Hunter Cutting: Climate Change Passes a Tipping Point in California

by Hunter Cutting, Huffington Post, October 1, 2015

With Californians crossing their fingers in hopes of a super El Niño to help end the state's historic drought, California's water agency just delivered some startling news: for the first time in 120 years of record keeping, the winter average minimum temperature in the Sierra Nevada was above freezing. And across the state, the last 12 months were the warmest on record. This explains why the Sierra Nevada snow pack that provides nearly 30% of the state's water stood at its lowest level in at least 500 years this last winter despite precipitation levels that, while low, still came in above recent record lows. The few winter storms of the past two years were warmer than average and tended to produce rain, not snow. And what snow fell melted away almost immediately. 

Thresholds matter when it comes to climate change. A small increase in temperature can have a huge impact on natural systems and human infrastructure designed to cope with current weather patterns and extremes. Only a few inches of extra rain can top a levee protecting against flood. Only a degree of warming can be the difference between ice-up and navigable water, between snow pack and bare ground.

Climate change has intensified the California drought by fueling record-breaking temperatures that evaporate critically important snowpack, convert snowfall into rain, and dry out soils. This last winter in California was the warmest in 119 years of record keeping, smashing the prior record by an unprecedented margin. Weather records tend to be broken when a temporary trend driven by natural variability runs in the same direction as the long-term trend driven by climate change, in this case towards warmer temperatures. Drought in California has increased significantly over the past 100 years due to rising temperatures. A recent paleoclimate study found that the current drought stands out as the worst to hit the state in 1,200 years largely due the remarkable, record-high temperatures. 

Looking forward to El Niño, California may find soon itself at the other extreme, with global warming fueling the swing from drought to torrent. When storms do break through to California, they are now loaded with additional rainfall due to global warming, dramatically increasing the risk of flooding.

As the world heats up and more heat is carried in the atmosphere as water vapor, heavy precipitation events are becoming more intense. Like a larger bucket, a warmer atmosphere can hold and dump more water. In the past half-century, climate change has charged the atmosphere with more water vapor, fueling extreme precipitation and loading storms of all types with additional moisture that ends up as more rain and, (ironically) even more snowfall when it's still cold enough. The fingerprint of global warming has been firmly documented in the shift toward extreme precipitation already observed in the northern hemisphere. 

Off the California coast, recent temperatures have been 5 to 6 °F warmer than historic averages -- among the warmest conditions of any time in the past 30 years. In August and September, California coastal buoys reached their warmest levels ever recorded. 

All these record warm temperatures will help supercharge the incoming fall storms for which Californians are praying. In a warming world, it's best to be careful about what you pray for.

http://www.huffingtonpost.com/hunter-cutting/climate-change-in-california-passes-a-tipping-point_b_8223556.html

Jason Box: Earth's Ice Is Melting Much Faster Than Forecast. Here's Why That's Worrying

by Jason Box, Professor of Glaciology, Geological Survey of Denmark and Greenland, Huffington Post, September 4, 2015

COPENHAGEN -- For me it was only after 8 years of studying Greenland -- installing and maintaining a network of on-ice climate stations and examining how much snow evaporates from the island -- that I suddenly realized glaciology textbooks needed a major revision. This was in 2002. Prior to the epiphany, conventional knowledge held that the ice sheet was frozen at its bed, and so the reaction time of the ice sheet to climate warming was measured in tens of thousands of years. A heck of a long time.

Climate warming had just infiltrated Greenland glaciology in earnest. Summer melt water, it turned out, drains down quickly to the bed, lubricating the glacier's flow. Suddenly we realized an expanding melt season meant the ice sheet would be sliding faster, longer. It was not to be the only time our philosophy got hit with a major surprise that connected the ice sheet with climate change and the threat of abrupt sea level rise.

The next one came in 2006.

Somehow all marine-terminating glaciers across the southern half of Greenland doubled in speed simultaneously between 2000 and 2005. [Readers, this news is what caused me to begin this blog -- I had the one and only epiphany in my life when I read about this.] We didn't yet know why.

