News Article | June 29, 2017
The June heat waves that impacted much of the UK and Western Europe were made more intense because of climate change say scientists. Forest fires in Portugal claimed scores of lives while emergency heat plans were triggered in France, Switzerland and the Netherlands. Britain experienced its warmest June day since the famous heat wave of 1976. Human-related warming made record heat 10 times more likely in parts of Europe the researchers say. During June, mean monthly temperatures about 3C above normal were recorded across western parts of the continent. France experienced its hottest June night ever on 21st when the average around the country was 26.4C. That same day had seen the mercury hit 34.5 at Heathrow in what was the UK's warmest June day for 40 years. It was a similar story in the Netherlands which is set to have its hottest June on record while in Switzerland it was the second warmest since 1864. Now, researchers with World Weather Attribution have carried out a multi-method analysis to assess the role of warming connected to human activities in these record temperatures. "We simulate what is the possible weather under the current climate and then we simulate what is the possible weather without anthropogenic climate change, and then we compare these two likelihoods which gives us the risk ratio," Dr Friederike Otto from the University of Oxford, one of the study's authors, told BBC News. That signal, according to the authors, made heat waves at least 10 times more likely in Spain and Portugal. Fires resulted in the deaths of 64 people in Portugal, while in Spain they forced the removal of around 1,500 people from holiday accommodation and homes. In Central England, France, Switzerland and the Netherlands the intensity and frequency of such extreme heat was four times as likely because of climate change, the study says. "We found clear and strong links between this month's record warmth and human-caused climate change," said Geert Jan van Oldenborgh, senior researcher at the Royal Netherlands Meteorological Institute (KNMI). "Local temperature records show a clear warming trend, even faster than in climate models that simulate the effects of burning fossil fuels but also solar variability and land use changes," van Oldenborgh added. The researchers say their reported results on the impact made by human related warming are conservative in some ways. Their study indicated that in countries like Spain, Portugal and France, climate change could be increasing the chances of extreme heat by up to forty times. The scientists believe that the chances of these extreme heat events becoming much more common will increase unless rapid steps are taken to reduce carbon emissions. "Hot months are no longer rare in our current climate. Today we can expect the kind of extreme heat that we saw in June roughly every 10 to 30 years, depending on the country," said Robert Vautard, a researcher at the Laboratory of Climate and Environmental Sciences (LSCE), who was also involved in the study. "By the middle of the century, this kind of extreme heat in June will become the norm in Western Europe unless we take immediate steps to reduce greenhouse gas emissions." The researchers are calling on city leaders in particular to work with scientists and public health experts to develop heat action plans. While, usually, researchers wait to publish research like this in a peer-reviewed journal, the team felt that speed was necessary to inform public debate. "When extreme events happen, the question is always asked 'what's the role of climate change?' and often the statement is made by a politician or by someone with a political agenda and not based on scientific evidence," said Dr Otto. "Our aim is to provide that for the role of climate change, to show what you can robustly say within the time frame when people are discussing the event." Follow Matt on Twitter and on Facebook
News Article | July 19, 2017
Hundreds of climate scientists, including many from the United States, have applied to work in France under a €60-million (US$69-million) scheme set up by the country's president, Emmanuel Macron, after his US counterpart Donald Trump rejected the Paris accord on global warming. And Germany has announced that it will set up a similar programme to lure researchers. Macron launched his ‘Make Our Planet Great Again’ initiative on 8 June, seeking to entice researchers in other countries to France with offers of 4-year grants worth up to €1.5 million. Six weeks on, the programme has been flooded with applicants, says Anne Peyroche, a biologist and the chief research officer of the CNRS, France’s national basic-research agency. "Applications continue to come in every hour," she says. Most applied for relatively short sabbaticals in France, but the 154 scientists attracted by longer-term stays of four years or more are of most interest to the initiative's organizers, Peyroche says. France is also headhunting some top climate scientists individually, she adds. The scheme will shortlist as many as 80 scientists by mid-September, with 50 or so winners to be announced around the end of November. One applicant is Ashley Ballantyne, a bioclimatologist at the University of Montana in Missoula. His proposal involves laying the foundation for a global integrated carbon-observing network, combining satellite and atmospheric data to seek insights into how ecosystems respond to climate change. "There are very few funding opportunities in the United States that promote research on carbon–climate interactions at the global scale, so the fact this programme was looking for visionary thinking was appealing," he