Heat still on despite warming slowdown

University of New South Wales Newsroom: The recent slowdown in the rise of global average air temperatures will make no difference to how much the planet will warm by 2100, a new study has found.

The peer-reviewed study, published today in Nature Climate Change, compared climate models that capture the current slowdown in warming to those that do not. The study found that long-term warming projections were effectively unchanged across the two groups of models.

“This shows that the slowdown in global warming has no bearing on long-term projections – it is simply due to decadal variability. Greenhouse gases will eventually overwhelm this natural fluctuation,” said lead author and Chief Investigator with the ARC Centre of Excellence for Climate System Science, UNSW Scientia Professor Matthew England.

To separate the long-term temperature outcomes from short-term variability the researchers took 200 climate simulations and re-evaluated them out to 2100 by comparing those that captured the current slowdown to those that did not.

The models were analysed using one of two IPCC carbon emission projections. The first was a scenario where greenhouse gas concentrations continue to rise unabated through the 21st Century. The second assumes emissions are reduced to address global warming, peaking by 2040 before declining sharply.

Under the high emissions scenario, the difference in average projected end-of-century warming between the two groups of models is less than 0.1°C; a tiny fraction of the projected 5°C global warming if emissions are not curbed. Warming of this magnitude is well beyond the 2°C threshold that is considered a target by the Australian Government and a safe limit by the IPCC....

Barbecue photo by Emilian Robert Vicol  Emilian Robert Vicol, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

Invasive species in the Great Lakes by 2063

A press release from McGill University: The Great Lakes have been invaded by more non-native species than any other freshwater ecosystem in the world. In spite of increasing efforts to stem the tide of invasion threats, the lakes remain vulnerable, according to scientists from McGill University and colleagues in Canada and the United States.

If no new regulations are enforced, they predict new waves of invasions and identify some species that could invade the Lakes over the next 50 years.

Over the past two centuries, more than 180 non-native species have been recorded in the Great Lakes and the rivers that flow into them. Nearly 20% of these species are considered to be harmful ecologically and economically, posing threats to the Lakes’ native biodiversity and multibillion dollar fishery. New threats are emerging because of risks associated with trade in live organisms and climate change, the researchers caution in a study in the Journal of Great Lakes Research.

In recent years, the pace of species invasions appears to have slowed dramatically, as measures have been taken to protect the lakes. This is why the three scenarios (optimistic, pessimistic and status quo) the researchers considered for the next 50 years hinge on the implementation and effectiveness of regulations aimed at blocking current means of entry for invasive species.

...In the most optimistic scenario, the risk of invasion is minimized by harmonized policies enforced by Canada and the United States. “Invasions are a transboundary issue,” says McGill professor Anthony Ricciardi, an invasive-species biologist who supervised the study. “In addition to harmonized regulations on live trade, the two countries must coordinate early detection and rapid response to new threats – before an invasion has progressed beyond control.”...

A photo from the EPA of a ship docked in Duluth, Minnesota

Worst case scenarios of sea level rise, and why scientists and policymakers consider them

Robert McSweeney in the Carbon Brief: Sea levels could rise by a maximum of 190 centimetres by the end of the century, according to a new study, which examines a worst case scenario for sea level rise. In reality, the amount of sea level rise we get is likely to be less than that. But scientists and policymakers examine such 'worst case' scenarios to safeguard against climate risks.

With 10 per cent of the world's population living less than 10 metres above sea level, the threat of  coastal flooding is significant. The Intergovernmental Panel on Climate Change (IPCC) expects sea level rise to cause a ' significant increase' in sea levels extremes and the risk of coastal flooding.

The new study, published in  Environmental Research Letters, considers the assessment of 13 ice sheet experts. They conclude that the contribution from ice sheets is likely to be greater than projected by the IPCC. The paper suggests that sea levels could rise by as much as 190 cm this century.

Projections of sea level rise are typically constructed by working out the contribution to sea level rise from different  factors. The biggest contribution is from water expanding as it warms, followed by melting glaciers, then melting ice sheets on Greenland and Antarctica.