In the meantime, scientists tried defining a plausible upper limit for the contribution to sea level rise from Greenland's ice. That was at a time when surging glacier speeds -- ice flow -- was thought to be the dominant conveyer of ice loss, and would be for the foreseeable future. Well, surprise! It became clear that for six years in a row, starting in 2007, ice loss from surface meltwater runoff took over the lead position in the competition for biggest loser.  [This was something I thought privately at the time -- that this must occur eventually, but I did not imagine that it would occur so soon. I never bought into the idea that the topography was a limit on glacial outflow and thus would restrain Greenland's contribution to sea level rise.] From 2007 to 2012, nearly each summer set higher and higher melt records, owing to persistent and unforeseen weather that by 2012 would become a signature of climate change.

The competition between how much ice is lost through glacier flows into fjords versus meltwater runoff is intimately synergistic with meltwater interacting with ice flow all along the way. Increasing melt sends more water down through the ice sheet, softening the ice so it flows faster. Once at the bed the water lubricates flow. Squirting out the front of glaciers into the sea, the meltwater drives a heat exchange that undercuts glaciers, promoting calving, loss of flow resistance and faster flow. Put it this way: in Washington, DC, to know what's happening, you follow the money; in Greenland you follow the meltwater.

Put it this way: in Washington, DC, to know what's happening, you follow the money; in Greenland you follow the meltwater.

Glaciologists became oceanographers when they realized, in 2008, the trigger effect for galloping glaciers was warm pulses of subtropical waters that undermine glaciers at great depth in the sea, at the grounding lines where this warm water can invade.

Indeed, ocean warming is arguably the climate change story. The planetary energy imbalance due to the enhanced greenhouse effect is loading far more heat into the oceans than the atmosphere or land. The world is 70% ocean-covered. after all. While there were signs of a warming hiatus in air temperatures from 1998 to 2012, the ocean continued to heat up, an equivalent of four Hiroshima bombs, per second, all day, every day. The increase is continuing as we load the atmosphere with CO2.

The fundamental climate heating issue is a problem of too much of a good thing. The natural greenhouse effect -- a good thing -- keeps temperatures tolerable at night. But it has been enhanced by more than a century of people externalizing the environmental costs of stupendous economic growth, loading the atmosphere now with 42% more carbon dioxide, 240% more methane, 20% more nitrous oxide, 42% more tropospheric ozone, etc. We have far too much gaseous carbon compounds now in our atmosphere, people. The carbon pollution is, by the way, making our oceans too acidic, threatening the base of the marine food chain. Would someone step forward and deny the changing ocean chemistry? Do I digress?

We have far too much gaseous carbon compounds now in our atmosphere, people.

The key question, as I see it, is how to project what the sea level will soon be due to ice sheet melting. But this is confounded by us not really knowing what to expect. We keep being surprised by nature being more sensitive and complex. As the science develops, we see more interconnection, where multiplying feedbacks produce surprisingly fast responses.

Will there be some saving self-regulation of human-induced climate warming and its melting land ice consequences? The enormous increase of heat in our oceans, from past decades of enhanced greenhouse effect, negates any hope that negative feedbacks or even solar output will prevent a much warmer world. The few negative feedbacks we have found for ice -- like more snow as a result of a warming climate, more reflective frost, more efficient sub-glacial water transmission -- are clearly being outdone. And at the global scale, despite some negative feedbacks like more clouds, clearly we are not seeing net cooling. Feedbacks, whether positive or negative, only do their thing after the initial effect. Negative feedbacks don't reverse the perturbation.

Seemingly the biggest issue with abrupt sea level rise comes from the now-unstoppable loss of key sectors of West Antarctic ice and the discovery of more marine instability than we thought elsewhere. Like glaciers thinning rapidly in East Antarctica. Or in Greenland, where improved bedrock maps reveal a marine connection an average of 40 kilometers further inland than previously thought. Or like how new fjord underwater mapping reveals greater fjord depths, increasing the odds that deep warm ocean water can communicate with more Greenland glaciers than previously thought. Surprise, surprise, surprise.

I'd say we are in for more surprises.

If the past decade of scientific inquiry is any indication, I'd say we are in for more surprises. That notion is further supported by the fact that the climate models used for projecting future temperatures lack key processes that likely reinforce warming or the effects of warming, not regulate it.

Despite decades of progress by many clever scientists engaged with climate modeling, climate models used to inform policymakers don't yet encode key pieces of physics that have ice melting so fast. They don't incorporate thermal collapse -- ice softening due to increasing meltwater infiltration.