says. Ballantyne has long had informal collaborations with French and other European scientists, including at the renowned Laboratory of Climate and Environmental Sciences (LSCE) at Gif-sur-Yvette near Paris. His principal motivation for applying was the opportunity to strengthen and formalize these ties, he says. The French offer is a "very attractive proposition for many scientists in the US", says Kim Cobb, a palaeoclimatologist at the Georgia Institute of Technology in Atlanta. US climate science is under pressure, she adds: scientists are waiting to hear whether Congress will approve Trump's proposed drastic cuts to the field. Cobb says that, were she not a tenured scientist working in an exceptional research environment, she would be "jumping at the opportunity" to work in France. Officials in Germany announced on 13 July that they will establish a scheme to operate alongside the French programme. The German fund will comprise €15 million of government money, matched by a sum from the country's participating research organizations. The details of the programme have not yet been finalized, but Germany's research ministry has created a website for interested scientists to sign up to receive details. Peyroche says that the German fund will target younger or more-junior scientists than its French counterpart. Climate scientists in France support Macron's strong political and diplomatic stance on the Paris agreement. But a vocal minority of researchers argue that the scheme is largely a public-relations exercise to boost France's image abroad, even while research funds at home are scarce. The French government last week proposed trimming the 2017 budget for research and higher education by €331 million, as part of more than €3 billion of cuts in public spending to pay for new initiatives without increasing the national deficit. (The cuts for research activities are distributed across several ministries, from agriculture to defence; the research and higher education ministry itself will see only a €180-million reduction in its €23.85-billion budget, says its minister Frédérique Vidal.) On 13 July, France's Conference of University Presidents said in a statement that it "deplored" what it described as "incomprehensible" cuts. "These numbers should make any foreign scientist wonder about the generous invitation of President Macron to relocate to France," says Patrick Lemaire, a biologist at the University of Montpellier and founder of the researcher-led campaign group Sciences en Marche. "The cuts are a warning that the scientific environment they would find in France may be very far from the one they are promised." But Sacha Wunsch-Vincent, an economist at the World Intellectual Property Organization in Geneva, Switzerland, says that Macron's prominent overtures to foreign scientists and entrepreneurs are helping to promote France as a good place to do research and innovation, which is important for attracting top talent. "There is a seismic shift in the branding of France," he says.
News Article | December 12, 2016
PARIS (Reuters) - Global methane emissions from agriculture and other sources have surged in recent years, threatening efforts to slow climate change, an international study has found. Researchers led by French Laboratoire des Sciences du Climat et de l'Environnement (LSCE) reported that methane concentrations in the air began to surge around 2007 and grew precipitously in 2014 and 2015. In that two-year period methane concentrations shot up by 10 or more parts per billion (ppb) annually, compared with an average annual increase of only 0.5 ppb during the early 2000s, according to the study released by the Global Carbon Project, which groups climate researchers. Marielle Saunois, lead author of the study and assistant professor at Université de Versailles Saint Quentin, said that the increase in methane emissions could threaten efforts to limit global warming. "We should do more about methane emissions. If we want to stay below a 2 degrees (Celsius) temperature increase, we should not follow this track and need to make a rapid turnaround," she said in a statement. Methane is much less prevalent in the atmosphere than carbon dioxide (CO2) -- the main man-made greenhouse gas -- but is more potent because it traps 28 times more heat. The report did not say to what extent methane contributes to global warming. CO2 emissions are expected to remain flat for the third year in a row in 2016, thanks to falls in China, the Global Carbon Project said last month. Saunois said that while the reasons behind the methane surge are not well understood, the most likely sources are cattle ranching and rice farming. Cows expel large quantities of methane and the flooded soils of rice paddies are homes for microbes that produce the gas. She cited data from the United Nations' Food and Agriculture Organization indicating that livestock operations worldwide expanded from producing 1.3 billion head of cattle in 1994 to nearly 1.5 billion in 2014, with a similar increase in rice cultivation in many Asian countries. Robert Jackson, a co-author of the paper and Professor in Earth System Science at Stanford University, said that methane can come from many different sources, including natural sources such as marshes and other wetlands, but about 60 percent comes from human activities, notably agriculture. A smaller portion of the human contribution, about a third, comes from fossil fuel exploration, where methane can leak from oil and gas wells during drilling. "When it comes to methane, there has been a lot of focus on the fossil fuel industry, but we need to look just as hard, if not harder, at agriculture," Jackson said.
