Runaway global warming

A few climate change stories bundled together

James Hansen and the Three Categories of the Runaway Greenhouse: Earth Uninhabitable for Humans at ~5,000 Gigatons Fossil Fuel Burned

( Image source: Arctic News)

Robertscribbler,

13 July, 2013

Forget for a moment that we can still emit about 530 gigatons of CO2 and still keep human warming in the ‘safe range’ of less than 2 degrees (Celsius) temperature increases this century. Forget for a moment how important to the sustenance of human civilization and the prevention of every worsening conditions this strict limit on carbon emissions is. Now think for a moment what will happen if Republicans in Congress and fellow conservatives aligned with fossil fuel companies across the country and around the world get their way.

In the past month, Republicans in the House of Representatives have pushed to increase US coal burning, approve the Tar Sands Keyston XL Pipeline, remove energy efficiency standards, and to slash US government (ARPA -E) R&D funding for new renewable energy technology by 80 percent. Fully 55% of all Republicans in the US Congress deny that human caused warming even exists. And the rest clearly are deluded enough to believe that it represents the climate version of a mild summer storm. Their legislative action over the past month, the past year, and for many years following that has been to enforce US dependence on oil, gas, and coal and to delay, diffuse and deny US access to new energy sources that may effectively serve as their replacements. And the millions of dollars in oil, gas and coal company largess they enjoy in the form of contributions is just the final proof that these members aren’t working for the best interests of the American people. They’re working for the international corporate state called Big Oil (BO).

So let’s consider for a moment what would happen if these BO lackeys in Congress were successful in their efforts to kill off alternative energy, to remove efficiency standards, and to shackle the US Energy future to Tar Sands, Coal, and Fracked Shale Oil and Gas.

What would happen?

It’s difficult to argue, given the current extreme and worsening state of the world’s climate, that blind Republican attempts to enforce dependence on BO would result in much in the way of US prosperity. It, essentially, would turn the entire North American Continent into a giant petro-state. It is possible that, for some years, the US will make some energy independence gains, possibly removing a larger fraction of imports from most states except Canada. But the loss of efficiency standards would do ongoing damage by increasing consumption of high-cost unconventional fuels, which would put a drag on the economy. The even greater drag would come from shackling US and North American economies to ever greater degrees to fuel sources, at best, that create a 6 to 1 energy return, where wind and solar could have supplied between 10 and 20 to 1 at ever-lower costs.

Worse still, is the fact that US and Canadian carbon emissions would go through the roof. Tar Sands, Coal, and Tight Shale Fracking are three horsemen of the apocalypse when it comes to climate change change (the fourth being fossil fuel company greed). Coal has always been the worst emitter. But both Tar Sands and Tight Shale Fracking are not far behind. The Republicans would have us depend on these, arguably vast, unconventional sources to the exclusion of all others. They wouldn’t care one whit about capturing the carbon (costs too much and reduces the energy return on already low energy fuels). And, adding yet one more insult, they allow BO to export the fracking and tar sands technologies to other countries consigning them and the world to similar fates.

Total carbon emissions in 2012 (including non CO2 sources) was 45 gigatons. But on the path Republicans set, this level of emission will look minor. Peak emissions would probably pair with peak human civilization at some time around 2050 near 80-90 gigatons per year. At this point, emissions are put in check by mother nature’s outrage at our insults. By 2050, the ‘burn everything’ strategy put in place by Republicans and enforced by conservatives around the world has resulted in near 600 ppm atmospheric CO2. Life in the oceans is in terminal collapse, major cities and island nations are being devoured by a combination of powerful storms and rising seas. The coastlines, for so long productive, have become unstable. And large regions of once fertile land are now being devoured by deserts. Water stress has caused entire countries to collapse. Mass migrations from both the coastlines and from desertified regions has already set in. Human population peaks at about this time near 10 billion.

But over the next 50 years humans maintain enough vestige of prior fossil-fuel based civilization to keep burning. They expend massive efforts to encircle coastal cities with walls. They try to farm indoors more and more. Miami is placed on giant oil platforms (we have more than enough in surplus) whose bases are driven into the limestone beneath the city. The New Orleans’ tidal wall is heightened to 30 feet. New York and the all important Wall Street is surrounded by increasingly high flood barricades. But the massive storms of this age are freakish, wrecking entire regions and knocking out power for weeks to months. Storms and heatwaves kill millions each year and millions more are rendered homeless. Entire countries collapse for want of food or under a tide of refugees they cannot support.

