Deciphering climate messages via the heart of the atom

June 15, 2013 — andyextance
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 »

Posted in climate, environment, Global warming, history, Ice sheets, news, Oceans, science, solar activity, Tree rings, Trees. Tags: , , , , , , , . 22 Comments »

Volcano cloud over tree-ring temperatures clears

February 11, 2012 — andyextance
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 »

Posted in Aerosols, climate, climate sensitivity, Climategate, environment, Global warming, Michael Mann, Modelling, radiative forcing, science, temperature records, Tree rings, Trees. Tags: , , , , , , , , , , . 2 Comments »

Tension simmers over climate link to plant growth

September 3, 2011 — andyextance
A misty canopy at dawn in the Amazon forest, where calculations of plant growth from satellite measurements that differ from direct measurements have come under criticism. Image courtesy of Peter van der Steen

A misty canopy at dawn in the Amazon forest, where calculations of plant growth from satellite measurements that differ from direct measurements have come under criticism. Image courtesy of Peter van der Steen

A surprise finding that plants are growing less quickly when, with current temperatures and CO2 levels, we might expect the opposite has come under fire from two independent groups of scientists. In August 2010, Maosheng Zhao and Steven Running from the University of Montana, Missoula showed that a measure of plant growth speed had slowed slightly since 2000. That’s even though it had accelerated in the 1980s and 1990s, a situation that fits the higher levels of CO2 in the atmosphere available to help plants grow through photosynthesis. But now, a year later, scientists from the US and Brazil have complained that this does not match what they’ve seen directly in Amazonian forests. Meanwhile, an Australian scientist adds to these objections with claims that Zhao and Running have over-estimated the effect that temperature has had on growth rates.

The disagreement focuses on how Zhao and Running calculated the measure of plant growth they use – net primary productivity (NPP) – from satellite data. “Measuring growth of a single tree is easy, however, at the global level, for billions of trees and plants, measurement of growth is only possible with data from satellites,” Zhao told Simple Climate. “Our model uses vegetation greenness information observed from satellites and daily global weather data to calculate vegetation growth of each kilometre over 110 million square kilometres of vegetated land surface.” The downside in this approach is that the view of Earth’s surface is often blocked, for instance by clouds and smoke. When that happens, the Montana researchers use the data from before and after the days the satellite can’t see the surface to fill in the missing measurements. They can then calculate NPP from those vegetation greenness measurements.   Read the rest of this entry »

Posted in Aerosols, climate, Drought, Global warming, news, satellites, science, Trees. Tags: , , , , , . 2 Comments »

Warming puts species at one in ten extinction risk by 2100

July 16, 2011 — andyextance
While Ilya Maclean and Robert Wilson found that measurements backed up predictions of climate change's impact on plants and animals, there were few studies in the tropics. Those that were investigated Mexican trees, like those shown here. Credit: Arturo Avila/Flickr

While Ilya Maclean and Robert Wilson found that measurements backed up predictions of climate change's impact on plants and animals, there were few studies in the tropics. Those that were investigated Mexican trees, like those shown here. Credit: Arturo Avila/Flickr

Climate change’s recent impact on Earth’s life has backed up previous assessments calling it “one of the major threats to global biodiversity”. Ilya Maclean and Robert Wilson at the University of Exeter, UK, compared predictions of warming’s effects on species since 2005 and actual measurements made in that time. Both predictions and observations gave an average extinction risk across all species by 2100 close to one in ten. “I was dismayed by the magnitude of potential extinctions that could occur, but was also relieved that we were able to show that scientific predictions were, on the whole, accurate,” Maclean told Simple Climate.

Individual studies on climate’s effects on species inevitably give a limited picture as they typically only focus on a few plants or animals at one time. Similarly, scientists’ predictions of the likely impacts of climate change are often met with scepticism. Maclean and Wilson therefore sought to bring prediction and measurements across different species together to address both issues. They gathered together data from 74 studies published since 2005, comparing their findings against well-established methods of judging extinction threats. 42 of these were predicting extinctions, movements of and changes in species’ populations, while 32 had recorded details of the actual responses to recent changes. Read the rest of this entry »

Posted in Animals, climate, environment, Global warming, news, Scepticism, science, Trees. Tags: , , , , . 2 Comments »

Chinese pollution postpones temperature rises

July 9, 2011 — andyextance
Sulphur emissions, which contribute to acid rain that can damage soil, plants and trees like these, have also slowed temperature rise between 1998 and 2008 compared to last quarter of the 20th Century. Credit: Wikimedia Commons