Climate models also don't yet incorporate increasing forced ocean convection at the ocean fronts of glaciers that forces a heat exchange between warming water and ice at the grounding lines.

Climate models don't yet include ice algae growth that darkens the bare ice surface.

Climate models don't yet prescribe background dark bare ice from outcropping dust on Greenland from the dusty last ice age.

Climate models don't include increasing wildfire delivering more light-trapping dark particles to bright snow-covered areas, yielding earlier melt onset and more intense summer melting.

As a result of some of these factors and probably some as yet unknown others, climate models have under-predicted the loss rate of snow on land by a factor of four and the loss of sea ice by a factor of two.

Climate models also don't yet sufficiently resolve extended periods of lazy north-south extended jet streams that produce the kind of sunny summers over Greenland (2007-2012 and 2015) that resulted in melting that our models didn't foresee happening until 2100.

While individual climate models come close to observations on this or that piece of the complex big picture, what ends up in global assessment reports intended to help guide policy decisions and national discussions of climate change are very conservative averages of dozens of models that don't include the latest, higher sensitivity physics.

So, alas, when it comes to ice, how fast it can go and how fast the sea will rise, if I were a betting man, I'd put my money on it going faster than forecast.

http://www.huffingtonpost.com/jason-e-box/ice-melt-fast_b_7927186.html

Peter Sinclair: Point of No Return, Deglaciation of West Antarctica, Meltwater Pulse 2B

by Peter Sinclair, This Is Not Cool, June 2, 2014

Today’s news will be dominated by discussion of new carbon regulations proposed by the Obama administration.  My contribution is to summarize the most recent evidence for why those regs are needed today, if not 25 years ago.

Bud Ward at Yale Climate Connections:

It’s not often that a scientific research paper generates the kind of media attention and scientific community buzz that resulted from a recent study on the apparent inevitability of substantial Antarctic glacial melting.

The early May research headed by lead author Eric Rignot of NASA called attention to melting now under way in Antarctica that CBS News anchor Scott Pelley reported “cannot be stopped.”

“Scientists say the situation is almost certainly unstoppable,” NBC News Anchor Brian Mitchell reported.

Rignot cautioned that the research indicates “we’ve passed the point of no return … It’s just a matter of time before these glaciers disappear to the sea.” While he indicated that the full melt, at the current pace, might not occur for two centuries, he pointed too to evidence suggesting the likelihood of an accelerating pace.

“There’s probably nothing that can be done to stop this,” Rignot said.

“This is really happening,” lead NASA lead polar ice researcher Tom Wagner said. “This weak underbelly of Antarctica is in fact starting to float out into the sea, and there’s not a lot to hold it back.”

A “This is Not Cool” video on the report by independent videographer Peter Sinclair is the first to be posted under the new Yale Climate Connections name, formerly The Yale Forum on Climate Change & The Media. The official transition to that newly named site is to get underway over the next few weeks, initially with a largely cosmetic rebranding, then to be followed by a substantial overhaul and a more multi-media emphasis aimed at better reaching the general public.

Note: link to the Guardian piece referenced in the video is here. Errata – I neglected to thank the European Space Agency for important video animations. Deepest apologies.

UPDATE: Per Stefan Rahmstorf, newly published study adds complexity.

eScience News:

“Conventional thinking based on past research is that the Antarctic Ice Sheet has been relatively stable since the last ice age, that it began to melt relatively late during the deglaciation process, and that its decline was slow and steady until it reached its present size,” said lead author Michael Weber, a scientist from the University of Cologne in Germany.

“The sediment record suggests a different pattern — one that is more episodic and suggests that parts of the ice sheet repeatedly became unstable during the last deglaciation,” Weber added.

The research also provides the first solid evidence that the Antarctic Ice Sheet contributed to what is known as meltwater pulse 1A, a period of very rapid sea level rise that began some 14,500 years ago, according to Peter Clark, an Oregon State University paleoclimatologist and co-author on the study.

The largest of the 8 episodic pulses outlined in the new Nature study coincides with meltwater pulse 1A.

“During that time, the sea level on a global basis rose about 50 feet in just 350 years — or about 20 times faster than sea level rise over the last century,” noted Clark, a professor in Oregon State’s College of Earth, Ocean, and Atmospheric Sciences. “We don’t yet know what triggered these eight episodes or pulses, but it appears that once the melting of the ice sheet began it was amplified by physical processes.”