By 2100, CO2 is at 1000 ppm and global temperatures are 7 degrees (Celsius) hotter. Fossil fuel based industry has emitted about 5,000 gigatons of carbon, enough to set off the stages for a mini runaway global warming scenario (Category 1). Sea levels have risen 12 feet and Earth’s population has been reduced to 6 billion. 40% of ocean species are extinct and 10% of land species have suffered the same fate. Summer time results in the emergence of large heat death zones experiencing wet bulb temperatures in excess of 35 degrees Celsius (hot enough to kill most large mammals, including humans, through heat stress alone). Even if all emissions ceased, global temperatures would still rise to around 12-14 degrees Celsius hotter than the Holocene. There is almost no chance, in this case, for human civilization to survive such an insult for more than another 50-100 years. And the chances for humans, long term, are dire indeed.

But the world’s fossil fuel companies are still around, still clawing coal, fracked oil and gas, tar sands, oil shale, and methane hydrates  from the Earth with whatever new high tech process they’ve invented. These manage to survive for another 50 years or so selling off enough dirty fuels to set world CO2 levels to 1500 ppm. And that’s when game over really sets in for just about everything that can’t run to a high mountain range.

Fossil fuel based industry had managed to survive just long enough to emit more than 8,000 gigatons of carbon into the atmosphere. Just long enough to kill off the rest of us and themselves too.

Three Categories of Runaway Warming

The above scenario isn’t science fiction. According to some hard science done by the world’s top climate scientists, it is entirely likely if Republican burn, baby burn policy and the fossil fuel companies that push it survive in their current forms for much longer.

Hansen’s new paper is a more in depth study of Earth Systems Climate Sensitivity to a given level of CO2 forcing. The study looks, with greater detail, into both how much Earth will warm, long term, given a certain level of CO2 emission and how much of this emission is required to set off one of three categories of a runaway greenhouse.

In a less than ideal scenario, Hansen investigates what will happen if we burn all or nearly all the fossil fuels currently included in the unconventional reserves. All, or nearly all, according to Hansen represents between 5,000 to 10,000 gigatons of carbon equivalent fuels. Chillingly, if we tap the most extreme sources, such as methane hydrates, that number could rocket to 20,000 gigatons or more. So even Hansen’s study isn’t an extreme worst case.

Category 1: The Mini-Runaway

The Hansen paper finds that burning between 3,500 and 6,500 gigatons of carbon based fuels is enough to raise world CO2 levels to between 800 and 1200 parts per million. This level of CO2 would set up climate conditions similar to those experienced during the Paleocene-Eocene Thermal Maximum (PETM) in which temperatures were between 10 and 12 degrees Celsius hotter (average) than today.

Hansen finds that this level renders much of the Earth mostly uninhabitable for humans. Hansen notes:

Earth was 10-12 °C warmer than today in the early Eocene and at the peak of the PETM (Fig. 4). How did mammals survive that warmth? Some mammals have higher internal temperatures than humans and there is evidence of evolution of surface-area-to-mass ratio to aid heat dissipation, e.g., transient dwarfing of mammals (Alroy et al., 2000) and even soil fauna (Smith et al., 2004)during the PETM warming. However, human-made warming will occur in a few centuries, as opposed to several millennia in the PETM, thus providing little opportunity for evolutionary dwarfism to alleviate impacts of global warming. We conclude that the large climate change from burning all fossil fuels would threaten the biological health and survival of humanity, making policies that rely substantially on adaptation inadequate.

It is also worth noting that much of the world’s land masses would experience average summer temperatures above the mammal-killing level of 35 degrees Celsius (wet bulb) in a PETM-like world. The added heat of this regime would swiftly soften and obliterate any ice on the planet. But given the killing heat and a hydrological cycle driving droughts and rainfall events that are 80% more extreme, a rapid sea level rise of 200+ feet would likely come as a harsh afterthought. (To this point, it is worth mentioning that most planetary ice disappears when CO2 levels hit and maintain between 500 and 620 parts per million over a number of centuries).

Nearly all climate scientists agree that a return to PETM conditions and CO2 levels, especially on so short a time-scale would be a mass extinction event on the land and in the ocean. Which is why policies that extend the burning of fossil fuels combine the travesties of ecocide, genocide, and suicide in equal measures and to ever greater degrees as time moves forward.

Category 2: The Moist Stratosphere Runaway

If the fossil fuel companies manage to stick around long enough, they may be able to burn through between 8,000 and 15,000 gigatons of additional carbon-based fuels. Such an event would almost certainly spell the end for human beings and probably most of the complex life on Earth as well.

