by Kieran Cooke, Climate News Network, November 30, 2013
The UK insurance industry is struggling to cope with the increased risk of flooding events associated with climate change.
LONDON – The insurance industry doesn't like climate change. Global warming is introducing a whole new element into the business of quantifying risk – the basic function of the insurance business. One of the main challenges facing insurers is the increased occurrence of floods in many countries.
The UK is one of the world’s leading insurance centres: a recent seminar at the University of Oxford in the UK examined flood patterns in Britain over recent years.
Not only is the incidence of flooding increasing – it is also becoming ever more unpredictable. “No business, particularly the insurance industry, likes volatility” says Matt Cullen, a floods specialist at the Association of British Insurers (ABI). “There’s no doubt there’s been a ramping up of flooding in the UK since the 1990s and this tends to spook the insurers. And the situation is only going to get worse with climate change.”
Assessing when and where flooding occurs is a highly complex business, says Professor Edmund Penning-Rowsell, of Oxford’s School of Geography and the Environment. Flooding is episodic and can also be very localised, he says: a particular area might be flooded for two years in succession and then be dry for ten years – while another, previously dry area sees the waters rise and homes wrecked.
Flood risk increasing
The ABI says flood-related costs in the UK have been rising dramatically: over the 2000 to 2010 period the industry paid out £4.5bn (US$7.2bn) to those whose homes or businesses had been hit by flooding – a 200% rise on pay-outs in the previous decade.
Under a long-standing agreement between the UK Government and the insurance industry, insurers have guaranteed that cover would be available to homeowners – even those judged to be in high flood risk areas - as long as the authorities continued to spend money on flood prevention works.
That agreement ended in mid-2013: in a move being keenly watched in other parts of the world, UK insurance groups and the Government are now trying to come up with a formula which both guarantees continuing flood risk cover for homeowners in future and also ensures the continued financial viability of the insurance industry.
Poor at greatest risk
Often, say insurance analysts, it’s the poorer in society who live in homes most exposed to flood risk. If there was a move towards a free-for-all in the insurance market, those households would either find it impossible to find insurance – or be forced to pay highly expensive premiums to specialist brokers.
The ABI is proposing setting up a new scheme called Flood Re which would provide insurance at what it says would be an affordable level for those most at risk from flooding. Flood Re would run a multi-million pound fund -- financed by a general levy on all household insurance policies -- which would cover the costs of flood claims.
The Government has given its tentative approval to the idea. However, the scheme is dependent on continuing government expenditure on building up flood defences.
According to UK government figures, about 5.2 million properties in England alone – that’s one in every six properties in the country – are at risk of flooding, either from rivers or the sea or from surface water flooding.
At present the UK is spending about £600m ($960m) per year on tackling flooding. The Government admits that, just to maintain existing flood protection levels, expenditure will need to rise by around 80% by 2035. And that estimate, say officials, does not include the cost of managing the risk of surface and groundwater flooding.
Saturday, November 30, 2013
Friday, November 29, 2013
World food security at risk as crop yields plateau
by Jake Lucas, Reuters, November 20, 2013
Wheat is seen during sunset in a field of the "Svetlolobovskoye" farm outside the village of Novosyolovo, some 240 km (149 miles) south of Russia's Siberian city of Krasnoyarsk, on October 7, 2013. REUTERS/Ilya Naymushin
LONDON (Thomson Reuters Foundation)–For the last decade and a half, a mysterious and worrisome trend has emerged in the farming world that has sent farmers, scientists and policy makers looking for answers.
Crop yields – how much of a crop is harvested per hectare – for some of the world’s major grains like rice, wheat and corn have gone from increasing year after year to plateauing in many of the world’s biggest grain producers.
Until about the middle of the 20th century, the only way farmers knew to increase production was to increase the area of land they farmed. But around that time, science and farming came together, and the advent of artificial fertilisers, advanced irrigation systems and a surge in selective breeding changed the way farmers grew their crops.
Suddenly, farmers could increase production without expanding farmland, and the global grain harvest exploded. From 1950 to 2011, the global grain harvest tripled, growing twice as much in those 61 years as it had in the history of agriculture before 1950, according to Lester Brown, founder of the Earth Policy Institute (EPI) and a food security expert.
But Brown, once a farmer himself, said farmers knew it would not last forever.
“The plateauing of grain yields is something we knew would come,” he said. “Farmers realize that there is a glass ceiling at some point that they can’t go beyond.”
