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.

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.

Monsoon instability raises food questions for India

A street in Calcutta floods during monsoon season. After some decades of increasing rainfall, climate change could bring drier monsoons, said Jacob Schewe from the Potsdam Institute for Climate Impact Research. Credit: Mark E Dyer/Flickr

Monsoon rains in India may fail more frequently as climate change proceeds into the 22^nd century, German researchers said this week. That danger could be critical for farming in what is set to become the world’s most highly populated country by 2030, and would follow an already expected wetter period. “Previous studies showed that Indian monsoon rainfall would increase more or less linearly with global warming over the next century,” said Jacob Schewe from the Potsdam Institute for Climate Impact Research. “The monsoon can respond to climate change in a more complicated way. We’ve seen that it matters to look further into the future.”

In South Asia, summer monsoon rains fall as winds blow from the southwest Indian Ocean over the continent between June and September. They end when the wind direction reverses in September or October. What Indian monsoon rain seasons will do as the world warms is an important and difficult question that many researchers are trying to answer. Though more rainfall has been predicted, recent years haven’t matched that expectation. While factors like pollution have an effect, changes climate scientists already know a major climate pattern plays a very important part in monsoons.

“There is a coupling between the El Niño Southern Oscillation and the monsoon that’s been observed for a long time,” Jacob told me. In years when El Niño occurs, an air movement pattern called the Walker circulation pattern gets shifted eastward. That brings high pressure over India and weakens the monsoon. While some changes in El Niño are already happening, the Walker circulation is expected to weaken, but not for some time yet. That could mean scientists’ climate models don’t pick up its effects. “People have looked at monsoon changes but not many studies have looked beyond 2100,” Jacob said. “You really have to consider longer timescales – beyond 2100 – to assess the full range of consequences for the monsoon.”

Warming brings more frequent and fickle European heatwaves

Heatwaves prompt creative ways to stay cool, as these children in Paris showed during the 2003 heatwave, and can lead to deadly consequences if people don’t stay cool enough, especially amongst the elderly. Credit: Christophe Becker/Flickr

Our changing climate will make future European summer heatwaves like the one in 2003, blamed for killing 35,000, more likely but harder to forecast a season in advance. That’s what research done by Benjamin Quesada from the Laboratoire des Sciences du Climat et de l’Environnement (LSCE) in Gif-sur-Yvette, France, suggests. Together with fellow climatologists, he has found that water trapped in Southern European soil during wet winters and springs keeps the continent reliably cool in summer. “Under global warming, climate models almost all agree about drier soils in Southern Europe and more frequent and long lasting summer heatwaves,” Benjamin told Simple Climate. Losing that cooling influence currently makes the weather less predictable but with a higher chance of being hot – though Benjamin hopes his findings will eventually bring more accurate forecasts.

The dramatic heatwaves in 2003 and 2010 took Europe by surprise. That has motivated the continent’s scientists to try to understand them and therefore predict them better. The role that water absorbed in soil plays has been one area that they’ve looked at. Their research shows a vicious “feedback” cycle where drier soils mean that less water reaches the atmosphere to create clouds. In turn, more heat from the sun reaches the ground and dries it out yet more. “Soil moisture can be seen as a buffer,” Benjamin said. “On dry soil, solar energy will directly heat soil, and isn’t ‘wasted’ first in evaporation as in wet soil.” Usually an escape from this cycle can come thanks to factors like winds circling the planet and carrying clouds with them, he added.

Baking sands worsen leatherback turtle survival crisis

Baby leatherback turtles face many threats, and climate change looks set to add to them. Credit: Juanma Carillo/Flickr

As the world warms in upcoming decades less than half the current number of Costa Rican leatherback turtles will succeed in their first, vital, journey from sandy nest to sea. That’s according to a team of US researchers who have closely monitored how regular climate fluctuations affect egg and hatchling survival. That’s allowed them to show a clear relationship that they can use to predict the turtles’ future prospects, explained James Spotila from Drexel University in Philadelphia, Pennsylvania. “With the projected warming that’s going to happen in this century, these eggs and hatchlings are going to have a serious problem,” Spotila told Simple Climate. “We’ll have to do some kind of mitigation to keep these animals alive.”

James, who is also chairman of the Leatherback Trust, has been studying nesting turtles, considered “critically endangered”, at Las Baulas Park in Costa Rica for 22 years. Over that time, he and his fellow scientists had noticed more hatchlings in some years than others, and wanted to know the cause. The close watch they keep on the turtles gave them the first clues that climate played a role. “We noted that as the season would progress, and got hotter and drier, you had a reduction in hatching success of the eggs,” James said.

To find a detailed link, the scientists focused on one important nesting area in the Las Baulas Park – Playa Grande – over 6 seasons, from 2004-2010. Over that time they tracked temperature and rainfall measurements recorded at a nearby airport. But the hardest part – much of which was done by James’ Drexel colleague Pilar Santidrian Tomillo – came after the nests hatched.

