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Cloud shortage will push temperatures higher as climate warms

by LorrineWomble Posted on January 3, 2014

Cloud shortage will push temperatures higher as climate warms

By

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Climate scientists have looked to the heavens for help with their latest decades-long weather forecast. Their conclusion? “Oh, my god.”

Science has long struggled to forecast how global temperatures will be affected by a doubling of carbon dioxide levels in the atmosphere compared with pre-industrial times, which looks likely to occur this century. Recent consensus suggests that temperatures will rise by between 1.5 and 5 degrees Celsius (2.7 to 5.4 F). With a rise in CO2 levels to 400 parts per million, up from 280 in the 19th century, the world has warmed by nearly 1 C so far.

By modeling how clouds will be affected by the rising temperatures, a team of Australian and French scientists reported Wednesday in Nature that they expect the temperature rise to be “more than 3 degrees” – at the upper end of the projected range.

“4C would likely be catastrophic rather than simply dangerous,” the report’s lead author, Australian climate scientist Steven Sherwood, told the Guardian. “For example, it would make life difficult, if not impossible, in much of the tropics, and would guarantee the eventual melting of the Greenland ice sheet and some of the Antarctic ice sheet.”

Using dozens of computer models, the researchers concluded that water vapor will circulate more extensively than previously anticipated between the different layers of the atmosphere as temperatures climb. That will mean fewer clouds will form, leaving more of the Earth exposed to the sun’s rays. And that means more warming.

“[S]uch mixing dehydrates the low-cloud layer at a rate that increases as the climate warms,” the scientists wrote in their paper. “[O]n the basis of the available data, the new understanding presented here pushes the likely long-term global warming towards the upper end of model ranges.”

The paper is one of several recent studies looking at feedback loops between climate change and clouds, according to Chris Bretherton, a professor of atmospheric science and applied mathematics at the University of Washington. “All of these studies suggest that cloud feedbacks may be at the more positive end of what climate models predict, which would be scary,” Bretherton wrote in an email to Grist. “None of them are without issues of interpretation that will require more research to delve into, so I would not rush to assume the case for strong positive cloud feedbacks and high climate sensitivity is settled.”

In the meantime, we’re all advised to pray for rain.


Source
Spread in model climate sensitivity traced to atmospheric convective mixing, Nature

John Upton is a science fan and green news boffin who tweets, posts articles to Facebook, and blogs about ecology. He welcomes reader questions, tips, and incoherent rants: johnupton@gmail.com.

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Which Hollywood-Style Climate Disasters Will Strike in Your Lifetime?

by Bikor11 Posted on December 5, 2013

Mother Jones

<!DOCTYPE html PUBLIC “-//W3C//DTD HTML 4.0 Transitional//EN” “http://www.w3.org/TR/REC-html40/loose.dtd”>

In a just-released report, the National Academy of Sciences (NAS) has taken an extensive look at the scary side, the dramatic side…let’s face it, the Hollywood side of global warming. The new research falls under the heading of “abrupt climate change”: The report examines the doomsday scenarios that have often been conjured in relation to global warming (frequently in exaggerated blockbuster films), and seeks to determine how likely they are to occur in the real world.

So here’s a list of some of the most dreaded abrupt changes (where abrupt means occurring within a period of a few decades or even years), and the probability that they’ll happen—even if nothing like the Hollywood version—before the year 2100:

20th Century Fox/Wikimedia Commons

Disruption of the Ocean’s “conveyor belt”

As Seen In: The scientifically panned 2004 blockbuster The Day After Tomorrow.

What Would Happen: The great overturning circulation of the oceans, driven by the temperature and the salt content of waters at high latitudes, transports enormous amounts of heat around the planet. If it is disrupted or comes to a halt, there could be stark changes in global weather patterns.

Chances It Will Happen This Century: Low. For future generations, however, The Day After Tomorrow might be slightly less laughable (if still wildly exaggerated). In the longer term, the NAS rates the probability of a disruption as “high.”

CBS/Wikimedia Commons

A sharp increase in extreme precipitation events

As Seen In: The over-the-top Category 7 and the even more over-the-top Sharknado.