With increases in population adding to the demand for food but eating up the land on which to grow it, that could pose an increasingly serious problem.
GROWING DEMAND
The U.N. Food and Agriculture Organisation (FAO) predicted in 2009 that a growing and increasingly affluent population will require 70% more food by 2050, and experts say we cannot count on creating new farmland to fill that gap.
“If we meet demand by expanding agriculture, that’s the worst thing you can do for climate change and biodiversity,” said Ken Cassman, Robert B. Daughtery professor of agronomy at the University of Nebraska-Lincoln.
He said we’re already seeing the effects of upping grain production by expansion in rainforests and on prairies, which has left us with only “remnants of ecosystems.” That leaves it to up to better yields to ensure we have enough grain to feed the world, he said.
Beginning in the 1980s, however, that has become more difficult. Around that time, rice yields in the Republic of Korea stopped increasing, and in the United States, some of the best maize farmers were increasingly hitting a wall.
Every year, farmers from all over the United States enter state and national farming contests to see who has the highest yield. The winner gets free seeds and tractors, and is paid to tour the country and give talks about how he or she did it.
“Thousands of farmers are motivated to win that contest,” Cassman said.
Yet, by the late 1990s, Cassman noticed the winning yields in those competitions had not changed significantly for several years. He gathered that if the most motivated farmers in the country failed to increase their yields, it was likely because they could not.
He hypothesised they had hit the crop’s yield potential, or the highest yield attainable using the best seeds and optimal levels of nutrients and water.
REACHING THE CEILING
Since then, he and other scientists have developed models, verified by crops grown in controlled lab settings, to estimate maize’s yield potential in different parts of the United States. They found those farmers had indeed reached it.
In December of 1998, Cassman presented a paper to the National Academy of Sciences that hypothesized national yields would plateau at about 70–80% of a crop’s yield potential.
“What we found initially is that all farmers can’t be operating at 100 percent of production,” he said. “You plateau because it’s no longer possible to do every little thing possible to push yields to the ceiling.”
He explained that, unlike farmers who enter yield contests, it does not make economic sense for most farmers to pour time and money into exacting applications of fertiliser and other inputs to increase yields by an extra 20 or 30%.
Using the models he and other scientists developed, the agronomist found countries were plateauing at just below their crops’ yield potential all over the world. Countries that have hit this point make up a sizeable chunk of the world grain market, he and other experts say.
“When you add up all the countries where yields are plateauing, they account for about 40% of world grain production,” Brown agreed.
Brown also thinks crops have hit a biological limit. Like an Olympic runner pushing the limits of the human body, some crops are hitting the limits of what they can produce, after being pushed as far as they can go through the use of fertilisers, better irrigation and selective breeding, he said.
“The ultimate limit is the process of photosynthesis itself, and that’s why we see gain yields plateau in country after country,” Brown said.
WATER LIMITS
But Tom Sinclair, an adjunct professor of crop science at North Carolina State University, with years of experience researching crop physiology, thinks water constraints will limit food production long before the limit of photosynthesis are reached.
“In the U.S. we’re starting to approach as much as you can get with the water we have,” he said – and the water is running out.
In some parts of the U.S., irrigation is what ensures crops prosper, and, in some cases, that they can survive at all. But nearly everywhere that crops are irrigated, water levels are dropping.
That leaves some experts concerned that if farmers continue to use as much water as they do now – 70% percent of the fresh water used each year around the world goes to grow crops – there won’t be enough left to continue irrigating in the future.
“If the irrigation level is not there then (farmers are) definitely bound by the amount of rainfall,” which a changing climate is making increasingly erratic and unpredictable, Sinclair said.
Not everyone agrees farmers are nearing yield limits, however. In the UK, many people say figuring out the cause of stagnating yields is not so simple.
“There is no one specific factor,” said James Mills, a policy advisor for the British National Farmers Union who represents the interests of wheat farmers. “If you talked to a hundred farmers you might get a hundred different answers.”
A report produced for the UK’s Department of Environment, Food and Rural Affairs (DEFRA) in 2012 investigated apparent yield plateaus for wheat and oilseed rape (used to produce vegetable oil) and found a variety of factors at play, including individual farming practices and regulatory constraints on fertilisers.
“It’s not a black and white picture,” said Simon Kightley of the UK-based National Institute for Agricultural Botany and an author of the report.