Sulphur emissions, which contribute to acid rain that can damage soil, plants and trees like these, have also slowed temperature rise between 1998 and 2008 from the more rapid warming seen between the mid-70s and mid-90s. Credit: Wikimedia Commons

The full climate impact of China’s massive industrialisation between 1998 and 2008 has yet to be felt, thanks to its reliance on coal, US and Finland-based researchers said this week. Using this fuel for energy generation did release large volumes of the greenhouse gas CO2 that will warm the planet in the long term. However, it also emitted pollutants derived from the element sulphur that oppose this warming effect in the short term, explained Boston University’s Robert Kaufmann. “That let natural variations in that decade really predominate,” Kaufmann told Simple Climate.

These findings help answer a long-standing climate question, which stumped Kaufmann when he was speaking about global warming to the public in New Jersey in 2008. “A member of the audience said that he had heard that global temperatures hadn’t risen for about 10 years,” the researcher explained. “He asked me why not, and I must admit that I was at a loss to explain it.” Climate scientists have conceded that there has technically been no warming in this time, even though the US National Oceanographic and Atmospheric Administration (NOAA) said 2005 was then the warmest year on record. Kaufmann found that in fact there hadn’t yet been any satisfactory explanation why this had happened, partly due to the tools used by climate scientists. Most “general circulation” models (GCMs) used to simulate processes in the atmosphere and on the Earth calculate climate patterns from the laws of physics. While these are good at modelling changes in the long term, they are much less accurate over periods of just a few years, Kaufmann said. Read the rest of this entry »

Posted in Aerosols, climate, environment, Global warming, Modelling, science, solar activity, temperature records, Trees. Tags: , , , , , , . 2 Comments »

Native tip-off reveals unmatched Arctic storm surge

May 21, 2011 — andyextance
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 »

Posted in Arctic, climate, environment, Glaciers, Global warming, Ice sheets, Icebergs, news, Oceans, science, Tree rings, Trees. Tags: , , , , , . 1 Comment »

Climate researchers warn of food and forest tinderbox

February 5, 2011 — andyextance
In January, food prices reached their highest levels since the UN Food and Agricultural Organisation began monitoring them in 1990. Credit: UN Food and Agricultural Organisation.

In January, food prices reached their highest levels since the UN Food and Agricultural Organisation began monitoring them in 1990. Credit: UN Food and Agricultural Organisation.

More frequent droughts are set to pose challenges to food supplies, and could worsen global warming still further. That’s a message that’s emerged over the past week, which has seen world food prices reach record highs, while researchers unveiled stark messages about drought in Africa and the Amazon forest.

Eastern Africa is seeing decreased rainfall due to warming in the Indian Ocean warn University of California, Santa Barbara, scientists Chris Funk and Park Williams. Over the past 60 years the Indian Ocean has warmed two to three times faster than the central tropical Pacific, they note in a paper published in the journal Climate Dynamics online ahead of print. This has driven increased rain and cycling of air through the atmosphere in the tropical Indian Ocean region. This has extended part of the air flow system known as the Walker circulation westwards, sending dry air towards eastern Africa. Read the rest of this entry »

Posted in agriculture, climate, Drought, environment, Global warming, IPCC, media, Modelling, news, Oceans, Precipitation, Regional prediction, science, Trees. Tags: , , , , , , , , , . 3 Comments »

Rain-soaked plants trudge downhill

January 22, 2011 — andyextance
Historical photo of vegetation of California from the early 20th century. This image is part of a US Forest Service effort to document the flora of the state in the 1920’s and 1930’s. Credit: Marian Koshland Library, UC Berkeley

Historical photo of vegetation of California from the early 20th century. This image is part of a US Forest Service effort to document the flora of the state in the 1920’s and 1930’s. Credit: Marian Koshland Library, UC Berkeley

Californian plants have responded to climate change in a surprising way, data collected under the direction of a forester born almost exactly 121 years ago have helped show. Albert Everett Wieslander headed surveys in the 1920s and 1930s covering 28 million hectares, over most of the state’s natural environment outside of deserts and larger agricultural areas. The data was originally intended to provide 220 detailed vegetation maps, but publication was halted by the Second World War after just 23 maps were released. Then in 2005 a digitized version of the raw data, now known as the Wieslander Vegetation Type Mapping (VTM) collection, was made available online.

