Feedback Loops and the Arctic

An example of a feedback loop is the melting of Arctic sea ice. Methane, one of the most severe greenhouse gases, is trapped under the ice. However, when global warming causes the sea ice to melt, methane is released. When methane is released it intensifies global warming, resulting in more ice melting. In turn, more methane is released causing an acceleration in global warming... and so on.

The Arctic has multiple feedback loops including: enhanced oceanic heating and ice-albedo feedback due to diminishing sea ice, Planck feedback, lapse-rate feedback, and cloud feedback. Sea ice reflects much of the heat. Dark ocean surface absorbs more heat. The warmer temperature melts more ice resulting in warmer ocean temperatures which in turn melts more ice. A study published in the journal Nature found The Arctic has warmed nearly four times faster than the globe since 1979.

From The Guardian
Fiona Harvey
Friday 25 November 2016 00.01 EST

How melting Arctic ice could cause uncontrollable climate change

Arctic scientists have warned that the increasingly rapid melting of the ice cap risks triggering 19 "tipping points" in the region that could have catastrophic consequences around the globe.

The Arctic Resilience Report found that the effects of Arctic warming could be felt as far away as the Indian Ocean, in a stark warning that changes in the region could cause uncontrollable climate change at a global level.

Temperatures in the Arctic are currently about 20C above what would be expected for the time of year, which scientists describe as "off the charts". Sea ice is at the lowest extent ever recorded for the time of year.

"The warning signals are getting louder," said Marcus Carson of the Stockholm Environment Institute and one of the lead authors of the report. "These developments also make the potential for triggering tipping points and feedback loops much larger."

From The Guardian
by Jonathan Watts Global environment editor
28 October 2020

Scientists have found evidence that frozen methane deposits in the Arctic Ocean – known as the “sleeping giants of the carbon cycle” – have started to be released over a large area of the continental slope off the East Siberian coast, the Guardian can reveal.

High levels of the potent greenhouse gas have been detected down to a depth of 350 metres in the Laptev Sea near Russia, prompting concern among researchers that a new climate feedback loop may have been triggered that could accelerate the pace of global heating.

The slope sediments in the Arctic contain a huge quantity of frozen methane and other gases – known as hydrates. Methane has a warming effect 80 times stronger than carbon dioxide over 20 years. The United States Geological Survey has previously listed Arctic hydrate destabilisation as one of four most serious scenarios for abrupt climate change.

Brown Carbon

Brown carbon from wildfires warms the arctic. The warmer arctic absorbs more heat causing more wildfires. In turn, more wildfires cause more brown carbon resulting in a warmer arctic. The cycle keeps reinforcing itself as it repeats.

A study published in One Earth entitled “Brown carbon from biomass burning imposes strong circum-Arctic warming” reports:
* Brown carbon imposes strong Arctic warming
* Warming effect of water-soluble brown carbon is 30% relative to black carbon
* Biomass burning (wildfires) contributes 60% of the warming effect of brown carbon
* Warming climate leads to increased wildfires that reinforce Arctic warming

Rapid warming in the Arctic has a huge impact on the global environment. Atmospheric brown carbon (BrC) is one of the least understood and uncertain warming agents due to a scarcity of observations. Here, we performed direct observations of atmospheric BrC and quantified its light-absorbing properties during a 2-month circum-Arctic cruise in summer of 2017. Through observation-constrained modeling, we show that BrC, mainly originated from biomass burning in the mid- to high latitudes of the Northern Hemisphere (60%), can be a strong warming agent in the Arctic region, especially in the summer, with an average radiative forcing of 90 mW m-2 (30% relative to black carbon). As climate change is projected to increase the frequency, intensity, and spread of wildfires, we expect BrC to play an increasing role in Arctic warming in the future.

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