Still, most people have a hunch what the major forces are holding back growth of yields. Kightley said he thinks on-the-farm practices, like how much or how little farmers plow, play a significant role in why yields are plateauing.
THE ROLE OF CLIMATE CHANGE
Mills said many farmers feel government regulations on fertiliser use and protective seed coating have kept them from getting the boost in yields they are hoping for. But increasingly extreme weather also has become a serious contributing factor, especially in the last year and a half, he said.
That was also the conclusion of a study published in 2010 in Fields Crop Research that asserted climate change, and the increases in drought and extreme heat that result from it, is the primary driver of Europe’s stagnation in wheat yields.
But Brown said it is difficult, if not impossible, to measure the impact of climate change.
Focusing on the places where there is still room to increase yields is key to producing enough food without further damaging the environment and its ecosystems, said Cassman, the Nebraska agronomist.
The first step, he said, is to identify those places. His work now focuses on cataloging the “yield gap” of crops in countries all over the world, looking at how much room there is to increase yields before they reach their limits.
“I’m completely optimistic we can meet food demand, but you have to start making the right choices and investing in the right research,” he said. “Global agriculture by intelligent design. That’s what we need.”
Jake Lucas is an AlertNet Climate intern.
Michael Mann's "The Hockey Stick and the Climate Wars" -- Now in paperback, highly recommended
by Rick Piltz, Climate Science Watch, November 22, 2013
In The Hockey Stick and the Climate Wars, Michael Mann brings a unique vantage point to his "dispatches from the front lines," chronicling the war on climate science and scientists by the global warming denial machine, alongside the advance of scientific research and understanding. Prof. Mann tells an essential story, as many readers of this site are well-aware -- with detail, references, and interpretation of events during the past two decades that make this book not only a very good read, but a good reference work on science versus the denial machine.
In The Hockey Stick and the Climate Wars, Michael Mann brings a unique vantage point to his "dispatches from the front lines," chronicling the war on climate science and scientists by the global warming denial machine, alongside the advance of scientific research and understanding. Prof. Mann tells an essential story, as many readers of this site are well-aware -- with detail, references, and interpretation of events during the past two decades that make this book not only a very good read, but a good reference work on science versus the denial machine.
The Hockey Stick and the Climate Wars: Dispatches from the Front Lines, is available from Amazon and from Columbia University Press. If you order from Columbia University Press, use the promotional coupon code HOCMAN to get a 30% discount on the purchase price.
* * *
The global warming denial machine's predatory "Serengeti strategy" of singling out individual scientists and scientific findings for attack has been applied relentlessly to several leading climate scientists, none more so than Mann and the iconic "hockey stick" graph from paleoclimate research published in 1998. That pathbreaking work found that warming in the late 20th century was unprecedented over the last millennium. Since then, a growing and diverse body of painstaking paleoclimate research has produced multiple studies that essentially confirm and strengthen that early finding.
Mann begins his chronicle by revisiting 1995, when the IPCC Second Assessment Report concluded that "the balance of evidence suggests a discernible human influence on climate." This conclusion, arrived at by the leading climate scientists who had authored the IPCC report, and adopted by the governments of the world in the assessment's Summary for Policymakers, was seen as a threat by climate change contrarians and by a fossil fuel industry-funded campaign of denialism and obstruction.
That campaign of contrarianism and obstruction had been underway at least since the time of the 1992 Earth Summit held in Rio de Janeiro, where the foundational Framework Convention on Climate Change was adopted. I saw it in operation at a meeting at the State Department under the first Bush Administration, and in testimony at a hearing on global warming I organized as a professional staff member on the House Science, Space and Technology Committee in 1992.
So, with the IPCC 1995 report, the denialists began to hone their Serengeti strategy in earnest, singling out Ben Santer, lead author of the climate change detection and attribution chapter of the report, for an attack that was intended to destroy his reputation and career. They failed to do this -- Santer remains an active scientist at the cutting edge of research -- but they did establish a method and a template for action by a denial machine that has played a seriously destructive role in recent years.
In addition to a good discussion of the early years of what Mann calls the "climate wars," the first several chapters of the book also discuss the advancement of climate research through the 1990s. Chapters 5 ("The Origins of Denial") and 6 ("A Candle in the Dark") run through a rogues gallery of predatory denialists and contrarian scientists and how they came to use the media and the Internet as a substitute for peer-reviewed science -- along with a good discussion of how real science advances, and the importance of the major, multiply-authored and carefully vetted climate science assessments.
