The Antarctic Ice Sheet had been thought relatively impervious to Climate Destabilization. New information indicates that accelerated ice stream flow from the effects of a warming ocean will thin the ice sheet far inland.
Fast-flowing and narrow glaciers have the potential to trigger massive changes in the Antarctic ice sheet and contribute to rapid ice-sheet decay and sea-level rise, a new study has found.
... warming waters in the Southern Ocean are connected intimately with the movement of massive ice-sheets deep in the Antarctic interior.
... ocean warming can trigger increased flow of ice through these narrow corridors. This can cause inland sectors of the ice-sheet -- some larger than the state of Victoria -- to become thinner and flow faster."
This observation is particularly important in light of recently observed dynamic changes at the margins of Antarctica.
Ramez Naam at Scientific American cogently explains the positive feedbacks associated with Arctic Ice melt. He describes what we'll see in years following that first year the Arctic becomes ice free in September. I extracted key points from his long detailed article.
Here's the historical perspective. That red smudge is recent ice melt.
... positive feedback. Not the “good job” kind of positive feedback, mind you. This type of feedback is more similar to what happens when a microphone comes too close to a speaker, and a random piece of noise gets amplified out of control. Any time a process can amplify itself, it’s a positive feedback loop. The melting ice is, in fact, amplifying its own destruction by helping to fuel accelerated arctic warming and thus more rapid disappearance of the ice that remains.
Over the years we can expect the ice free period to expand from September, when the sun is low and weak, toward June, when it's shining high 24-7.
In June, the Arctic ice cap covers around 2% of the Earth’s surface... And that 2% of the Earth’s surface, for a period of roughly two months, receives more solar energy per day than even the sunniest areas on the equator.
... the loss of the Arctic ice throughout the summer would have a warming effect roughly equivalent to all human activity to date. That is to say, with the ice gone in summer, the planet would have an additional heating effect just as large as the heating effect of all human CO2 and other greenhouse gasses to date.
In other words, the complete meltdown of the Arctic could roughly double the rate of warming of the planet as a whole.
The addition of a new source of warming may dash any hopes of arresting climate change by reducing greenhouse gas emissions.
If even 10% of the northern permafrost’s buried carbon were released as methane, it would have a heating effect over the next decade equivalent to ten times all human greenhouse emissions to date, and over the next century equivalent to roughly four times all human greenhouse emissions to date.
If one third ... were released as methane, then the heating effect each year would be roughly equivalent to that of the amount of CO2 and other greenhouse gases human civilization releases each year.
That is to say, we could end all our burning of fossil fuels – take them all the way to zero – and still see greenhouse gas levels rising just as rapidly as they are today.
... in past periods of rapid sea ice loss, Arctic land warmed three and a half times as fast as the warming that models predict for the 21stcentury.
... vaster methane deposits in methane hydrates frozen below shallow waters of the Arctic Ocean’s continental shelves. That store of carbon is enough that, if all of it were to go, it would have a warming effect equivalent to hundreds of times the total human carbon emissions to date.
... most of the methane is believed to be buried roughly 200 meters below the sea bed, only the top 25 meters or so of sea-bed are currently thawed, and thawing seems to have only progressed by about one meter in the last 25 years – a pace that suggests that the large bulk of the buried methane will stay in place for centuries to come.
...we are probably not in danger of a methane time bomb going off any time soon.
However, even a slow, gradual release of just a tiny fraction of the methane buried beneath the Arctic Ocean could significantly add to the pace of climate change. If the Arctic sea floor methane deposits started to outgas at a rate that would empty them into the atmosphere in 10,000 years, that would still be an added annual warming effect roughly on par with the amount of carbon humans emit into the atmosphere each year. If the rate of Arctic sea floor methane release were faster – more like a 1,000 year pace to empty those deposits – then we’d be looking at a warming effect each year from that methane outgassing that would be many times greater than the warming from the fossil fuels we burn.
...the jet stream is now weaker than it once was – about 14% weaker than it was in 1980.
Every step we take to cut greenhouse gas emissions today is far easier than fighting the triple whammy we could be facing just a few years in the future.