What Would Happen: The frequency and/or intensity of extreme precipitation events—including heavy rains, damaging flooding, droughts, and hurricanes—would show a relatively sudden increase. The consequence would be not only the potential for more weather disasters and their associated costs but also, the NAS warns, the possibility of “increased conflict” following disasters. No Category 7s, but still something worth worrying about.

Chances It Will Happen This Century: According to the NAS, we can already detect a clear trend towards more extreme flooding, although trends in other extreme weather phenomena, such as droughts and hurricanes, are more murky for the moment. As for an abrupt change this century? NAS rates the outlook as “moderate.”

Universal/Wikimedia Commons

Extreme Sea Level Rise Due to Polar Ice Sheet Collapse

As Seen In: The 1995 Kevin Costner classic Waterworld.

What Would Happen: Here is arguably the scariest global warming scenario—the collapse of all or part of the ice sheets of Greenland and Antarctica, leading to rapid and extreme sea level rise. (But no, the continents would not disappear as in Waterworld. Not remotely.)

Chances It Will Happen This Century: Fortunately, this risk is not likely to materialize before 2100, according to the NAS—with one possible exception, the West Antarctic Ice Sheet, which contains the equivalent of 3 to 4 meters of sea level rise. The NAS judges that an abrupt change here during this century is “plausible, with an unknown although probably low probability.” In the longer term, meanwhile, the probability is high that some of the great ice sheets of the planet will indeed melt substantially and drive sea level rise on a scale measured in meters, rather than inches.

Universal/Wikimedia Commons

Worse Heat Waves, More Often

As Seen In: Spike Lee’s Do the Right Thing (which isn’t directly about global warming, of course, but is definitely about heat).

What Would Happen: Heat waves can be devastating. Not only can they kill significant numbers of people (and spark conflict), but they also can imperil agriculture and water supplies.

Chances It Will Happen This Century: According to the NAS, a climate-related trend towards more intense and frequent heat waves has already been detected. And the outlook for an abrupt change for the worse in this century is “moderate.”

Catastrophic Methane Release from the Arctic

As Seen In: Amazingly, to our knowledge Hollywood hasn’t made use of this one yet.

What Would Happen: One oft-touted climate fear is that undersea Arctic deposits of methane hydrate will be destabilized or even explode, releasing large volumes of gas into the atmosphere that, in turn, trigger rapid global warming. This scenario is particularly frightening because methane is a much more potent greenhouse gas than carbon dioxide. By worsening global warming, an Arctic methane “bomb” would also increase the risk of other dangerous abrupt climate changes.

Chances It Will Happen This Century: “Low,” says the NAS. Over the longer term, however, the risk rises to “moderate”; and when it comes to a related threat—the release of stored carbon from the thawing of northern permafrost, which would also amplify global warming—the long-term risk is “high.”

Warner Bros.

disappearing Arctic sea ice

As Seen In: The 2012 Imax film To the Arctic (yes, a documentary).

What Would Happen: The loss of summer Arctic sea ice has profound effects, ranging from opening up dramatic new opportunities for shipping and resource exploitation, to reshaping ecosystems and native cultures, to changing global weather patterns.

Chances it Will Happen This Century: The NAS considers the ongoing changes in the Arctic region to be an abrupt climate change that is already upon us. So you can watch this one in a documentary, or even in satellite images.

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Which Hollywood-Style Climate Disasters Will Strike in Your Lifetime?

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Antarctica’s permafrost is melting

by sepjod5 Posted on July 25, 2013

Antarctica’s permafrost is melting

By John Upton

NASA’s Marshall Space Flight Center

Antarctica.

Things are getting ugly on Earth’s underside.

Antarctic permafrost, which had been weathering global warming far better than areas around the North Pole, is starting to give way. Scientists have recorded some of it melting at rates that are nearly comparable to those in the Arctic.

Scientists used time-lapse photography and LiDAR to track the retreat of an Antarctic ice cliff over a little more than a decade. They reported Wednesday in the journal Scientific Reports that the cliff was “backwasting rapidly.” The permafrost that made up the cliff was found to be disappearing nearly 10 times more quickly than was the case during recent geological history. And the rate of melting is picking up pace. From the Los Angeles Times:

Cliff-face measurements of the buried ice in the four-mile-long Garwood Valley revealed melt rates that shifted from a creeping annual rate of about 40,000 cubic feet per year over six milleniums, to more than 402,000 cubic feet last year alone. … (That’s a leap from the capacity of about eight standard railroad boxcars to 77.)