The scientifically based assessment, produced by leading experts in a field, which synthesizes the state of knowledge and relates it to the concerns of its intended users, is an exceptionally significant scientific-intellectual creation of the past several decades. And whether it's the international assessments of the Intergovernmental Panel on Climate Change or the periodic U.S. National Climate Assessments, the denial machine always goes to great lengths in seeking to discredit them.
I saw this in action while working in the U.S. Global Change Research Program/Climate Change Science Program Office, in particular under the second Bush Administration. The Bush White House did its best to ignore the IPCC Third and Fourth Assessment Reports (2001 and 2007), as well as the Arctic Climate Assessment Report (2004) -- and they went so far as to officially disown and effective suppress the first National Climate Assessment report (2000-2001). I have written and spoken about this Bush Administration science scandal at length on numerous occasions.
The work of Mann and his co-authors on the temperature record from paleoclimate research, i.e., the hockey stick graph, was given high salience in the IPCC 2001 Third Assessment Report -- and thus, predictably in retrospect, the authors and their findings became the target of a Serengeti strategy denialist attack that continued over the past decade. We had seen it with Ben Santer, with Jim Hansen, the most eminent federal climate scientist, and with my dear friend the great Stephen Schneider, a pioneering scientist on multiple fronts who also knew how to communicate. The denialists acted as though they believed that, if one or a few key scientists, or a single piece of significant research, was discredited, that the science of anthropogenic global warming would collapse.
But the denial machine hasn't really been interested in advancing the science of climate change, which is a complex and multifaceted body of work developed by thousands of scientists. Their fundamental aim is more in the realm of politics: manufacture an enhanced impression of fundamental scientific uncertainty -- create a sense in the media, in public opinion, that there is a raging debate in the science community over what are essentially widely-agreed findings -- provide talking points to elected politicians who have an interest in blocking policy action on climate -- and use attack tactics to question the credibility of climate science as an enterprise and undermine the reputations of leading scientists.
In Chapter 7-11 Mann tells his story, as a participant, of a years-long series of climate war battles, leading up to late 2009, over the effort to undermine climate science, in particular by undermining the temperature record established by Mann and his fellow paleoclimate researchers. Some of this focuses on the denial machine inside the Bush Administration (events that led to my decision to become a whistleblower are summarized on pages 110-112). Some of it focuses on the denial machine in Congress. These chapters document Mann's perspective on and analysis of the criticism from McIntyre and McKitrick, the inquisition of the scientists by the egregious Rep. Joe Barton (R-Texas) and the notorious Wegman report he commissioned, and the sorry case of the Soon and Baliunas study and how it was used by the denialists.
This, like the rest of the book, is valuable memoir material on the collision between the world of science and the realities of politics. For those who already know something about these events, Mann's narrative is a must-read. For attentive readers coming to this story for the first time, it is likely to be a real eye-opener.
Then, in Chapter 14, 207 pages into the book, we come to 'Climategate' -- the bogus controversy over scientists’ stolen emails – a denialist propaganda coup and allegation of scandal that was mishandled with shameful credulity in the mainstream media. Climate Science Watch had quite a bit to say about this matter while it was unfolding, and in connection with events leading up to it, in particular the denialist-contrarian attack on EPA's "Endangerment Finding" on greenhouse gases in 2009 -- including posting relevant statements by Santer, Schneider, and Phil Jones. We defended the scientists throughout against what was clearly a scurrilous attack in the war on climate science and scientists. Mann's 26-page exposition on "Climategate: The Real Story" is a must-read discussion by one who was caught up in the storm and profoundly influenced by the experience.
In the final chapter of the book, "Fighting Back," in an Epilogue, and now in a 14-page Postscript to the paperback edition, Mann brings the story up to date. As Climategate receded in the rearview mirror, ongoing attacks on climate science continued. But at least some members of the science community, which had been so ill-prepared to deal with the kind of politically motivated attacks it was subjected to by the denial machine, seemed to learn from bitter experience the need to confront the attacks and push back in a more timely and concerted way. Scientists have an essential role to play in keeping the public discourse honest, and we need more of them who have the ability and the guts to help hold politicians and the media accountable for not letting scientific illiteracy, misinformation, and the denial machine drive the public narrative.
