Smashing Through 490 — Fragmenting Prospects for Avoiding 2 C Warming

“The IPCC indicated in its fourth assessment report that achieving a 2 C target would mean stabilizing greenhouse gas concentrations in the atmosphere at around 445 to 490 ppm CO2 equivalent or lower. Higher levels would substantially increase the risks of harmful and irreversible climate change.” –Johan Eliasch

NOAA's Greenhouse Gas Index

(NOAA’s greenhouse gas index shows that CO2e concentration for 2015 averaged 485 ppm. Given recent rates of rise, the 2016 average should be near 490 ppm CO2e. At the latest, this key threshold will be crossed some time during 2017. Image source: NOAA’s Earth Systems Research Laboratory.)

*****

There are a few things we know about climate change that should really keep us up at night. The first is that the world is warming, and this warming of the Earth, in so many ways, is dangerous to human beings and all the other innocent creatures living here.

The second is that, over recent years, this warming has been very rapid. In the three years from 2014 through 2016, the Earth’s atmospheric temperature is likely to have increased by 0.2 degrees Celsius or more to around 1.2 C above 1880s levels. When thinking about this in absolute terms, it doesn’t sound like much. But in geological terms, this is very rapid warming, especially when you consider that, at the end of the last ice age, it took about 400 years to produce a similar amount of atmospheric temperature gain.

What all this boils down to is that as global temperatures have spiked, we’ve rapidly crossed an established climate threshold into a far more geophysically dangerous time.

Surging Levels of Heat-Trapping Gasses

405 parts per million carbon dioxide. That’s about the average level of CO2 accumulation the Earth’s atmosphere will see by the end of 2016, due primarily to fossil-fuel burning. It’s a big number. The Earth hasn’t seen a number like that in millions of years. But 405 ppm CO2 doesn’t tell the whole story of heat-trapping gasses in the atmosphere. To do that, we have to look at another number — carbon dioxide equivalent or CO2e.

The Keeling Curve August

(During a typical September and October, daily or weekly values may briefly dip below 400 ppm CO2, as detected at the Mauna Loa Observatory. But after September-October 2016, it’s unlikely that you or I will ever see such low levels of CO2 from that measure again in our lifetimes. Image source: Scripps Institution of Oceanography.)

490 ppm CO2e. That’s about the total amount of CO2-equivalent heat forcing from all the human-added greenhouse gasses like CO2, methane, various nitrogen compounds, and other gaseous chemical waste that the Earth’s atmosphere will see by late 2016 to early 2017.

Why is this a big deal?

Four reasons —

First, hitting 490 CO2e crosses the Intergovernmental Panel on Climate Change‘s (IPCC) lowest climate threshold. If this were a highway, and climate change were a collision, we’d now be careening through the first guardrail.

Second, 490 CO2e represents significant current and future warming (and there’s good reason to believe that IPCC’s estimates of that warming may be a bit conservative).

Third, it signifies that we have now fully entered the era of catastrophic climate change, with some bad climate outcomes almost certainly locked in as a result. We see a number of these instances now in the form of extreme rainfall events, extreme drought, coral bleaching, sea ice and glacial melt, threatened crops, ocean anoxia and dead zones, widespread harmful algae blooms, ocean acidification, and expanding infectious disease ranges. However, what we are experiencing now is just the tip of the (melting) climate change iceberg if we do not rapidly respond.

Fourth, if we were never really aware before that we very urgently need to get serious about swiftly cutting fossil-fuel emissions, protecting and regrowing forests, and working to help people to adapt to climate change, then this is our wake-up call.

Crossing the First Climate Threshold — 490 ppm CO2e

How did 490 ppm CO2e become a climate milestone? In short, it represents the threshold at which the first of four global-warming scenarios is basically locked in.

To understand this more, we need to take a closer look at these four scenarios, which were established by the IPCC in 2007. The IPCC calls these scenarios Representative Concentration Paths or RCPs. The four potential pathways are informed by the amount of fossil fuels potentially burned through the year 2100, the levels of CO2e heat-trapping gasses in the atmosphere as a result, and how much the world consequently warms over this timeframe.

