Climate change is altering Greenland ice sheet, accelerating sea level rise

The Greenland ice sheet has traditionally been pictured as a bit of a sponge for glacier meltwater, but new research has found it is rapidly losing the ability to buffer its contribution to rising sea levels, says a York University researcher.

York U Professor William Colgan, a co-author on the study published in the journal Nature Climate Change, helped analyse data from three expeditions to the Greenland ice sheet in 2012, 2013 and 2015. The research was done in conjunction with lead researcher Horst Machguth of the Geological Survey of Denmark and Greenland, Mike MacFerrin of the University of Colorado at Boulder and Dirk van As of the Geological Survey of Denmark and Greenland Copenhagen, Denmark.

Colgan spent five weeks with the team in 2013 drilling firn cores in the interior of the Greenland ice sheet. Firn is multi-year compacted snow that is not as dense as glacier ice. Instead, it forms a porous near-surface layer over the ice sheet. Dropped off by a ski-equipped US Air National Guard C-130 Hercules in minus 40 degrees Celsius weather, with 6,000 kilos of supplies and equipment, the team set up several camps and drilled a series of shallow firn cores about 20 metres deep during their time on the ice sheet.

"We were interested in the thin porous near-surface firn layer, and how its physical structure is changing rapidly with climate change," said Colgan of the Lassonde School of Engineering. "The study looked at very recent climate change on the ice sheet, how the last couple of years of melt have really altered the structure of the ice sheet firn and made it behave differently to future melt."

The researchers also towed a radar unit behind their skidoos to gather profiles between core sites along a 100-kilometre path from the low elevation ice sheet margin into the high elevation ice sheet interior. They analysed the firn cores on the spot by cutting them into small sections to quantify their properties, such as their density, so they could compare them with samples collected the following year. "The year-on-year firn changes were quite dramatic," said Colgan.

The team was surprised by what they found. An extreme melt that occurred in 2012 caused a layer of solid ice, several metres thick, to form on top of the porous firn in the low elevation areas of the ice sheet. "In subsequent years, meltwater couldn't penetrate vertically through the solid ice layer, and instead drained along the ice sheet surface toward the ocean," said Colgan. "It overturned the idea that firn can behave as a nearly bottomless sponge to absorb meltwater. Instead, we found that the meltwater storage capacity of the firn could be capped off relatively quickly."

As Machguth said, "Basically our research shows that the firn reacts fast to a changing climate. Its ability to limit mass loss of the ice sheet by retaining meltwater could be smaller than previously assumed."

Because the models scientists use to project Greenland's sea level rise contribution do not presently take firn cap-off into consideration, it means that Greenland's projected sea level rise due to meltwater runoff is likely higher than previously predicted. Getting this newly observed physical process into these models is an important next step for the team.

Using unmanned aerial vehicles, Colgan also plans to begin surveying the changes in ice sheet surface reflectance caused by the development of massive ice layers associated with firn cap-off. There are preliminary indications that firn cap-off is also occurring in the ice caps of the Canadian High Arctic. More

 

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Why Greenland’s “Dark Snow” Should Worry You

Jason Box's research into Greenland's dark snow raises more concerns about climate change.

Jason Box knows ice. That’s why what’s happened this year concerns him so much. Box just returned from a trip to Greenland. Right now, the ice there is … black:

The ice in Greenland this year isn’t just a little dark—it’s record-setting dark. Box says he’s never seen anything like it. I spoke to Box by phone earlier this month, just days after he returned from his summer field research campaign.

"I was just stunned, really," Box told me.

The photos he took this summer in Greenland are frightening. But their implications are even more so. Just like black cars are hotter to the touch than white ones on sunny summer days, dark ice melts much more quickly.

As a member of the Geological Survey of Denmark and Greenland, Box travels to Greenland from his home in Copenhagen to track down the source of the soot that’s speeding up the glaciers’ disappearance. He aptly calls his crowdfunded scientific survey Dark Snow.

There are several potential explanations for what’s going on here. The most likely is that some combination of increasingly infrequent summer snowstorms, wind-blown dust, microbial activity, and forest fire soot led to this year’s exceptionally dark ice. A more ominous possibility is that what we’re seeing is the start of a cascading feedback loop tied to global warming. Box mentions this summer’s mysterious Siberian holes and offshore methane bubbles as evidence that the Arctic can quickly change in unpredictable ways.

