Deciphering climate messages via the heart of the atom

Vemork Hydroelectric Plant at Rjukan, Norway, which Hans Suess advised on heavy water production, telling Nazi Germany it couldn’t make heavy water quickly enough for military use. His expertise with heavy water was part of an interest in nuclear science that led him to become a pioneer in carbon dating.

When Hans Suess chose to study physical chemistry, he went nuclear, apparently overturning two generations of family tradition. Hans was born in 1909, just as his father Franz succeeded his grandfather Eduard as a geology professor at the University of Vienna. Hans got his PhD from the same university in 1936, but in studying heavy water he was set to aid the historic advances in nuclear science of the time. Yet a transatlantic scientific coincidence would bring him back to more environmental science, and see him help pioneer radiocarbon measurements. With that expertise, Hans showed humans were raising atmospheric CO2 levels, and revealed another surprising source of variations in climate.

The common theme to these achievements was how neutrons and protons combine in an atom’s nucleus. For example, hydrogen atoms found in conventional water have just a single proton in their nuclei. In heavy water, some of these atoms are replaced by a rarer form of hydrogen, known as deuterium, whose atoms have an extra neutron in their nuclei. That gives heavy water properties that can help nuclear reactors, which Nazi Germany notoriously hoped to exploit to make nuclear weapons.

With Hitler’s armies occupying Austria just two years after Hans finished his PhD, his expertise brought him to the attention of the Nazi regime. They called him in to advise a hydroelectric power plant in Vemork, Norway, that was making heavy water. Hans visited several times, reporting that it couldn’t make heavy water quickly enough for military use. Allied forces destroyed it in 1943 anyway, in audacious raids fictionalised in the film “Heroes of Telemark”.

Alongside working with heavy water, Hans studied why the chemical elements exist in the amounts that they do. The answer laid in how stable different numbers of protons and neutrons are when they come together in nuclei. He continued this work after the Second World War in West Germany, helping develop the “Nuclear Shell Theory” explanation, which other scientists won the Nobel Prize for Physics for in 1963. Suess missed out on this acclaim partly because two teams came up with the explanation at the same time. But when the other team, based at the University of Chicago, invited him to visit, Hans’ life changed course towards unravelling the secrets of Earth’s history.

Historical sea voyage sends manmade warming signal

The HMS Challenger sailed 69,000 miles, taking around 360 temperature soundings on the first global marine expedition from 1873-1876. This painting, by William Frederick Mitchell, is from its earlier life as a warship, in 1858.

Data from a 19^th century scientific mission, the first global marine research expedition, have provided strong evidence that humans have influenced climate throughout the entire 20th century. From 1873–1876 the HMS Challenger, a corvette of the British Royal Navy, sailed 69,000 miles and took hundreds of ocean temperature soundings. Last year, scientists used its measurements to show the top 700 metres of the ocean has warmed around 0.33°C since Challenger’s voyage. Understandably, seeing a global effect in the limited Challenger data is fraught with difficulty. Nevertheless, Will Hobbs from the University of Tasmania, Australia, and Joshua Willis at NASA’s Jet Propulsion Laboratory in Pasadena, California, have now checked if this warming is linked to humans. “Even accounting for all uncertainties and limitations, the temperature change could not be realistically explained by natural variability alone, implying a long-term human signal,” Will told me.

Having swapped cannons for labs, among HMS Challenger’s projects was a series of around 360 soundings for temperature. At each sounding, its scientists dropped pressure-protected thermometers into the ocean attached to a rope every 100 fathoms (182 m) down to 1000 fathoms depth. “The scientists kept detailed records of how each measurement was taken, problems encountered, and how accurate and precise their measurements were,” Will said. “All instruments were calibrated in a lab before and after the expedition. So we have a lot of information about what level of accuracy we can expect, in some ways more than from modern automated observing systems, which are usually left to their own devices after deployment.”