RCPs range from 2.6 to 8.5 watts per meter squared, with these measurements indicating the amount of added heat from the greenhouse gas additions trapped at the top of the atmosphere. A more direct measure is to look at the total greenhouse gas thresholds for each scenario. Broken down, the four RCP pathways represent 490 ppm CO2e (RCP 2.6), 650 ppm CO2e (RCP 4.5), 850 ppm CO2e (RCP 6.0), and 1370 ppm CO2e (RCP 8.5). For reference, atmospheric CO2e levels just prior to the start of large-scale fossil fuel burning were around 300 ppm. By comparison, 1370 ppm CO2e is about equivalent to the levels during some of the worst hothouse mass extinctions the Earth has experienced.

In a nutshell, RCPs represent potential warming scenarios. A middle-range temperature increase estimate by the year 2100 for each scenario can be seen below in this table provided by Skeptical Science:

rcp pathways

Developed at the IPCC’s 2007 meeting, these RCPs also describe a range of potential human civilization responses to global warming. RCP 2.6 allows for fast emissions cuts beginning at the time of the 2007 meeting. These cuts would swiftly level off and then reduce fossil-fuel emissions and ultimately generate one of the milder warming scenarios. The IPCC envisioned that warming would remain near 1.5 C this century under these emissions cuts. Scientists hoped this scenario would allow the avoidance of most of climate change’s bad outcomes.

RCP 4.5 assumes somewhat less aggressive emissions cuts, with fossil-fuel burning and related carbon emissions peaking near 15 billion tons per year by the mid-2040s. Stronger warming is locked in with this scenario — about 2.4 C according to IPCC — and scientists were doubtful that serious climate impacts could be avoided.

emissions-graph-rpc-small

(We’ve pretty much missed the window for the IPCC’s mildest possible climate scenario, RCP 2.6, which would have required strong policies and policy support almost immediately following the IPCC’s 2007 meeting. Image source: Skeptical Science.)

RCP 6.0 shows emissions cuts that are slow to unfold. Global carbon emissions would peak around 19 billion tons per year by 2060 and then rapidly drop off. Warming under this scenario is considerable, hitting 3 C by the end of this century. So much warming and such high levels of greenhouse gasses would result in some seriously bad outcomes.

The final pathway, RCP 8.5, represents an absolute nightmare climate scenario. Under this path, real emissions cuts are not achieved. Despite growth in renewable energy, all energy use continues to grow as well, including fossil fuels. As a result, in this scenario, the IPCC expects the Earth to warm by a catastrophic 4.9 C by 2100.

In the context of understanding climate change, particularly for someone interested and patient enough to read the IPCC reports, the various RCP scenarios were a real help in exploring climate change options and outcomes. They helped many scientists and policymakers provide clear warnings and rewards for action by governments, the public, and business leaders.

projected impacts of climate change

(Climate change produces multiple difficult-to-predict impacts. As temperatures rise, conditions grow ever more extreme. In the graph above, it’s worth noting that sea-level rise is already an issue for many cities and regions including numerous Pacific islands, Bangladesh, the Indus Delta region, South Florida, New Orleans, New York, and the various low-lying coastal and river delta regions around the world. Image source: Federal Highway Administration.)

But despite very clear communication and activism from scientists like Dr. James Hansen, policy bloggers like Joe Romm, and climate activists like Bill McKibben, overall global emissions policy has not moved swiftly enough to stay within the RCP 2.6 pathway in the 9 years since its creation. In fact, decent global emissions reduction policies didn’t begin to universally take hold until recently, in 2014 and 2015, and those implemented were often ardently opposed by fossil fuel-related political interests in countries like Australia, Great Britain, Germany, Canada, and the United States.

As a result, emissions stayed near or just below worst-case pathway ranges (RCP 8.5). As of this year, the window for achieving the RCP 2.6 scenario — or the mildest and most optimistic warming scenario — appears to have closed.

Possibly More Warming From 490 CO2e Than We Feared

Hitting 490 CO2e in 2016 means that the 1.5 C warming IPCC predicted for this amount by 2100 is almost certainly locked in. With the world hitting near 1.2 C above 1880s temperature averages in 2016, some reasonable questions have been raised, the most relevant being if 490 ppm CO2e will result in more warming than IPCC predicted.