During the past 25 years, the climate science community, through an extraordinary collaborative effort, has made great advances in understanding the Earth system, global climatic disruption, and the role of human activity in influencing global change. Some of them have made great contributions in communicating their findings and the implications of climate change -- in scientific assessments, congressional testimony, books, articles, and media appearances. There is much more to be done on this score.
We need more scientist-citizens -- experts who sometimes will step out of their labs, as it were, to act as public intellectuals, addressing their fellow citizens and those with policymaking and management responsibilities, drawing on their expertise and translating it for 'civilians' in a way that will elevate the national discourse on climate change and push society to do what needs to be done.
But climate scientists have identified and are characterizing a set of problems that go far beyond the ability of the science community to solve, no matter how well scientists communicate. Climate change must be dealt with in the arenas of politics, public policy, management, the media, and public opinion -- where scientific literacy is generally low and many conflicting agendas compete, driven by leaders with values, and interests to protect, that may be indifferent to, or even antithetical to, the norms and findings of scientific research. Communication and advice from the science community isn't simply delivered into a rational, intellectually sophisticated, public-spirited, pragmatic, problem-solving arena (although reading a nearly impenetrable Summary for Policymakers of an IPCC assessment report might give the impression the scientists believe it does) -- rather, it gets caught up in a political atmosphere that can be downright toxic.
Congress has settled into a gridlock of climate policy inaction, and international negotiations under the climate treaty drag along ineffectually. The U.S., and the world, are far short of where they need to be in order to deal meaningfully with the threat of global climatic disruption. That is a problem that concerns all of us. But it is great, and indispensable, to have outspoken scientist-citizens who are willing to join the fray.
* * *
A review at Skeptical Science includes this:
The sustained level of attack that Mann has been forced to endure is extraordinary. He's withstood threats to himself and his family, sustained PR campaigns targeting his university, mocking Youtube videos, slandering Google ads and intimidation from Republican congressmen and district attorneys. While reading through the litany of attacks, I couldn't help wondering what the attackers thought will happen - if they successfully intimidate the scientists, do they think the ice sheets will stop sliding into the ocean and sea levels will stop rising?
The book ends on a hopeful note. The virulent attacks on climate scientists have woken a sleeping bear as the scientific community has not stood by while their own are attacked. Mann speculates that perhaps Climategate and the attack campaign was the turning point when the denial movement tacitly accepted they had no honest, science-based case for denying human-caused global warming and had to resort to smearing and intimidation.
(UPDATE November 28) Also see these reviews:
Sylvia S. Tognetti, More reasons to read The Hockey Stick and the Climate Wars, November 28
D.R. Tucker, Amazing Grace: A Survivor's Story, November 26
* * *
For the record, some earlier posts, selected from a large archive of Climate Science Watch posts that cover events and themes developed in The Hockey Stick and the Climate Wars:
“The Hockey Stick and the Climate Wars” – and a skirmish with denialists on Amazon (February 11, 2012)
On the denialist inquisition against Mann and the University of Virginia:
Closing the book on Ken Cuccinelli, climate science denialist witch-hunter and Tea Party favorite (November 6, 2013)
Court rules for Univ. of Virginia and Michael Mann against denialist inquisition - scholarly e-mail and documents are protected communication (September 17, 2012)
Washington Post editorial: Resist denialist ‘freedom of information’ harassment of climate change scientists (May 30, 2011)
On Mann's current defamation lawsuit against the National Review and the Competitive Enterprise Institute:
DC judge denies another effort to derail Michael Mann's defamation lawsuit (September 13, 2013)
On the "Climategate" stolen scientists' email controversy:
Interview with Michael Mann on the Penn State Final Report and the war on climate scientists (July 1, 2010)
A review of the climate science stolen email controversy, with a few lessons for the future (April 28, 2011)
Open letter to Congress from U.S. scientists on Climate Change and Recently Stolen Emails
On the Congressional denialist witch hunt:
Reports and articles on the denial machine:
New Greenpeace report documents machinations of corporate-funded climate denial machine (September 12, 2013)
Books on the denial machine:
Political interference with climate science communication under the Bush Administration:
Rick Piltz testimony before the Senate Commerce Committee (February 7, 2007)
Climate Science Watch testimony at House Oversight Hearing (January 30, 2007)
Investigation documents political interference with climate science communication (January 30, 2007)
Atmosphere of Pressure (February 2007): Along with the Union of Concerned Scientists, this Government Accountability Project report uncovers new evidence of widespread political interference in federal climate science.