This year, Greenland’s ice sheet was the darkest Box (or anyone else) has ever measured. Box gives the stunning stats: "In 2014 the ice sheet is precisely 5.6 percent darker, producing an additional absorption of energy equivalent with roughly twice the US annual electricity consumption."

Perhaps coincidentally, 2014 will also be the year with the highest number of forest fires ever measured in Arctic.

Box ran these numbers exclusively for Slate, and what he found shocked him. Since comprehensive satellite measurements began in 2000, never before have Arctic wildfires been as powerful as this year. In fact, over the last two or three years, Box calculated that Arctic fires have been burning at a rate that’s double that of just a decade ago. Box felt this finding was so important that he didn’t want to wait for peer review, and instead decided to publish first on Slate. He’s planning on submitting these and other recent findings to a formal scientific journal later this year.

Box’s findings are in line with recent research that shows the Arctic is in the midst of dramatic change.

A recent study has found that, as the Arctic warms, forests there are turning to flame at rates unprecedented in the last 10,000 years. This year, those fires produced volumes of smoke and soot that Box says drifted over to Greenland.

In total, more than 3.3 million hectares burned in Canada’s Northwest Territories alone this year—nearly 9 times the long term average—resulting in a charred area bigger than the states of Connecticut and Massachusetts combined. That figure includes the massive Birch Creek Complex, which could end up being the biggest wildfire in modern Canadian history. In July, it spread a smoke plume all the way to Portugal.

In an interview with Canada’s National Post earlier this year, NASA scientist Douglas Morton said, "It’s a major event in the life of the earth system to have a huge set of fires like what you are seeing in Western Canada."

Box says the real challenge is to rank what fraction of the soot he finds on the Greenland ice is from forest fires, and what is from other sources, like factories. Box says the decline of snow cover in other parts of the Arctic (like Canada) is also exposing more dirt to the air, which can then be more easily transported by the wind. Regardless of their ultimate darkening effect on Greenland, this year’s vast Arctic fires have become a major new source of greenhouse gas emissions from the thawing Arctic. Last year, NASA scientists found "amazing" levels of carbon dioxide and methane emanating from Alaskan permafrost.

Earlier this year, Box made headlines for a strongly worded statement along these lines:

If even a small fraction of Arctic sea floor carbon is released to the atmosphere, we're f'd.

— Jason Box (@climate_ice) July 29, 2014

That tweet landed Box in a bit of hot water with his department, which he said now has to approve his media appearances. Still, Box’s sentiment is inspiring millions. His "f’d" quote is serving as the centerpiece of a massive petition (with nearly 2 million signatures at last count) that the activist organization Avaaz will deliver to "national, local, and international leaders" at this month’s global warming rally in New York City on Sept. 21. More

 

 

 

 

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Climate Change Will Force Us to Abandon Coastal Cities

On Monday, the New York Times reported on two new climate change studies that came to the same, terrifying conclusion: “The heat-trapping gases could destabilize other parts of Antarctica as well as the Greenland ice sheet, potentially causing enough sea-level rise that many of the world’s coastal cities would eventually have to be abandoned.”

Abandoned.

While actual abandonment would not happen for many years (we’re talking centuries), the studies warned that our actions now are irrevocable and will lock in these future sea level rises. In other words, our descendants will be dealing with irreversible damage that we are committing today.

So, fast forward a few centuries from now, what will the world look like? What will the United States look like? Will people still live in Miami? Boston? New York? We don’t know what technology we will have then and we aren’t able to predict the pattern of storms. We do know that sea levels are rising and will threaten cities along the coasts of the United States.

“Barring some extraordinary advances in technology that we currently do not foresee,” Robert Hartwig, the president of the Insurance Information Institute, said, “you are left with the options of retreating from coastal areas not only in the United States, but around the world, or building fortifications against rising sea levels that would make the projects that we now see in places like the Netherlands look like child’s play.”

