How a beer bottle helped reveal rapid past climate change

According to Willi Dansgaard "A sophisticated experimental set-up on the lawn became the beginning of a new field in geophysics." Credit: Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen.

According to Willi Dansgaard “A sophisticated experimental set-up on the lawn became the beginning of a new field in geophysics.” Credit: Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen.

On Saturday June 21, 1952, in a garden in Copenhagen, Denmark, raindrops fell through the slim neck of a beer bottle, splattering and splashing as they hit its bottom. But the bottle wasn’t carelessly left behind – Willi Dansgaard had inserted a funnel into its neck so he could use it for an experiment. He was watching it closely, collecting rain to later measure in his lab. Each drop brought Willi closer to revealing the secrets of Earth’s history, by giving scientists a way to work out temperature from ancient ice. In doing so, he would help show how climate can change much faster than experts had thought possible.

Willi was born in Copenhagen in 1922, living and studying physics and biology there until going to work for the Danish Meteorological Institute (DMI) in 1947. The DMI sent Willi and his wife Inge to Greenland, first to study the Earth’s magnetic fields, and then to help improve the reliability of weather forecasts. Their time there left the pair with ‘deep impressions of the course of Greenland nature, its forces, its bounty, its cruelty, and above all its beauty,’ Willi wrote in his autobiography. ‘We were both bitten with Greenland for life, but after a year the need for further education forced us to turn homeward.’

So in 1951, Willi took a job at the biophysics research lab at the University of Copenhagen, where his first job was to install a mass spectrometer. Able to distinguish between chemicals using weight differences, mass spectrometers are often described as atomic-level weighing scales. But they actually measure molecules’ weight by firing them through an electromagnetic field at a detector, similarly to how bulky old TVs fire electrons at their screens. Though mass spectrometers existed since the early 20th century, Second World War US efforts to produce uranium for an atomic bomb had boosted their power. Willi set up the type of machine that had been invented in the course of that work, so his department could detect tracers used in medicine and biology.

By 1952, Willi knew that his mass spectrometer could separate forms of the same chemical elements – or isotopes – that could differ in weight by as little as a single neutron. And faced with a wet weekend in June, he wondered whether the amount of these isotopes in rainwater could change from one shower to the next. ‘Now when I had an instrument that ought to be able to measure it, there was no harm in trying,’ he writes. ‘I placed an empty beer bottle with a funnel on the lawn and let it rain.’

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Space agencies pinpoint polar ice sheet damage

The midnight sun casts a golden glow on an iceberg and its reflection in Disko Bay, Greenland, where ice sheet mass loss was five times higher in 2011 than it was in 1992. Much of Greenland’s annual mass loss occurs through 'calving' of icebergs such as this. Credit: Ian Joughin.

The midnight sun casts a golden glow on an iceberg and its reflection in Disko Bay, Greenland, where ice sheet mass loss was five times higher in 2011 than it was in 1992. Much of Greenland’s annual mass loss occurs through ‘calving’ of icebergs such as this. Credit: Ian Joughin.

47 scientists from 26 key laboratories across the world. 10 satellite missions flown over a period of 20 years, whose data adds up to 51 years’ worth. This giant effort looks to have squashed stubborn uncertainty surrounding one key climate question: How quickly are ice sheets resting on land masses at the North and South Poles shrinking? The international team has now found that Greenland’s mass loss is five times as fast as it was in 1992. Overall loss rates in Antarctica are roughly constant in this period, though the east of the continent is actually gaining ice. Over the past 20 years, the polar ice sheets have added 11 mm to sea level rise across the world, one-fifth of the total rise seen in that time.

“Our new estimates are the most reliable to date and they provide the clearest evidence yet of polar ice sheet losses,” said Andrew Shepherd from the University of Leeds, UK, co-leader of the project. “They also end 20 years of uncertainty concerning changes in the mass of the Antarctic and Greenland ice sheets and they’re intended to become the benchmark dataset for climate scientists to use from now on.”