To be fair, the 1.5 C figure above is a simplification of model predictions ranging from about 0.9 C to around 2.3 C during this century under a 490 ppm CO2e forcing. However, since we’ve already surpassed the lower portion of this range, and we’re barely into the beginning of this century, it appears that some of the lower sensitivity model runs were rather far off the mark. Moreover, paleoclimate proxy temperature data indicates that 490 ppm CO2 during the Middle Miocene produced warming in the range of 4 C long-term (over hundreds of years). Given this implied long-term impact, and coupled with annual readings that are already in the 1.2 C range, it’s possible to infer an ultimate warming closer to 2 C by 2100 from a maintained 490 ppm CO2e. Hitting such a mark would only require about 0.11 C warming per decade — a rate of decadal warming about 40 percent slower than the temperature rise seen from the late 1970s through the 2010s.

Arctic Sea Ice August 9 2016

(Amplifying feedbacks due to loss of sea ice reflectivity in the Arctic and Antarctic, reduced carbon-store uptake and carbon-store emissions can result in an overall greater sensitivity to an initial heat forcing such as the current 490 ppm CO2e. Paleoclimate proxies hint that these feedbacks may cause the Earth System to be more sensitive than IPCC models currently indicate. Image source: LANCE MODIS.)

The paleoclimate-implied warming from the other climate scenarios is likely higher as well. RCP 4.5 probably hits closer to 3 C under such a climate sensitivity range. RCP 6.0 probably sees 4 to 4.5 C warming by 2100. And the worst-case RCP 8.5 probably achieves closer to 6 C warming.

It’s for these and other reasons that some scientists say that avoiding 1.5 C at this time is probably impossible. Meanwhile, it’s pretty reasonable to say that avoiding 2 C presents a huge challenge requiring a very rapid response, a goal that will probably require reducing the atmospheric CO2e levels below their current ranges.

CO2e Increasing by 3 ppm Per Year

Human beings are still dumping massive volumes of carbon into the atmosphere. Carbon emissions are still near record-high levels. As a result, atmospheric CO2e levels are rising by about 3 ppm or more each year. For 2016, CO2 alone may rise by 3.4 ppm or more, and CO2e may jump by more than 4 ppm — to hit near 490 ppm CO2e. This is due in part to the 2015-2016 El Nino’s cyclical warming of the Equatorial oceans, forests, and lands on top of the already-strengthening heat of human warming. And this added heat reduces the ability of these carbon sinks to take in CO2.

Even if this rate of CO2e rise is just maintained, it’s possible that we’ll see 1.5 C warming not by the end of this century, but by the early 2030s. And as the world heats up, it’s likely we’ll see additional emissions coming as carbon sinks become stressed and stop taking in such high volumes of greenhouse gasses or even turn into sources.

The result is that the challenge presented to us now is far greater, far more urgent than that of 2007. We risk, over the next few decades, locking in not just 2 C warming, but 3 C warming or more if we do not act swiftly and seriously. And with 1.5 C warming coming with almost 100 percent certainty, we need to ramp up climate-change mitigation strategies as well as provide aid and succor for the increasing harms, dislocations, and inequalities that will likely emerge.

Links:

NOAA’s Earth Systems Research Laboratory

The Keeling Curve

Intergovernmental Panel on Climate Change

Hansen and Sato Estimated Paleoclimate Temperatures

Skeptical Science — Beginner’s Guide to RCP Scenarios

Transportation’s Role in Reducing Greenhouse Gas Emissions

LANCE MODIS

Carbon Sinks in Crisis

Climate Change — Financing Global Forests

Advertisements

“Please Get Us Out” — Hothouse Wildfire Threatens to Engulf Tar Sands City of Fort McMurray, 88,000 Evacuated, 1,600 Structures Burned

Emergency situation now ongoing in Fort McMurray, Alberta where a massive wildfire in this northern climate zone is engulfing the city. This is a very dangerous developing situation that includes hundreds of structure fires and what is now the largest evacuation in the history of Alberta — the first time an entire Canadian city has ever had to evacuate due to a wildfire. Frequent updates to follow (refresh page for new updates).