The scientists also monitored the weather at the cliff and found that rising air temperatures were not to blame for the melt. Rather, they think it was caused by growing amounts of dark debris on the surface of the ice and snow that absorbed the sun’s rays.

How did the debris get there? During sudden bursts of warmth brought to the area by strong winds from other regions, ice expanded and cracked and sometimes broke up, throwing the dark debris up to the surface.

Scientific Reports

Monitoring equipment placed in front of the cliff.

If temperatures in the valley eventually start to rise, as expected with global warming, then things could get really watery. From the L.A. Times again:

[The scientists] found that changing patterns of soil erosion altered the amount of solar radiation absorbed in the area, known as the albedo effect, adding about two watts of energy per square meter. (That’s about the power of a candle style lightbulb radiating on less than a third of a sheet of plywood.)

“It doesn’t sound like much to crank up two watts at a time but when you add this up over the last several decades, it’s enough to tip the balance in Garwood from having buried ice in equilibrium to having accelerated melting,” [said geologist Joseph Levy, lead author of the study]. “It’s serious because when you think about permafrost thaw in the Arctic and Antarctic peninsula, usually people think about air temperature. But the dry valley has been in a cooling trend that started about 20 years ago.”

Adding a small rise in temperature, as predicted by climate models, would cause a wide swath of the valley to melt, Levy warned. …

That type of accelerated melt could become typical at the fringes of much larger areas, such as Antarctica’s ice sheets and the land ice in Greenland. Unlike the dry valley thaw, those melts would contribute significantly to rising sea levels.

The scientists reported on the results of studies of just one Antarctic ice cliff, but their findings suggest that similar frozen features across swaths of the southern continent are also vulnerable. “Garwood Valley ice cliff recession may be a leading indicator of more widespread landscape change,” they wrote in the paper. Such changes could “transform low elevation and coastal Antarctic landscapes by the close of the century.”

John Upton is a science fan and green news boffin who tweets, posts articles to Facebook, and blogs about ecology. He welcomes reader questions, tips, and incoherent rants: johnupton@gmail.com.

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Could melting glaciers slow down climate change?

by RupertxMcmillan Posted on March 12, 2013

Could melting glaciers slow down climate change?

By John Upton

Shutterstock

/ Anders PeterChockablock with plankton food.

As glaciers and ice sheets melt and flood the world, they are releasing a type of nutrient that’s lapped up by tiny creatures that could help reduce global warming.

Glaciers contain surprisingly high concentrations of iron, according to the results of a study published Sunday in the journal Nature Geoscience. Iron is a nutrient that’s essential for the growth of plankton, which forms the base of ocean food webs.

As plankton blooms feast on iron and grow, they also suck down large quantities of carbon dioxide. Some of that carbon is then passed up the food chain to larger animals. When plankton and animals that feed upon them die, some of the biomass sinks to the bottom of the ocean, taking all that carbon to a deepwater grave and removing it from the atmosphere.

From R&D Magazine:

Iron from wind-blown dust and river runoff fuels annual plankton blooms in the world’s ocean. Ice sheets and glaciers are now also thought to contribute iron from sediments on the bottom of calved icebergs and glacially-derived dust. Until now, meltwater runoff from glaciers and ice sheets was considered too dilute to carry much iron, although previous research has shown a strong correlation between the plankton blooms and the runoff from Greenland ice sheet.

“Glacial runoff has only recently been considered a potentially important source of nutrients that are useable, or bioavailable, to downstream ecosystems,” says [Woods Hole Oceanographic Institution researcher Maya] Bhatia. “We believe our study now adds iron to that list of nutrients, and underscores the potential for a unique but as-yet-undetermined chemical impact from increasing ice sheet meltwater runoff.”

The scientists warn that more research is needed to establish whether the melting glaciers and ice sheets are actually serving the counterintuitive purpose of slowing down the very global warming that is leading to their demise. To grow in large enough volumes to affect global warming, they say, plankton would also need phosphates and nitrates — and it’s unclear at this point whether there are enough of those nutrients to help make a difference.