Until the early 1990s, climate researchers expected that mass lost by ice sheets in Greenland as the planet warmed would be balanced by that gained by Antarctica. But measurements showed that both melting and ‘calving’ of icebergs could be speeding up at both poles. This meant the UN’s Intergovernmental Panel on Climate Change (IPCC) couldn’t put an upper limit on what ice sheets might add to sea levels in its last major report on global warming in 2007. And the overall picture has been confused, as efforts to measure whether ice sheets are shrinking or growing have given differing results. Since 1998, there have been 29 different estimates of changes in ice sheet mass. “Taken all of the past studies together, the recent global sea level contribution due to Antarctica and Greenland may have been anywhere between a 2 mm per year rise and a 0.4 mm per year fall,” Andrew told a press conference yesterday. At a workshop in 2010, the IPCC said it was concerned that no further progress would be made by its next report, due in 2014. Read the rest of this entry »

Climate change brings landscapes to their last days

Like icebergs, much of the mass of Arctic ice lies under the surface, making studying its thickness important, as well as the area it covers. Thick, multiyear Arctic sea ice is disappearing, giving way to thin, young ice, according to University of Colorado at Boulder scientists. Credit: James Maslanik, University of Colorado

Like icebergs, much of the mass of Arctic ice lies under the surface, making studying its thickness important, as well as the area it covers. Thick, multiyear Arctic sea ice is disappearing, giving way to thin, young ice, according to University of Colorado at Boulder scientists. Credit: James Maslanik, University of Colorado

Nature’s beauty means different things to each of us – but undoubtedly it burns some images onto our souls. Our favourite scenery is less constant than we sometimes suppose,  changing from day to day and season to season. But the slowest changes can be the most heartbreaking, eventually robbing us of our favourite landscapes.

Some destructive changes you might consider man-made,  for example city sprawl overflowing, and some natural, such as coastal erosion. Landscape losses brought by global warming are a curious mixture of these two – humanity somehow pushing nature into a more savage mood.

In the two and a half years since I started this blog, I’ve often reported on science’s efforts to monitor how climate change is affecting landscapes in different parts of the world.  In this week’s blog entry I’ve decided to bring together pictures indicating what their work has told us – you can click on the pictures to read the original blog posts.

With the Arctic changing most rapidly as the world warms, it’s one of the most studied areas, and so its striking environment features highly. But if you look enough at your favourite landscapes, and at when its more regular changes happen, it’s likely you’ll already be able to see the signs of a slow and potentially troublesome revolution in progress.

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Weather watching hits home with powerful warming warning

UK and Japanese scientists compared climate models to show that greenhouse gas emissions affected flooding in the UK, finding that they "substantially increased the odds of these floods occurring in 2000, with a likely increase of about a doubling or more". Credit: Met Office

UK and Japanese scientists compared climate models to show that greenhouse gas emissions affected flooding in the UK, finding that they “substantially increased the odds of these floods occurring in 2000, with a likely increase of about a doubling or more”. Credit: Met Office

Pictures of people forced from their homes by floods, storms, drought-driven famines or fires are among the most dramatic displays of weather and climate’s power that we see.  Just as the world has steadily warmed in recent decades, these “extreme weather events” have also changed. For example, evidence suggests substantial increases in intensity and duration of tropical storms and hurricanes since the 1970s.  Extreme weather events happen all over the world, and the possibility that they will be more likely to hit our homes perhaps should be the best motivation to cut greenhouse gas emissions.

Since Simple Climate started, I’ve regularly featured extreme weather and its links to man-made climate change. Those links are usually put carefully. Scientists typically can only say whether the greenhouse gases we’ve added to the atmosphere have raised the chances of events happening, or whether they will increase the chances they’ll happen in future.  But recently, they’ve been using powerful computer systems to look at whether specific events have been made more likely by climate change in “attribution studies”.  This week, I’ve brought together a few pictures of events that have been included in such attribution studies, and other research that I’ve covered.  I’ve also included images of how climate is affecting people in different parts of the world. Click on the pictures to read the original blog posts.

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Fjord beds show climate role in glacier mass loss

Sun setting over Sermilik Fjord into which Helheim Glacier calves large amounts of icebergs each summer. Credit: Camilla S. Andresen.

Sun setting over Sermilik Fjord into which Helheim Glacier calves large amounts of icebergs each summer. Credit: Camilla S. Andresen.

A recent surge of icebergs produced by Helheim Glacier in Greenland has only been exceeded once in more than a century. That’s according to Camilla Andresen from the Geological Survey of Denmark and Greenland (GEUS) and her colleagues, who have reconstructed a record of iceberg production back to 1890. Their work helps add to our currently limited knowledge of what causes glaciers to grow and shrink, pointing to water temperature and an Atlantic climate cycle as being largely responsible at Helheim. Andresen underlined that this establishes a role for climate in iceberg formation or “calving” from glaciers – one that suggests that it will increase as temperatures rise. “With the link we have found to climate I find it very likely that they will respond to future warming and continue to lose mass,” she told Simple Climate.