(BBC report on the latest news from Fort McMurray.)

Conditions Consistent With Climate Change Fan Massive Fire Invading City Made by Tar Sands Production

Monday, a massive wildfire began to encroach upon the City of Fort McMurray, Alberta — a region of Canada known for its production of the hothouse gas emitting tar sands. An emission that has almost certainly contributed to increasing fire danger to the city during recent years and decades as tar sands crude is one of the highest carbon fuels now in production (See: IPCC — How Climate Change is Worsening Wildfires).

The McMurray Fire slowly expanded over the weekend under unseasonably hot and dry conditions. It surprised fire officials by jumping the Athabasca River on Monday night and, with a switch in the wind toward the southwest, began to approach and invade northward into the city on Tuesday. By early evening Wednesday, the fire still raged out of control — swelling to more than 10,000 hectares as more than 1,600 buildings fell victim to the flames.

Reporter Reid Fiest in a tweet at 12:05 PM Wednesday briefly described what is now a city under existential threat:

The catastrophic wildfire is 10,000 ha and resisted all the suppression efforts. Today’s weather could cause explosive conditions.

And by 2:37 PM, fire activity within the city had become so intense that the roof of the Fort McMurray emergency operations center began to smolder and those working within were ordered to evacuate.

Extreme Temperatures in Northwest Canada

(It was hotter in Northwest Canada Tuesday than it was in the Central US. Extreme heat related to human-forced warming that contributed to a dangerous developing fire situation in Fort McMurray, Alberta. Image source: Earth Nullschool.)

The southerly winds and hot airs fanning such explosive conditions ran up behind a high amplitude wave in the Jet Stream pushing temperatures into the upper 80s and lower 90s (F) — readings that are about 30-35 degrees (F) above average for this time of year — over a broad swath of Northwestern Canada on Tuesday. The heat-baked air wrung out moisture and drew humidity readings into the very dry 20 percent range. Similar extreme fire conditions continued into Wednesday — with temperatures in Fort McMurray hitting a very unseasonal 87 degrees — as the fire now burns through the city proper.

Clouds of My Grandchildren over Fort McMurray

Pyrocumulus cloud over Fort McMurray on Tuesday. Clouds of this kind can form in the strong updraft zone of powerful wildfires. During recent years, pyrocumulus formation over the Arctic and other northern regions during spring and summer has been very intense and widespread. A climate change enhanced phenomena that could rightly be called ‘The Clouds of My Grandchildren.’ Image source: Randy Vanberg.

To the north, a very early recession of sea ice in the Beaufort and an opening up of waters there likely assisted this Jet Stream anomaly, a related strong high pressure system, extreme high temperatures, and hot southerly winds that pushed fire conditions in Alberta to unprecedented levels. The south winds, far, far hotter than normal temperatures and very low humidity contributed to a very dangerous situation fanning flames as they encroached upon and invaded the city — burning structures, igniting oil fires and forcing motorists to abandon their vehicles. All while a massive pyrocumulus cloud expanded — casting a dark shadow and dumping soot over this bitumen-laden region of Alberta.

For this region of Canada, these are highly abnormal conditions consistent with weather pattern alterations forced by human-caused climate change. “This (fire) is consistent with what we expect from human-caused climate change affecting our fire regime,” noted Mike Flannigan a wildfire researcher at the University of Alberta who was cited in a report on the climate context of the McMurray Fire on Wednesday.

All Fort McMurray City Residents Ordered to Flee

As of latest reports, all of Fort McMurray’s city proper has been placed under mandatory evacuation orders. That makes for a total of more than 88,000 people evacuated so far. Including outlying suburbs and migrant residents, the city likely is home to a total of more than 100,000 souls — a good number of whom will also be forced to leave. A fire-driven evacuation of this size — basically resulting in the mandatory emptying of an entire city — has never occurred before in the history of Alberta. And the odd nature of this event is magnified by the fact that a very large early May fire — a period when fire activity is typically far more quiescent — is the cause.

Please Get Us Out

(Abasand resident pleas for assistance as fires encroach.)