Lippold J.,University of Heidelberg |
Gherardi J.-M.,LSCE |
Gherardi J.-M.,University of Bergen |
Luo Y.,University of British Columbia
Geophysical Research Letters | Year: 2011
Variations of the Atlantic Meridional Overturning Circulation (AMOC) are believed to have crucially influenced Earth's climate due to its key role in the inter-hemispheric redistribution of heat and carbon. To assess its past strength, the sedimentary 231Pa/230Th proxy has been developed and improved but also contested due to its sensitivity to other factors beyond ocean circulation. In order to provide a better basis for the understanding of the Atlantic 231Pa/230Th system, and therefore to shed light on the controversy, we compare new measurements of Holocene sediments from the north Brazilian margin to water column data and the output of a two-dimensional scavenging-circulation model, based on modern circulation patterns and reversible scavenging parameters. We show that sedimentary 231Pa/230Th data from one specific area of the Atlantic are in very good agreement with model results suggesting that sedimentary 231Pa/230Th is predominantly driven by the AMOC. Therefore, 231Pa/230Th represents an appropriate method to reconstruct past AMOC at least qualitatively along the western margin. © 2011 by the American Geophysical Union.
Cattiaux J.,LSCE |
Vautard R.,LSCE |
Cassou C.,European Center for Research and Advanced Training in Scientific Computation |
Yiou P.,LSCE |
And 2 more authors.
Geophysical Research Letters | Year: 2010
The winter of 2009/2010 was characterized by record persistence of the negative phase of the North-Atlantic Oscillation (NAO) which caused several severe cold spells over Northern and Western Europe. This somehow unusual winter with respect to the most recent ones arose concurrently with public debate on climate change, during and after the Copenhagen climate negotiations. We show however that the cold European temperature anomaly of winter 2010 was (i) not extreme relative to winters of the past six decades, and (ii) warmer than expected from its record-breaking seasonal circulation indices such as NAO or blocking frequency. Daily flow-analogues of winter 2010, taken in past winters, were associated with much colder temperatures. The winter 2010 thus provides a consistent picture of a regional cold event mitigated by long-term climate warming. © 2010 by the American Geophysical Union.
Carrer D.,French National Center for Scientific Research |
Roujean J.-L.,French National Center for Scientific Research |
Hautecoeur O.,French National Center for Scientific Research |
Journal of Geophysical Research: Atmospheres | Year: 2010
This paper presents an innovative method for obtaining a daily estimate of a quality-controlled aerosol optical thickness (AOT) of a vertical column of the atmosphere over the continents. Because properties of land surface are more stationary than the atmosphere, the temporal dimension is exploited for simultaneous retrieval of the surface and aerosol bidirectional reflectance distribution function (BRDF) coming from a kernel-driven reflectance model. Off-zenith geometry of illumination enhances the forward scattering peak of the aerosol, which improves the retrieval of AOT from the aerosol BRDF. The solution is obtained through an unconstrained linear inversion procedure and perpetuated in time using a Kalman filter. On the basis of numerical experiments using the 6S atmospheric code, the validity of the BRDF model is demonstrated. The application is carried out with data from the Spinning Enhanced Visible and Infra Red Imager (SEVIRI) instrument on board the geostationary Meteosat Second Generation (MSG) satellite from June 2005 to August 2007 for midlatitude regions and from March 2006 to June 2006 over desert sites. The satellite-derived SEVIRI AOT compares favorably with Aerosol Robotic Network (AERONET) measurements for a number of contrasted stations and also similar Moderate Resolution Imaging Spectroradiometer (MODIS) products, within 20% of relative accuracy. The method appears competitive for tracking anthropogenic aerosol emissions in the troposphere and shows a potential for the challenging estimate of dust events over bright targets. Moreover, a high-frequency distribution of AOT provides hints as to the variability of pollutants according to town density and, potentially, motor vehicle traffic. The outcomes of the present study are expected to promote a monitoring of the global distributions of natural and anthropogenic sources and sinks of aerosol, which are receiving increased attention because of their climatic implications. Copyright 2010 by the American Geophysical Union.