The crucial question for sea level rise this century is how much ice will be lost from the ice sheets, the authors argue. But it remains one of the largest uncertainties. In its Fifth Assessment Report (AR5), the IPCC  says there isn't sufficient evidence for them to give probabilities of large-scale losses of ice sheets.

The new study uses expert judgement to consider areas of ice sheet loss that are often not included in the sea level  models that the IPCC bases its assessment on. They then combine these judgements with the methods used in AR5 to produce their upper-limit figure of 190 cm....

A 2008 FEMA photo by Patsy Lynch of Hurricane Ike debris in Port Arthur, Texas

Limits to Growth was right. New research shows we're nearing collapse

Graham Turner and Cathy Alexander in the Guardian (UK): The 1972 book Limits to Growth, which predicted our civilisation would probably collapse some time this century, has been criticised as doomsday fantasy since it was published. Back in 2002, self-styled environmental expert Bjorn Lomborg consigned it to the “dustbin of history”.

It doesn’t belong there. Research from the University of Melbourne has found the book’s forecasts are accurate, 40 years on. If we continue to track in line with the book’s scenario, expect the early stages of global collapse to start appearing soon.

Limits to Growth was commissioned by a think tank called the Club of Rome. Researchers working out of the Massachusetts Institute of Technology, including husband-and-wife team Donella and Dennis Meadows, built a computer model to track the world’s economy and environment. Called World3, this computer model was cutting edge.

The task was very ambitious. The team tracked industrialisation, population, food, use of resources, and pollution. They modelled data up to 1970, then developed a range of scenarios out to 2100, depending on whether humanity took serious action on environmental and resource issues. If that didn’t happen, the model predicted “overshoot and collapse” – in the economy, environment and population – before 2070. This was called the “business-as-usual” scenario.

The book’s central point, much criticised since, is that “the earth is finite” and the quest for unlimited growth in population, material goods etc would eventually lead to a crash.

So were they right? We decided to check in with those scenarios after 40 years. Dr Graham Turner gathered data from the UN (its department of economic and social affairs, Unesco, the food and agriculture organisation, and the UN statistics yearbook). He also checked in with the US national oceanic and atmospheric administration, the BP statistical review, and elsewhere. That data was plotted alongside the Limits to Growth scenarios.

The results show that the world is tracking pretty closely to the Limits to Growth “business-as-usual” scenario. The data doesn’t match up with other scenarios...

Straits of Mackinac ‘worst possible place’ for a Great Lakes oil spill

University of Michigan News: Because the strong currents in the Straits of Mackinac reverse direction every few days, a rupture of the oil pipeline beneath the channel would quickly contaminate shorelines miles away in both lakes Michigan and Huron, according to a new University of Michigan study commissioned by the National Wildlife Federation.

In one scenario examined in the study and accompanying animations, oil from a hypothetical pipeline break reached Mackinac Island and Round Island after 12 hours and Bois Blanc Island after two days. All three islands are in westernmost Lake Huron, just east of the straits.

Within 20 days of a spill in the Straits of Mackinac -- which separates Michigan's upper and lower peninsulas and connects lakes Michigan and Huron -- oil would spread as far west as Beaver Island in Lake Michigan, a distance of roughly 35 miles, and as far southeast as Rogers City in Lake Huron, a distance of about 50 miles, according to the computer-simulation study released today and conducted by hydrodynamics expert David Schwab of the U-M Water Center.

The area around the 5-mile-wide straits is considered ecologically sensitive and is a major tourist draw. "If you were to pick the worst possible place for an oil spill in the Great Lakes, this would be it," Schwab said. "The currents are powerful and change direction frequently. In the event of an oil spill, these factors would lead to a big mess that would be very difficult to contain."

Just west of the Mackinac Bridge, two 20-inch underwater pipes carry 23 million gallons of crude oil daily through the straits. The 61-year-old pipeline is operated by Enbridge Inc.

..."Any material released into the straits will go into both Lake Michigan and Lake Huron, which would complicate containment efforts," Schwab said. "Hopefully, these simulations and animations will be useful in understanding and preparing for potential impacts."...