Many residents, like Jenine in the tweet above, had to scramble to vehicles as fires approached their neighborhoods on Tuesday, spurring some to turn to social media in order to plea for assistance. The proximity of the flames was so close that many residents were unable to bring any personal belongings. With the entire city being ordered to evacuate, both lanes of Highway 63 were used for outbound traffic. Even so, motorists remained stuck in gridlock or stop and go traffic and were forced to drive through billowing smoke and along beside the raging fires. Some vehicles stalled in the hot winds or simply ran out of gas — leaving highway 63 strewn with empty cars, trucks, and buses.

The flow of evacuees has been driven northward ahead of the fire. Emergency shelters have popped up all along route 63 with many tar sands workers hunkering down in camps within the hothouse fuels extraction zone itself. A region that may also fall under threat by the fire.

The closest tar sands facilities are located within 16 miles of the city center. However, fuels for the fires in the form of trees run right up to the edge of the industrial zone and southerly winds expected to continue through late morning on Thursday may drive the flames closer. After that time, a front sweeping in from the north should shift the wind direction to northwest — pushing the fires away from these facilities. Currently, the possibility of the fires affecting these facilities is low. However, both Shell and Suncor have now suspended operations — presenting a brief silver lining to an, overall, terrible situation.

Huge Mobilization Underway, But Much of the City May Succumb to the Fire

Firefighters, who early on Tuesday acknowledged the severity of the situation, are now scrambling to deal with numerous very large blazes raging throughout the town. Social media imagery now shows images of gas stations, stores, and homes being burned or left in ruins by the fires. As of current reports, more than 1,600 structures been destroyed by the flames. By 2:28 PM Wednesday, these included 70 percent of the homes in Beacon Hill, 50 percent of the homes in Abasand, 90 percent of the homes in Waterway, and about 60 other homes and additional structures lost throughout other sections of the city. Unfortunately, given the severity of the situation, the number of burned structures is likely to grow as Wednesday progresses into Thursday.

NASA Shot of Fort McMurray Fire

Large active fires running north of a huge, 15 kilometer, burn scar. Satellite shot of Fort McMurray Fire and burn scars posted in the NASA twitter feed on Wednesday afternoon.

Considering the massive pall of smoke covering Fort McMurray and the fact that firefighters have been overwhelmed by the intensity of the fires — leaving many structures to burn — the situation has run completely out of control. National officials are scrambling to allocate more resources to attempt to abate what is a very difficult and dangerous inferno. A national emergency has been declared and an outpouring of assistance and resources is now aimed in the direction of Fort McMurray. Reports as of Wednesday afternoon indicated that there were 250 firefighters on the ground in the fire zone with more on the way. And by evening a number of defensive fire breaks appear to have been cut in an attempt to control the blaze’s expansion.

However, with numerous other fires now raging throughout Canada and with fire conditions at extreme levels over such a large area, at least one province — British Columbia — is already at the limits of its fire suppression manpower and was unable to provide aid to Fort McMurray. As a result, Alberta officials are now coordinating with national and military firefighting forces as fires continue to expand through the city and along the Athabasca River.

Conditions in Context — More Tar Sands Burning Generates More Wildfire Risk

It’s true that the people of Fort McMurray have suffered enough from this disaster and that the people of Canada and the world should do their best to help them in their hour of need. However, one cannot look at the situation truthfully without taking into account the impact of the Canada’s tar sands upon what is now a broadening climate crisis.

For years and decades now, IPCC has been warning that increasing greenhouse gas emissions and related rising global temperatures will result in increasing, expanding, and extreme wildfire hazards. The region of Northwest Canada is particularly vulnerable due to the influence of sea ice melt on the local Jet Stream pattern and due to the fact that many plant species in the region are ill-adapted to warming temperatures making them far more vulnerable to wildfires. In addition, permafrost thaw in the Arctic zone provides peat-like fuels that add to the fire risk. An issue where the ground itself burns.

Failure to view the current crisis in Fort McMurray in the context of global temperatures that have now exceeded 1 C above preindustrial averages and in the context of a failure to halt tar sands extraction is a failure to view the situation realistically. Much talk has been made of getting Fort McMurray’s tar sands industry back on track. But it’s the tar sands that have greatly contributed to the intensity of the dangerous fire that is now threatening that city’s very existence. And it’s the tar sands that will produce far-flung harmful impacts affecting so, so many other cities around the world. Will Fort McMurray respond to their hour of need by finding a better way of doing business? Or is it all just still denial and doubling down in a way that hurts just about everyone involved?