Despite his optimistic tone, "with the ice gone in summer, the planet would have an additional heating effect just as large as the heating effect of all human CO2 and other greenhouse gasses to date." felt like a body blow. *Wham!* "If even 10% of the northern permafrost’s buried carbon were released as methane, it would have a heating effect over the next decade equivalent to ten times all human greenhouse emissions to date" *Blam!* "methane hydrates frozen below shallow waters of the Arctic Ocean’s continental shelves ... If the rate of Arctic sea floor methane release were faster – more like a 1,000 year pace to empty those deposits – then we’d be looking at a warming effect each year from that methane outgassing that would be many times greater than the warming from the fossil fuels we burn." *Whomp!*
I can't even estimate imagine what that all combined would do in terms of drought and heat emergencies, floods, hurricanes, Derechos, Haboobs, and global starvation. We've only dipped a toe tip into Eaarth the last few years. What's ahead is a nightmare where we've lost control of our planet and it's killing us.
In Feb, above, Ramez Naam said
...we are probably not in danger of a methane time bomb going off any time soon.
That may have been too optimistic, based on the latest data off the US east coast.
A changing Gulf Stream off the East Coast has destabilized frozen methane deposits trapped under nearly 4,000 square miles of seafloor, scientists reported Wednesday. And since methane is even more potent than carbon dioxide as a global warming gas, the researchers said, any large-scale release could have significant climate impacts.
Temperature changes in the Gulf Stream are "rapidly destabilizing methane hydrate along a broad swathe of the North American margin," the experts said in a study published Wednesday in the peer-reviewed journal Nature.
Using seismic records and ocean models, the team estimated that 2.5 gigatonnes of frozen methane hydrate are being destabilized and could separate into methane gas and water.
"It is unlikely that the western North Atlantic margin is the only area experiencing changing ocean currents," they noted. "Our estimate ... may therefore represent only a fraction of the methane hydrate currently destabilizing globally." [emphasis mine]
An Earth Tipping Point Study in Nature describes tipping points well.
Earth is rapidly headed toward a catastrophic breakdown if humans don't get their act together, according to an international group of scientists.
Writing Wednesday (June 6) in the journal Nature, the researchers warn that the world is headed toward a tipping point marked by extinctions and unpredictable changes on a scale not seen since the glaciers retreated 12,000 years ago.
"There is a very high possibility that by the end of the century, the Earth is going to be a very different place," study researcher Anthony Barnosky told LiveScience. Barnosky, a professor of integrative biology from the University of California, Berkeley, joined a group of 17 other scientists to warn that this new planet might not be a pleasant place to live.
"You can envision these state changes as a fast period of adjustment where we get pushed through the eye of the needle," Barnosky said. "As we're going through the eye of the needle, that's when we see political strife, economic strife, war and famine."
Barnosky and his colleagues reviewed research on climate change, ecology and Earth's tipping points that break the camel's back, so to speak. At certain thresholds, putting more pressure on the environment leads to a point of no return, Barnosky said. Suddenly, the planet responds in unpredictable ways, triggering major global transitions.
The results are difficult to predict, because tipping points, by their definition, take the planet into uncharted territory. [emphasis mine]
Seawater temperature in the Arctic Ocean is reaching a tipping point where the burst of algae growth in April, which normally absorbs CO2, will result in CO2 emission instead.
An international team of researchers has issued a stark warning about the perils the world faces in the near future because of mounting evidence confirming the carbon dioxide effects of a 5º C increase in the temperature of the Arctic Ocean.
Rapid melting of ice in Greenland and the Arctic Ocean last year showed catastrophic acceleration in 2012, qualifying the effects in the Arctic as “dangerous climate change” under the UN Climate Convention.
The five-year-long research revealed that the two-week spring algal bloom occurring each April, as the Arctic emerges from its winter darkness and the sea-ice starts to thin, is so productive it can fuel the food web for the entire year and remove significant amounts of CO2 from the atmosphere annually.
But ... the plankton community switches from acting as a sink to becoming a source of atmospheric CO2 as seawater temperatures exceed 5º C.
The researchers noted that this temperature would be regularly observed in the European sector of the Arctic Ocean over coming decades.
“Warmer temperatures enhance respiration rates by plankton organisms, particularly bacteria, leading to a shift in the size of photosynthetic plankton, which decompose quickly, and results in a major release of CO2 from excess respiration,” the researchers say. [emphasis mine]
Extreme weather decreases CO2 uptake, in a power law relationship. This means that the most severe drought events cause disproportionate damage. We always knew that Climate Destabilization caused extreme weather. Now it seems extreme weather, particularly drought, also causes Climate Destabilization to escalate - another positive feedback surprise.
Measurements indicated that the extreme weather events had a much greater impact on the carbon balance than had previously been assumed. It is possible that droughts, heat waves and storms weaken the buffer effect exerted by terrestrial ecosystems on the climate system. In the past 50 years, plants and the soil have absorbed up to 30% of the carbon dioxide that humans have set free, primarily from fossil fuels.