Under the Mackinac Bridge crossing the Straits of Mackinac, shot by varnent, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Climate models underestimate costs to future generations

A press release from the University of Gothenburg: Future generations will have to pay more for today's carbon emissions than what governments across the world currently understand. The climate models used by policymakers around the world to estimate the economic and social costs of CO2 emissions have to be improved according to Thomas Sterner, professor of Environmental Economics at the School of Business, Economics and Law, University of Gothenburg, and six other scientists in the prestigious journal Nature.

The seven scientists behind the article, due to be published 10 April[,] .... conclude that the reports by the UN climate panel serve an important function in setting the agenda for climate research. Yet the most
important role of the Intergovernmental Panel on Climate Change (IPCC) is to inform the global political discussion on how the harm caused by climate change should be handled.

Thomas Sterner, expert on policy instruments to reduce greenhouse gas emissions, is a Coordinating Lead Author of one key chapter on policy instruments in the Working Group III of the Fifth Assessment Report of the UN (IPCC) climate report that is scheduled to be presented on Sunday 13 April in Berlin.

‘Our purpose with this article in Nature is to discuss models that will enable us to calculate a necessary minimum level for the global environmental damage of emitting an additional ton of carbon dioxide. This cost is very relevant given the attempts of the White House to raise the so-called social cost of carbon in the U.S. to 37 dollars per ton. All U.S. authorities (such as the Departments of Energy or Transport) must take this cost into account in calculations of investments in roads and energy supply,’ says Sterner.

The social cost of carbon correspond to the money saved when damages due to climate change are avoided as a result of the countries of the world undertaking policy that leads to reduced emissions of CO2.  ‘Sweden has already gone further than what the U.S. is discussing, since we have a CO2 tax of about USD 150 per ton, or SEK 1 per kilo, of CO2 emissions from transports and energy,’ says Sterner....

Image by Barbara Lock, Wikimedia Commons, under the Creative Commons CC0 1.0 Universal Public Domain Dedication 

Warming climate may spread drying to a third of earth

A press release from the Earth Institute at Columbia University: Increasing heat is expected to extend dry conditions to far more farmland and cities by the end of the century than changes in rainfall alone, says a new study. Much of the concern about future drought under global warming has focused on rainfall projections, but higher evaporation rates may also play an important role as warmer temperatures wring more moisture from the soil, even in some places where rainfall is forecasted to increase, say the researchers.

The study is one of the first to use the latest climate simulations to model the effects of both changing rainfall and evaporation rates on future drought. Published this month in the journal Climate Dynamics, the study estimates that 12 percent of land will be subject to drought by 2100 through rainfall changes alone; but the drying will spread to 30 percent of land if higher evaporation rates from the added energy and humidity in the atmosphere is considered. An increase in evaporative drying means that even regions expected to get more rain, including important wheat, corn and rice belts in the western United States and southeastern China, will be at risk of drought. The study excludes Antarctica.

“We know from basic physics that warmer temperatures will help to dry things out,” said the study’s lead author, Benjamin Cook, a climate scientist with joint appointments at Columbia University’s Lamont-Doherty Earth Observatory and the NASA Goddard Institute for Space Studies. “Even if precipitation changes in the future are uncertain, there are good reasons to be concerned about water resources.”

...Using two drought metric formulations, the study authors analyze projections of both rainfall and evaporative demand from the collection of climate model simulations completed for the IPCC’s 2013 climate report. Both metrics agree that increased evaporative drying will probably tip marginally wet regions at mid-latitudes like the U.S. Great Plains and a swath of southeastern China into aridity. If precipitation were the only consideration, these great agricultural centers would not be considered at risk of drought. The researchers also say that dry zones in Central America, the Amazon and southern Africa will grow larger. In Europe, the summer aridity of Greece, Turkey, Italy and Spain is expected to extend farther north into continental Europe....

A NOAA image of a dust storm

Massive UN report says climate risks go beyond red alert

NBC News: Global warming is driving humanity toward a whole new level of many risks, a U.N. scientific panel reports, warning that the wild climate ride has only just begun. Disasters such as killer heat waves in Europe, wildfires in the United States, droughts in Australia and deadly flooding in Mozambique, Thailand and Pakistan highlight how vulnerable humanity is to extreme weather, a Nobel Prize-winning group of scientists says in a massive new report released early Monday. The dangers are going to worsen as the climate changes even more, the report's authors say, and no one is immune.

