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.

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. Read the rest of this entry »

Alternate histories back unique modern warmth claims

Tree rings have a light-colored band, or earlywood, that forms in the spring and a dark-colored band, or latewood, that forms in the summer. The width of the band tells how much the tree grew during that period and therefore can be used as a proxy for the climate during that season. That approach has some uncertainties, but Martin Tingley and Peter Huybers have reduced their impact on telling if any year is the warmest. Credit: thaths via Flickr Creative Commons license

Tree rings have a light-colored band, or earlywood, that forms in the spring and a dark-colored band, or latewood, that forms in the summer. The width of the band tells how much the tree grew during that period and therefore can be used as a proxy for the climate during that season. That approach has some uncertainties, but Martin Tingley and Peter Huybers have reduced their impact on telling if any year is the warmest. Credit: thaths via Flickr Creative Commons license

If you build a temperature record going back in time to judge modern warming against, how certain can you be of your answer? That’s a big question for scientists making such records from effects temperatures have had on the natural world. And figuring out if today’s heat is unique is too great a challenge for the methods scientists normally use to calculate uncertainty, according to Harvard University’s Martin Tingley.

But Martin and Peter Huybers have shown the precise chances that northern areas of the world are warmer than any time in rebuilt records reaching back to the year 1400. They have worked out that there’s less than one chance in 20 that 2005, 2007, 2010 and 2011’s northern summers weren’t the warmest in that time. They also find that summer 2010 has a 99% chance of being the warmest western Russia has seen. There have already been lots of claims made over the unusualness of recent warmth, Martin pointed out, but his and Peter’s are the most robust yet. “We put these estimates on a much sounder statistical footing,” he told me.

Saying one year’s summer is uniquely warm across a long period is difficult for subtle reasons that Martin explained through his height. “I’m a tall guy, 6 foot 4 inches,” he said. “I’ve never met you, but I’m going to bet I’m taller than you. What’s the intuition behind my bet? We have a sense of the distribution of heights. I’m aware I fall pretty far out on the tail, so the chances are if I meet an average person they don’t fall further out than I do. What if I’m in a room with 1,000 people I’ve never met before? Am I still likely to be the tallest in the room? Probably not.” Read the rest of this entry »

Volcano cloud over tree-ring temperatures clears

Pennsylvania State University's Michael Mann thinks he has found the reason behind key outstanding disagreements between the historical temperature record based on tree rings and climate models for the same period. Credit: Pennylvania State University

Pennsylvania State University’s Michael Mann thinks he has found the reason behind key outstanding disagreements between the historical temperature record based on tree rings and climate models for the same period. Credit: Pennylvania State University

The sudden chills violent volcano eruptions cast over the world centuries ago effectively erased themselves from the historical climate record produced by examining tree-rings. So suggests a team led by Michael Mann from Pennsylvania State University, who famously used 1,000 years of tree-ring measurements in the “hockey stick” graph showing how unusual today’s temperatures are. Michael warns the skipped years could affect scientists’ estimates of how much the world warms in response to greenhouse gases in the atmosphere, known as its climate sensitivity. But other than the volcano years, the scientist notes that tree-ring data is a remarkably accurate match with the climate models they used for comparison. “Interestingly, the effect has little influence on long-term trends, including conclusions about how previous temperatures compares to modern ones,” he told me. “Instead, it appears only to have implications for how strong past short-term cooling events were.”

A tree’s age can usually be told from the rings that form across its trunk representing each year’s growth. How thick each ring is shows how much the tree grew in the year in question, which is influenced by the temperatures that tree experienced. That means examining the thickness of rings in old trees can provide a way to tell temperatures back through history. Many challenges have already been overcome in turning this simple-sounding idea into a history of the world’s temperature, but Michael was still troubled by one particular detail. Read the rest of this entry »

Native tip-off reveals unmatched Arctic storm surge

Dead vegetation killed by a 1999 storm surge in the Mackenzie Delta is in stark contrast to the vegetation along the edges of waterways that receive regular freshwater (and thus survived the damage). Credit: Trevor Lantz, University of Victoria