In such a situation, average global temperatures rise by between 15 and 20 degrees Celsius. A 15 degree Celsius temperature rise increases temperatures over land by around 20 degrees C. This puts Earth’s average land temperatures at around 35 degrees Celsius with average daily (wet bulb) highs in the range that is hot enough to kill humans. The entire Earth, in this case, is an enormous human killing field.

The only regions able to even marginally support human life or agriculture would be the high mountains. But even these regions would be under threat. Global heating of around 15 degrees Celsius or greater would pump ever greater levels of moisture into the stratosphere. The added H20 would substantially degrade stratospheric ozone. The added UV radiation would severely hamper both plant and animal life in the remaining habitable regions. Human food crops are highly sensitive to excess UV radiation. So it is seriously doubtful if humans could continue cultivation even on the Himalayan Plateau during a Category 2 Runaway.

Category 3: Evaporated Oceans, Baked Crusts

Thankfully, even the fossil fuel companies aren’t likely to bring about even the worst of the climate change nightmares — Earth transitioning to a state more like Venus. In order to do that, global heating would have to evaporate all of Earth’s oceans and then bake the remaining carbon out of the Earth’s crust. According to new models constructed by Hansen, such conditions would take between 100 million and one billion years to develop. Hansen’s models also show that climate sensitivity is not enough, at the higher CO2 levels, to finally set off the kind of runaway that would force such catastrophic events to occur.

That said, the first two categories of global warming runaway are well within the reach of current fossil fuel reserves. And the fact that all fossil fuel companies are doing everything they can to burn all the reserves on their books and to find ever greater quantities of these fuels is not at all comforting, especially when they have a number of hired trolls in Congress and elsewhere (Republicans) to do their dirty work for them…

Links:

New Hansen Paper on Climate Sensitivity, CO2 and Sea Level Rise

What Burns Today, Melts Tomorrow: Report

New study finds that sea-level will rise 2.3 meters for each increase in degree

- Lauren McCauley, staff writer

Over the next two millennia, the melting of the Antarctic ice sheet is projected to contribute to half of all sea-level rise. (Photo: Rita Williaert/ cc/ Flickr)

Common Dreams,

16 July, 2013

"Greenhouse gases emitted today will cause sea level to rise for centuries to come," concluded a team of scientists behind a new study published Monday in the Proceedings of the National Academy of Sciences.

The study, conducted by a group from Germany's Pottsdam Institute for Climate Impact, found the sea levels may rise by as much as 2.3 meters (roughly 7.5 feet) with each degree Celsius that global temperatures increase.

"Sea-level rise might be slow on time scales on which we elect governments, but it is inevitable and therefore highly relevant for almost everything we build along our coastlines, for many generations to come,” cautioned Anders Levermann, lead author of the study.

The study is the first of its kind to combine evidence from climate history with computer simulations of contributing factors to long-term sea-level increases: thermal expansion of oceans, the melting of mountain glaciers and the melting of the Greenland and Antarctic ice sheets.

According to their findings, though thermal expansion and melting glaciers are thus far the greatest contributing factors to sea-level change, the melting of the ice sheets will be the dominant contributors within the next two millennia.

As Levermann explains, because of their enormous mass, the oceans and ice sheets are slow in responding to the global temperature increase. However, like a rolling stone, "once heated out of balance, they simply don’t stop."

“CO2, once emitted by burning fossil fuels, stays an awful long time in the atmosphere,” he adds. “Consequently, the warming it causes also persists.”

Scientists predict that as much as half of total sea-level rise will come from ice-loss in Antarctica, with Greenland melting contributing another 25 percent. 

Describing the impact of the study's predictions, David Vaughan, head of the ice2sea project, told Reuters the most grave consequences will be seen in the frequency and severity of storms.

"It's not about chasing people up the beach or the changing shape of coastlines," he said. "The big issue is how the storms will damage our coasts and how often they occur. That'll increase even with small levels of sea rise in coming decades."

“Continuous sea-level rise is something we cannot avoid unless global temperatures go down again,” Levermann adds. “Thus we can be absolutely certain that we need to adapt.”

Like butter: CIRES study explains surprising acceleration of Greenland’s inland ice -

Meltwater from the surface of the Sermeq Avannarleq Glacier drains down toward interior ice. This photograph depicts a region about 10 miles from the ice sheet margin in Southwest Greenland. A new CIRES-led study helps explain the surprising acceleration of inland ice. Meltwater draining through the ice likely warms the ice sheet from the inside and like a stick of warm butter, the sheet softens, deforms and can flow faster. (Photo by William 

University of Colorado,

16 July, 2013

Surface meltwater draining through cracks in an ice sheet can warm the sheet from the inside, softening the ice and letting it flow faster, according to a new study by scientists at the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder.