Increased calving in the early 2000s helped rapidly shrink the Greenland Ice sheet – but scientists were unclear why, and whether the event was unusual. “Many scientists believe that this was associated with increased inflow of warm Atlantic Ocean waters deep into the fjords to where the glaciers terminate,” Andresen explained. “Changes in the volume and/or temperature of these water masses would affect underwater melting of the glacier front and iceberg calving rates. We know these processes are important for understanding the future behaviour of the inland ice sheet.” Read the rest of this entry »

Shrinking Arctic ice area is just the tip of the iceberg

Like icebergs, much of the mass of Arctic ice lies under the surface, making studying its thickness important, as well as the area it covers. Credit: Florida State University

Like icebergs, much of the mass of Arctic ice lies under the surface, making studying its thickness important, as well as the area it covers. Credit: Florida State University

A sheer white glacial mountain apparently floating on the sea emerges from the freezing mists. A lone lookout cries “Iceberg!”, stirring the crew into panic, before the stomach-churning sound of ripping metal sends them to the lifeboats. It’s a familiar scene from the TV and movies, and one where the main threat comes because eight-ninths of a typical iceberg lies below the waterline. While sea ice formed from ocean water is much thinner than such glacier ice, its thickness also lies mostly beneath the surface. Consequently, knowing that thickness is “perhaps the most basic measure of how the ice is responding to climate change”, according to the University of Colorado’s James Maslanik. Although it’s possible to track the area that the Arctic ice cap covers from space, knowing the depth it reaches is harder. “While the European Space Agency has just launched Cryosat-2 to measure thickness, the US no longer has a satellite operating that is capable of directly measuring ice thickness from space,” the scientist explained.

To tackle this problem, Maslanik and Colorado colleagues Julienne Stroeve, Charles Fowler, and William Emery have turned to assessing how many summer melt periods the ice is surviving. Maslanik says not only is this closely linked to ice thickness, it also reflects the influence of many climate- and weather-related factors. Ice that survives one summer melt is called “multi-year ice”. In a Geophysical Research Letters paper soon to be published, they find that multi-year ice makes up 45 per cent of the total Arctic ice cover in 2011, down from about 75 per cent in the mid 1980s. The proportion of ice older than five years fell from 50 per cent of all ice that has survived more than one summer to 10 per cent in the same period.

“The work of our Colorado group and other researchers clearly shows extreme decreases in the area of the Arctic Ocean covered by the oldest and thickest sea ice types,” Maslanik told Simple Climate. “This loss has accelerated in recent years, and while we continue to search for factors such as natural variability that could account for the changes, the effects of large-scale warming in the Arctic, including changes in the Arctic Ocean itself, are the most likely drivers for the loss in the old sea ice.” Read the rest of this entry »

Climate forces penguin populations into a dive

Ice-loving Adélie penguins, once thought to be more at risk than ice-avoiding chinstrap penguins but actually faring better as the climate changes, in Admiralty Bay, Antarctica. Credit: Lenfest Ocean Program

Ice-loving Adélie penguins, once thought to be more at risk than ice-avoiding chinstrap penguins but actually faring better as the climate changes, in Admiralty Bay, Antarctica. Credit: Lenfest Ocean Program

Dwindling food supplies, caused by climate change, are threatening two species of penguin. Adélie and chinstrap penguins are both suffering thanks to falling availability of tiny shrimp-like crustaceans called krill that they eat. This is contrary to previous predictions, explained George Watters, director of the US National Oceanic and Atmospheric Administration (NOAA)’s Antarctic Ecosystem Research Division. That’s because those predictions directly link the amount of sea ice cover to the number of penguins.

“The prevailing ‘sea-ice hypothesis’ would say that chinstrap penguins might be expected to benefit from climate change because they are “ice-avoiding” penguins,” Watters told Simple Climate. By contrast, “ice-loving” Adélie penguin populations had been expected to fall as the planet warms and ice cover decreases. “But we’re showing that in fact the populations of both species are declining,” Watters said. “We think that the the availability of krill is governing the decline of both animals.”