(Best hopes and prayers to everyone involved in this terrible situation. Please stay safe and stay tuned to official broadcasts for updated information on fires and evacuations.)

Links:

Fort McMurray Homes Destroyed as Wildfire Forces Mandatory Evacuation Orders

Fort McMurray Residents take to Social Media as Situation Intensifies

Jenine’s Twitter Feed

Earth Nullschool

LANCE MODIS

Canadian Fire Danger Map

Fort McMurray Area Updates

It’s Apocalyptic. No Way out But North.

Here’s the Climate Context for the Fort McMurray Wildfire

Alberta Burning

Randy Vanberg

NASA Twitter Feed

Hat tip to Cate

Hat tip to Mike Crews

Hat tip to Andy in San Diego

Hat tip to DT Lange

Hat tip to Redsky

Hat tip to TodaysGuestIs

Warm Water Rising From the Depths: Much of Antarctica Now Under Threat of Melt

Antarctica. A seemingly impregnable fortress of cold. Ice mountains rising 2,100 meters high. Circumpolar winds raging out from this mass of chill frost walling the warm air out. And a curtain of sea ice insulating the surface air and mainland ice sheets from an increasingly warm world. A world that is now on track to experience one of its hottest years on record.

Antarctica, the coldest place on Earth, may well seem impregnable to this warming. But like any other fortress, it has its vulnerable spots. In this case, a weak underbelly. For in study after study, we keep finding evidence that warm waters are rising up from the abyss surrounding the chill and frozen continent. And the impact and risk to Antarctica’s glacial ice mountains is significant and growing.

Rapid Break-up of Ice From Filchner Ronne Ice Shelf in Jan 2010

(Collapse of ice structure at the leading edge of the Filchner-Ronne Ice Shelf adjacent to a rapidly warming Weddell Sea during January of 2010. A new study has found warm water upwelling from the Circumpolar Deep Water is rapidly approaching this massive ice shelf. Loss of Filchner-Ronne and its inland buttressed glaciers would result in 10 feet of sea level rise. Image source: Commons.)

For a study this week confirmed that Antarctica is now seeing a yearly loss of ice equal to one half the volume of Mt Everest every single year. A rate of loss triple that seen just ten years ago. An acceleration that, should it continue, means a much more immediate threat to coastal regions from sea level rise than current IPCC projections now estimate.

Shoaling of the Circumpolar Deep Water

The source of this warm water comes from a deep-running current that encircles all of Antarctica. Called the Circumpolar Deep Water, this current runs along the outside margin of the continental shelf. Lately, the current has been both warming and rising up the boundaries of the continental zone. And this combined action is rapidly bringing Antarctica’s great ice sheets under increasing threat of more rapid melt.

According to a new study led by Sunke Schmidtko, this deep water current has been warming at a rate of 0.1 degrees Celsius per decade since 1975. Even before this period of more rapid deep water warming, the current was already warmer than the continental shelf waters near Antarctica’s great glaciers. With the added warming, the Circumpolar Deep Water boasts temperatures in the range of 33 to 35 degrees Fahrenheit — enough heat to melt any glacier it contacts quite rapidly.

Out in the deep ocean waters beyond the continental shelf zone surrounding Antarctica, the now warmer waters of this current can do little to effect the great ice sheets. Here Sunke’s study identifies the crux of the problem — the waters of the Circumpolar Deep Water are surging up over the continental shelf margins to contact Antarctica’s sea fronting glaciers and ice shelves with increasing frequency.

In some cases, these warm waters have risen by more than 300 feet up the continental shelf margins and come into direct contact with Antarctic ice — causing it to rapidly melt. This process is most visible in the Amundsen Sea where an entire flank of West Antarctica is now found to be undergoing irreversible collapse. The great Pine Island Glacier, the Thwaites Glacier and many of its tributaries altogether composing enough ice to raise sea levels by 4 feet are now at the start of their last days. All due to an encroachment of warm water rising up from the abyss.