Redacting the Science of Climate Change (March 2007): Details the findings of a yearlong investigation by the Government Accountability Project into political interference at federal climate science agencies.
Methane Tracker
A very interesting site called Methane Tracker shows atmospheric methane over the Arctic.
Best viewed when choosing the layers from 650 mb / 11775 feet through 469 mb / 19819 feet.
http://www.methanetracker.org/
Take note that there is plenty of methane coming from other shelves around the Arctic, in particular off Greenland.
Best viewed when choosing the layers from 650 mb / 11775 feet through 469 mb / 19819 feet.
http://www.methanetracker.org/
Take note that there is plenty of methane coming from other shelves around the Arctic, in particular off Greenland.
NPS researchers predict summer Arctic ice might disappear by 2016, 84 years ahead of schedule
by David Schmalz, Monterey County Weekly, November 27, 2013
Tucked away on the third floor of the Naval Postgraduate School’s building of Engineering and Applied Sciences, a small team of researchers is leading an effort that will change the way the world thinks about the world. Their project is the Regional Arctic System Model (RASM), and it is arguably the most advanced – and accurate – Arctic climate model in existence.
Lt. Dominic DiMaggio describes the area captured by NPS’s innovative Arctic climate model, a project involving 25 researchers and graduate students from 10 institutions.
On a recent, sunny winter day, U.S. Navy Lt. Dominic DiMaggio – a master’s student in physical oceanography and meteorology and a RASM team member – lays out the model’s virtues and complexities, casually throwing around terms like “parameterization” and “highly non-linear functions.”
Then, almost 60 dizzying minutes later, he just as casually points to a graph showing a RASM projection for melting Arctic sea ice, a phenomenon that occurs every summer but has been accelerated by climate change: By the summer of 2016, the Arctic Ocean could be ice-free, opening the door to vast reserves of fossil fuel, and eventually, freeing up a shipping lane between Europe and Asia.
NPS Professor Wieslaw Maslowski, who leads the team of researchers behind RASM, says 2016 is at “the lower bound” of the current range of projections, while DiMaggio calls it “an aggressive interpretation” of RASM. But most conventional climate models predict the Arctic won’t have a sea ice-free summer until 2100. So why is the RASM model so different?
Mainly, it’s a matter of scope. Because most climate models are projecting the global climate, there is not enough computing power to account for what can often be key regional details.
One example DiMaggio gives is the Bering Strait, a narrow strip of water that is too small (51 miles wide) to be accurately accounted for in the wider lens of global models, but which “is significant in its impacts to the central Arctic.”
The amount of detail that RASM is able to capture in the Arctic is at least 10 times greater than a global model, and not only calculates projections based on air, ocean and ice conditions (which are standard in global models), but also includes inputs for land and riverflow.
“We’re modeling river runoff, the permafrost, the glaciers, even the chemical and biological processes,” says DiMaggio. “The ocean isn’t just the water, it’s the entire environment. And that’s what we’re trying to capture.”
RASM’s findings will help inform the Navy’s understanding of a region that is home to over a thousand miles of U.S. coastline, and which is changing faster than many expected, a reality charged with geopolitical implications. The Navy predicts the potential for extracting fossil fuels and minerals, as well as significantly shorter shipping routes, will likely attract commercial interests.
The stark image of an ice-free Arctic, meanwhile, might also impact the climate change discussion, one that Maslowski hopes “will be a critical argument against skeptics of global warming.”
RASM has the potential to greatly alter current global climate models.
“We’re hoping global modeling groups will use what we’ve learned to improve their models,” Dimaggio says, “so the decision makers have a better understanding of what’s actually happening.”
Jennifer Francis: The where and when of wetter and drier: disappearing Arctic sea ice plays a role
Environmental Research Letter, 8 (2013) 041002; doi:10.1088/1748-9326/8/4/041002
The where and when of wetter and drier: disappearing Arctic sea ice plays a role
Abstract
Summer precipitation in northern Europe has been above average for each of the past six years (2007–2012), a pattern that is unprecedented in over a century. During these same years, the summer Arctic sea-ice cover has averaged about 40% below its typical extent prior to the 1950s and set two new record minima. Could there be a connection? This is the question that motivated the new study by Dr. James Screen, a Research Fellow at the University of Exeter, UK, that appears in this issue of ERL (2013 Environ. Res. Lett. 8 044015). Adding to the growing body of evidence linking rapid Arctic warming to changing weather patterns in the northern hemisphere mid-latitudes, he concludes that sea-ice loss and associated surface warming lead to large-scale circulation patterns that favor wet summers in northern Europe and dry summers along the northern Mediterranean.