Dead vegetation killed by a 1999 storm surge in the Mackenzie Delta is in stark contrast to the vegetation along the edges of waterways that receive regular freshwater (and thus survived the damage). Credit: Trevor Lantz, University of Victoria

Plants and animals living along the coast of the Mackenzie Delta in the Canadian Arctic have been devastated by a salt-water flood, made more severe by climate change. After local Inuvialuit natives told them that where they could hunt had changed, Canadian scientists showed the damage was unrivalled during the period they could document by studying tree rings and lake sediments. “The impacts of this storm were truly unique in the last millennium,” commented biologist John Smol of Queen’s University in Kingston, Ontario.

“The Inuvialuit brought to our attention the occurrence of a large storm surge that happened in late September 1999,” said Joshua Thienpont, a postgraduate student at Queen’s. “The region was frequented by members of the local communities to hunt waterfowl that would nest near the delta front. The Inuvialuit hunters noted that, after the storm, birds no longer nested there.” At that point, however, it wasn’t clear how common such events were, so Smol, Thienpont, and their colleagues exploited the nearby “natural archives” to try and find out. One such record of previous surges came because they thought that plants not used to being covered in saltwater would grow less quickly when under the flood waters. “With this in mind, we sampled alder shrubs and measured their growth rings using a microscope and specialized measuring system,” said Michael Pisaric, a geographer at Ottawa’s Carleton University. Read the rest of this entry »

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

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 16th and 17th century in what’s going on with the weather and climate and so they would be documenting these,” Fischer noted. Read the rest of this entry »

Saturday round-up: Hot water awaits?

Global temperatures haven’t risen as much as the amount of energy the planet has absorbed since 2003 would suggest, but the rises may just have been delayed. That’s according to Kevin Trenberth and John Fasullo of the US National Center for Atmospheric Research (NCAR).

Kevin Trenberth explains where the sun’s energy goes when it reaches Earth. Credit: NCAR.

In a paper published in Science yesterday they compare satellite data measuring the amount of energy from the sun entering the atmosphere and returning back into space. Since 2000, the Earth has absorbed around 0.9 watts per square metre more at the top of the atmosphere than it has released. “It is this imbalance that produces global warming,” Trenberth and Fasullo write. Read the rest of this entry »

Inquiry clears US Climategate researcher of falsification, questions “conduct of science”

The Michael Mann 'hockey stick graph' incorporating tree rings to calculate temperatures since 1000AD in the Northern Hemisphere. Credit: IPCC

Penn State University’s inquiry into Michael Mann has dismissed widespread claims that he made up climate measurements, deleted information, or misused his position. Mann, whose emails were among those published in the University of East Anglia (UEA) leak, is however to be investigated further by a panel of Penn State researchers. Five scientists from a range of different subjects will examine whether how Mann proposed, did, or reported research differed from what is expected of an academic.

A first committee of senior university management suggests that doubts about how Mann has done his work “may be undermining public trust in science in general and climate science specifically.” Although Mann was cleared by a similar US National Academy of Sciences investigation in 2006, the University’s leaders say that the emails give a new insight into how he works that needs more attention. They have set up the second, five-strong, committee to do just this within 120 days.

Despite this, the February 3 report disagrees with those criticising the work of Mann and others on the basis of the word “trick” used in what it calls “purloined emails”.

“There exists no credible evidence that Dr. Mann had or has ever engaged in, or participated in, directly or indirectly, any actions with an intent to suppress or to falsify data. The so-called “trick” was nothing more than a statistical method used to bring two or more different kinds of data sets together in a legitimate fashion by a technique that has been reviewed by a broad array of peers in the field.”

Another key concern to come out of the Climategate emails surrounds the suggestion of the UEA’s Phil Jones that Mann and others delete emails. Henry Foley, vice president for research at Penn State therefore requested that Mann provide him with all emails related to the fourth report (AR4) of the Intergovernmental Panel on Climate Change (IPCC). Mann duly provided a zip file containing these emails, leading the committee to conclude:

“There exists no credible evidence that Dr. Mann had ever engaged in, or participated in, directly or indirectly, any actions with intent to delete, conceal or otherwise destroy emails, information and/or data related to AR4.”