The researchers suspect that a feedback mechanism may have accelerated the melting, possibly by changing ocean circulation that brought warmer water to the Antarctic subsurface, according to co-author Axel Timmermann, a climate researcher at the University of Hawaii at Manoa.

“This positive feedback is a perfect recipe for rapid sea level rise,” Timmermann said.

Some 9,000 years ago, the episodic pulses of melting stopped, the researchers say.

“Just as we are unsure of what triggered these eight pulses,” Clark said, “we don’t know why they stopped. Perhaps the sheet ran out of ice that was vulnerable to the physical changes that were taking place. However, our new results suggest that the Antarctic Ice Sheet is more unstable than previously considered.”

http://climatecrocks.com/2014/06/02/new-video-meltwater-pulse-2b/http://climatecrocks.com/2014/06/02/new-video-meltwater-pulse-2b/

MUST READ: Fugitive Methane Emissions from Fracking Oil and Gas Production Can Cause a ‘Global Catastrophe’ and Point of No Return

by Bobby Magill, Climate Central, May 15, 2014

A Cornell University scientist's claims that oil and gas development is so harmful to the climate that methane emissions and oil and gas production in general need to be cut back immediately to avoid a "global catastrophe" are adding more fuel to the scientific debate over the climate implications of shale oil and gas production. 

Fossil fuels production is the largest methane pollution source in the U.S., and ignoring those emissions will lead to a climate change “tipping point” from which there is no return, Cornell environmental biology professor Robert Howarth said in a statement Wednesday. He was unavailable for an interview.

Excess methane is often burned off from oil and gas production and distribution systems. Credit: Center for Enabling New Technologies Through Catalysis

Though scientists say there are avenues to preventing catastrophe other than curbing methane emissions, Howarth’s previous research with Cornell environmental engineering professor Anthony Ingraffea and others concluded that the climate impact of natural gas produced from shale — most of which involves hydraulic fracturing, or fracking — may be worse than that of coal and crude oil. That's because methane leaks from natural gas production have a greater effect on the climate than carbon dioxide emissions, Howarth said. 

Over a 100-year timeframe, methane is about 34 times as potent as a climate change-driving greenhouse gas than carbon dioxide, and over 20 years, it's 86 times more potent. Of all the greenhouse gases released by humans globally, methane contributes more than 40 percent of all radiative forcing, a measure of trapped heat in the atmosphere and a measuring stick of a changing climate, Howarth said.

“We have to control methane immediately, and natural gas is the largest methane pollution source in the United States,” Howarth said. “If we hit a climate-system tipping point because of methane, our carbon dioxide problem is immaterial. We have to get a handle on methane, or increasingly risk global catastrophe.”

RELATED	Methane Leaks May Negate Benefits of Natural Gas

Howarth's research is controversial, with the energy industry trying to discredit his work and other scientists questioning his methods. Those questions come amid a steady stream of studies released over the past year that strongly suggest either that methane emissions emanating from oil and gas fields are greater than U.S. Environmental Protection Agency estimates or that the impact those emissions will have on climate change is extremely complex and difficult to determine. And even many scientists who agree with Howarth's research say there are other ways to curb methane emissions without shutting down natural gas production.

In other words, Howarth's critics say, methane's effect on the climate is too complicated to demand that emissions be cut dramatically and immediately. 

Howarth's new paper, to be published May 20 in the journal Energy Science and Engineering, reviews much of the oil and gas-related methane emissions research conducted nationwide over the 4 years since his initial methane research was published in 2011, and in the context of the Intergovernmental Panel on Climate Change’s Fifth Assessment Report released last year.

Howarth’s conclusion: Producing natural gas of any kind has a worse greenhouse gas footprint than burning coal and crude oil over a 20-year timeframe. In other words, the idea that natural gas is a “bridge fuel” between carbon-producing coal and clean renewable energy sources simply isn’t true, especially if natural gas is used for home heating, the study says.

At best, Howarth said natural gas might lead to a “very modest” reduction in greenhouse gas emissions if it is used in place of coal to generate electricity and only with “unprecedented” investment in natural gas infrastructure and regulatory oversight.

The paper is the latest in a long line of recent studies suggesting that methane emissions from shale oil and natural gas production and distribution equipment are much greater than previously thought.

