Groundwater stores 100 times more water than all the world’s lakes put together and supplies around 40% of the water for irrigated agriculture. And most of that groundwater is “surprisingly old”, according to James Kirchner of ETH Zurich and Swiss Federal Research Institute WSL in Switzerland, speaking at a press conference at the European Geosciences Union general assembly in Vienna.
The bulk – 42-85% – of this groundwater in aquifers in the upper 1 km of the Earth’s crust is “fossil” groundwater that’s more than 12,000 years old, Kirchner, Scott Jasechko and colleagues have estimated, so it was around “when mammoths roamed”. There’s roughly twice as much of this ancient water by volume as modern groundwater that collected within the last 60 years.
What’s more, previously scientists had assumed that this ancient water was isolated from modern contamination such as pesticides. But Kirchner and the team found that around half of the wells dominated by fossil groundwater contained modern water too. So it’s not safe to assume that the older groundwater is free from manmade contaminants like fertilizers or chlorinated hydrocarbons.
“It’s like going to a giant old folks’ home and finding little kids running round,” said Kirchner. “It’s great unless the kids have ‘flu.”
Kirchner stressed that it’s not that half of the world’s groundwater is now known to be contaminated but that we cannot exclude the possibility that it may include contaminants.
To age the groundwater, the researchers assembled existing data on the age of groundwater from thousands of wells based on its contents of isotopes of carbon and tritium. A hydrogen isotope, tritium was released into the atmosphere in large quantities by thermonuclear testing that began in the early 1950s so it acts as a tracer for more recently recharged groundwater. Carbon-14 has a half life of nearly 6,000 years so if water is depleted in C-14 it hasn’t “seen the atmosphere” for at least 12,000 years.
The fossil and modern groundwater may mix either in the well or in the aquifer beneath; it’s not yet clear which. Wells deeper than about 250 metres mainly pump fossil groundwater, Kirchner explained. Many of these fossil sources may be non-renewable on human timescales. The High Plains aquifer in the US, for example, contains rain that mainly fell in the Pleistocene but its water level has dropped more than 100 metres in the last few decades and it would take 6,000 years to replenish.
The paper was published in Nature Geoscience yesterday.
by Liz Kalaugher
In 2016 Arctic sea ice extent set a new record low, and every single month that year had an Arctic sea ice extent more than two standard deviations – corresponding to over 1 million square km of ice – below the long-term mean. That’s according to Julienne Stroeve of the University of Colorado, US, and UCL, UK, speaking at the European Geosciences Union meeting in Vienna.
Stroeve, who came back from Arctic field work on Friday, reported that both the first year sea ice and the multiyear ice that she measured were thinner than usual. As she left, strong winds were starting to create open water. “I think it’s going to be an exciting summer,” she said.
As the ice thins, it becomes more vulnerable to atmospheric conditions. Since 2007 Arctic sea ice extent has shown larger variability, making it harder to predict the ice cover in September. But at some point the ice may become so thin that atmospheric circulation doesn’t matter anymore, Stroeve explained.
Over the long term, the ice has retreated by 14% per decade, with the ten lowest summer sea ice extents all occurring within the last ten years. And the last seven months, including January through March of 2017, have been the longest consecutive run of unusually low sea ice extents.
Stroeve’s calculations, based on field observations, indicate that each metric ton of carbon dioxide entering the atmosphere melts three square metres of ice. That makes the ice more sensitive to greenhouse gases than models suggest. And it reveals that emission of a further 1000 Gigatonnes of carbon dioxide (which would be likely to create a 2 degree temperature rise) would create an ice-free Arctic in summer. At our current emission rates of roughly 30-40 Gigatonnes per year, that would mean an ice-free Arctic in September by 2045.
This date agrees with a climate model-based projection by James Screen of the University of Exeter, UK, and his colleague Daniel Williamson, who estimated that the first ice free September will be in around 2046, for a temperature rise of 2.1 degrees. This date would come forward to 2040 if emissions were higher or be delayed until 2050 if they were lower. And natural variability makes it accurate only to within 20 years. Screen’s earliest possible ice-free scenario was in the mid-2020s, for a temperature rise of 1.7 degrees.