The Dutch government has set aside one billion euros a year through 2100 to strengthen dunes and dams throughout the country. Due to its low-lying position, the Netherlands is one of the most at-risk countries and has already crafted a long-term strategy to ensure the country’s survival. But in the United States, where one of our two main political parties remains skeptical about man-made climate change, such planning is unlikely to happen.

“If you have a plan and vision to stay there it is more likely to occur,” Robert Nicholls, a professor of coastal engineering at the University of Southampton, wrote in an email. “But USA does not have a planning culture.”

Planning will not come cheap. The mitigation techniques needed to fortify a city like Miami will cost billions of dollars, if not more. State and local governments will undoubtedly turn to the federal government for help, but that will be a political nightmare. Americans from non-coastal regions will likely object to paying for the restoration and fortification of coastal cities that are no longer naturally fit for habitation.

“Ultimately, reality will set in in the United States too, despite it being a relatively wealthy country,” Hartwig said. “Some areas will necessarily be abandoned or potentially become, in effect, islands. That’s another possibility. You say to yourself, do I abandon Miami or do I simply wall in a certain number of square miles of what is currently Miami and in effect create an island?

“Resources are always scarce and there are going to be many in the United States who think spending every available dime of every available tax dollar to save people from rising sea levels on the coast is a complete waste of money,” Hartwig added. “And they will have a point, because they’re paying tax dollars in Missouri or in North Dakota and they will not directly see a return on this investment.”

Global warming poses risks besides rising sea level. Severe storms may increase in frequency, although it’s difficult to predict how they will play out. Saltwater intrusion could imperil farm land up the Mississippi River. Droughts may become more common. Already now, scientists are wondering whether we’ve reached Peak Phosphorus—the point at which we reach the maximum global production rate of phosphorus, an essential fertilizer for crops.

Colin Green, a professor of water economics at Middlesex University, wrote in an email that he tells his students three things: “(1) they will not be able to retire until they are 75; (b) they will need to become vegetarians because we don't have enough water to support a high meat based diet; and (c) that when they go to the supermarket, they will need to take their urine with them which will be analysed and then they will be able to buy food with the same phosphorus content as the urine they bought in.”

The consequences of our inaction today will not be fixable down the road, no matter how much money the government spends. Instead, we will focus on containing the damage, whether through mitigation or abandonment. Insurance will be an important tool to allow the government to spread around some of that risk. But that assumes insurers don’t deem certain areas uninsurable—and that in turn depends on what we do today.

“I would say that if you look at the gradual sea level rise predicted over the next century, provided appropriate mitigation on the structures and in the communities in the higher cities are undertaken, then insurance is possible in these areas albeit at higher costs,” Hartwig said.

In some cases, the federal government may sell the insurance. For instance, right now, the feds offer subsidized flood insurance to homeowners in at-risk areas. When Congress passed the Biggert-Waters Act in 2012 to allow those rates to rise to their market level, they faced a swift backlash from homeowners who were going to see their insurance rates skyrocket. Led by congressmen from Gulf states, Congress gutted the bill in March. If that is any sign of what is to come, then policymakers are not prepared for the infinitely higher costs and tough choices they will face down the road. More

 

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Rising sea levels threaten survival of cities like Kolkata: Pachauri

Rising sea levels due to climate change are threatening the survival of big cities located near coastal areas like Kolkata, Shanghai and Dhaka, said Dr RK Pachauri, chairperson of the Intergovernmental Panel on Climate Change (IPCC).

“There is a very high risk in delta cities like Kolkata, Shanghai and Dhaka. They are very vulnerable to the impacts of climate change due to sea level rise and coastal flooding. Both people and property would be affected in such a scenario,” Pachauri told reporters.

Asking governments worldwide to start adaptation measures as soon as possible to counter the effects of climate change, the scientist said the matter has to be taken up in all seriousness.

“Scientific factors are evident. We cannot keep our eyes shut,” he said.

Earlier, delivering the convocation address at the Indian Institute of Management, Calcutta, last night, Pachauri said, “Partial loss of ice sheets on polar land could imply metres of sea level rise, major changes in coastline, and inundation of low lying area, with greatest effects in river deltas and low-lying areas.”

Such changes are projected to occur over millennial timescales, but more rapid sea level rise on century timescales cannot be excluded, he warned.