The third accusation not to be investigated further is that Mann and other climate change researchers had early access to research papers that they disagreed with, and prevented their publication. The committee asked what papers were involved, it found enormous confusion over the interpretation of the emails supposedly showing this. Some referred to papers written by the researchers themselves, but were not yet published as they were under embargo, a common situation in academic journals. Others referred to papers that were published, but that they disagreed with.

“The committee found no research misconduct in this,” the report says. “Science often involves different groups who have very different points of view, arguing for the intellectual dominance of their viewpoint.”

Mann himself responded to the report:

“This is very much the vindication I expected since I am confident I have done nothing wrong. I fully support the additional inquiry which may be the best way to remove any lingering doubts.”

Friday round-up: “Glaciergate” and climate research holes

False-colour image of the UK acquired on 8th January 2010, following heavy snow storms which saw the UK blanketed in snow. These images were captured by the Advanced Along-Track Scanning Radiometer (AATSR) instrument on board ESA’s ENVISAT satellite. The images were generated using three spectral channels: red - 0.87 microns; green - 0.67 microns; blue - 0.55 microns. Vegetated surfaces are much 'brighter' in the near infra red region (0.87 micron channel) than in the visible regions, therefore these regions appear more ‘red’. (Images courtesy of G. Corlett, University of Leicester)

Climate change researchers faced more public humiliation this week, as claims that the Himalayan glaciers were set to melt by 2035 were shown to be unfounded. The Intergovernmental Panel on Climate Change (IPCC), a United Nations body, included the claim in a 2007 report aimed to feed into international negotiations.

However, after questions about the claims were raised shortly prior to December’s Copenhagen summit, it emerged that they were not based on the usual peer-reviewed sources that the IPCC uses. Instead, the source referred to was a 2005 report by the Worldwide Fund for Nature. In turn, that report cited as its source a 1999 New Scientist article reporting claims made by a researcher made in a brief telephone interview, that never made it into an academic journal.

“Clear and well-established standards of evidence were not applied properly,” the IPCC said in response to the news. “The IPCC regrets this.” Nevertheless, it also stressed that it stood by its ultimate conclusion on glaciers:

“Widespread mass losses from glaciers and reductions in snow cover over recent decades are projected to accelerate throughout the 21st century, reducing water availability, hydropower potential, and changing seasonality of flows in regions supplied by meltwater from major mountain ranges (e.g. Hindu-Kush, Himalaya, Andes), where more than one-sixth of the world population currently lives.”

With the IPCC having jointly won joint the 2007 Nobel peace prize with Al Gore for its efforts to disseminate knowledge on climate change, this is rightly judged to be a big knock to its credibility. Yet, the IPCC itself had already pointed out that climate science and scientists can be fallible, pointing out 54 ‘key uncertainties’ in the very same report containing the incorrect glacier claims. In this week’s Nature, Quirin Schiermeier points out that although these do not undermine the fundamental conclusion that humans are warming the climate, they do hamper efforts to plan for the future.

Schiermeier picks up on four major areas. In regional climate prediction, basic models don’t get more accurate than 1-3° of latitude, or 70-210 miles. This is especially troublesome in regions with varied terrain, for example when dealing with areas where two climatically different plains are separated by a mountain plateau. In precipitation, while models agree that global warming will dry equatorial areas and make areas nearer the poles wetter, they don’t agree on much else. Researchers are especially worried as their estimates for how much precipitation was due to change until now are already too small. In the third area, airborne liquid or solid particles in the form of atmospheric aerosols are thought to block and reflect heat from the sun. There is a great deal of uncertainty about how large an impact these have, especially given that nobody knows accurately how many particles are up there.