Melting sea ice plays critical role in winter whiteouts

Arctic sea ice near its smallest extent of 2011 on Sept. 9, 2011 recorded by NASA's Aqua satellite. Low sea ice cover levels are linked to snowy winters, Jiping Liu from the Georgia Institute of Technology and his colleagues have found. Credit: NASA's Scientific Visualization Studio, Goddard Space Flight Center.

The snowy winters that have wreaked havoc in the northern half of the planet over the past five years are linked to dwindling Arctic sea ice. US and Chinese scientists this week said that they have provided evidence supporting that surprising connection between our warming world and the recent unusually cold spells. “There are some uncertainties, but probably we will see more persistent snowstorms and cold conditions in the future,” explained Georgia Institute of Technology‘s Jiping Liu.

Between 1979 and 2010 the area of Arctic sea ice in September, October and November fell by over a quarter. It reached its lowest ever value in 2007 unexpectedly quickly, outpacing the changes climate models predicted the greenhouse effect would cause. In the following winters, large areas of the US, Europe, and China have seen especially heavy snowfall. 2009-10 and 2010-11 saw the second and third largest snow cover since records began respectively for the northern half of the planet. It could have been a coincidence. But despite some other researchers blaming the cold on existing climate patterns, Jiping Liu and his colleagues thought the sea ice and snowfall might be tied together somehow.

To test their idea, the scientists turned first to existing measurements. “We analysed observational data for the past thirty years,” Jiping Liu told Simple Climate. They checked satellite records of how large Arctic ice cover has been from the US National Snow and Ice Data Center. The researchers also got a similar satellite measure of snow cover from the Rutgers University Global Snow Lab, and other data including surface air temperature and pressure from the US National Oceanic and Atmospheric Administration.

Fish in hot water pose tough dilemma

Spring run Chinook salmon, photographed in Butte Creek, upstream from Centerville, Calif., may become extinct in the future due to warming waters. Credit: Allen Harthorn, Friends of Butte Creek

Is it more important that the water in our rivers is available for rearing fish to eat or generating clean electricity? And how is that decision affected by rising worldwide average temperatures? A group of US scientists has now found ways to help answer these questions, inspired by the plight of spring run Chinook salmon – though the prospects for the fish remain bleak. “These fish are very vulnerable to climate change,” Lisa Thompson, director of the Center for Aquatic Biology and Aquaculture at University of California, Davis, told Simple Climate. “It is likely that these salmon will decline, and may not persist to the end of the century.”

Salmon are famous for their exhausting upstream “run” from the ocean back to the water they hatched in, where they spawn the next generation of fish, and then die. It’s estimated that at the beginning of the 20th century the waters in California’s Central Valley, running from San Joaquin to Sacramento, teemed with 1-3 million Chinook salmon making this journey every year. In the last five years this number has fallen below 100,000, contributing to ocean stocks declining to levels where no salmon fishing was allowed off the California coast in 2008 and 2009. There are many reasons for this, including overfishing, changing sea conditions and water quality.

In the Sacramento-San Joaquin River system, each season there is a run of Chinook salmon spawning. The spring run used to number approximately 1 million fish in 18 separate populations, but they have been reduced to approximately 16,000 in three groupings. Spring run Chinook salmon are therefore listed as threatened under both the California and US Endangered Species acts, Thompson said. “The adults must survive the summer in freshwater before spawning in the fall,” she noted. That means they are waiting to spawn during the state’s hottest, driest months, where raised temperatures can kill them. In trying to stay cool, the salmon can get trapped on the wrong side of stretches of warmer river water separating them from their spawning grounds.

History warns of civilisation-crushing climate change

The preparedness of the survivalist couple to fight giant sandworms, like the one shown here, in the film Tremors has made me remember that climate has influenced civilization collapses. Credit: Universal Studios

The fall of the Roman Empire, the Vikings, the Mayans, four Chinese dynasties, and the overshadowing of a dinner date in Exeter, UK. These are just a few examples of how climate change’s influence can adversely affect humanity, and why people should take this threat seriously. They have also shown me that even I might not have been taking that danger as seriously as I should.

It all started innocently enough, when my girlfriend and I were discussing the classic movie “Tremors” over noodles at a favourite restaurant of ours. Kendra had watched it the previous night, and was particularly entertained by a survivalist couple that help the desert community make a stand against the movie’s bad guys – giant alien sandworms. I wondered whether survivalism is very common any more, and that perhaps it would be a good thing if it wasn’t. Despite having had some sympathy with survivalists in the past, I commented that by assuming that a disaster would happen, their outlook takes away the feeling of responsibility to avert that disaster in the first place. By contrast, I said, these days I feel that a major civilisation-squashing disaster is unlikely, even with the threat of climate change. That’s because since the European Renaissance civilisation has advanced relatively steadily to its modern status, and surely the future will continue to be like the past? Won’t this society acknowledge its responsibility, and successfully avert the disaster?