Screen has calculated that if we keep to the UN “stretch target” of 1.5 degrees of warming, the probability of the Arctic being ice-free in summer is less than 1%. But for 2 degrees of warming, the chances are 39%, or “toss a coin” as he put it, and for 3 degrees, the probability is 73%, “likely” in IPCC terms.
This is in line with field observations of ice extent being more sensitive to climate change than models project – Stroeve’s observation-based calculations projected an ice-free Arctic in summer for 2 degrees of temperature rise, whilst Screen’s modelling indicates a 39% chance.
So what’s our temperature rise trajectory? Business-as-usual emissions would bring a global average temperature rise of 3-5 degrees by the end of the century, Screen detailed, whilst current emissions pledges to the UN would see temperature rises of 2.6-3.1 degrees. We’ve already raised temperatures by 0.9-1 degrees so we have around half a degree to go before hitting the UN stretch target.
“If we really want to save Arctic sea ice, we need to push for 1.5 degrees, not 2,” said Screen.
by Liz Kalaugher
The 17th century saw Japanese citizens sprinkle water onto the ground and walls around their temples, gardens and houses. Not only did this suppress dust formation but it also cooled temperatures by evaporation. Now Tokyo is promoting uchimizu once more and a team from the Netherlands has investigated exactly how much this uchimizu technique could benefit today’s cities.
As Anna Solcerova of the Delft University of Technology in The Netherlands detailed at the European Geosciences Union (EGU) meeting in Vienna, adding just 1 or 2 mm of water to a paved area can reduce air temperatures near the ground by as much as 8-10 degrees and at human height by up to 2 degrees.
To come up with these figures, Solcerova and colleagues Tim van Emmerik and Koen Hilgersom fitted a 1 x 1 x 1 m cube with fibreoptic temperature sensors, providing 3D Distributed Temperature Sensing (DTS) measurements at 35 heights.
Adding water always cools the ground, the team found, but the effect is greater when the heat is less intense, or in shade. Solcerova stressed that it’s important to use rainwater rather than tap water for uchimizu and that the technique boosts humidity – whilst this would not be an issue in the Netherlands, it may be elsewhere.
The uchimizu technique died out with the advent of aircon units that can cool a room to any temperature desired, although on the downside, the units spew additional heat into the city outside. Perhaps we’ll see more of uchimizu in the future.
by Liz Kalaugher
According to psychologists, the vivid orange, red and turquoise sky in Munch’s famous Scream painting of the late 19th and early 20th century may represent his emotional state. But meteorologists argued that it depicted a colourful sunset caused by the eruption of Krakatoa in 1883. Now a team from Norway has proposed that rather than painting the results of volcanic ash, Munch was inspired by unusual “mother-of-pearl” clouds high up in the stratosphere.
“We are natural scientists so we tend to look for answers in nature whilst the psychologists have looked for inner torment,” said Helene Muri of the University of Oslo, speaking on behalf of meteorological consultant Svein Fikke at a press conference at the European Geosciences Union General Assembly in Vienna.
These “mother-of-pearl” clouds, otherwise known as nacreous clouds or polar stratospheric clouds type II, form when the stratosphere is both unusually cold (-85°C compared to its average of -60°C) and humid. Such conditions typically occur in high latitudes during the winter, often near mountains. The clouds contain small ice crystals – about 1 micron across – and sit at 20-30 km, well above the heights clouds normally form. They often have a wavy appearance because of the lee-waves behind mountain ranges.
Mother-of-pearl clouds are too thin to be visible during the day but appear around half an hour after sunset or before dawn, when the sun shines onto them at a low angle. Their sudden appearance in a dark sky and their changing colours can be striking, particularly if you don’t know about the phenomenon. Munch wrote in a poem in his diary between 1890 and 1892, “I went along the road with two friends – the sun set…The sky suddenly became bloodish red….watched over the flaming clouds as blood and sword….I felt this big infinite scream through nature”.