John Upton is a science aficionado and green news junkie who

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One step forward, one step back for tar-sands protesters

by 7MelansonHayden940 Posted on January 28, 2013

One step forward, one step back for tar-sands protesters

By Susie Cagle

It’s a bittersweet moment for direct environmental action against nasty tar-sands pollution. (So many moments are bittersweet in the fight against nasty tar-sands pollution …)

On the sweet side, Canada’s Idle No More movement has gone global today, mobilizing protests around the world to highlight mistreatment of indigenous peoples and the environment. The movement has been galvanized by plans to pipe tar-sands oil across First Nations land in British Columbia and by the Canadian government’s attempts to roll back environmental protections for most of the country’s waterways. Actions are already rolling across Canada, at U.N. headquarters in New York, and as far away as Australia and Greenland.

“This day of action will peacefully protest attacks on Democracy, Indigenous Sovereignty, Human Rights and Environmental Protections when Canadian MPs return to the House of Commons on January 28th,” organizers said in a statement.

But for the bitter: The Tar Sands Blockade, which is fighting ongoing construction of the southern leg of the Keystone XL pipeline in Texas, faced a significant setback in court on Friday.

In a lawsuit against 19 individual activists as well as the groups Tar Sands Blockade, Rising Tide North Texas, and Rising Tide North America, pipeline builder TransCanada sought $5 million in damages, stating that the activists had disrupted pipeline construction and caused financial losses for the company (despite at other times claiming they had no impact at all). Activists settled the lawsuit without paying damages, but agreed not to trespass on Keystone XL property in Texas or Oklahoma.

“TransCanada is dead wrong if they think a civil lawsuit against a handful of Texans is going to stop a grassroots civil disobedience movement,” said Ramsey Sprague, a spokesperson for the Tar Sands Blockade.

Sprague is right. This court loss might be bitter, but I wouldn’t count out the blockaders in this fight. And when even the Sierra Club is preparing to tape up and jump in the ring, you know the real shit is still yet to go down.

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Greenland’s ‘extraordinary’ summer ice melt may have been caused by tundra fires

by Myrna Posted on December 7, 2012

Greenland’s ‘extraordinary’ summer ice melt may have been caused by tundra fires

By Philip Bump

Last July, over the course of a week, 97 percent of Greenland’s ice surface melted. The response from scientists can be summarized as: “Um, shit.” Or, by way of a direct quote: “This was so extraordinary that at first I questioned the result: was this real or was it due to a data error?”

It was real. And it’s one of the things that the National Oceanic and Atmospheric Administration’s 2012 Arctic report card cites as an unexpected anomaly in a season full of them.

Researchers now think they know why it happened. Like so much of what’s happening in the Arctic, the melt likely stems from another aspect of climate change: fire.

From the Guardian:

Satellite observations, due to be presented at the annual meeting of the American Geophysical Union on Friday, for the first time tracks smoke and soot particles from tundra wildfires over to Greenland.

Scientists have long known that soot blackens snow and ice, reducing its powers of reflectivity and making it more likely to melt under the sun.

But the satellite records, due to be presented by the Ohio State University geographer Jason Box, go a step further, picking up images of smoke over Greenland at the time of last summer’s extreme melt.

Byrd Polar Research

Click to embiggen.

The study, from a team centered at Ohio State’s Byrd Polar Research Center, works backward from the presence of smoke over Greenland (seen above) to possible sources. A series of tundra fires in Alaska and Western Canada and wildfires in Labrador earlier in the summer appear on this June 25 thermal map.

Byrd Polar Research

Click to embiggen.

Analysis of barometric pressures in the week preceding the start of the melt suggests that winds passing over the areas of wildfire could have carried the smoke seen in the image at top.

Byrd Polar Research

Click to embiggen.

Along with the smoke came soot, particulate matter of the type that’s also prompting concern over Arctic air travel. Such pollution demonstrably contributes to ice melt.

And, in yet another feedback loop, those tundra fires themselves are exacerbated by and contribute to climate change. From NPR:

Tundra fires have become more common over the past two decades as average temperatures in the Arctic have risen and sea ice has receded. And according to scientists, there has been a marked increase in lightning activity on the North Slope in the last two decades. Warmer temperatures may allow more vegetation to grow — which, in turn, makes it more of a fire risk when lightning strikes.