Vikings’ Greenland demise tells climate tale

Braya Sø, one of the two lakes in Greenland William D’Andrea and colleagues took sediment from to reconstruct 5,600 years of climate history. Credit: Credit: William D’Andrea/Brown University

Known as a scourge of Europe through the middle ages, the mighty Vikings disappeared from their Greenland settlements in the face of abruptly changing temperatures. In doing so, they followed the example of the Saqqaq people, whose Greenland existence also ceased in a period of rapid climate change. Climate is probably only one of many factors that led to these upheavals, warns William D’Andrea of University of Massachusetts, Amherst, one of the researchers who has made this link. However, studying past climate changes should help us better anticipate how climate may change in the future.

“Climate is a major factor that influences societies and cultures,” D’Andrea told Simple Climate, “but there are other factors that are social in origin and involve the way that cultures adapt. There have been very large changes in Earth’s climate system both over the last 10,000 and 100,000 years. Now, the globe as a whole is getting warmer and it’s because of greenhouse gases in the atmosphere in very large part. But what we really want to know is how will the places that we’re living in change. We can’t begin to do that unless we understand how the climate system has responded to changes in the past.”

It was the search for that in-depth climate knowledge that originally drove D’Andrea and his colleagues from Brown University, in Providence, Rhode Island, University of Nebraska, Lincoln, and Loughborough University, UK, to Greenland. “The goal of the paleoclimate community is to generate climate records from all over the world,” he explained. “No single site is going to be able to inform us about the climate system. We had identified western Greenland as a site that was interesting to work in because there weren’t many records from there.”

Pinning detailed climate impacts on people could cost conservation

The endangered Quino checkerspot butterfly experiences pressures in Southern California from climate change, but also urban development, invasive species and pollution. Credit: Lawrence Gilbert and Michael C. Singer

Efforts to understand the biological impacts of climate change on a detailed local scale are “misguided”, and conservation research should be favoured instead, a small but influential group of scientists have suggested this week. “This focus diverts energies and research funds away from developing crucial adaptation and conservation measures,” wrote biologists Camille Parmesan and Michael Singer from University of Texas, Austin, and their colleagues. Parmesan was a lead author for the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), for  which it won a Nobel Peace Prize jointly with Al Gore in 2007.

With a strong body of evidence showing that climate change is happening, the IPCC is now recommending scientists try and link its effects on plants and animals to human actions. “Biologists are now expected to shift away from detection towards attribution – that is assessing the extent to which observed biological changes are being driven by greenhouse-gas-induced climate change versus natural climate variability,” the team wrote.

Singer told Simple Climate that the consequences of human activity can be puzzled out on a global scale, though this is easier for climate effects than for biological impacts. However, the IPCC is encouraging ever more detailed attribution studies, something he feels is understandable but ill-judged. “From a basic research standpoint, once you’ve shown something at a large or rough scale, people then work at finer and finer detail,” he explained. “So, it seems the obvious ‘next step’ for the new IPCC assessment would be this kind of trajectory. Folk who work with modelling seem particularly attracted to this question. Folk who work with natural biological systems are more leery of it, because of feasibility, not interest.”

2010′s European heatwave unmatched in centuries

A thermometer in Moscow, where 2010's heatwave had a particulalrly great impact, on August 6 2010. Credit: Timon91/Flickr

Europe has experienced two heatwaves in the past decade unlike any experienced in the previous 500 years, and is set to see more in coming decades. The fires that scorched Russia last year were part of a heatwave hotter and even more widespread than the previous record event in 2003. “What was really striking was that there was another such enormous heatwave in Europe in such a short period,” explained Erich Fischer. Together with four other European scientists, the Swiss Federal Institute of Technology, ETH Zurich, researcher has found that major heatwaves are set to become five to ten times more likely over the next 40 years. Yet despite this, another event like 2010′s is unlikely to occur until after 2050.

In a paper published in leading academic journal Science on Thursday, the Portuguese, Spanish, Swiss and German scientists analysed the significance of last summer’s average temperatures against three different historical temperature records. Two sets together provide measured daily average temperatures across Europe back as far as 1871, while the third reconstructs average temperatures for each season back to 1500. “For 500 years further back, we use tree rings, plus ice cores, plus documentary evidence,” Fischer told Simple Climate. Tree rings show how temperatures in a given year have affected the trees’ growth rates. Likewise, ice cores show how temperatures influenced ice sheets in places like Greenland and the Arctic through time, while documentary evidence speaks for itself. “In Europe, there’s many places where people already were interested back in the 16^th and 17^th century in what’s going on with the weather and climate and so they would be documenting these,” Fischer noted.