A study by researchers from Purdue and Cornell universities published in April showed that natural gas drilling could emit up to 1,000 times the methane previously thought.

Just last week, the Cooperative Institute for Research in Environmental Sciences at the University of Colorado-Boulder released a study by National Oceanic and Atmospheric Administration atmospheric scientist Gabrielle Petron showing that an airplane flying over a large northeast Colorado shale oil and gas field measured atmospheric methane concentrations three times greater than U.S. Environmental Protection Agency estimates for the area.

EPA estimates are based on oil industry-reported data. In the EPA’s summary of its latest greenhouse gas emissions inventory, the agency cited one of Petron’s earlier methane emissions studies as evidence that the EPA’s industry-based methane estimates differ from the results of research that involves actual emissions measurements. The summary says the EPA “has engaged with researchers” on how measurements could improve understanding of inventory estimates.

“These discrepancies are substantial,” Petron said in a May 7 statement. “Emission estimates or ‘inventories’ are the primary tool that policymakers and regulators use to evaluate air quality and climate impacts of various sources, including oil and gas sources. If they’re off, it’s important to know.”

But different methods of measuring methane emissions get different results, and it's critical those differences be reconciled, said Robert Jackson, a professor of global environmental change at Duke University whose research has shown methane leaks are a hazard in natural gas distribution systems in the U.S. 

By using an airplane to fly over an oil and gas field to directly measure methane concentrations in the air, Petron's study used a "top-down" approach to estimating oil and gas field emissions. Other scientists have used a "bottom up" approach by measuring emissions from oil and gas facilities on the ground, a method used in a University of Texas study published last year suggesting fracked natural gas wells leak less methane than the EPA previously estimated. 

The simplest explanation for the discrepancy is that a few oil and gas wells emit a lot of methane, while others measured in "bottom up" studies release much less methane, Jackson said. Hundreds or thousands of wells would have to be sampled on the ground for the "bottom up" studies to accurately measure emissions, he said. 

"The key point is the data that have come in in the last couple of years, it's not a huge dataset," Jackson said. "The data that have come in seem to suggest the EPA estimates are too low. Will they turn out that they're high enough that Bob Howarth is right? We don't know that yet, and it may not be the case." 

The overall implications of natural gas production on a changing climate are extremely complicated, a Duke University study published in April by researchers Richard Newall and Daniel Raimi concluded.

Natural gas use can increase overall energy use and alter economy-wide greenhouse gas emissions, but it's unclear whether that means an increase or decrease in those emissions, and without specific emission targets, trends in atmospheric greenhouse gas emissions aren't likely to change even with widespread use of natural gas, Newall and Raimi conclude.

Howarth disagrees, saying there’s enough evidence that the climate implications of methane emissions from oil and gas development could be catastrophic and that it’s important to act now.

Crude oil tanks in northeast Colorado's suburban Wattenberg oil field, where measurements showed atmospheric methane concentrations were three times the levels reported in EPA inventories. Scientists say most of that methane came from the oil and gas operations in the area. Credit: Bobby Magill

If shale oil and gas methane emissions aren’t reined in quickly, the earth could warm a critical 2 °C within 15 to 35 years, he said. In order for the earth to avoid the most serious consequences of global warming, the planet’s average temperature cannot warm more than 2 °C above where it was in the 1800s. Global average temperatures have already warmed 1 °C.

Lawrence Cathles, a Cornell earth and atmospheric sciences professor whose criticism of Howarth's previous research made national headlines along with Howarth's rebuttal, said the science does not suport Howarth's claim that immediate curbs on methane emissions are necessary to avoid the 2 °C warming thresshold. 

"For methane to be a significant climate driver between now and 2035, its rate of increase in the atmosphere would need to accelerate dramatically, and so far we don't see this happening," Cathles said. "Curbs on methane emissions are desirable, but they will make a small player in climate change even smaller, and reducing emission rates below present levels is not a matter of necessity in controlling global warming." [Yeah, right.]

[snip]

Drew Shindell, a NASA Goddard Institute for Space Studies scientist on whose research Howarth draws but was not involved in Howarth's study, said that Howarth’s research is sound, but slashing methane emissions from natural gas isn’t the only way to keep global warming under 2 °C.

Keeping the earth from warming will involve more than cutting carbon dioxide emissions alone or methane alone. Cutting a combination of some CO2, some methane, some black carbon and anything else that contributes to radiative forcing could keep warming down, too, Shindell said.