Risi C.,University Pierre and Marie Curie |
Landais A.,LSCE |
Bony S.,University Pierre and Marie Curie |
Jouzel J.,LSCE |
And 2 more authors.
Journal of Geophysical Research: Atmospheres | Year: 2010
Combined measurements of δ18O, δ17O, and δD in ice cores, leading to d excess and 17O excess, are expected to provide new constraints on the water cycle and past climates. We explore different processes, both in the source regions and during the poleward transport, that could explain the 17O excess increase by 20 per meg observed from the Last Glacial Maximum (LGM) to Early Holocene (EH) at the Vostok station. Using a singlecolumn model over tropical and subtropical oceans, we show that the relative humidity at the surface is the main factor controlling 17O excess in source regions. Then, using a Rayleigh-type model, we show that the 17O excess signal from the source region is preserved in the polar snowfall, contrary to d excess. Evaporative recharge over mid and high latitudes and δ18O seasonality in polar regions can also affect the Vostok 17O excess but cannot account for most of the 20 per meg deglacial increase from LGM to EH. On the other hand, a decrease of the relative humidity at the surface (rhs) by 8 to 22% would explain the observed change in 17O excess. Such a change would not necessarily be incompatible with a nearly unchanged boundary layer relative humidity, if the surface thermodynamic disequilibrium decreased by 4°C. Such a change in rhs would affect source and polar temperatures reconstructions from δ18O and d excess measurements, strengthening the interest of 17O excess measurements to better constrain such changes. Copyright 2010 by the American Geophysical Union.
News Article | February 2, 2016
Because of spiking levels of human-induced greenhouse gas emissions, global warming will possibly unleash devastating and extreme flooding in the coming years. Scientists say it will be similar to the severe storms that targeted a coastal plain in England in 2014. In a new report, a team of experts explained that climate change had "amplified" the violent storms that flooded Somerset Levels during late 2013 and early 2014. Now, man-made greenhouse gas emissions have upped the chances of extreme flooding by 43 percent, scientists said, as increasingly warmer temperatures hold larger amounts of moisture that lead to heavier downpour. "What was once a 1 in 100-year event in a world without climate change is now a 1 in 70-year event," said Oxford University's Friederike Otto, co-author of the report. Their paper is the first research to look into the likely role of climate change in the winter flooding of Somerset Levels. During December 2013 and January 2014, heavy rainfall poured down the coastal plain and wetland area of central Somerset in South West England, affecting Somerset, Dorset, Devon, Cornwall and the Thames valley. The downpour led to extensive flooding, where more than 5,000 houses and establishments, as well as 17,000 acres of agricultural land, were submerged. Losses amounted to more than £450 million ($647 million). The truth is, no single extreme weather occurrence can be linked to climate change, but Otto says it is more possible to estimate how much more likely an event is shaped by global warming. Aside from the Somerset Levels, Otto also calculated the severe flooding that occurred in Cumbria by Storm Desmond in December. Otto found that it was made 40 percent more possible by climate change, and that the record rainfall in the UK over the whole of that month was 50 to 75 percent more likely because of global warming. "We can definitely say with climate change that the issue of flooding isn't going to go away," said Otto. "As a society we need to think hard about the question of our vulnerability and exposure to flooding." The study also applied contributions from citizen scientists all over the world who had all used spare processing time on their computers to calculate more than 130,000 simulations of what the weather would have been like with and without human interference in the climate. According to Dr. Pascal Yiou of the Laboratoire des Sciences du Climat e l'Environnement (LSCE), the increase in amount of rainfall had been due to a rise in moisture. "The more extreme the weather, the stronger the effect of climate change over the UK," said Yiou. Meanwhile, Beate Werner, one of the authors of the report, said the recent flooding in the UK are adding to evidence of worsening flood problems across Europe, which has occurred also because of draining, barricading and building on the flood plains around major rivers. The Somerset Levels study, which is featured in the journal Nature Climate Change, was conducted by experts from LSCE and the Center for Ecology and Hydrology.