"We're all sitting ducks," Princeton University professor Michael Oppenheimer, one of the main authors of the 32-volume report from the Intergovernmental Panel on Climate Change, said in an interview.

After several days of late-night wrangling, more than 100 governments unanimously approved the scientist-written 44-page summary — which is aimed at world political leaders. The summary mentions the word "risk" an average of about five times per page. "Changes are occurring rapidly and they are sort of building up that risk," said the overall lead author of the report, Chris Field of the Carnegie Institution for Science in California.

These risks are both big and small, according to the report. They are now and in the future. They hit farmers and big cities. Some places will have too much water, some not enough, including drinking water. Other risks mentioned in the report involve theprice and availability of food, and to a lesser and more qualified extent some diseases, financial costs and even world peace.

"Things are worse than we had predicted" in 2007, when the group of scientists last issued this type of report, said report co-author Saleemul Huq, director of the International Centre for Climate Change and Development at the Independent University in Bangladesh. "We are going to see more and more impacts, faster and sooner than we had anticipated."....

Canberra bush fires in 2003, public domain

A ‘Back to the Future’ approach to taking action on climate change

A press release from the University of Cincinnati: How can communities dodge future disasters from Mother Nature before she has dealt the blow? Researchers are taking a unique approach to the issue and gaining input and support from community stakeholders. Daniel Murphy, a University of Cincinnati assistant professor of anthropology, will present findings on March 20, at the 74th annual meeting of the Society for Applied Anthropology (SFAA) in Albuquerque, N.M.

The presentation reveals an innovative, interdisciplinary research technique for approaching climate change vulnerability that’s called Multi-scale, Interactive Scenario-Building (MISB). The project focuses on two geographic case studies: Big Hole Valley in Montana – a high-altitude ranching valley – and Grand County in Colorado – a resort community west of Denver and south of Rocky Mountain National Park.

...The researchers posed three scenarios involving future drastic climate changes. The one-on-one interviews involved around 30 people for each region, ranging from ranchers to teachers, small business owners, hunting guides, county planners and representatives from federal and state agencies. Ecologists on the research team would then predict the impact of the suggested planning. The three possible scenarios were:

• Some Like it Hot – Describes years and years of consistent summer drought. 
• The Seasons, They’re a-Changing – Describes changes in seasonality, such as significantly increased rainfall in the spring.
• Feast or Famine – Describes big swings in temperature and precipitation between years.

“Areas like the Big Hole depend on snow to irrigate their hayfields,” explains Murphy, “so little snowfall could pose a big problem. Not only does it affect their hay crop, but in a region with the Arctic Grayling, a candidate for endangered listing, the water shortage would affect wildlife. Because of these scenarios, more groups were open to conservation efforts. All community interests were able to see the benefits of conservation efforts.”

...A lot of research in this area tends to focus on past vulnerability or past adaptation, and from my perspective, that’s come and gone. The real opportunities lie in the future, and we’re examining how city planners, urban planners and extension agents can utilize our research in future decision-making,” says Murphy...

Big Hole Pass in Big Hole Valley, Idaho, shot by Spend A Day Touring, LLC, Wikimedia Commons via Flickr, under the Creative Commons Attribution-Share Alike 2.0 Generic license

Unstable Atlantic deep ocean circulation under future climate conditions

AlphaGalileo via University of Bergen: A new study looking at past climate change, asks if these changes in the future will be spasmodic and abrupt rather than a more gradual increase in the temperature.

Today, deep waters formed in the northern North Atlantic fill approximately half of the deep ocean globally. In the process, this impacts on the circum-Atlantic climate, regional sea level, and soak up much of the excess atmospheric carbon dioxide from industrialisation — helping to moderate the effects of global warming. Changes in this circulation mode are considered a potential tipping point in future climate change that could have widespread and long-lasting impacts including on regional sea level, the intensity and pacing of Sahel droughts, and the pattern and rate of ocean acidification and CO2 sequestration.

Until now, this pattern of circulation has been considered relatively stable during warm climate states such as those projected for the end of the century. A new study led by researchers from the Bjerknes Centre of Climate Research at the University of Bergen (UiB) and Uni Research in Norway, suggests that Atlantic deep water formation may be much more fragile than previously realised.