Fikke observed such clouds above Oslo in December 2014 and noticed their similarity to the sky in the 1910 version of The Scream. He and colleagues Øyvind Nordli of the Norwegian Meteorological Institute and the late Jón Egill Kristjánsson of the University of Oslo believed that Munch painted mother-of-pearl clouds rather than a volcanic-ash-enhanced sunset because colourful sunsets caused by volcanoes have a stratified appearance and don’t exhibit wavy lines. What’s more, volcanoes tend to produce frequent colourful sunsets over a couple of years whereas Munch’s diary indicates that his experience was a one-off.
Muri, an Oslo resident for around 25 years, has seen mother-of-pearl clouds only once. But the phenomenon was definitely seen in the Oslo area on the right timescale for Munch – physicist Fredrik Carl Stőrmer documented its appearance in January 1890, when he was just 16, making detailing drawings of the clouds’ shapes and colours. “They are so beautiful you could believe you were in another world,” Stőrmer wrote when he published his observations 42 years later. Munch painted four versions of The Scream between 1893 and 1910.
Fikke and colleagues published their results today in the journal Weather. An EGU session this morning was dedicated to Kristjánsson’s memory.
Last week saw Environmental Research Letters – environmentalresearchweb’s sister product – celebrate its tenth anniversary with a party at the AGU Fall Meeting in San Francisco, US. Editor-in-chief Dan Kammen of the University of California, Berkeley made a speech thanking the environmental research community for its support, whilst ERL guests toasted the open-access publication with cake and prosecco and were able to take away copies of the journal’s 10th anniversary collection.
Earlier in the day, Kammen had participated in an AGU session on the shifting landscape for science.
By Liz Kalaugher
The mood, amongst panel members at least, at the session on the shifting landscape for science at the AGU Fall Meeting was surprisingly upbeat. Perhaps the “pep talk” from Governor of California Jerry Brown earlier in the day, as AGU president-elect Eric Davidson put it, had helped. Though that’s not to dismiss the very real worries of many Earth and space scientists following the US election.
“The landscape for science is shifting and uncertain,” said AGU CEO Chris McEntee as she introduced the panel. “Use this session as an opportunity to tell us about your concerns and what you think we should be doing.”
To kick off, AGU public affairs director Lexi Shultz said she knows there’s a great deal of anxiety about what the political landscape means for science. Lots of the areas of concern are in climate change, given that there are nominees to lead the Environmental Protection Agency and the Department of Energy who hold views incompatible with climate science. Shultz stressed, however, that these nominees must undergo a lengthy Senate confirmation process and there will be plenty of opportunities to raise questions.
Another area of concern, Shultz said, is the questionnaire that’s been sent out to Department of Energy employees at national laboratories, including questions such as what associations they are part of. The Department of Energy has told employees not to answer these questions. (Yesterday, Greg Dalton of Climate One, chairing a panel on Shifting the Energy Mix in a Post-Paris World asked Howard Gruenspecht, deputy administrator of the US Energy Information Administration whether he felt the questionnaire was reminiscent of Hollywood in the 1950s. Gruenspecht said he wasn’t going to answer that one.)
Shultz stressed, however, that all US government science agencies are funded at existing levels through to April and “we have time to make our case”. There may also be opportunities as Trump has promised to invest in infrastructure, which is “very dependent on science”. There is bipartisan support in Congress for basic research, and the scientific community has allies in the business community and beyond, Shultz added. Although Trump originally said he wants to withdraw from the Paris agreement on climate, many businesses have stated that they’d like to stay in. Since then Trump has said he has an open mind.
Shultz added that we don’t know what the administration will be able to do: “the wheels of the policy process grind very slowly.” The AGU will be a strong advocate for Earth and space science. “Your voice matters,” she said, urging scientists to make the case for their science by talking to their representatives and community, and encouraging their colleagues to do the same. Any scientists who feel less comfortable with this approach can tell their story to the AGU, she suggested.
Up next, Dan Kammen of the University of California, Berkeley took Shultz’s lead immediately and strongly argued the case for science. “Every step the US makes away from the mandate for science leaves good jobs and opportunities on the table for others,” he said. “Stepping away from that would be an incredibly foolish move.”
Although Kammen feels that Rex Tillerson is an inappropriate and incorrect choice for secretary of state as he is the CEO of a major oil company, he has in the past supported a price on carbon. “That is a door that needs to be pushed on,” Kammen said.