During the last decade, researchers have captured compelling evidence of accelerating ice flow at terminal regions, or “snouts,” of Greenland glaciers as they flow into the ocean along the western coast. The new CIRES research now shows that the interior regions also are flowing much faster than they were in the winter of 2000-01, and the paper proposes a reason for the speedup.

“Through satellite observations, we determined that an inland region of the Sermeq Avannarleq Glacier, 40 to 60 miles from the coast, is flowing about one and a half times faster than it was about a decade ago,” said Thomas Phillips, lead author of the new paper and a CIRES research associate at the time of the study. In 2000-01, the inland segment was flowing at about 130 feet (40 meters) per year; in 2007-08, that speed was closer to 200 feet per year (60 meters).

“At first, we couldn’t explain this rapid interior acceleration,” Phillips said. “We knew it wasn’t related to what was going on at the glacier’s terminus. The speedup had to be due to changes within the ice itself.”

To shed light on the observed acceleration, Phillips and his team developed a new model to investigate the effects of meltwater on the ice sheet’s physical properties. The team found that meltwater warms the ice sheet, which then—like a warm stick of butter—softens, deforms and flows faster.

Previous studies estimated that it would take centuries to millennia for new climates to increase the temperature deep within ice sheets. But when the influence of meltwater is considered, warming can occur within decades and produce rapid accelerations. The paper has been accepted for publication in the Journal of Geophysical Research: Earth Surface, a journal of the American Geophysical Union.

“Traditionally, latent energy has been considered a relatively unimportant factor, but most glaciers are now receiving far more meltwater than they used to and are increasing in temperature faster than previously imagined,” said William Colgan, a co-author and CIRES adjunct research associate. “The chunk of butter known as the Greenland Ice Sheet may be softening a lot faster than we previously thought possible.”

The CIRES researchers were tipped off to this mechanism by the massive amount of meltwater they observed on the ice sheet’s surface during their summer field campaigns, and they wondered if it was affecting the ice sheet. During the last several decades, atmospheric warming above the Greenland Ice Sheet has caused an expanding area of the surface to melt during the summer, creating pools of water that gush down cracks in the ice. The meltwater eventually funnels to the interior and bed of the ice sheet.

As the meltwater drains through the ice, it carries with it heat from the sun.

“The sun melts ice into water at the surface, and that water then flows into the ice sheet carrying a tremendous amount of latent energy,” said William Colgan, a co-author and CIRES adjunct research associate. “The latent energy then heats the ice.”

The new model shows that this speeds up ice flow in two major ways: One, the retained meltwater warms the bed of the ice sheet and preconditions it to accommodate a base layer of water, making it easier for the ice sheet to slide by lubrication. Two, warmer ice is also softer (less viscous), which makes it flow more readily.

“Basically, the gravitational force driving the ice sheet flow hasn’t changed over time, but with the ice sheet becoming warmer and softer, that same gravitational force now makes the ice flow faster,” Colgan said.

This transformation from stiff to soft requires only a little bit of extra heat from meltwater. “The model shows that a slight warming of the ice near the ice sheet bed—only a couple of degrees Celsius—is sufficient to explain the widespread acceleration,” Colgan said.

The findings have important ramifications for ice sheets and glaciers everywhere. “It could imply that ice sheets can discharge ice into the ocean far more rapidly than currently estimated,” Phillips said. “It also means that the glaciers are not finished accelerating and may continue to accelerate for a while. As the area experiencing melt expands inland, the acceleration may be observed farther inland.”

The new model will help scientists more accurately forecast these impacts, and it is being incorporated into Earth-system models for predicting future ice discharge from the Greenland Ice Sheet.

The findings suggest that to understand future sea-level rise, scientists need to account for a previously overlooked factor—meltwater’s latent energy—and its potential role in making glaciers and ice sheets flow faster into the world’s oceans. In 2007, the Intergovernmental Panel on Climate Change (IPCC) wrote that one of the most significant challenges in predicting sea-level rise was “limited” understanding of the processes controlling ice flow. This paper, and others that have advanced scientific understanding of ice sheet and glacier behavior, are likely to inform the IPCC’s next assessment, due out in 2014.