...“Our study demonstrates that deep water formation can be disrupted by the freshening of the regional surface water, which might happen due to enhanced precipitation and glacier melting under future climate change scenarios,” says Yair Rosenthal, a co-author on the paper.

...Many models have actually predicted a slow and gradual decline in North Atlantic circulation over the next century. However, different models offer widely different scenarios for what will happen in the future. While the climate of the last interglacial is not exactly what will be the case in a future greenhouse world, it does share some features, including being fresher and warmer by a few degrees Celsius in the northern Atlantic....

Ocean Circulation Conveyor Belt. The ocean plays a major role in the distribution of the planet's heat through deep sea circulation. This simplified illustration shows this "conveyor belt" circulation which is driven by the difference in heat and salinity. Records of past climate suggest that there is some chance that this circulation could be altered by the changes projected in many climate models.  US federal government image

New report calls for attention to abrupt impacts from climate change, emphasizes need for early warning system

A press release from the National Academy of Sciences: Climate change has increased concern over possible large and rapid changes in the physical climate system, which includes the Earth's atmosphere, land surfaces, and oceans.  Some of these changes could occur within a few decades or even years, leaving little time for society and ecosystems to adapt.  A new report from the National Research Council extends this idea of abrupt climate change, stating that even steady, gradual change in the physical climate system can have abrupt impacts elsewhere -- in human infrastructure and ecosystems for example -- if critical thresholds are crossed.  The report calls for the development of an early warning system that could help society better anticipate sudden changes and emerging impacts.

"Research has helped us begin to distinguish more imminent threats from those that are less likely to happen this century," said James W.C. White, professor of geological sciences at the University of Colorado, Boulder, and chair of the committee that wrote the report.  "Evaluating climate changes and impacts in terms of their potential magnitude and the likelihood they will occur will help policymakers and communities make informed decisions about how to prepare for or adapt to them."

Abrupt climate changes and impacts already under way are of immediate concern, the report says.  These include the disappearance of late-summer Arctic sea ice and increases in extinction rates of marine and terrestrial species.

Other scenarios, such as the destabilization of the west Antarctic ice sheet, have potentially major consequences, but the probability of these changes occurring within the next century is not well-understood, highlighting the need for more research.

In some cases, scientific understanding has progressed enough to determine whether certain high-impact climate changes are likely to happen within the next century.  The report notes that a shutdown in the Atlantic Ocean circulation patterns or a rapid release of methane from high-latitude permafrost or undersea ice are now known to be unlikely this century, although these potential abrupt changes are still worrisome over longer time horizons....

The calving front of the Pine Island Glacier in Antarctica, shot by NASA ICE, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic licens

Lancet highlights key links between consumption and climate change

AlphaGalileo via the Lancet: Models of future climate scenarios have taken insufficient account of population patterns and trends, according to a UCL review to be published in the print edition of The Lancet on 15th November 2013. The review, “Population, development, and climate change, links and effects on human health”, examines the interconnections between population growth and climate change, from the perspective of global health.

The authors found that while population growth is an important factor, it is consumers, rather than people per se, who drive climate change. Reducing consumption thus represents the most effective way to reduce carbon emissions. This can have substantial health co-benefits, and consideration of human health should therefore be integral to future plans for tackling climate change.

Professor Judith Stephenson, UCL’s Institute for Women’s Health, says: "Disruption of the environment and climate system caused by unprecedented human activity since the industrial revolution confronts us with an urgent and complex problem that requires reduction in growth of both consumption and population for a sustainable world.”

...Although population is an important factor, demographic trends are more significant for climate change than total population, says the review. Consumption patterns, together with ageing and urbanisation in some countries, have bigger implications for health and the reduction of carbon emissions than the total number of people in the world...

A detail of Hieronymous Bosch's "The Seven Deadly Sins"

Scientists develop new method to help global coasts adapt to sea level rise

A press release from the University of Southampton: A team of scientists, led by the University of Southampton, has developed a new method to help the world’s coasts adapt to global sea-level rises over the next 100 years.