Regarding Howarth’s views denying that natural gas is a bridge fuel, Shindell said Howarth is pointing out that unless the methane leak rate from natural gas production and distribution is extraordinarily low, the reduction in greenhouse gas emissions compared to coal doesn’t exist.

If natural gas could be produced with the very lowest possible methane leak rate, natural gas might come out ahead of coal for greenhouse gases, Shindell said.

“Whether that’s feasible, I don’t know,” he said.

In his paper, Howarth is adamant that replacing climate-changing coal with climate-changing natural gas does nothing to slow global warming.

“Society needs to wean itself from the addiction to fossil fuels as quickly as possible,” Howarth said in a statement. “But to replace some fossil fuels — coal, oil — with another, like natural gas, will not suffice as an approach to take on global warming. Rather, we should embrace the technologies of the 21st century and convert our energy systems to ones that rely on wind, solar and water power.”

Jackson said he wouldn't quite go so far as to call for running away from natural gas. 

"We need to do everything we can to cut methane emissions right now," Jackson said. "Using less natural gas might be one approach, but given that we are going to continue to use natural gas, my research (focuses on) how can we detect leaks quickly and fix them cheaply to reduce that leakage term?"  [Would need the states' departments of natural resources to write and enforce regulations for detection, measurement, and remediation, and hire and train thousands of inspectors -- not gonna happen.  For example, at the moment, the Illinois DNR has so few inspectors that it would take over 300 years to inspect wells.  And the Illinois DNR has no will to enforce anything on oil and gas companies -- currently, they are bending over backwards to help the oil and gas companies run roughshod over anything in their way.]

Shifting over completely to renewables would be great for human health and the environment, "but that's not the world we live in," Jackson said. "I want to know if you turn the spigot off for natural gas, do we get wind or do we get a new coal plant? And Bob (Howarth) might say that even if we got a coal plant, that's a good thing. It's not so black and white for me."

http://www.climatecentral.org/news/fracking-methane-emissions-catastrophe-17439

Dr. Mauri Pelto interviewed by Peter Sinclair on Antarctic melt, Part II

interview by Peter Sinclair, Weekend Wonk, May 18, 2014

Link:  http://climatecrocks.com/2014/05/18/the-weekend-wonk-dr-mauri-pelto-on-antarctic-melt-part-2/

Tipping point for polar ice cap may have come in 2012

by Yereth Rosen, Alaska Dispatch, October 16, 2013

The dramatic reduction of Arctic sea ice witnessed from 2007 to 2012 is now considered by some scientists to be a "persistent and permanent feature of the summer Arctic environment." Kathryn Hansen/NASA photo

This year may have granted a slight reprieve for vanishing Arctic sea ice, but evidence gathered to date shows that summer shrinkage will likely continue its downward spiral in future years, according to a new paper published in the Oct. 4 edition of the journal Geography Compass. 

The paper, by Kent State University doctoral candidate Thomas Ballinger and Jeffrey Rogers, a geography professor at Ohio State University, synthesizes information about weather, ocean currents and ice conditions in the Beaufort and Chukchi seas between 2007 through 2012, a six-year period of severe melt. Conditions in those seas appear to have changed for good, the paper says.

“Dramatic reduction in late summer sea ice on these seas occurring in 2007 and subsequent years now appears to be a persistent and permanent feature of the summer Arctic environment,” it says.

Perfect storm for vanishing ice

RELATED: 

Arctic ice melting rapidly, but some 'signs' are false alarms

The paper describes how, in the biggest ice-loss years, weather and ocean patterns aligned into almost a perfect storm to erase large amounts of ice.

That happened in 2007, when a Beaufort Sea high-pressure system persisted all summer, instead of being limited to short spurts, as is typical, Ballinger said in a telephone interview.

The year “was really remarkable” because there was still a lot of thicker multiyear ice around then, he said. Persistent high pressure brought clear skies, though, and intense solar radiation melted ice and was absorbed by the widened stretches of open ocean, where it amplified its effects, he said. That and other factors hammered the 2007 ice, he said. “It really cleared out a lot of that thicker ice,” he said.

