Scientists play down 'tipping point' theory

Terra Daily via AFP: A doomsday-like scenario of sudden, irreversible change to the Earth's ecology -- a tipping point -- is not supported by science, Australian researchers say.

Writing in the journal Trends in Ecology and Evolution, scientists from the University of Adelaide, along with U.S. and British colleagues, argue that global-scale ecological tipping points are unlikely and that ecological change over large areas seem to follow a more gradual, smooth pattern.

"This is good news because it says that we might avoid the doom-and-gloom scenario of abrupt, irreversible change," Barry Brook, lead author of the paper and Director of Climate Science at the University of Adelaide, said. "A focus on planetary tipping points may both distract from the vast ecological transformations that have already occurred, and lead to unjustified fatalism about the catastrophic effects of tipping points."

The scientists say they refute recent efforts to define "planetary tipping points" -- critical levels of biodiversity loss or land-use change that would have global effect -- often presented as fact to policy makers.

"An emphasis on a point of no return is not particularly helpful for bringing about the conservation action we need," Brook said in a university release Thursday...

Sebastien Bourdon's 1657 painting, "The fall of Simon Magus"

Not-so-permanent permafrost

US Geological Survey: As much as 44 billion tons of nitrogen and 850 billion tons of carbon stored in arctic permafrost, or frozen ground, could be released into the environment as the region begins to thaw over the next century as a result of a warmer planet according to a new study led by the U.S. Geological Survey. This nitrogen and carbon are likely to impact ecosystems, the atmosphere, and water resources including rivers and lakes. For context, this is roughly the amount of carbon stored in the atmosphere today.

The release of carbon and nitrogen in permafrost could exacerbate the warming phenomenon and will impact water systems on land and offshore according to USGS scientists and their domestic and international collaborators. The previously unpublished nitrogen figure is useful for scientists who are making climate predictions with computer climate models, while the carbon estimate is consistent and gives more credence to other scientific studies with similar carbon estimates.

"This study quantifies the impact on Earth's two most important chemical cycles, carbon and nitrogen, from thawing of permafrost under future climate warming scenarios," said USGS Director Marcia McNutt. "While the permafrost of the polar latitudes may seem distant and disconnected from the daily activities of most of us, its potential to alter the planet’s habitability when destabilized is very real."

To generate the estimates, scientists studied how permafrost-affected soils, known as Gelisols, thaw under various climate scenarios. They found that all Gelisols are not alike: some Gelisols have soil materials that are very peaty, with lots of decaying organic matter that burns easily – these will impart newly thawed nitrogen into the ecosystem and atmosphere. Other Gelisols have materials that are very nutrient rich – these will impart a lot of nitrogen into the ecosystem. All Gelisols will contribute carbon dioxide and likely some methane into the atmosphere as a result of decomposition once the permafrost thaws – and these gases will contribute to warming. What was frozen for thousands of years will enter our ecosystems and atmosphere as a new contributor.

"The scientific community researching this phenomena has made these international data available for the upcoming Intergovernmental Panel on Climate Change. As permafrost receives more attention, we are sharing our data and our insights to guide those models as they portray how the land, atmosphere, and ocean interact," said study lead Jennifer Harden, USGS Research Soil Scientist....

Permafrost patterns shot from a helicopter in the High Arctic by Brocken Inaglory, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Are we prepared for total monsoon failure?

Hari Pulakkat in the Economic Times (India):  By the end of this week, the South West monsoon would have hit Indian shores. During a period of economic crisis, it would be one of the few welcome developments, although few people would look at it that way. The arrival of the South West monsoon is an event that is taken for granted, as surely as the arrival of summer or winter every year.

However, climatologists are now beginning to question this certitude. The South Indian monsoon has switched off completely in the past, sometimes for as much as ten seasons. Are we prepared for a scenario when the monsoon fails totally for ten years?