...A new study led by Professor Robert Nicholls from the University of Southampton, has combined the available data on a number of different climate and non-climate (such as uplift, subsidence and natural phenomena - earthquakes for example) mechanisms, which contribute to sea-level change, to create appropriate scenarios of sea-level rise at any location when policy-makers consider impacts and adaption.

Professor Robert Nicholls says: “The goal here is not to ‘scare people’ but rather to encourage policy makers to think across the full range of possibilities. Hence, the problem can be addressed in a progressive and adaptive manner where sea-level rise is planned for now, and that plan includes monitoring and learning about sea-level change over the coming decades. This means that sea-level rise can be fully prepared for without over-adapting.

“Given that the uncertainties of sea-level rise are global, this approach will probably be widely applicable around the world’s coasts, especially in major coastal cities with high values and growing flood risk.”

To help develop the scenarios, the scientists from the universities of Southampton, Durham, Reading and Curtin University in Australia, along with the United Nations Development Programme, considered a wide range of situations - from cases of little data and few or no previous studies, to those where significant data and experience of earlier studies are available. This allowed them to explore the full range of uncertainties and risks to avoid estimates of sea-level impacts being made invalid every time new projections were published.

The timescale for the study is between 30 and 100 years into the future as this corresponds to the most relevant timescales considered for most developments in coastal zones....

A view of Rio from Corcovado, shot by Cafezinho, public domain

Urgent new time frame for climate change

EurekAlert via the University of Hawaii at Manoa: Ecological and societal disruptions by modern climate change are critically determined by the time frame over which climates shift. Camilo Mora and colleagues in the College of Social Sciences' Department of Geography at the University of Hawaii, Manoa have developed one such time frame. The study, entitled "The projected timing of climate departure from recent variability," will be published in the October 10 issue of Nature and provides an index of the year when the mean climate of any given location on Earth will shift continuously outside the most extreme records experienced in the past 150 years.

The new index shows a surprising result. Areas in the tropics are projected to experience unprecedented climates first – within the next decade. Under a business-as-usual scenario, the index shows the average location on Earth will experience a radically different climate by 2047. Under an alternate scenario with greenhouse gas emissions stabilization, the global mean climate departure will be 2069.

"The results shocked us. Regardless of the scenario, changes will be coming soon," said lead author Camilo Mora. "Within my generation, whatever climate we were used to will be a thing of the past."

...The study found that the overarching global effect of climate change on biodiversity will occur not only as a result of the largest absolute changes at the poles, but also, perhaps more urgently, from small but rapid changes in the tropics.

...Rapid change will tamper with the functioning of Earth's biological systems, forcing species to either move in an attempt to track suitable climates, stay and try to adapt to the new climate, or go extinct. "This work demonstrates that we are pushing the ecosystems of the world out of the environment in which they evolved into wholly new conditions that they may not be able to cope with. Extinctions are likely to result," said Ken Caldeira of the Carnegie Institution for Science's Department of Global Ecology, and who was not involved in this study. "Some ecosystems may be able to adapt, but for others, such as coral reefs, complete loss of not only individual species but their entire integrity is likely."...

Based on the cited public-domain source: The graph shows the average of a set of temperature simulations for the 20th century (black line), followed by projected temperatures for the 21st century based on a range of emissions scenarios (colored lines). The shaded areas around each line indicate the statistical spread (one standard deviation) provided by individual model runs. The net impacts of human actions and choices on future greenhouse gas concentrations are fed into models as different “scenarios.” For example, the scenario represented by the blue trend line above (IPCC Scenario B1) assumes that humans worldwide will make more sustainable development choices by using a greater range of, and more efficient, technologies for producing energy.

More than 500 million people might face increasing water scarcity

A press release from the Potsdam Institute for Climate Impact Research: Both freshwater availability for many millions of people and the stability of ecosystems such as the Siberian tundra or Indian grasslands are put at risk by climate change. Even if global warming is limited to 2 degrees above pre-industrial levels, 500 million people could be subject to increased water scarcity – while this number would grow by a further 50 percent if greenhouse-gas emissions are not cut soon. At 5 degrees global warming almost all ice-free land might be affected by ecosystem change. This is shown by complementary studies now published by scientists of the Potsdam Institute for Climate Impact Research (PIK).