Ocean heat puts pressure on poorest fisheries

Warm water Red Mullet catches in the UK have increased as sea temperatures have warmed, which William Cheung has linked to global warming. Credit: Nate Gray: A Culinary (Photo) Journal via Flickr Creative Commons License

Since 1970, our warming seas have driven fish across the world into cooler, deeper waters, potentially threatening fishing in Earth’s hottest seas. By analysing worldwide fish catches, Canadian and Australian scientists have found that the proportion of warmer-water fish caught has steadily grown. And in future, the warmest waters are set to become too hot for some of the fish that might previously have been caught there.

“Tropical fisheries are likely to be most impacted by ocean warming,” William Cheung from the University of British Columbia in Vancouver, Canada, told me. “We expect that the current trend would continue, and will reduce the catch for tropical fisheries. Many tropical fishing communities are in developing countries with limited socio-economic scope to deal with changes in resource abundance. Thus, these communities are most vulnerable to ocean warming.”

Like all living creatures, fish have a range of temperatures that they can comfortably live in. Sea temperatures are rising, with the US coast from North Carolina to Maine reaching the warmest level in 150 years last year, for example. Changing climate has already been linked to fish catches in some places, with William previously suggesting it’s behind rapid increases in warm-water red mullet catches around the UK. “However, there was no study that assessed the linkages between ocean warming and fisheries changes in the global scale,” he said.

So William and his teammates set about bringing together fish catch information from 52 ecosystems, including most of the world’s fisheries. That included data on 990 species, which the scientists analysed using a new measure, the ‘mean temperature of the catch’ or MTC, which William also calls a ‘fish thermometer’. To find the MTC, the scientists start by working out the preferred temperature of each species, based on the sea water temperatures in the areas that they used to live in. “For example, fishes that live in colder area, such as cod, will have a lower preferred temperature than a tropical fish, such as a tropical grouper,” William explained.

Arctic mission recovers record of surprising warmth

All cargo for the drilling operation on Lake El’gygytgyn in winter 2008/09 had to be transported to the lake from the nearest settlement, Pevek, located 360 km north across the frozen tundra with trucks supported by bulldozers. Credit: Pavel Minyuk

A warm climate with CO2 levels similar to today delayed ice sheets from forming over land in the Arctic until less than 2 million years ago. That’s the latest instalment in a climate history scientists are building using sediment from a lake created by a giant meteorite impact around 3.6 million years ago. The international team has found that 3-3.2 million years ago, summer temperatures in the region were about 8°C warmer than they are today.

Julie Brigham-Grette from the University of Massachusetts, Amherst, explained that other scientists have estimated CO2 levels in the Pliocene period from 5.3 to 2.6 million years ago. “Though the estimates are quite broad, most scientists suggest that 2-3 million years ago CO2 levels may have been similar to today,” she told me. “Our data are consistent with that – the world today could be headed toward a Pliocene-like world.” And as well as pointing to the warmer future, these findings could also help unpick climate puzzles from our past.

These insights are the prize Julie and her team-mates sought on an epic trek to North-East Russia’s frozen wilderness in 2009. She was chief scientist for the US side of the team, leading the expedition alongside Martin Melles and Pavel Minyuk, chief scientists for the German and Russian sides. Their goal lay at the bottom of Lake El’gygytgyn, or Lake E. A 13 km wide crater blasted by a meteorite up to a kilometre in diameter that filled with water, Lake E has slowly collected sediment ever since. It’s unusual because it largely escaped damage from the creep of ice sheets, meaning scientists can use its sediment to rebuild conditions further back in time.

And to get there, Julie, Martin and Pavel had to pave political, financial, logistical, and actual physical paths, Julie explained. “This lake sits in an area that has no roads,” she said. “It was an amazing logistical feat to gather the drillers and equipment and get there, without damaging the environment. It was the most difficult scientific project I’ve ever undertaken.”

Temperature patterns produce perplexing Pliocene puzzle

Lafayette College’s Kira Lawrence and her teammates have used ocean bed sediment cores, like this one, to produce a 5 million year climate record. © Intergrated Ocean Drilling Program

US, UK and Hong Kong Researchers have produce a unique ‘movie’ of climate reaching back 5 million years, by bringing together data drilled from ocean beds. It reveals three important temperature patterns during the warm early part of the Pliocene period that they couldn’t recreate together in climate models using existing explanations. That’s important because scientists hope the Pliocene could help us know what the future of a warmer Earth might be like. And having uncovered another layer to the Pliocene puzzle, team member Kira Lawrence from Lafayette College in Easton, Pennsylvania, underlined the value of finding its solution.