Subsequent years showed large ice losses in the Beaufort and Chukchi, though not as bad as 2007. Then last year, the persistent Beaufort Sea high struck with a vengeance, followed by a strong cyclone in August. That helped break up fragile single-year ice that replaced multi-year ice lost in 2007, he said. The result was the lowest Arctic ice cover on record.

Thanks to the weaker nature of the ice, a record low would have been reached in 2012, even without the August cyclone, some scientists argue.

Interplay of sea ice and weather 

Scientists for years have studied the interplay between Arctic sea-ice dynamics and Arctic weather, as well as the impact on long-term climate beyond the Arctic. 

But any connection between the Arctic ice loss and specific weather events in southern latitudes is a complicated question, Ballinger said. “The link between the ice loss and any particular storm event is kind of hard to match up,” he said.

One recent study suggests sea-ice loss is a culprit in the nation’s biggest weather disaster of 2012. The study, published in the March edition of the journal Oceanography, is titled “Superstorm Sandy: A Series of Unfortunate Events?” 

Another study, published by the American Meteorological Society, ties Arctic sea-ice loss to a prediction of more extreme winter-weather events in northern Eurasia. 

Contact Yereth Rosen at yereth(at)alaskadispatch.com 

http://www.alaskadispatch.com/article/20131016/tipping-point-polar-ice-cap-may-have-come-2012

David Spratt: Is climate change already dangerous? Part IV. Tipping points and climate modelling

by David Spratt, Climate Code Red, September 24, 2013
Fourth in a series
A tipping point may be understood as a step change, or passing of a critical threshold, in a major earth-climate system component, where a small perturbation (a small push or change) unleashes a bigger change in the component.  Potsdam Institute Director, Prof. Hans Joachim Schellnhuber, says that tipping points “identify the most vulnerable components (tipping elements) of the Earth System, the critical warming thresholds where the respective Earth System elements flip into a qualitatively new state.”  These elements include ecosystems, major ocean and atmospheric circulation patterns, the polar ice sheets, and the land- and ocean-based carbon stores.
This process is often tied to positive feedbacks, where a change in a component leads to other changes that eventually “feed back” onto the original change to amplify it.  The classic case in global warming (or, in reverse, cooling) is the ice-albedo feedback, where decreases (increases) in the ice cover area change surface reflectivity (albedo), trapping more (less) heat and producing further ice loss (gain).

In some cases, passing one threshold will trigger further threshold events, for example where substantial releases from permafrost carbon stores increase warming, releasing more permafrost carbon but also pushing other systems, for example parts of the Antarctic ice sheet, past a threshold point.
Once a tipping point is crossed, it is irreversible (under natural conditions) within certain time frames, so the consequence is to significantly affect the earth’s climate and ecosystems, for example by raising temperatures or greenhouse gas levels, or changing the efficiency of the land and ocean carbon sinks.  Given enough time and the right conditions, most processes (but not extinctions, for example) can be reversed.
In a period of rapid warming, most major tipping points once crossed (ice sheet loss, large-scale land carbon store releases such as permafrost) are irreversible on human time frames running to a few generations, principally due to the longevity of atmospheric CO2 (several thousand years). Large-scale human interventions in slow-moving earth system tipping points might allow a tipping point to be reversed (for example, a large-scale atmospheric CO2 drawdown program, or solar radiation management).
There is discussion, for example, that Arctic sea-ice loss is “easily reversible” in a cooling world, but that is easier said than done.  That would require greenhouse gas levels to be reduced significantly, below the level equivalent to the temperature at which the sea-ice system tipped in 2007, to produce a sufficiently cooler world.  This would be around 300–325 ppm CO2, compared to the present level of 400 ppm, so it is not so “easy” in the real world.
The scientific literature on tipping points is relatively recent, with a significant contribution by Lenton, Held et al. in 2008 on “Tipping elements in the Earth’s climate system” in an issue of the journal Proceedings of the National Academy of Sciences devoted to the subject. However, our knowledge is limited because “a system-level understanding of critical Arctic processes and feedbacks is still lacking” (Maslowski, Kinney et al.) and “no serious efforts have been made so far to identify and qualify the interactions between various tipping points” (Schellnhuber).
 