IPCC’s fourth assessment report on climate change had stated, “Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global sea average level.” More

 

Scientists Seek Strategy to Convey Seriousness of Sea-Level Rise

LA JOLLA, Calif. — Sea-level rise threatens cities around the world, and academic leaders must talk about it differently to help people grasp the potential dangers and costs, climate experts said last week.

Researchers must detail effects at the local and regional levels, members of the Association of Pacific Rim Universities (APRU) Sustainability and Climate Change Program said as they met at the University of California, San Diego. They need to talk shorter time windows, mentioning impacts in 2050 as well as in 2100. And they should drive home to people that actions to limit climate change can help protect their children and grandchildren from huge economic and social impacts.

“Sea-level rise is not a problem that’s going away,” said Dan Cayan, a climate researcher at the Scripps Institution of Oceanography at UC San Diego. “In some sense, this is an important investment. This is a multigenerational issue.”

Climate researchers from around the world gathered for three days at UC San Diego to share information and formulate strategies. They discussed the importance of talking about sea-level rise and climate change as they brainstormed what advice they should give to university presidents. During that session, some of the APRU members urged more of an activist role, saying too much time already has been lost.

“People who don’t believe climate change is real, and sea-level rise is real, are really few and far between,” said Bernard Minster, a UC San Diego professor and Scripps researcher.

The conference took place just after sea-level rise and climate change happened to surface on the national stage. At the Republican National Convention, presidential nominee Mitt Romney in his acceptance speech derided President Obama’s position on the issues.

“President Obama promised to begin to slow the rise of the oceans,” Romney said as some in the audience snickered, “and to heal the planet. My promise is to help you and your family.”

Obama in his speech at the Democratic National Convention said that “climate change is not a hoax.”

“More droughts and floods and wildfires are not a joke. They are a threat to our children’s future. And in this election, you can do something about it.” More

 

Satellites See Unprecedented Greenland Ice Sheet Surface Melt

July 24, 2012: For several days this month, Greenland's surface ice cover melted over a larger area than at any time in more than 30 years of satellite observations. Nearly the entire ice cover of Greenland, from its thin, low-lying coastal edges to its two-mile-thick center, experienced some degree of melting at its surface, according to measurements from three independent satellites analyzed by NASA and university scientists.

On average in the summer, about half of the surface of Greenland's ice sheet naturally melts. At high elevations, most of that melt water quickly refreezes in place. Near the coast, some of the melt water is retained by the ice sheet and the rest is lost to the ocean. But this year the extent of ice melting at or near the surface jumped dramatically. According to satellite data, an estimated 97 percent of the ice sheet surface thawed at some point in mid-July.

Researchers have not yet determined whether this extensive melt event will affect the overall volume of ice loss this summer and contribute to sea level rise.

"The Greenland ice sheet is a vast area with a varied history of change. This event, combined with other natural but uncommon phenomena, such as the large calving event last week on Petermann Glacier, are part of a complex story," said Tom Wagner, NASA's cryosphere program manager in Washington. "Satellite observations are helping us understand how events like these may relate to one another as well as to the broader climate system." More

 

Greenland Ice Sheet Melt Nearing Critical ‘Tipping Point’

The Greenland ice sheet is poised for another record melt this year, and is approaching a "tipping point" into a new and more dangerous melt regime in which the summer melt area covers the entire land mass, according to new findings from polar researchers.

The ice sheet is the focus of scientific research because its fate has huge implications for global sea levels, which are already rising as ice sheets melt and the ocean warms, exposing coastal locations to greater damage from storm surge-related flooding.

Greenland's ice has been melting faster than many scientists expected just a decade ago, spurred by warming sea and land temperatures, changing weather patterns, and other factors. Until now, though, most of the focus has been on ice sheet dynamics — how quickly Greenland's glaciers are flowing into the sea. But the new research raises a different basis for concern.

The new findings show that the reflectivity of the Greenland ice sheet, particularly the high-elevation areas where snow typically accumulates year-round, have reached a record low since records began in 2000. This indicates that the ice sheet is absorbing more energy than normal, potentially leading to another record melt year — just two years after the 2010 record melt season. More