“Our community of scientists think of the Pliocene as though it was about 3°C warmer than modern temperatures with CO2 concentration about where we are right now,” Kira told me. “But we haven’t recognised before that the pattern of temperature was a lot different. If that’s where we’re headed in the not too distant future, if the temperature and precipitation patterns change in that way, we should have some significant things to think about.”

The Pliocene period started 5.3 million years ago, during which primates made important evolutionary steps towards humanity. Since 2000, there has been a climate data explosion reaching back through this era. Around the world, international drilling expeditions have pierced ocean beds kilometres below sea level, reaching hundreds of metres into sediment to bring back ‘core’ samples. Tiny fossils within that rock and mud can tell scientists temperatures through history, which can give climate scientists real data to test their models against.

Diving deep into ocean data uncovers ‘missing heat’ treasure

A new ocean reanalysis called ORAS4, here showing the difference between September 2012 sea temperatures and the average for 1989-2009 (not part of the latest study), has helped show that extra heat trapped in the atmosphere by CO2 humans are emitting is buried in the deep ocean. Credit: ECMWF

A newly-made picture of ocean history has backed a theory that the missing piece of a climate puzzle at the edge of space lies deep in Earth’s waters. The puzzle comes because the amount of heat energy our planet has absorbed should have warmed it more than it seems to have done. But now, using an ocean reanalysis assembled from data gathered from many sources, UK and US researchers have shown especially strong recent warming in oceans below 700m. “We have found some energy buried at depths,” Kevin Trenberth from the National Center for Atmospheric Research (NCAR) in Boulder, Colorado. “We also have a plausible explanation for it related to changes in winds.”

In 2010, Kevin went public over his worries about a budget that didn’t balance. But rather than money, that budget tallies heat energy from the Sun entering the top of the atmosphere against energy the Earth radiates back out into space. Satellite measurements show more energy coming in than leaving, which is what causes global warming. But Kevin noticed that existing measurements showed the world hadn’t warmed as much since 2003 as this budget would suggest.

With over nine-tenths of the surplus energy coming into the Earth going into the sea, the deep ocean has always looked the likeliest hiding place for the missing heat. However, temperature data from those depths is scarce, making the theory hard to prove. Yet, in the years since Kevin pointed out the problem, scientists have gathered some clues to back that explanation. For example, some used a model that includes the complex links between the atmosphere, land, oceans, and sea ice to run five simulations of the 21^st century. They found warming slowdowns on the Earth’s surface similar to what has happened in the 2000s, with the heat going into the deep oceans. But even this just underlined the importance of using measurements to see the effect directly.

Climate change set to bring Western Europe more hurricanes

In January 2009 a cyclone called Klaus, which is shown here and boasted hurricane-force winds, hit France, Spain and Italy. Such conditions could become much more common in Europe by the end of the 21st century, according to Rein Haarsma and his KNMI team. Credit: H de C via Flickr Creative Commons license

Current once-in-a-century hurricane-force winds may become as much as 25 times as likely in parts of Western Europe at the end of the 21^st century. That’s what Rein Haarsma and a team from the Royal Netherlands Meteorological Institute (KNMI) have shown using one of the highest-resolution climate models around today. Their findings spring from a change in where hurricanes will develop that could also affect western North America, though more research is needed to study this. “The statement that the wind climate in Western Europe will not change significantly is questionable,” Rein told me. “Significant changes in wind climate will have consequences for agriculture – the increased winds are during the autumn – infrastructure and coastal defence.”

With Europe so far from the tropical regions where warmth and unstable atmosphere spawns hurricanes, it rarely sees them today. But when hurricane conditions do happen, like the ‘Great Storm’ in 1987, or Hurricane Floyd in 1993, they live long in the memory. The hurricane remnants that sometimes reach Western Europe usually bring a lot of rain, Rein noted, and only occasionally hurricane-force winds.