News Article | June 11, 2016
An extreme shift in the weather brought on by manmade emissions likely caused the torrential rains that flooded Paris last month, a new study says. Researchers at the Laboratory for Climate and Environment Sciences (LSCE) in France said the likelihood of unusual heavy rainfall, such as the one that caused the flooding of areas along the Seine River in May, has doubled in the past five decades as a result of global warming. They found that the probability of such extreme weather patterns happening had increased by more than 40 percent at the very least. LSCE senior scientist Robert Vautard said the rainstorms that flooded the French capital recently can be tied directly to the impacts of global warming on the Earth. During the three days of heavy raining, the water in the river Seine reached 6.07 meters (19.9 feet), which is the highest point it has ever been in the past three decades. The overflow from river tributaries forced thousands of people living in nearby towns to be evacuated. Torrential rains also caused widespread flooding in southern Germany, which destroyed several houses and vehicles. Reports say at least 18 people were killed in subsequent flooding in four European countries. The researchers, however, were not able to retrieve evidence from the heavy rainfall in Germany that it is strong enough to establish its potential connection to global warming. Despite this, the researchers believe that climate change may have also played a crucial role in the torrential rains in Germany. This only means that their observations were not in line with the climate models used, which would have allowed the researchers to draw robust conclusions similar to those from France. Climate scientists have found it difficult to establish a connection between extreme weather patterns, such as droughts and superstorms, and the impacts of climate change, which can take hundreds of years to measure. Richard Black, head of the London-based advocacy group Energy and Climate Intelligence Unit, explained that researchers are now able to make similar judgments such as provided by the LSCE study. He said that we now know that the heatwave in Europe and the heavy rainfall in the United Kingdom, which both occurred just last year, were made more likely because of climate change. Both events can be attributed to basic physics. As the atmosphere continues to become warmer, the more it is going to be able hold and discharge rainwater. Recent measurements show that the average surface temperature of the Earth has increased by as much as 1 degree Celsius (1.8 degrees Fahrenheit) as a result of manmade warming. If current trends continue, the temperature of the planet could rise up to 2 degrees Celsius (3.6 degrees Fahrenheit). This assessment takes into account efforts by national governments to reduce carbon emissions around the world. Satellite readings conducted for the past 25 years show that water vapor levels in the Earth's atmosphere have also increased by as much as 4 percent. This means that western and central Europe could continue to experience record-breaking rainfall events in the coming years. The findings of the Laboratory for Climate and Environment Sciences are set to be featured in the journal Hydrology and Earth System Sciences. © 2016 Tech Times, All rights reserved. Do not reproduce without permission.
Berg A.,LOCEAN |
Sultan B.,LOCEAN |
De Noblet-Ducoudre N.,LSCE
Geophysical Research Letters | Year: 2010
A large-scale crop model is forced by a range of climate datasets over West Africa to test the sensitivity of simulated yields to errors in input rainfall. The model skill, defined as the correlation between observed and simulated yield anomalies over 1968-1990 at the country scale, is used for assessment. We show that there are two essential rainfall features for the model to skillfully simulate interannual yield variability at the country scale: cumulative annual variability and frequency. At such a scale, providing additional information on intraseasonal variability, such as the chronology of rain events, does not improve the model skill. We suggest that such information is relevant at smaller spatial scales but is not spatially consistent enough to impact large-scale yield variability. Copyright © 2010 by the American Geophysical Union.