Rivers of Ice Antarctica

(Antarctic rivers of ice. Rising and warming waters from the Circumpolar Deep Water along continental margins have been increasingly coming into contact with ice shelf and glacier fronts that float upon or face the surrounding seas. The result has been much higher volumes of melt water contributions than expected from Antarctica. Image source: University of California.)

But the warm water rise is not just isolated to the Amundsen Sea. For Sunke also found that the warm water margin in the Weddell Sea on the opposite flank of West Antarctica was also rapidly on the rise. From 1980 to 2010, this warm water zone had risen from a depth of about 2100 feet to less than 1100 feet. A rapid advance toward another massive concentration of West Antarctic ice.

The impacts of a continued rise of this kind can best be described as chilling.

Sunke notes in an interview with National Geographic:

If this shoaling rate continues, there is a very high likelihood that the warm water will reach the Filchner Ronne Ice Shelf, with consequences which are huge.

Filchner Ronne, like the great Pine Island Glacier, has been calving larger and larger ice bergs during recent years. Should warm waters also destabilize this vast ice shelf another 1.5 feet of sea level rise would be locked in due to its direct loss. Including the massive inland glaciers that Filchner Ronne buttresses against a seaward surge, much larger than the ones near the Amundsen sea, would add a total of 10 feet worth of additional sea level rise.

Together, these destabilized zones would unleash much of West Antartica and some of Central Antartica, resulting in as much as 14 feet of sea level rise over a 100 to 200 year timeframe. This does not include Greenland, which is also undergoing rapid destabilization, nor does it include East Antarctica — which may also soon come under threat due to the encroachment of warm waters rising from the depths.

Are IPCC Projected Rates of Sea Level Rise Too Conservative?

The destabilization of glaciers along the Amundsen sea, the imminent threat to the Filchner Ronne Ice Shelf, and the less immediate but still troubling threat to East Antarctica’s glaciers, together with a rapidly destabilizing Greenland Ice Sheet, calls into question whether current IPCC predictions for sea level rise before 2100 are still valid.

IPCC projects a rise in seas of 1-3 feet by the end of this Century. But much of that rise is projected to come from thermal expansion of the world’s oceans — not from ice sheet melt in Antarctica and Greenland. Current rates of sea level rise of 3.3 milimeters each year would be enough to hit 1 foot of sea level rise by the end of this Century. However, just adding in the melting of the Filchner Ronne — a single large ice shelf — over the same period would add 4.4 milimeters a year. Add in a two century loss of the Amundsen glaciers — Pine Island and Thwaites — and we easily exceed the three foot mark by 2100.

Notably, this does not include the also increasingly rapid loss of ice coming from Greenland, the potential for mid century additions from East Antarctica, or lesser but still important additions from the world’s other melting glaciers.

Such more rapid losses to ice sheets may well reflect the realities of previous climates. At current CO2e levels of 481 ppm (400 ppm CO2 + Methane and other human greenhouse gas additions) global sea levels were as much as 75-120 feet higher than they are today. Predicted greenhouse gas levels of 550 to 600 ppm CO2e by the middle of this century (Breaking 550 ppm CO2 alone by 2050 to 2060) are enough to set in place conditions that would eventually melt all the ice on Earth and raise sea levels by more than 200 feet. For there was no time in the past 55 million years when large ice sheets existed under atmospheric CO2 concentrations exceeding 550 parts per million.

Glaciologist Eric Rignot has been warning for years that the IPCC sea level rise estimates may well be too conservative. And it seems that recent trends may well bear his warnings out. If so, the consequences to millions of people living along the world’s coastlines are stark and significant. For the world, it appears we face the increasing likelihood of a near-term inland mass-migration of people and property. A stunning set of losses and tragedy starting now and ongoing through many decades and centuries to come.

Links:

Warming Seas Drive Rapid Acceleration of Melting Antarctic Ice

Mass Loss of the Amundsen Sea Embayment of West Antarctica

Multidecadal Warming of Antarctic Waters

Research Casts Alarming Light on Decline of West Antarctic Glaciers

Antarctic Ice Shelf Being Eaten Away by Sea

%d bloggers like this: