domingo, 12 de fevereiro de 2017
Temperatures in the Arctic are skyrocketing — for the third time this winter / Could a £400bn plan to refreeze the Arctic before the ice melts really work? / Humans causing climate to change 170 times faster than natural forces
Energy and Environment
Temperatures in the Arctic are skyrocketing — for the third time this winter
By Chelsea Harvey February 10
Image obtained using Climate Reanalyzer, Climate Change Institute, University of Maine.
While much of the Northeast was forced to batten down the hatches this week against strong winds, heavy snow and other icy conditions, the usually frigid Arctic experienced the opposite — a period of unseasonably mild weather and high temperatures, for at least the third time this winter.
A powerful low-pressure storm system in the northern Atlantic has helped carry warm air up to the frozen north this week, sending temperatures in the Arctic soaring. Data from the Danish Meteorological Institute suggests that, as of Thursday, temperatures in the area above 80 degrees north latitude were already more than 20 degrees warmer than the average temperature for this time of year. As the image above from Climate Reanalyzer shows, the most unusually warm region is right over the North Pole.
It’s at least the third such extreme winter-warming event for the Arctic this season — temperatures skyrocketed on two occasions in November and December as well. Similar incidents also occurred in December of 2015 and 2014.
Scientists believe that a number of different factors are feeding into these warming events, including the steady march of climate change and interactions between the air and Arctic sea ice, which global warming is melting a little more each year. And a good low-pressure system, like the one that barreled through this week, can help to jump-start these kinds of sudden warming events by carrying a large amount of warm air up to the North Pole all at once.
The presence of the storm itself isn’t exactly unusual, according to atmospheric physics expert Kent Moore of the University of Toronto. Each year, there are some storms that roll through the northern Atlantic. What’s uncommon is just how far north some of them have been making it lately.
“There’s these extratropical cyclones that appear to be tracking farther north than they usually do, and these low-pressure systems are bringing the heat up into the polar region,” he said. It’s unclear why this happens, he added. But when it does, temperatures can vault up above zero degrees, or in extreme cases, sometimes even above freezing.
In a recent paper published in December, Moore notes that these types of anomalous warming events have been recorded since the 1950s — but they usually only occur once or twice a decade. Scientists believe that factors related to climate change may now be making it easier for weather systems like this week’s storm to carry warm air into the Arctic.
Changes in Arctic sea ice extent are one major issue. As a result of global warming, temperatures in the Arctic are rising at about twice the global average rate, and one of the consequences is a reduction in Arctic sea ice. These changes are most obvious in the warm summer months, when sea ice is at a minimum anyway — but lately, scientists have been observing record lows for the frozen winter months as well, a time of year when the ice is actually expanding. But where it is missing, those parts of the ocean become warmer.
“As that sea ice moves northward, there’s a huge reservoir of heat over the north Atlantic,” Moore said. “As we lose the sea ice, it allows essentially this reservoir of warmth to move closer to the pole.”
When this happens, storm systems may be able to carry heat farther north than usual. In fact, earlier this week, scientists at the National Snow and Ice Data Center announced that sea ice remained at record low daily extents through the month of January. Sea ice extent for the month averaged 5.17 million square miles, the lowest January extent on record.
(National Snow and Ice Data Center)
Some scientists also believe that rapid warming in the Arctic has helped bring about changes in certain atmospheric patterns — causing the jet stream’s flow to become more “wavy,” for instance — in ways that can affect weather systems in the north Atlantic.
Moore noted that weather-induced warming events in the Arctic tend to be short-lived, meaning this week’s event — like similar others in the past — will probably not persist for more than a few days. But he added that an increase in the frequency of temperature extremes at the North Pole is just another indicator of climate change’s disproportionate effect on the Arctic.
“There’s more and more evidence that the Arctic, especially, is warming quite dramatically and that we should expect to see more of these events,” he said. “I think it’s just more evidence that the climate is, in fact, changing.”
Could a £400bn plan to refreeze the Arctic before the ice melts really work?
Temperatures are now so high at the north pole that scientists are contemplating radical schemes to avoid catastrophe
Robin McKie Observer science editor
Sunday 12 February 2017 00.05 GMT
Physicist Steven Desch has come up with a novel solution to the problems that now beset the Arctic. He and a team of colleagues from Arizona State University want to replenish the region’s shrinking sea ice – by building 10 million wind-powered pumps over the Arctic ice cap. In winter, these would be used to pump water to the surface of the ice where it would freeze, thickening the cap.
The pumps could add an extra metre of sea ice to the Arctic’s current layer, Desch argues. The current cap rarely exceeds 2-3 metres in thickness and is being eroded constantly as the planet succumbs to climate change.
“Thicker ice would mean longer-lasting ice. In turn, that would mean the danger of all sea ice disappearing from the Arctic in summer would be reduced significantly,” Desch told the Observer.
Desch and his team have put forward the scheme in a paper that has just been published in Earth’s Future, the journal of the American Geophysical Union, and have worked out a price tag for the project: $500bn (£400bn).
It is an astonishing sum. However, it is the kind of outlay that may become necessary if we want to halt the calamity that faces the Arctic, says Desch, who, like many other scientists, has become alarmed at temperature change in the region. They say that it is now warming twice as fast as their climate models predicted only a few years ago and argue that the 2015 Paris agreement to limit global warming will be insufficient to prevent the region’s sea ice disappearing completely in summer, possibly by 2030.
“Our only strategy at present seems to be to tell people to stop burning fossil fuels,” says Desch. “It’s a good idea but it is going to need a lot more than that to stop the Arctic’s sea ice from disappearing.”
The loss of the Arctic’s summer sea ice cover would disrupt life in the region, endanger many of its species, from Arctic cod to polar bears, and destroy a pristine habitat. It would also trigger further warming of the planet by removing ice that reflects solar radiation back into space, disrupt weather patterns across the northern hemisphere and melt permafrost, releasing more carbon gases into the atmosphere.
Hence Desch’s scheme to use wind pumps to bring water that is insulated from the bitter Arctic cold to its icy surface, where it will freeze and thicken the ice cap. Nor is the physicist alone in his Arctic scheming: other projects to halt sea-ice loss include one to artificially whiten the Arctic by scattering light-coloured aerosol particles over it to reflect solar radiation back into space, and another to spray sea water into the atmosphere above the region to create clouds that would also reflect sunlight away from the surface.
All the projects are highly imaginative – and extremely costly. The fact that they are even being considered reveals just how desperately worried researchers have become about the Arctic. “The situation is causing grave concern,” says Professor Julienne Stroeve, of University College London. “It is now much more dire than even our worst case scenarios originally suggested.’
Last November, when sea ice should have begun thickening and spreading over the Arctic as winter set in, the region warmed up. Temperatures should have plummeted to -25C but reached several degrees above freezing instead. “It’s been about 20C warmer than normal over most of the Arctic Ocean. This is unprecedented,” research professor Jennifer Francis of Rutgers University told the Guardian in November. “These temperatures are literally off the charts for where they should be at this time of year. It is pretty shocking. The Arctic has been breaking records all year. It is exciting but also scary.”
Nor have things got better in the intervening months. Figures issued by the US National Snow and Ice Data Center (NSIDC), in Boulder, Colorado, last week revealed that in January the Arctic’s sea ice covered 13.38 million sq km, the lowest January extent in the 38 years since satellites began surveying the region. That figure is 260,000 sq km below the level for January last year, which was the previous lowest extent for that month, and a worrying 1.26 million sq km below the long-term average for January.
In fact, sea ice growth stalled during the second week of January – in the heart of the Arctic winter – while the ice cap actually retreated within the Kara and Barents seas, and within the Sea of Okhotsk. Similarly, the Svalbard archipelago, normally shrouded in ice, has remained relatively free because of the inflow of warm Atlantic water along the western part of the island chain. Although there has been some recovery, sea ice remains well below all previous record lows.
The area covered by Arctic sea ice at least four years old has decreased from 1,860,000 sq km in September 1984 to 110,000 sq km in September 2016. In this visualisation, the age of the ice is indicated by shades ranging from blue-gray for the youngest ice to white for the oldest. Photograph: Scientific Visualization Studio/Nasa
This paucity of sea ice bodes ill for the Arctic’s summer months when cover traditionally drops to its lower annual level, and could plunge to a record minimum this year. Most scientists expect that, at current emission rates, the Arctic will be reliably free of sea ice in summer by 2030.
By “free” they mean there will be less than 1m sq km of sea ice left in the Arctic, most of it packed into remote bays and channels, while the central Arctic Ocean over the north pole will be completely open. And by “reliably”, scientists mean there will have been five consecutive years with less than 1m sq km of ice by the year 2050. The first single ice-free year will come much earlier than this, however.
And when that happens, the consequences are likely to be severe for the human and animal inhabitants of the region. An ice-free Arctic will be wide open to commercial exploitation, for example. Already, mining, oil and tourism companies have revealed plans to begin operations – schemes that could put severe strain on indigenous communities’ way of life in the region.
Equally worrying is the likely impact on wildlife, says Stroeve. “Juvenile Arctic cod like to hang out under the sea ice. Polar bears hunt on sea ice, and seals give birth on it. We have no idea what will happen when that lot disappears. In addition, there is the problem of increasing numbers of warm spells during which rain falls instead of snow. That rain then freezes on the ground and forms a hard coating that prevents reindeer and caribou from finding food under the snow.”
Nor would the rest of the world be isolated. With less ice to reflect solar radiation back into space, the dark ocean waters of the high latitudes will warm and the Arctic will heat up even further.