Now, Solomon Dobrowski, from the University of Montana’s Department of Forest Management and his colleagues have compared this record with modern studies of plant populations for Northern California. “We used their survey plots,” Dobrowski told Simple Climate. “Basically they’d delineate a fixed area on the ground as roughly 800 square metres in size and they would document the types of trees and shrubs and other plants they found within that location.”

Prior studies of how plants are reacting to climate change have shown them moving to habitats in pursuit of their preferred temperatures as the planet warms. This typically means that they move towards the poles, or up mountainsides to higher altitudes. However, what Dobrowksi’s team found from their comparison, and published in top journal Science yesterday, at first glance seems to almost directly disagree with this. “I was mildly incredulous when my graduate student Shawn Crimmins first approached me and said that things are moving downhill,” Dobrowski admitted. “I asked him to go back and revisit his analysis and make certain that it was right. When he came back and said yes, we’ve dotted our i’s and crossed our t’s, I realised we had to revisit our assumptions about what was going on.” Read the rest of this entry »

Posted in climate, environment, Global warming, news, science, Trees, Uncategorized. Tags: , , , , . 1 Comment »

Methane release undermines CO2 emissions slowdown

November 27, 2010 — andyextance

Atmospheric radiative forcing - a measure of the degree of warming Earth experiences - of all long-lived greenhouse gases and the 2009 update of the US National Oceanic and Atmospheric Administration Annual Greenhouse Gas Index (AGGI), which shows radiative forcing has increased 27.5% since 1990. Credit: World Meteorological Organisation

Atmospheric radiative forcing - a measure of the degree of warming Earth experiences - of all long-lived greenhouse gases and the 2009 update of the US National Oceanic and Atmospheric Administration Annual Greenhouse Gas Index (AGGI), which shows radiative forcing has increased 27.5% since 1990. Credit: World Meteorological Organisation

The amount of greenhouse gases in the atmosphere reached the highest level recorded since pre-industrial times in 2009, despite a fall in CO2 emissions during the year, scientists have underlined this week.

Writing in Nature Geoscience on Sunday, a group of UK, US and Australian scientists found that global CO2 emissions from burning fossil fuel in 2009 were 1.3 percent below the record 2008 figures. However, the World Meteorological Organization (WMO) on Wednesday underlined that the overall amount of “radiative forcing” from greenhouse gases – a measure of the warming energy that they contribute – actually rose by 1 percent in 2009. The WMO notes that reduced growth rates for concentrations of greenhouses gases like CO2 and nitrous oxide last year were accompanied by more rapid growth for methane. Read the rest of this entry »

Posted in climate, environment, Global warming, Grazing, news, science, Trees. Tags: , , , , . 3 Comments »

Climate change shifts organisms in space and time

November 10, 2010 — andyextance

Duke University Biologist Bill Morris. Credit: Duke University

Duke University Biologist Bill Morris. Credit: Duke University

As our climate changes, we might expect to see some familiar plants and animals in our local environment replaced by new ones. That’s according to Bill Morris from Duke University in Durham, North Carolina, who recently published work studying shifts in where mountain plants live in top science journal Nature. “Species will likely be found in different places than where they are found now, creating new combinations that did not interact in the recent past,” he told Simple Climate. “What the consequences of these new interactions will be are hard to predict, because it is difficult to study interactions that don’t currently exist.”

Together with Daniel Doak at the University of Wyoming, Morris studied two tundra plant species whose habitat extends south from the Arctic. Higher global temperatures are expected to make conditions for the moss campion and alpine bistort better at the northern end of their geographical ranges. By contrast, at the southern end higher temperatures might be expected cause the plants to decline. Consequently their southern range limit should move northwards, but Morris and Doak found that in fact this had not happened – at least not yet.

Morris explained that the question of whether species’ ranges are spreading, or if it’s more common for the range to stay the same size, but move, remains unanswered. “We have much better evidence that species such as butterflies and birds are shifting toward the poles and to higher elevations, because these species are more often noticed by amateur naturalists, and because they likely move faster than do plants,” he said. “But we do know that many plants in Europe, where historical information about plant distributions is better, have moved to higher elevations over the last century.” Read the rest of this entry »

Posted in Animals, Arctic, climate, environment, Global warming, media, news, Precipitation, science, Trees. Tags: , , , , , , , , . 5 Comments »
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