Normally, the tundra in this region of Alaska, near the Anaktuvuk River, takes up more CO2 from photosynthesis than it gives off every year from natural decomposition. …

Overall, the amount of carbon released — about 2.1 terragrams — is comparable to what comes from forest fires in warmer parts of the planet, according to Dr. Mack. “But what’s surprising to me,” she says, “is that forests have huge trees, and tundra has six-inch-tall, tiny little plants. All that extra carbon is coming from the soil.”

And the extra carbon heads into the atmosphere. In school kids learn about the water cycle. Maybe the carbon circle should be added to the curriculum.

The link between these fires and the Greenland melt is still circumstantial. So the team behind the initial research has launched Dark Snow, a proposed 2013 expedition to Greenland for which they are soliciting contributions. Once there, they plan to analyze the extent to which soot affects the melt.

If they raise the money for the trip, a bit of good news: They can probably leave the ice cleats at home.

Source

Smoke from Arctic wildfires may have caused Greenland’s record thaw, Guardian

Philip Bump writes about the news for Gristmill. He also uses Twitter a whole lot.

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The 2012 Arctic report card: We’re going to need some summer school

by Myrna Posted on December 6, 2012

The 2012 Arctic report card: We’re going to need some summer school

By Philip Bump

Each year, the National Oceanic and Atmospheric Administration releases a “report card” for how the Arctic is doing. This year, the Arctic gets an incomplete and a notice to be signed by its parents stating that it will require tutoring.

Warning: sad polar bears.

The report focuses on two primary findings. First, that the year’s record ice loss comes despite a relatively unremarkable year, temperature-wise.

A major finding of the Report Card 2012 is that numerous record-setting melting events occurred, even though, with the exception of a few limited episodes, Arctic-wide it was an unremarkable year, relative to the previous decade, for a primary driver of melting — surface air temperatures. From October 2011 through August 2012, positive (warm) temperature anomalies were relatively small over the central Arctic compared to conditions in recent years (2003-2010). Yet, in spite of these moderate conditions, new records were set for sea ice extent, terrestrial snow extent, melting at the surface of the Greenland ice sheet, and permafrost temperature.

A reminder: Here’s how this year’s ice melt compared to the past.

Pettit Climate Graphs

Click to embiggen.

The unusually severe melt despite non-unusual temperatures is in part due to the feedback loop of melt itself.

A major source of this momentum is the fact that changes in the sea ice cover, snow cover, glaciers and Greenland ice sheet all conspire to reduce the overall surface reflectivity of the region in the summer, when the sun is ever-present. In other words, bright, white surfaces that reflect summer sunlight are being replaced by darker surfaces, e.g., ocean and land, which absorb sunlight. These conditions increase the capacity to store heat within the Arctic system, which enables more melting — a positive feedback.

The other main finding is that the melt of ice in the Arctic region is affecting the food chain.

A second key point in Report Card 2012 is that changes in the Arctic marine environment are affecting the foundation of the food web in both the terrestrial and marine ecosystems. …

For instance, new satellite remote sensing observations show the near ubiquity of ice-edge blooms throughout the Arctic and the importance of seasonal sea ice variability in regulating primary production. These results suggest that previous estimates of annual primary production in waters where these under-ice blooms develop may be about ten times too low. At a higher trophic level, seabird phenology, diet, physiology, foraging behavior and survival rates have changed in response to higher water temperatures, which affect prey species.

Changes in the terrestrial ecosystem are exemplified by vegetation and mammals. The tundra continues to become more green and in some locations above-ground plant biomass has increased by as much as 26% since 1982.

That change in surface vegetation has caused the lemming population to drop, which, in turn, has done the same to the Arctic fox, a species near extinction. At the same time, red foxes are migrating north, providing additional competition for shrinking food supplies.

So: That’s grim.

The report is loaded with graphs featuring lines that typically start at the upper left corner and then plummet down and to the right. It also contains interesting graphics like this one, showing the effect that an August storm had on ice breakup and melt near Alaska.

NASA

Click to embiggen.

It’s probably not really accurate to call this document a report card. It’s far more of a crystal ball, sort of an SAT gauging how the future might look. And it doesn’t look very good.

Philip Bump writes about the news for Gristmill. He also uses Twitter a whole lot.

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