This question seems increasingly important as we - at least some countries - prepare responses to natural disasters. In India, policy-makers have prepared responses - at least in theory - for dealing with earthquakes, cyclones, tsunamis, infectious diseases like dengue fever and so on. They have discussed, probably without any serious conclusions, what would happen if there was a nuclear war between India and Pakistan.

No one has prepared a response or even remotely imagined a scenario where the monsoon fails completely, not just for a year but for a whole decade or forever. It would be India's ultimate natural disaster, following a nuclear war closely in terms of impact on people. Yet it is one disaster for which India would be completely unprepared...

Monsoon clouds over Lucknow, shot by Sunnyoraish, public domain

Regional warming a bumpy ride, warns climate scientist

Victoria University (Australia): Regional warming occurs in a series of steps rather than as a gradual trend, a new study by Victoria University has found. Climate scientist Professor Roger Jones from the Centre for Strategic Economic Studies told the Greenhouse 2011 Conference in Cairns this week that south-eastern Australia had experienced two large steps in warming during the past 45 years. The evidence showed most of the change was not due to natural climate variability.

The first step-change was in 1968 when minimum temperature increased by 0.7°C. There was also an underlying change in maximum temperature, which was masked by increased rainfall. During the second period of major change, from 1997–98, maximum temperatures increased by 0.9°C and rainfall fell by 9 per cent. Most of the warming in south-eastern Australia has occurred during these two periods, with little change in between.

The southern hemisphere also warmed in a step-wise fashion in these two periods. In 1997, the step-change was mirrored globally, with average temperatures worldwide increasing by 0.3°C. When regional climate simulated by eleven climate models was analysed, the same patterns of change were found. “Early 20th century climate is stable in all simulations until the second half of the 20th century”, he said. “Warming begins abruptly in one or two steps, then during the 21st century as greenhouse gas emissions accelerate, regional temperature warms in steps and trends.”

…“Most planning for adaptation to climate change is based on assuming gradual change. These findings have the potential to completely alter how we manage changing climate risks.”

Looking across the Wannon River valley to Mount Sturgeon (left) and Mount Abrupt (right). Dunkeld, Victoria, Australia, shot by Melburnian, Wikimedia Commons, under the Creative Commons Attribution 3.0 Unported license

Northern wildfires threaten runaway climate change, study reveals

EurekAlert: Climate change is causing wildfires to burn more fiercely, pumping more greenhouse gases into the atmosphere than previously thought, according to a new study to be published in Nature Geosciences this week. This is the first study to reveal that fires in the Alaskan interior - an area spanning 18.5 million hectares - have become more severe in the past 10 years, and have released much more carbon into the atmosphere than was stored by the region's forests over the same period.

"When most people think of wildfires, they think about trees burning, but most of what fuels a boreal fire is plant litter, moss and organic matter in surface soils," said University of Guelph professor Merritt Turetsky, lead author of the study.

"These findings are worrisome because about half the world's soil carbon is locked in northern permafrost and peatland soils. This is carbon that has accumulated in ecosystems a little bit at a time for thousands of years, but is being released very rapidly through increased burning."

"Essentially this could represent a runaway climate change scenario in which warming is leading to larger and more intense fires, releasing more greenhouse gases and resulting in more warming. This cycle can be broken for a number of reasons, but likely not without dramatic changes to the boreal forest as we currently know it."…

Wildfires in the Alaskan Interior. Shot David Wright, US Forest Service

Monsoon model indicates potential for abrupt transitions

Science Daily: A self-amplifying effect presently sustains monsoon winds, but it could also disrupt the circulation over land and sea. The periodical rainfall could stop from one season to another or for months within seasons. High air pollution could lead to the disruption, researchers of the Potsdam Institute for Climate Impact Research report in the Proceedings of the National Academy of Sciences, Online Early Edition. Global warming increases the risk of abrupt monsoon transitions from high-precipitation to dry periods.