Tree rings are a particular cause for consternation. Used by modern researchers to get information about temperatures for the years before humanity had thermometers, some trees at northern latitudes now seem to be responding differently to temperature. No-one yet knows why and as long as this is the case, although evidence suggests that 1998 was the warmest year in a millennium, there will remain doubt. Yet even studies raising uncertainties show the current warming to be unprecedented, Schiermeier reports, and the IPCC again stands by its assertion that there is a greater than 90% chance that this is caused by human-produced increases in greenhouse gases.

The UK has recently been glacial: this has been picked upon by some as another reason why global warming is over-hyped. Contrary to such suggestions, Philip Eden, the president of the UK’s Royal Meteorological Society, chose to emphasise that the wonderful satellite photo above of the recent cold snap is “certainly not evidence that ‘climate change’ has ceased”. Instead he cites a number of factors, including a weak jet-stream and a blocking high-pressure system making it easier for cold Arctic winds to reach where I live than warmer Atlantic air. “Such year-to-year, regional anomalies are intrinsic; it is the long-term, global trend that is important when assessing climate change,” Eden said.

What the leaked “Climategate” emails meant

Trevor Davies of the Univerity of East Anglia

Trevor Davies

The volume of the argument over climate change was turned up a notch at the end of November 2009, thanks to emails leaked from the Climatic Research Unit at the University of East Anglia. Shortly after the scandal broke I asked Trevor Davies, who was formerly a director of the CRU, and now has overall responsibility for research at the university, what it all meant. To start with, he told me: “There is no evidence that the research produced by CRU is flawed. On the contrary, it has been scrutinised and improved by the peer review process by which the global scientific community challenges and accepts new science. CRU’s research is consistent with other, independent, analyses, particularly two independent data sets in the US.”

As commentators locked horns, throwing up clouds of confusion, just a few of the hundreds of emails were the focus of the battle. Perhaps the most damning was a quote from the CRU’s Phil Jones in 1999, saying: “I’ve just completed Mike’s Nature trick of adding in the real temps to each series for the last 20 years (ie, from 1981 onwards) and from 1961 for Keith’s to hide the decline.”

Researchers collect tree ring cores

Researchers collect tree ring cores

The trick in question concerns tree rings. “This refers to a clever way of portraying in a diagram an analysis of, and compensation for, the breakdown in the strong relationship between tree-ring density and temperature in some parts of the world since the 1960s,” Davies told me. When compared to temperature data back as far as the middle ages and beyond, wood density increases have been directly proportional – until the second half of the 20th century. Jones himself contributed to a paper published in Nature – arguably the most difficult scientific journal to get published in – explaining this phenomenon nearly twelve years ago. So, charts using trees to measure temperatures over the whole century would need to use the “Nature trick”, taking into account how the link between wood density and temperature changed.

Critics have also focused on Jones’ suggestions that emails should be deleted to prevent them being accessed using freedom of information laws. These have been mentioned closely alongside criticisms that the raw data used by the CRU scientists had not been made available. Together, these give a particularly worrying sense that perhaps measurements have been destroyed to exaggerate the case for global warming. As mentioned in the last blog entry, the UK’s Met Office, a key collaborator with the CRU, has now released the raw data, to be met by fresh accusations of selective use of measurements. No definitive proof has yet come to light to support such claims, Davies points out. “There is no evidence that data have been lost, inappropriately adjusted or hidden,” he said.

Jones’ apparent efforts to try and suppress research criticising CRU research via the peer review process that Davies celebrates are at the centre of a third common criticism. Peer review, gathering and sharing of information and an investigation into suppression of data are all on the agenda of the independent review that the CRU has commissioned. “This demonstrates the commitment of the university to transparency and integrity in research,” Davies told me. “This is the correct way of responding to the orchestrated furore, rather than the many irresponsible distortions which have appeared in the blogosphere and some media. If the review concludes that there are issues to address, then address them we shall.”

Whatever the outcome of the review, Davies warns against discounting the majority view of the scientific community, on the basis of unsubstantiated allegations about what one part of it did. “The bigger picture is that the sum total of scientific evidence for global warming largely as a result of human activity is overwhelming,” he emphasised.

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