks.
Slumping can occur with sudden catastrophic force. Kokelj, a permafrost expert with the Northwest Territories Geological Survey, a rapidly thawing cliff bordering the shores of a tundra lake collapsed into the Peel River watershed in the Northwest Territories. The waterfall that was created drained approximately 800,000 gallons of water from that upland lake in just two hours. Heavy metals in the permafrost, such as mercury, were flushed downstream along with silt and peat, tainting the river system for miles downstream.
Permafrost occurs in areas where the temperature of the ground remains below the freezing mark for two years or more. About a quarter of the Northern Hemisphere’s landscape fits this definition. Most of the world’s permafrost is found in northern Russia, Canada, Alaska, Iceland, and Scandinavia. Much of it underlies peat ecosystems. But like peat, they also found permafrost in the Rocky Mountains of Canada and Alaska, the Alps and more.
The rapid thawing of permafrost has enormous implications for climate change. There are an estimated 1,656 gigatons of carbon frozen in permafrost, making the Arctic one of the largest carbon sinks in the world. That’s about four times more than humans have emitted since the industrial revolution, and they currently contain nearly twice as much as there is in the atmosphere. According to a recent report, a 3.6-degrees Fahrenheit (2 degrees Celsius) increase in temperature is expected by the end of the century — this will cause a loss of about 40 percent of the world’s permafrost by 2100, releasing the toxins into the atmosphere.
This is a big concern, as how do you stop something millions of feet beneath the ground and at the bottom of a lake thawing? If you have seen other pages on my blog you know our planet is going to be going through great permanent changes.
However, polar and high altitude regions are some of the most climate-sensitive places on the planet. According to the National Oceanic and Atmospheric Administration (NOAA). The Arctic is warming twice as fast as the rest of the planet, at a rate of temperature change that has not being witnessed in at least the last 2,000 years. In 2016, annual average surface temperatures were 3.5 degrees Celsius warmer than they were at the start of the 20th century. That year, (2020) permafrost temperatures in the arctic were the warmest ever recorded.
The ‘active layer’ of soil on top of the permafrost is approximately 3 metres deep, and can retain plant life. This top layer thaws each summer and releases carbon from the roots of plants that respire out CO2. Some microbes break down the organic matter into CO2. Others, called Archaea, produce methane instead. This happens when anaerobic conditions are made—this is when the soil is saturated with water or no oxygen is accessible. Methane is 20 to 30 times more potent than carbon dioxide at exacerbating global warming, but it remains in the atmosphere for less time.
As permafrost thaws, the active layer deepens. The microbes become active and plant roots can penetrate further down, resulting in the production of more CO2. The amount of methane generated depends on how saturated the ground is.
A 2017 study estimated that if global temperatures rise 1.5˚C above 1861 levels, thawing permafrost could release 68 to 508 gigatons of carbon. Without factoring in human activity, this carbon alone would increase global temperatures 0.13 to1.69˚C by 2300. Since we may have already locked in 1.5˚C of warming above pre-industrial levels, this amount of additional warming could cause catastrophic affects of climate change, out of our control.
Although a warmer arctic could support more plants, and plants absorb carbon dioxide through photosynthesis. It projects the fresh growth to offset only about 20 percent of the permafrost’s carbon release.
What Protects Permafrost
One thing that protects permafrost from the affects of climate change is peat, the partly decayed vegetation that accumulates in water-saturated environments with no oxygen. Found in much of the low arctic peat can overlie or encompass the whole active layer.
Ben Gaglioti, a postdoctoral research scientist at Lamont-Doherty Earth Observatory, studied lake sediment records in northern Alaska to determine how much carbon the permafrost released in response to warming periods at the end of the last ice age. It turns out that the permafrost was much more sensitive—meaning it released more carbon—during past warming events, with gradually less response over time. In the most recent 150 years of warming, there has been relatively little response.
“Our hypothesis is that the buildup of organic matter or peat in the watershed has occurred because of a relatively warm and stable climate since the ice age,” said Gaglioti. “That peat, which started accumulating around 13,000 years ago, does a great job at insulating the underlying ground from thaw, so we think it’s buffering the permafrost.”
Gaglioti’s models show that the sensitivity of the underlying permafrost highly depends on the thickness of the peat. “The fate of the underlying permafrost rests in some ways on the stability of the peat layer,” he said.
An Irreversible Cycle?
Wildfires can peel back the peat and make permafrost more sensitive to climate change—and they’re expected to increase in tundra regions, Gaglioti said. Warmer and drier summers make vegetation more combustible. Warmer temperatures also bring about more thunderstorms and lightning strikes that can spark wildfires.
Fire near Ivotuk, AK. Photo: Ben Gaglioti
Fires not only release CO2 as they burn; afterwards, the blackened ground absorbs more solar radiation and warms further. And once fire removes the peat and vegetation that shades the ground, the landscape can become too well-drained to regenerate the peat.
It troubled many scientists that thawing permafrost could be a tipping point that brings about an inevitable and reversible cycle: When permafrost releases its carbon as CO2 or methane, it will stimulate warming up, which will then trigger more permafrost thaw, and so on. There will be nothing humans can do to stop it.
It can also harm natural ecosystems. Thermokarst lakes—depressions formed when thawing permafrost collapsed and filled with meltwater—are important for wildlife and provide water to local communities. But if the underlying permafrost continues to thaw, lakes and wetlands can drain completely, destroying these biologically important resources.
People, animals and their diseases have been suspended in the permafrost for hundreds of millions of years, bacteria and viruses can survive in permafrost for hundreds of thousands of years—scientists recently revived a 30,000-year-old virus that infects amoebas. Epidemics like the Spanish flu, smallpox, or the plague that were wiped out decades ago were discovered asleep in the permafrost.
While the most recent Intergovernmental Panel on Climate Change’s report acknowledged that permafrost is warming, its climate models did not account for these emissions when making climate projections.
Ultimately, how much the planet warms from thawing permafrost will depend on how much carbon we release now. If we can meet the Paris Agreement, then we have a fighting chance. But to get a fuller understanding of this phenomenon and to make more accurate climate projections, scientists need to better assess the vulnerability of permafrost to thawing and its many consequences for the arctic and the planet.
“Scientific research is so important in understanding,” said Anderson. “We just can’t predict from what’s already known because we’ve never had permafrost thawing previously to this extent. It’s only through more careful scientific research that we can answer these questions.”
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