The warming Arctic is reducing ocean temperature differences that help create Europe’s traditional storms, meaning they pose less of a threat. But recently findings have shown that a warmer atmosphere raises hurricane risks. “Many model simulations suggest that the strength of hurricanes will increase due to climate change,” Rein explains. “The area where hurricanes develop appears to move poleward and the moisture content in a warmer atmosphere will increase. These factors might alter the possibility that these remnants of hurricanes are still strong enough to produce hurricane-force winds.”

Temperature cuts swathe through Australian seaweed

A mixed seaweed canopy in Western Australia, including Scytothalia dorycarpa (far right), which was completely killed along 100km of the Australian coast by a heatwave in 2011. Credit: Dan Smale

A record-breaking heat wave in 2011 killed a seaweed species that many fish and other creatures call home along a 100 km stretch of the Western Australian coast. That underlines the threat from climate change, which is driving more regular ‘extreme events’ like heatwaves, according to Dan Smale of the University of Western Australia (UWA). “Extreme events can wipe out species at their range edge incredibly quickly, which may have wide ranging implications for whole communities of associated plants and animals,” he said.

Metre-plus tall strands of Scytothalia dorycarpa seaweed sway around cool water rocky reefs in southern Australia, forming a playground for other species. It is thought to have evolved in cool conditions, and therefore to be sensitive to warmth. For that reason, in 2006, Dan and his UWA colleague Thomas Wernberg started tracking it in two main locations, Jurien Bay and Hamelin Bay, and 27 other sites. “We suggested that by monitoring its abundance and distribution, we could detect ecologically-significant climate change impacts over periods of years to decades,” Dan said. “We did not realise, however, that the highest-magnitude seawater warming event on record was just around the corner, and we did not expect to see such sudden and extensive shifts in its distribution.”

That extreme was reached in 2011 during the cooler ‘La Niña’ phase of the El Niño Southern Oscillation climate cycle. By contrast to the current Australian heatwave, temperatures rose thanks to an especially strong La Niña increasing the flow of warm water from the tropics. In March 2011 Thomas and Dan measured sea surface temperatures up to 4°C higher than the average for 2006-2010. The heatwave temperatures stayed more than 2°C above the 2006-2010 level for around 10 weeks in both bays.

CO2 casts off shackles to power up Atlantic hurricanes

NOAA’s GOES-13 satellite captured this visible image of Hurricane Sandy battering the U.S. East coast on Monday, Oct. 29 at 9:10 am EDT. Sandy’s center was about 310 miles south-southeast of New York City. Tropical Storm force winds are about 1,000 miles in diameter, and are set to intensify in the 21st century. Credit: NASA GOES Project

Changes in greenhouse gases and other air pollution will likely make Atlantic storms that could hit the Caribbean and Eastern US more intense through this century. That’s according to research from Gabriel Vecchi at the US National Oceanographic and Atmospheric Administration (NOAA) in Princeton, New Jersey, and Gabriele Villarini at the University of Iowa. They’ve found that more greenhouse gases strengthen these storms but other pollutants known as aerosols or particulates, which include soot, do the opposite. Increases in both types of pollution through the 20^th century therefore cancelled each other out. But with more recent efforts to limit aerosol pollution succeeding, Atlantic storms now look set to become more destructive. “Both reductions in particulate pollution and increases in greenhouse gases are going to co-operate, we think, to give us more intense hurricanes in the Atlantic,” Gabriel said.

Gabriel has long studied Atlantic storms, and together with Gabriele recently found that how often they happen will likely only increase during the first half of the 21^st century. “The number of storms in a season is only part of the story,” Gabriel told me. “A big question for society is the intensity.” So it was natural, he added, to follow on by looking at how strong and long-lasting they are. Scientists have already looked at their intensity for narrow “time-slices”, for example from 1985-2005 and then predicting from 2080 to 2100. “People haven’t explored how we go from the late 20^th century to the late 21^st century,” Gabriel said.” That’s because to do this research they need complex and very detailed ‘high resolution dynamical’ climate models, which use up scarce time on the world’s most powerful computers. For the same reason, previous studies only look at a few possible scenarios for how much of the greenhouse gas CO2 humans will produce by burning fossil fuels.

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.