The team then fed the various readings into complex computer models to calculate the global effect of extreme weather on the carbon balance. The models showed that the effect is indeed extreme: on average, vegetation absorbs 11 billion fewer tonnes of carbon dioxide than it would in a climate that does not experience extremes. "That is roughly equivalent to the amount of carbon sequestered in terrestrial environments every year," says Markus Reichstein. "It is therefore by no means negligible."
Periods of extreme drought in particular reduce the amount of carbon absorbed by forests, meadows and agricultural land significantly. "We have found that it is not extremes of heat that cause the most problems for the carbon balance, but drought," explains Markus Reichstein. He and his colleagues expect extreme weather events to have particularly pronounced, varied and long-term effects on forest ecosystems. Drought can not only cause immediate damage to trees; it can also make them less resistant to pests and fire. It is also the case that a forest recovers much more slowly from fire or storm damage than other ecosystems do ...
The researchers also discovered that serious failures to absorb carbonare distributed according to a so-called power law, like avalanches, earthquakes and other catastrophic events. This means that a few major events dominate the global overall effect, while the more frequent smaller events occurring throughout the world play a much less significant part.
... the consequences of weather extremes can be far-reaching. "As extreme climate events reduce the amount of carbon that the terrestrial ecosystems absorb and the carbon dioxide in the atmosphere therefore continues to increase, more extreme weather could result," explains Markus Reichstein. "It would be a self-reinforcing effect." [emphasis mine]
Yet another positive feedback has been discovered for Climate Destabilization. Increasing ocean acidification reduces the amount of sulfur aerosols from the ocean, which impacts cloud formation.
Scientists at the Max Planck Institute for Meteorology (MPI-M), Dr. Katharina Six, Dr. Silvia Kloster, Dr. Tatiana Ilyina, the late Dr. Ernst Maier-Reimer and two co-authors from the US, demonstrate that ocean acidification may amplify global warming through the biogenic production of the marine sulfur component dimethylsulphide (DMS).
The reduced DMS emissions induce a significant positive radiative forcing of which 83% (0.4 W/m2) can, in the model, be attributed to the impact of ocean acidification alone. Compared to Earth system response to a doubling of atmospheric CO2 this is tantamount to an equilibrium temperature increase between 0.23 and 0.48 K.
Simply put, their research shows that ocean acidification has the potential to speed up global warming considerably. [emphasis mine]
These positive feedback mechanisms are being discovered so often, how will science integrate all of them into a comprehensive predictive climate model? It feels as if we will necessarily always be ignorant of the magnitude of irreversible damage we're creating, always be too optimistic, always be taken by surprise as the consequences of our actions cascade.
Reversal of the Beaufort Gyre in the Arctic Ocean could occur in the years ahead, probably in the Fall, initiating another climate tipping point.
The normal (historical) clockwise rotating Beaufort Gyre keeps fresher surface water and floating ice in the Arctic and helps the production of multi year ice by keeping the ice in the Arctic Ocean. A counter clockwise Beaufort Gyre pushes surface water and ice into the trans-polar drift and out of the Arctic.
If you look at the October 2012 edition of the NSIDC report, they already report rising air over the Arctic ocean with winds from the south. It makes sense that fall would be when we would first see this situation. The land is cooling rapidly as the sun leaves the north while the sea has an accumulation of heat from the summer. Offshore (southern) winds will result, causing a counter clockwise rotating weather system which in turn will reverse the direction of the Gyre. As mentioned, such a system will also fling floating ice outward, possibly to be caught by the Transpolar Current and expelled from the Arctic through Fram Strait. Whether this 2012 reversal of the air circulation was strong enough or lasted for long enough to reverse the Beaufort Gyre is unclear.
There is enough heat in the deeper Atlantic water to melt all the surface ice about three times over. This looks to be another of these much anticipated tipping points. Warmed surface water gives rise to a counter clockwise Beauford gyre which in turn brings up deep salty warmer water to melt more ice which leads to more warming as more of the surface of the ocean becomes open water.
Floating ice and the lighter, fresher surface water is pushed into the trans-polar current and expelled from the Arctic ocean through the Fram strait. Likely it would also be expelled through the Bearing Strait. As surface water is pushed out of the Arctic by the counter clockwise rotating wind system, aided by coriolis, the fresh(er) water layer thins and deeper, warmer water from the Atlantic and Pacific pours in to replace it. The disappearance of the Arctic ice accelerates far faster than would be expected from considerations of climate sensitivity or thermodynamics. [emphasis mine]