"The agricultural food supply for around two billion people in Asia and Africa depends on the eponymous regularity of monsoon rainfall," says the lead author Anders Levermann. The name "monsoon" stems from the Arabic word "mausim" for "season." However, months with extremely scarce precipitation have been observed within monsoon seasons, as in India in 2002, causing economic and humanitarian problems in the affected regions. During the past 11,000 years rainfall in monsoon regions has undergone strong and abrupt changes repeatedly.

The researchers investigated how such irregularities or disruptions of monsoon circulations can come about. "Our analysis shows on the basis of observations that there could be two stable states for monsoon systems and the possibility of abrupt transitions from one to the other," says Levermann.

The driving force of monsoon systems depends on different air temperatures. In spring, the air over land is warmed up more rapidly than the air over the sea. The warmer air rises and moist and cooler air from the ocean flows landwards and yields precipitation, which has two effects: the rainfall cools the land surface, but also releases latent heat, when water vapour condenses to raindrops. The more moist air is transported landwards, the more latent heat is released through rainfall and the more moist air is drawn towards land. This self amplification, named moisture-advection feedback, sustains the temperature difference and the entire circulation. However, the self-amplification is vulnerable and may lead to abrupt changes in response to relatively weak external perturbations, the authors state….

A sunset view on monsoon clouds over the Bay of Bengal, from a beach in Tamil Nadu, India. Shot by mmj171188, Wikimedia Commons via Flickr, under the Creative Commons Attribution ShareAlike 2.0 License.

Similar early warning signals of change in climate, ecosystems, financial markets, human health

National Science Foundation: What do abrupt changes in ocean circulation and Earth's climate, shifts in wildlife populations and ecosystems, the global finance market and its system-wide crashes, and asthma attacks and epileptic seizures have in common? According to a paper published this week in the journal Nature, all share generic early-warning signals that indicate a critical threshold of change dead ahead.

In the paper, Martin Scheffer of Wageningen University in The Netherlands and co-authors, including William Brock and Stephen Carpenter of the University of Wisconsin at Madison and George Sugihara of the Scripps Institution of Oceanography in La Jolla, Calif., found that similar symptoms occur in many systems as they approach a critical state of transition. "It's increasingly clear that many complex systems have critical thresholds--'tipping points'--at which these systems shift abruptly from one state to another," write the scientists in their paper.

Especially relevant, they discovered, is that "catastrophic bifurcations," a diverging of the ways, propel a system toward a new state once a certain threshold is exceeded. … "These are compelling insights into the transitions in human and natural systems," says Henry Gholz, program director in the National Science Foundation (NSF)'s Division of Environmental Biology, which supported the research along with NSF's Division of Ocean Sciences.

"The information comes at a critical time--a time when Earth's and, our fragility, have been highlighted by global financial collapses, debates over health care reform, and concern about rapid change in climate and ecological systems."

It all comes down to what scientists call "squealing," or "variance amplification near critical points," when a system moves back and forth between two states. "A system may shift permanently to an altered state if an underlying slow change in conditions persists, moving it to a new situation," says Carpenter. Eutrophication in lakes, shifts in climate, and epileptic seizures all are preceded by squealing….

Early warning indicators have been found in Wisconsin's side-by-side Peter and Paul Lakes. Credit: Steve Carpenter, University of Wisconsin

Arctic climate change may be forcing faster warming on entire globe: report

Bob Weber in the Canadian Press: A new report says Arctic climate change is happening faster than anyone anticipated and may soon be forcing more rapid warming on the rest of the planet. "It is a tipping point," said Craig Stewart of the World Wildlife Fund, which was to release the report Wednesday in London.

The report is an attempt to update the work of scientists involved in the 2007 Intergovernmental Panel on Climate Change as world leaders prepare to gather in Copenhagen next December to discuss how to deal with the issue. The conclusion of many of those same top researchers is that changes are occurring much more quickly - especially in the Arctic - than was believed even two years ago. "We thought by 2050, multi-year (sea) ice would be cut in half," said Stewart from Ottawa. "Well, it happened in 2007."