Climate models are not yet good at dealing with tipping points. This is partly in the nature of tipping points, where a particular and complex confluence of factors suddenly change a climate system characteristic and drives it to a different state. To model this, all the contributing factors and their forces have to well identified, as well as their particular interactions, plus the interactions between tipping points. Duarte, Lenton et al. conclude that “complex, nonlinear systems typically shift between alternative states in an abrupt, rather than a smooth manner, which is a challenge that climate models have not yet been able to adequately meet.”
The classic case was the Arctic sea ice “big melt” in 2007. Many models, including those on which the 2007 IPCC report had relied to conclude that Arctic sea-ice was pretty much likely to remain till the end of the century, did not fully capture the dynamics of sea-ice loss. Thus when in 2007 the summer sea-ice extent dropped radically compared to previous years, some model-oriented researchers exclaimed that the Arctic was melting “a hundred years ahead of schedule.”
Even today, papers are still being published with modelling that suggests a sea-ice free Arctic will not occur till mid-century. Given the observations, it’s difficult not to conclude that given a choice between their models and real-world observations, some modellers will always choose the former. 
In an overview of the current state of Arctic climate research, Maslowski, Kinney et al. conclude that: “Model limitations are hindering our ability to predict the future state of Arctic sea ice,” and that the majority of general climate models (GCMs) including those used in IPCC (2007) “have not been able to adequately reproduce observed multi-decadal sea-ice variability and trends in the pan-Arctic region,” and their ensemble mean trend in September Arctic sea-ice extent “is approximately 30 years behind the observed trend.”
For example, what would be the impact of a sea-ice-free Arctic summer and the consequent amplified regional warming on the stability of the Greenland Ice Sheet (GIS)? Research does not yet provide a robust framework for considering such questions, yet most scientists if asked for their expert elicitation would probably say that it is hard to imagine the GIS doing anything other than melting at an accelerating rate and passing a critical tipping point in such circumstances.
The sea-ice model that has performed best (acronym NAME), is one of a new range of more specialised regional climate models developed by Dr Wieslaw Maslowski and colleagues. Maslowski is highly regarded, in part because his position at the American Naval Postgraduate School has given him unique access to half a century of Arctic sea-ice thickness scans from polar US military submarines. Maslowski told BBC News:

In the past… we were just extrapolating into the future assuming that trends might persist as we’ve seen in recent times. Now we’re trying to be more systematic, and we’ve developed a regional Arctic climate model that’s very similar to the global climate models participating in IPCC assessments. We can run a fully coupled model for the past and present and see what our model will predict for the future in terms of the sea ice and the Arctic climate. 

He emphasizes “the need for detailed analyses of changes in sea ice thickness and volume to determine the actual rate of melt of Arctic sea ice,” and concludes that:

The modeled evolution of Arctic sea ice volume appears to be much stronger correlated with changes in ice thickness than with ice extent as it shows a similar negative trend beginning around the mid-1990s. When considering this part of the sea ice–volume time series, one can estimate a negative trend of −1,120 km3 year−1 with a standard deviation of +/-2,353 km3 year−1 from combined model and observational estimates for October–November 1996–2007. Given the estimated trend and the volume estimate for October–November of 2007 at less than 9000 km3, one can project that at this rate it would take only 9 more years or until 2016 +/-3 years to reach a nearly ice-free Arctic Ocean in summer. Regardless of high uncertainty associated with such an estimate, it does provide a lower bound of the time range for projections of seasonal sea ice cover.

The point cannot be emphasized enough that the best-performing Arctic sea-ice model projects 2016 +/-3 years to reach a nearly ice-free Arctic Ocean.

Arctic sea ice volumes estimates from observations and from the NAME model
(Maslowski, Kinney et al., 2012, Figure 9)

 The non-linear problem still plagues many Arctic GCMs, and indeed parts of the IPCC process which largely excludes tipping points and carbon cycle feedbacks from consideration, exemplified by the 2007 IPCC’s reticence on sea level rises. Several fundamental projections found in IPCC reports have consistently underestimated real-world observations in at least eight key areas.  In its February 2007 report on the physical basis of climate science, the IPCC said that Arctic sea-ice was responding sensitively to global warming: ‘While changes in winter sea-ice cover are moderate, late summer sea-ice is projected to disappear almost completely towards the end of the twenty first century.’ And apparently the forthcoming 2013 IPPC AR5 has omitted consideration of permafrost feedbacks – another glaring example of that body’s scientific reticence (Romm, 2012).

http://www.climatecodered.org/2013/09/is-climate-change-already-dangerous-4_24.html