by Jennifer Francis
Dr. Screen used a state-of-the-art atmospheric model to compare the mid-latitude circulation during conditions of extensive sea ice (representative of the late 1970s) to that with much reduced sea ice (representative of present day). Except for the sea-ice extent and ocean temperatures where ice was lost, all surface conditions were fixed at climatological values in the model, thereby isolating the influence of sea-ice loss. Observation-constrained reanalysis fields were composited for the wettest and driest summers in northern Europe and used to verify the model simulations.
The atmospheric responses to reduced sea ice in both real and modeled worlds show not only precipitation patterns in Europe similar to those observed during the past six abnormally wet summers, but they also reveal features in the large-scale circulation that appear coincident with unusual weather patterns experienced elsewhere around the Northern Hemisphere in recent years. For example, the meridional wind anomalies near the jet-stream level (Figure 6a in Screen 2013) suggest that reduced sea ice favors enhanced ridging over the western North Atlantic, which is consistent with increased high-pressure blocking observed during June (Hanna et al. 2013) and expanded melting of the Greenland ice surface (Nghiem et al. 2012). The increased ridging implied by the pair of positive/negative anomalies over North America is consistent with recent drought and heat waves in the western part of the continent. Enhanced troughing in the eastern North Pacific agrees with an observed poleward shift in the Aleutian storm track (Bender et al. 2012). More generally, the patterns of response to sea-ice loss revealed in this investigation further support previous studies linking Arctic warming and ice loss with changes in the large-scale circulation (e.g., Overland et al. 2012, Screen and Simmonds 2013, Francis and Vavrus 2012, Petoukhov et al. 2013 and Cassano et al. 2013 and references therein).
This new study by Dr. Screen contributes additional evidence that Arctic sea-ice loss is partly responsible for shifting weather patterns, and provides new detail about the timing, location, and types of patterns that are expected to emerge as Arctic and global warming continue unabated.
'Brown Oceans' Known to Fuel Tropical Systems Over Land
by Sean Breslin, Weather Channel, July 19, 2013
A handful of tropical storms and hurricanes have defied the odds and strengthened over land. Now researchers believe they have a better understanding why this occurs.
Tropical systems are expected to weaken while interacting with land, but if conditions are ideal, a land mass can feed these entities and act as a "brown ocean." A recently released study, funded by NASA and conducted by Drs. Theresa Andersen and Marshall Shepherd of the University of Georgia has found that abundant soil moisture can continue to feed a tropical storm or hurricane long after it has left the warm waters of an ocean.
According to Shepherd, 227 of the 3,254 storms from 1979 to 2008 met the criteria for landfalling tropical systems globally. Of those 227, 182 storms weakened after moving over land, but 45 maintained or increased in strength. Those 45 storms -- roughly 20 percent of all landfalling storms in the study -- became the subject of the team's investigation.
"This is particularly critical since a study by former National Hurricane Center deputy director Ed Rappaport found that 59 percent of fatalities in landfalling tropical cyclones are from inland freshwater flooding," Shepherd said in the report.
Tropical Storm Erin was one of those such storms in 2007. As it moved over moisture-rich Oklahoma, Erin picked up steam, forming an eye-like feature over the Plains.
"Erin's remnant in 2007 is forever burned in my mind," said weather.com senior meteorologist Jon Erdman. "I had never seen a tropical cyclone remnant that far inland behave like that."
During Erin, Watonga, Okla. recorded more than three consecutive hours of high winds, with a peak gust to 82 mph, during the overnight hours of Aug. 19, 2007, Erdman said.
NWS RADAR IMAGE
(MORE: The Storm That Killed 300,000)
In retrospect, Stu Ostro, meteorologist at The Weather Channel, wrote that the storm should have been reclassified by the National Hurricane Center as a tropical cyclone as it passed over Oklahoma.
These inland tropical cyclone maintenance and intensification events (TCMI) have been observed in the U.S. and China, butoccur in Australia most frequently, according to a LiveScience story on the report.
As hurricane season ramps up, researchers will be closely watching these "brown oceans" to see if they revive more tropical cyclones passing over our heads.
MORE ON WEATHER.COM: The Deadliest Hurricanes of All-Time
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