But the biggest worry is the so-called methane hydrates - a strange, slushy form of methane frozen in ice molecules that exists in vast volumes in permafrost and continental shelves around the circumpolar globe. Cold and high pressure have so far kept that methane - a greenhouse gas 25 times more potent than carbon dioxide - out of the atmosphere….

Research indicates ocean current shutdown may be gradual

Oregon State University News: The findings of a major new study are consistent with gradual changes of current systems in the North Atlantic Ocean, rather than a more sudden shutdown that could lead to rapid climate changes in Europe and elsewhere. The research, based on the longest experiment of its type ever run on a "general circulation model" that simulated the Earth's climate for 21,000 years back to the height of the last Ice Age, shows that major changes in these important ocean current systems can occur, but they may take place more slowly and gradually than had been suggested.

The newest findings, to be published Friday in the journal Science, are consistent with other recent studies that are moving away from the theory of an abrupt "tipping point" that might cause dramatic atmospheric temperature and ocean circulation changes in as little as 50 years.

"Research is now indicating that this phenomenon may happen, but probably not as a sudden threshold we're crossing," said Peter Clark, a professor of geosciences at Oregon State University. "For those who have been concerned about extremely abrupt changes in these ocean current patterns, that's good news.

“In the past it appears the ocean did change abruptly, but only because of a sudden change in the forcing,” he said. “But when the ocean is forced gradually, such as we anticipate for the future, its response is gradual. That would give ecosystems more time to adjust to new conditions."

The findings do not change broader concerns about global warming. Temperatures are still projected to increase about four to 11 degrees by the end of this century, and the study actually confirms that some of the world's most sophisticated climate models are accurate….

Physiography for High Schools by Albert L. Arey, Frank L. Bryant, William W. Clendenin and William T. Morrey, USA: 1911.

Australian report on rapid climate change risks

Reuters: Rising seas, a rapid weakening of the Indian monsoon and spiraling costs of adapting to a warmer, drier world are just some of the looming risks from rapid climate change, a report for the Australian government says. The report, "Climate change 2009, faster change and more serious risks," examines the rapid progress of climate change science in recent years and the growing threats that face billions of people around the planet.

Rising temperatures, drought and long-term drying out of farmlands in Australia, Africa, the United States, acidifying oceans and rapid switches in weather patterns all threaten to undermine societies and cost billions in damage.

"Part of the reason for suggesting that the risks are higher than we thought is that the climate system appears to be changing faster than we thought likely a decade ago," the report's author Will Steffen told Reuters on Friday from Canberra, Australia. The report was written for the Department of Climate Change and comes five months before a major U.N. meeting that aims to seal a broader pact to fight global warming.

Many scientists have revised upwards their projections for the pace of global warming since United Nation's Climate Panel issued a major report in 2007, underscoring the increased focus on understanding the risks from climate change.

Steffen, executive director of the Climate Change Institute at the Australian National University, said drought and long-term drying out of farmlands and water catchment areas will likely cause costs to spiral as societies try to adapt….

US Geological Survey: Slight changes in climate may trigger major abrupt ecosystem responses that are not easily reversible. Some of these responses, including insect outbreaks, wildfire, and forest dieback, may adversely affect people as well as ecosystems and their plants and animals.

The U.S. Geological Survey led a new assessment of the implications of a warming world on "ecological thresholds" in North America. The report, which was commissioned by the U.S. Climate Change Science Program and authored by a team of federal and academic climate scientists, is based on a synthesis of published scientific literature and addresses what research and steps are needed to help mitigate resulting effects.

An ecological threshold is the point at which there is an abrupt change in an ecosystem that produces large, persistent and potentially irreversible changes. "One of our biggest concerns is that once an ecological threshold is crossed, the ecosystem in question will most likely not return to its previous state," said USGS Associate Director for Biology Susan Haseltine. "The existence of thresholds should be a key concern of scientists and natural resource managers."