“Traditionally, latent energy has been considered a relatively unimportant factor, but most glaciers are now receiving far more meltwater than they used to and are increasing in temperature faster than previously imagined,” Colgan said. “The chunk of butter known as the Greenland Ice Sheet may be softening a lot faster than we previously thought possible.”

The study was funded through a NASA ROSES grant, NASA’s Greenland Climate Network and the National Science Foundation. Other co-authors on the paper were CIRES Director Waleed Abdalati, former CIRES Director Konrad Steffen and 

CU-Boulder engineering Professor Harihar Rajaram.

Meltwater pools on the surface of the Sermeq Avannarleq Glacier, in a region about 10 miles from the ice sheet margin in Southwest Greenland. A new CIRES-led study helps explain the surprising acceleration of inland ice. Meltwater draining through the ice likely warms the ice sheet from the inside and like a stick of warm butter, the sheet softens, deforms and can flow faster. (Photo by William Colgan/CIRES) 

CIRES is a joint institute of CU-Boulder and the National Oceanic and Atmospheric Administration.

Contact:
Katy Human, CIRES communications director, 303-735-0196
kathleen.human@colorado.edu
Thomas Phillips, +41 79 120 0858
Thomas.Phillips@Colorado.EDU, Thomas.Phillips (Skype)
William Colgan, +45 38 14 29 30
william.colgan@colorado.edu

Massive ice sheets melting 'at rate of 300bn tonnes a year', climate satellite shows

The Grace satellite measures tiny fluctuations of the Earth’s gravity field resulting from the loss of ice into the sea

the Independent,

14 July, 2013

A satellite that measures gravity fluctuations on Earth due to changes in the massive ice sheets of Greenland and Antarctica has detected a rapid acceleration in the melting of glacier ice over the past decade, which could have a dramatic impact on sea levels around the world.

The sheets are losing around 300 billion tonnes of ice a year, the research indicates.

However, scientists have warned that the measurements gathered since 2002 by the Gravity Recovery and Climate Experiment (Grace) flying in space are still too short-term for accurate predictions of how much ice will be lost in the coming decades, and therefore how rapidly sea levels will rise.

“In the course of the mission, it has become apparent that ice sheets are losing substantial amounts of ice – about 300 billion tonnes a year – and that the rate at which these losses occurs is increasing,” said Bert Wouters of Bristol University’s Glaciology Centre.

“Compared to the first few years of the Grace mission, the ice sheets’ contribution to sea-level rise has almost doubled in recent years,” added Dr Wouters, the lead author of the study published in the Earth sciences journal Nature Geoscience.

The Grace satellite measures tiny fluctuations of the Earth’s gravity field resulting from the loss of ice into the sea, but it cannot yet point to a long-term trend. Ice sheets also melt because of variations in the weather due to shifting ocean currents or decade-long oscillations in the weather systems of the North Atlantic Ocean.

A few more years of observations would be needed for the Grace experiment to point to whether global warming rather than natural variability is behind the loss of ice in the Antarctic, while it could take another 10 years of data to demonstrate a link with the loss of ice in Greenland, Dr Wouters said.

At the moment, the ice loss detected by the Grace satellite is larger than what would be expected from just natural fluctuations, but the acceleration in ice loss over the last few years is not, the scientists said.

Professor Andrew Shepherd of the University of Leeds said that less than a decade of satellite data from the Grace experiment is too short to establish with confidence whether the ice sheet losses are truly accelerating.

“Fortunately, we can appeal to data from other, longer satellite missions to get a long-term perspective, and our own analysis of their data confirms that the rate of ice sheet losses has indeed accelerated over the past 20 years,” Professor Shepherd said.

The melting of the world’s two great ice sheets is one of the greatest unknowns in climate-change science. Together, the ice sheets of Greenland and Antarctica contain about 99.5 per cent of the Earth’s glacier ice, which could increase average sea levels by 63 metres if they were ever to melt completely – an event that would in any case take many centuries.

Trying to predict how much they are likely to contribute to sea-level rise over the coming century has been notoriously difficult because of a lack of reliable and widespread ground observations from these remote and inaccessible places.

An estimate published earlier this year suggested that the ice sheets together, combined with mountain glaciers, could contribute anywhere between 3.5cm and 36.8cm to average sea levels by the year 2100, which would be in addition to the smaller sea-level rise due to the thermal expansion of the warmer oceans.

In its last report in 2007, the Intergovernmental Panel on Climate Change said that average sea levels are rising by about 2 millimetres a year. But, other scientists calculated last year that the true rate is about 3.2mm a year – about 60 per cent faster.