Katharine Hayhoe of Texas Tech University never expected that the topic she studies – climate science – would become “more polarised than gun rights, immigration and abortion”. But science does not require belief. “If you step off a cliff, whether you believe in gravity or not, you’re going down,” she said.
Scientists’ instinct is to say we need more scientifically literate people, Hayhoe explained. But social science has shown that more science-literate people are more polarised on climate change. The real problem, she feels, is how much we prioritize climate change – it’s at or near the bottom of many people’s lists of important issues. People think it’s a long-term problem, or only matters if you’re a “bleeding-heart tree hugger”, or that somebody else, like the government, will take care of it for them.
In the last few weeks, however, Hayhoe said there’s been a huge rise in concern as “suddenly someone else is not going to fix it for us”. She’s also noticed a general rise in concern over the last five to ten years as people have realised climate change is affecting us now.
Hayhoe stressed the importance of connecting with people’s hearts as well as their heads. She used to “start with the science, continue with the science and finish with the science”. But now she begins with an issue that she and the person she’s talking to both value before talking about her concerns about it in scientific terms. Finally, Hayhoe makes sure to bring the conversation back to an inspiring solution. “There is a problem but there are amazing solutions,” she said.
Like Shultz, Hayhoe acknowledged that scientists are all different. “There is a spectrum of engagement,” she said, “where we fall on it is a personal choice.” Hayhoe suggested the Climate Voices network for those willing to speak in public, Climate Feedback for those who prefer to write, and the Union of Concerned Scientists and AGU for those who’d like to participate in civic engagement. Those scientists needing a support group could turn to AGU, Earth Science Women’s Network (ESWN) or the Climate Science Legal Defense Fund.
Up last, Davidson highlighted that the AGU is in a position of resilience, having built up its public affairs programme and created a geosciences caucus on Capitol Hill. The AGU has members form every single congressional district. Immediately after the election the AGU co-ordinated with 28 other societies on a statement about the importance of science and the need for a science adviser. There’s also a petition on the change.org site for Trump to appoint a science adviser. Next the AGU will step up its Thriving Earth Exchange programme that links scientists to communities to show how science can improve lives. And there are plans to build a storybook (name to be decided) containing examples of traditional storytelling, and perhaps using other media, to show the importance of Earth and space sciences.
Davidson finished by mentioning the open letter from one president-elect to another that he posted to the AGU’s From the Prow blog the previous evening. “I’d love to have your opinion on that,” he said.
By Liz Kalaugher
The Arctic in winter is cold, dark and dangerous. So it’s no surprise that it’s not seen too much research. But in January 2015 the Norwegian Young Sea Ice Cruise embedded a research ship in the ice, in only the second expedition of its type. The first was 20 years ago when the SHEBA expedition monitored multi-year sea ice in the Pacific sector. The N-ICE expedition, in contrast, moored in the Atlantic sector north of Spitsbergen, where the ice was first- or second-year and thin.
“Lots of the things we experienced took us by surprise,” said Mats Granskog of the Norwegian Polar Institute, who was chief scientist for N-ICE, at a press conference. “We saw a new Arctic, with ice 3-4 feet thick that behaves differently.”
This ice moves more quickly, breaks up more easily and is more vulnerable to storms and winds, Granskog explained. Learning about it should improve weather forecasts in North America and Asia. This is one of the reasons the team went, Granskog said – to find out how well we know the Arctic and to determine the validity of the ice data in our climate models.
During the trip the researchers had to “battle the dark, the cold” and cope when the ice broke up under their feet and they had to rescue their equipment. “It was no simple ordeal,” Granskog said of the six-month long expedition.
Amelie Meyer of the Norwegian Polar Institute was a member of the kit rescue team. The equipment had been installed on an ice floe a few miles wide next to the ship. On the morning of the 19th June, the floe cracked. Fortunately no researchers were out on the ice at the time. Within a few hours, the floe had broken up into hundreds of pieces. “It was a bit epic,” Meyer said, describing her trips in a Zodiac boat to retrieve the instruments, many of which contained data.