“If you warm the Arctic you decrease the temperature difference between the poles and the mid-latitudes, and that affects the polar vortex, the winds that blow between the mid latitudes and the high latitudes,” says Henry Burgess, head of the Arctic office of the UK Natural Environment Research Council.
“Normally this process tends to keep the cold in the high north and milder air in mid-latitudes but there is an increasing risk this will be disrupted as the temperature differential gets weaker. We may get more and more long, cold spells spilling down from the Arctic, longer and slower periods of Atlantic storms and equally warmer periods in the Arctic. What happens up there touches us all. It is hard to believe you can take away several million sq km of ice a few thousand kilometres to the north and not expect there will be an impact on weather patterns here in the UK.”
For her part, Stroeve puts it more bleakly: “We are carrying out a blind experiment on our planet whose outcome is almost impossible to guess.”
This point is backed by Desch. “Sea ice is disappearing from the Arctic – rapidly. The sorts of options we are proposing need to be researched and discussed now. If we are provocative and get people to think about this, that is good.
“The question is: do I think our project would work? Yes. I am confident it would. But we do need to put a realistic cost on these things. We cannot keep on just telling people, ‘Stop driving your car or it’s the end of the world’. We have to give them alternative options, though equally we need to price them.”
THE BIG SHRINK
The Arctic ice cap reaches its maximum extent every March and then, over the next six months, dwindles. The trough is reached around mid-September at the end of the melting season. The ice growth cycle then restarts. However, the extent of regrowth began slackening towards the end of the last century. According to meteorologists, the Arctic’s ice cover at its minimum is now decreasing by 13% every decade – a direct consequence of heating triggered by increased levels of carbon dioxide in the atmosphere.
Climate change deniers claim this loss is matched by gains in sea ice around the Antarctic. It is not. Antarctic ice fluctuations are slight compared with the Arctic’s plummeting coverage and if you combine the changes at both poles, you find more than a million sq km of ice has been lost globally in 30 years.
Humans causing climate to change 170 times faster than natural forces
Researchers behind ‘Anthropocene equation’ say impact of people’s intense activity on Earth far exceeds that of natural events spread across millennia
Sunday 12 February 2017 06.44 GMT
For the first time, researchers have developed a mathematical equation to describe the impact of human activity on the earth, finding people are causing the climate to change 170 times faster than natural forces.
The equation was developed in conjunction with Professor Will Steffen, a climate change expert and researcher at the Australian National University, and was published in the journal The Anthropocene Review.
The authors of the paper wrote that for the past 4.5bn years astronomical and geophysical factors have been the dominating influences on the Earth system. The Earth system is defined by the researchers as the biosphere, including interactions and feedbacks with the atmosphere, hydrosphere, cryosphere and upper lithosphere.
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But over the past six decades human forces “have driven exceptionally rapid rates of change in the Earth system,” the authors wrote, giving rise to a period known as the Anthropocene.
“Human activities now rival the great forces of nature in driving changes to the Earth system,” the paper said.
Steffen and his co-researcher, Owen Gaffney, from the Stockholm Resilience Centre, came up with an “Anthropocene Equation” to determine the impact of this period of intense human activity on the earth.
Explaining the equation in New Scientist, Gaffney said they developed it “by homing in on the rate of change of Earth’s life support system: the atmosphere, oceans, forests and wetlands, waterways and ice sheets and fabulous diversity of life”.
“For four billion years the rate of change of the Earth system has been a complex function of astronomical and geophysical forces plus internal dynamics: Earth’s orbit around the sun, gravitational interactions with other planets, the sun’s heat output, colliding continents, volcanoes and evolution, among others,” he wrote.
“In the equation, astronomical and geophysical forces tend to zero because of their slow nature or rarity, as do internal dynamics, for now. All these forces still exert pressure, but currently on orders of magnitude less than human impact.”
According to Steffen these forces have driven a rate of change of 0.01 degrees Celsius per century.
Greenhouse gas emissions caused by humans over the past 45 years, on the other hand, “have increased the rate of temperature rise to 1.7 degrees Celsius per century, dwarfing the natural background rate,” he said.
This represented a change to the climate that was 170 times faster than natural forces.
“We are not saying the astronomical forces of our solar system or geological processes have disappeared, but in terms of their impact in such a short period of time they are now negligible compared with our own influence,” Steffen said.
“Crystallising this evidence in the form of a simple equation gives the current situation a clarity that the wealth of data often dilutes.
“What we do is give a very specific number to show how humans are affecting the earth over a short timeframe. It shows that while other forces operate over millions of years, we as humans are having an impact at the same strength as the many of these other forces, but in the timeframe of just a couple of centuries.
“The human magnitude of climate change looks more like a meteorite strike than a gradual change.”
Gaffney and Steffen wrote that while the Earth system had proven resilient, achieving millions of years of relative stability due to the complex interactions between the Earth’s core and the biosphere, human societies would be unlikely to fare so well.
Failure to reduce anthropological climate change could “trigger societal collapse”, their research concluded.