The team also emphasized that human actions may increase an ecosystem's potential for crossing ecological thresholds. For example, additional human use of water in a watershed experiencing drought could trigger basic changes in aquatic life that may not be reversible. Researchers and decision makers need to develop the tools necessary to predict the effects of specific ecological disturbances and to understand early warning signals of impending ecological thresholds.

…To view the full report, Synthesis and Assessment Product 4.2: Thresholds of Climate Change in Ecosystems, visit http://climatescience.gov.

"Surprise," by Henri Rousseau, 1891

A Yankee-centric version of the IPCC

In case you missed this publication, from the U.S. Climate Science Program: The United States faces the potential for abrupt climate change in the 21st century that could pose clear risks to society in terms of our ability to adapt. “Abrupt” changes can occur over decades or less, persist for decades more, and cause substantial disruptions to human and natural systems.

A new report, based on an assessment of published science literature, makes the following conclusions about the potential for abrupt climate changes from global warming during this century:

• Climate model simulations and observations suggest that rapid and sustained September arctic sea ice loss is likely in the 21st century.
• The southwestern United States may be beginning an abrupt period of increased drought.
• It is very likely that the northward flow of warm water in the upper layers of the Atlantic Ocean, which has an important impact on the global climate system, will decrease by approximately 25–30 percent. However, it is very unlikely that this circulation will collapse or that the weakening will occur abruptly during the 21st century and beyond.
• An abrupt change in sea level is possible, but predictions are highly uncertain due to shortcomings in existing climate models.
• There is unlikely to be an abrupt release of methane, a powerful greenhouse gas, to the atmosphere from deposits in the earth. However, it is very likely that the pace of methane emissions will increase.

The U.S. Geological Survey led the new assessment, which was authored by a team of climate scientists from the federal government and academia. The report was commissioned by the U.S. Climate Change Science Program with contributions from the National Oceanic and Atmospheric Administration and the National Science Foundation….

Abrupt climate change in this century?

US Geological Survey: The United States faces the potential for abrupt climate change in the 21st century that could pose clear risks to society in terms of our ability to adapt. "Abrupt" changes can occur over decades or less, persist for decades more, and cause substantial disruptions to human and natural systems.

A new report, based on an assessment of published science literature, makes the following conclusions about the potential for abrupt climate changes from global warming during this century.

* Climate model simulations and observations suggest that rapid and sustained September arctic sea ice loss is likely in the 21st century.
* The southwestern United States may be beginning an abrupt period of increased drought.
* It is very likely that the northward flow of warm water in the upper layers of the Atlantic Ocean, which has an important impact on the global climate system, will decrease by approximately 25-30 percent. However, it is very unlikely that this circulation will collapse or that the weakening will occur abruptly during the 21st century and beyond.
* An abrupt change in sea level is possible, but predictions are highly uncertain due to shortcomings in existing climate models.
* There is unlikely to be an abrupt release of methane, a powerful greenhouse gas, to the atmosphere from deposits in the earth. However, it is very likely that the pace of methane emissions will increase.

The U.S. Geological Survey led the new assessment, which was authored by a team of climate scientists from the federal government and academia. The report was commissioned by the U.S. Climate Change Science Program with contributions from the National Oceanic and Atmospheric Administration and the National Science Foundation.

"This report was truly a collaborative effort between world renowned scientists who provided objective, unbiased information that is necessary to develop effective adaptation and mitigation strategies that protect our livelihood," said USGS Director Mark Myers. "It summarizes the scientific community's growing understanding regarding the potential for abrupt climate changes and identifies areas for additional research to further improve climate models."

...To view the full report, titled Synthesis and Assessment Product 3.4: Abrupt Climate Change, and a summary brochure on abrupt climate change, visit http://www.climatescience.gov/default.php.

The Illustrated London News for 23 January 1847 depicts the loss of USS Somers off Vera Cruz.