As well as the unplanned rescue, the researchers also saw way more snow than expected, Granskog said. In places, the snow was so heavy that it caused the sea ice to float below the surface of the sea, inundating the bottom layer of the snow with salt-water. This phenomenon has been seen in Antarctica, where the sea ice is generally thinner and there’s more snow, but this was the first sighting in the Arctic.
Von Walden of Washington State University joined the trip to characterise atmospheric conditions. In winter, the Arctic atmosphere tends to be either clear or overcast. When clear, he found, atmospheric conditions were similar to those discovered by the SHEBA expedition.
But N-ICE also saw significant storms, carried from the south by an unusual jet stream. These storms brought large amounts of warmth and moisture to the Arctic, restricting sea ice growth, whilst the winds pushed the ice out. Early February 2015 saw the lowest ever winter sea ice extent. One storm brought a temperature rise from -40 F to 32 F in less than 48 hours, and winds of more than 50 miles per hour, as well as increasing moisture levels ten-fold.
Whilst von Walden examined the atmosphere, Meyer was there to examine conditions below the ice. The Arctic Ocean is relatively warm, she explained, with temperatures of 32 F below the ice and 40 F a few hundred feet below the surface. It’s generally calm beneath the ice, which isolates the water from the atmosphere. But the winter storms, Meyer discovered, made the ice drift so fast that it mixed the water beneath, bringing warm water up from the depths and melting the ice from below.
Algae bloomed early beneath the thin ice, the trip revealed. You might think that would absorb more carbon, Meyer said, but these algae didn’t sink well, so didn’t export carbon to the ocean depths.
By Liz Kalaugher
“Don’t talk to me about climate communication, I hate that.” Those were the words of Stephan Lewandowsky of the University of Bristol, UK, and University of Western Australia during a session on climate literacy at the AGU Fall Meeting in San Francisco.
Lewandowsky has stopped saying that The Debunking Handbook he wrote with John Cook is fantastic. “It’s still right,” he said, “but we’re no longer dealing with misinformation.” Instead, many Americans share a belief system that’s disconnected from “what we might call facts or evidence”. This goes beyond misinformation – “it’s an alternative reality”.
Lewandowsky’s research has shown that if you give people false information but then correct it, the correction has no effect on their voting intentions.
Given our post-truth and post-fact world, “it’s not a matter of climate communication, it’s about politics,” Lewandowsky explained. “There’s an ethical imperative for us to frame the issue as it really is, rather than accepting other people’s frames. And that’s politics.”
Although a social scientist himself, Lewandowsky thinks there are limits to what social scientists can do on the public rejection of science. “We can analyse it,” he said, “…but it’s ultimately all about politics and we need a political solution.” As a first step, he recommended scientists attend the “Rally to stop attack on science” in San Francisco’s Jessie Square on Tuesday at noon.
What’s the story?
Ironically, up next after Lewandowsky was science historian Naomi Oreskes of Harvard University to speak about climate communication. Oreskes detailed how a scientific training can hamper scientists’ ability to communicate to the public about their work. “Almost everything we learn to do as scientists acts against effective science communication,” she said. As she learned whilst working with film-maker Robert Kenner on the documentary about her book Merchants of Doubt, the keys to good communication are keeping it simple, telling a story and making it stick.
But scientists hate to keep it simple “because simple feels simplistic” and they’re not comfortable with stories because they feel they’re made up. On both these points, Oreskes thinks the solution is for scientists to “get over it”. It’s a narrative structure that makes something a story, not whether it’s true or not. An Inconvenient Truth, for example, was the story of Gore’s run for president.
When it comes to the last point, making a story memorable, “short of singing a song, and I’m not going to to do that”, the keys are to say something personal and evoke emotion, Oreskes explained. But scientists think science should be impersonal, unemotional and dispassionate – people believe that to make good decisions you have to separate reason from emotion. Here Oreskes was able to use science to prove her point; we now know that this is wrong scientifically. Studies have shown that emotion is an essential part of reasoning.
“It is rational to be upset about things that are upsetting and it is rational to be alarmed about things that are alarming,” Oreskes said.
by Liz Kalaugher
It’s highly likely that the world’s polar bear population, currently 26,000 strong, will decrease by a third within the next 35-40 years. That’s according to Kristin Laidre of the University of Washington, US, speaking at a press conference at the AGU Fall Meeting in San Francisco.