The sea-ice theory developed from some of the earliest penguin population studies in the 1970s and 1980s, showing that Chinstrap penguin populations were increasing as Adélie penguins decreased. The team that did that work included Wayne Trivelpiece, lead author of the Proceedings of the National Academy of Sciences USA paper published on Monday that now shows both species are in decline. Both studies involved extensive fieldwork in the world’s coldest continent. “Wayne has been going since the Antarctic was invented,” Watters joked. Read the rest of this entry »

Ice melt poses dual sea rise and water access threat

Ice from Arctic Canada, like this small unnamed valley glacier and the Kaskawulsh glacier in the background in Saint Elias Mountains, Yukon Territory, will be among the largest contributors to sea level rise as ice caps and glaciers across the world melt in the 21st century. Credit: Christian Schoof.

Ice from Arctic Canada, like this small unnamed valley glacier and the Kaskawulsh glacier in the background in Saint Elias Mountains, Yukon Territory, will be among the largest contributors to sea level rise as ice caps and glaciers across the world melt in the 21st century. Credit: Christian Schoof.

Around one-fifth of the total volume of ice held in ice caps and glaciers will melt by 2100, adding around 12 cm to sea levels and threatening very low-lying coastal regions. That’s according to the latest simulations from Valentina Radić of the University of British Columbia, Canada and her US-based colleague Regine Hock from the University of Alaska, Fairbanks. “The problem will be floods and storm surges which also will be higher if the sea level is higher than today,” Radić told Simple Climate. She and Hock used detailed glacier measurements to model how the world’s ice will respond to predicted temperature changes. Their results, published in leading journal Nature Geoscience last Sunday, also show that Europe and New Zealand look set to lose around three-quarters of their glacier volume, impacting water supplies.

So far, there have been few predictions of what will happen to the world’s ice this century, and there has been large disagreement among those that have been produced. The resulting sea-level rise predictions range from a minimum of 5 cm to an extreme maximum of 36 cm. The issue, Radić explained, is that there are surprisingly few measurements of glaciers to begin predictions from. “The World Glacier Inventory today covers approximately 40 percent of the total ice area,” she said. “For the remaining 60 percent we still do not know how many glaciers there are, what is their surface area, elevation range, and so on.”

Worse still, less than one percent of the world’s glaciers have been measured for mass balance – the difference between the mass a glacier gains through the accumulation of snow, and what it loses – over the long term. “Observations of glacier mass balance are extremely important for the modellers,” Radić explained. “To reassure ourselves that the models are performing well, we need to validate their results with the ‘real world’. A lack of these observations presents a major obstacle for modelling of future glacier volume changes.” Read the rest of this entry »

Arctic warming full ahead

It may be plunging towards the depths of its long, dark, cold, winter now, but 2010 has been another hot year for the Arctic. Air temperatures over Greenland reached the highest directly recorded levels, according to the 2010 Arctic Report Card. This meant that ice melted from the island’s huge inland sheet for 1 month longer than the average melt period over the past 30 years.

This summary, compiled by the US National Oceanic and Atmospheric Administration (NOAA), also documents an “exceptional” loss of glaciers around Greenland in 2010. 110 square miles of ice, four times the area of Manhattan Island, entered the ocean in the single largest glacier loss at Petermann glacier. “There is now no doubt that Greenland ice losses have accelerated,” the report underlines. “The implication is that sea level rise projections will again need to be revised upward.”

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Saturday round-up: All quiet on the northern seas

The Arctic may become more serene, as a slowly warming sea stabilises atmospheric circulation, reducing the frequency of "polar lows", with the progress of climate change. Image © Science/AAAS

The Arctic may become more serene, as a slowly warming sea stabilises atmospheric circulation, reducing the frequency of "polar lows", with the progress of climate change. Image © Science/AAAS

Highly-waterproofed sailors used to fighting howling winds and avoiding icebergs in the world’s northernmost oceans are set to have their struggles eased by climate change. That’s because, not only is Arctic ice area decreasing, but severe North Atlantic storms will decrease in frequency as the world warms.

These storms are small and therefore difficult to observe, Matthias Zahn and Hans von Storch from Germany’s GKSS Research Centre write in top journal Nature this week, but still dangerous. “Accompanied by strong winds and heavy precipitation, these often explosively developing cyclones – termed polar lows – constitute a threat to offshore activities such as shipping or oil and gas exploitation,” they say.

Polar lows, or ‘Arctic hurricanes’, start as low level airflows that are built up by air circulation caused by large temperature differences between different levels of the atmosphere. They occur every winter, and while there are weaknesses in direct historical measurement, a previous simulation based on climate data from 1948–2006 showed an average of 56 polar lows per year.

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