This finding supports the listing of polar bears as vulnerable by the International Union for Conservation of Nature (IUCN) Red List, which requires projection of species population numbers after three generations. Laidre and colleagues found that the average age of a female polar bear with dependent cubs is 11.5 years so 35 years corresponds to roughly three generations.
Polar bears use ice for traveling, hunting, mating and, in some cases, for their maternity dens. From 1979 to 2015, Arctic sea ice shrank at an average rate of 53,100 square km per year.
“When we look forward several decades, climate models predict such profound loss of Arctic sea ice that there’s little doubt this will negatively affect polar bears throughout much of their range, because of their critical dependence on sea ice,” said Laidre in a press release.
There are 19 sub-populations of polar bears around the Arctic Circle, living in 4 eco-regions. Some of these populations have never been studied whilst the number of animals in others have only been counted one or two times. Two or three populations have been studied on an annual basis, Laidre explained.
Some regions of the Arctic, such as the Chukchi Sea, are highly ecologically productive. Even though sea ice cover here has decreased, polar bears in the area are in better condition than they were 20 years ago; there could be a time lag before the full effects of the ice loss kick in. In other areas, like western Hudson Bay, polar bear survival and reproduction have declined as sea ice availability has dropped.
Laidre, Eric Regehr of the US Fish and Wildlife Service, and colleagues made their predictions by analysing sea ice extent from satellite observations and projecting this forward by 35 years. They evaluated three different relationships of polar bear numbers to sea ice – a decline proportional to the sea ice loss, and two changes based on previous data – before taking a median value across all three scenarios.
This revealed that the probability of a more than 30% reduction in polar bear numbers in the next 35-40 years is 0.71. The probability of a decrease in headcount of more than half was just 0.07.
by Liz Kalaugher
At the EGU General Assembly debate on “Is global economic growth compatible with a habitable climate?” there was discussion whether the session was even titled with the right question. Not to mention the pre-debate issue of whether the speakers should stand up or sit down.
To Clive Spash of WU Vienna University of Economics and Business, the title was too tightly focused on climate and should have widened out to a habitable planet. Spash, who believes that the economic view of the world is unrealistic, said he disagrees that economic growth is vital and thinks it’s politically naïve to try and shut down the debate on whether we need growth. In his view a carbon tax won’t work and decoupling of growth and carbon emissions won’t save us.
Narasimha Rao of IIASA, Austria, also wanted the question to be broader. Rao called for consideration of dimensions of wellbeing beyond economic growth, since the economy doesn’t reflect phenomena such as air pollution and oil spills.
Kevin Anderson of the University of Manchester, UK, reckons the answer depends on whom we’re referring to – rich people, people in poorer nations, or other species. Some in the rich parts of the world believe we can cope with 2, 3 or even 4 degrees of temperature rise, he said, whilst many developing countries believe that the maximum habitable temperature change for them is 1 or 1.5 degrees, given that many are already feeling the effects of climate change. And significant numbers of animal species are already struggling with temperature rise today, particularly as they’re under other environmental stresses too.
Given the rates of emissions reductions we’d need, Anderson said that a 1-1.5 degree threshold is no longer viable and we’re stuck with 2 or 2.5 degrees at best. “Economic growth is not compatible with a habitable climate for people like us,” he said, arguing that since the relatively poor need economic growth to have a habitable climate, it means big emissions cuts for the rich. And for non-human species, economic growth is again not compatible with a habitable climate.
Finally, Jorgen Randers confessed that having worked in sustainable development since 1972, he has failed as the world is less sustainable now. Randers argued that economic growth is compatible with a habitable climate but human society has not been willing to implement the solutions. To him, the question is “is humanity going to be able to reduce greenhouse gas emissions per unit GDP fast enough to get greenhouse gas emissions to decrease?” Whilst technically “it’s a piece of cake”, and shifting from dirty to clean production is cheap at a cost of just 1% of GDP, it has not been done and will not be done because people think too short-term. “That’s the sad story,” Randers added.