 “We managed to quantify a number of crucial impacts of climate change on the global land area,” says Dieter Gerten, lead-author of one of the studies. Mean global warming of 2 degrees, the target set by the international community, is projected to expose an additional 8 percent of humankind to new or increased water scarcity. 3.5 degrees – likely to occur if national emissions reductions remain at currently pledged levels – would affect 11 percent of the world population. 5 degrees could raise this even further to 13 percent.

“If population growth continues, by the end of our century under a business-as-usual scenario these figures would equate to well over one billion lives touched,” Gerten points out. “And this is on top of the more than one billion people already living in water-scarce regions today.” Parts of Asia and North Africa, the Mediterranean and the Middle East are particularly vulnerable.

For the green cover of our planet, even greater changes are in store. “The area at risk of ecosystem transformation is expected to double between global warming of about 3 and 4 degrees,” says Lila Warszawski, lead author of another study that systematically compared different impact models – and the associated uncertainties – in order to gain a fuller picture of the possible consequences of climate change for natural ecosystems. This is part of the international Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP)....

View of Dhaulagiri mountain from Ghorepani, Nepal, shot by Bernard Gagnon, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported, 2.5 Generic, 2.0 Generic and 1.0 Generic license

Terrestrial ecosystems at risk of major shifts as temperatures increase

A press release from the European Geosciences Union: Over 80% of the world’s ice-free land is at risk of profound ecosystem transformation by 2100, a new study reveals. “Essentially, we would be leaving the world as we know it,” says Sebastian Ostberg of the Potsdam Institute for Climate Impact Research, Germany. Ostberg and collaborators studied the critical impacts of climate change on landscapes and have now published their results in Earth System Dynamics, an open access journal of the European Geosciences Union (EGU).

The researchers state in the article that “nearly no area of the world is free” from the risk of climate change transforming landscapes substantially, unless mitigation limits warming to around 2 degrees Celsius above preindustrial levels.

Ecosystem changes could include boreal forests being transformed into temperate savannas, trees growing in the freezing Arctic tundra or even a dieback of some of the world’s rainforests. Such profound transformations of land ecosystems have the potential to affect food and water security, and hence impact human well-being just like sea level rise and direct damage from extreme weather events.

The new Earth System Dynamics study indicates that up to 86% of the remaining natural land ecosystems worldwide could be at risk of major change in a business-as-usual scenario (see note). This assumes that the global mean temperature will be 4 to 5 degrees warmer at the end of this century than in pre-industrial times – given many countries’ reluctance to commit to binding emissions cuts, such warming is not out of the question by 2100.

“The research shows there is a large difference in the risk of major ecosystem change depending on whether humankind continues with business as usual or if we opt for effective climate change mitigation,” Ostberg points out.

But even if the warming is limited to 2 degrees, some 20% of land ecosystems – particularly those at high altitudes and high latitudes – are at risk of moderate or major transformation, the team reveals.

The researchers studied over 150 climate scenarios, looking at ecosystem changes in nearly 20 different climate models for various degrees of global warming. “Our study is the most comprehensive and internally consistent analysis of the risk of major ecosystem change from climate change at the global scale,” says Wolfgang Lucht, also an author of the study and co-chair of the research domain Earth System Analysis at the Potsdam Institute for Climate Impact Research....

Land ecosystem changes under global warming (Credit: Ostberg et al., 2013)

Warming is not the crucial uncertainty

Jon Cartwright in Environmental Research Web: Governments often have to perform cost-benefit analyses to determine which is the best climate policy. For instance, a more stringent fuel-efficiency target may cost car companies money to implement today, but that must be weighed up against the potential environmental damage, in terms of cost, that higher emissions would generate in the future. Such costs cannot be known for certain; they always have a degree of uncertainty.

Unfortunately, this uncertainty is often complex. For example, sea ice melts when heated, leaving less reflective ocean water in its place. Melting sea ice "non-linearly" translates into a large temperature increase because the water left absorbs more heat, creating more warming and thereby melting more sea ice.

Now economist Derek Lemoine at the University of Arizona and climate scientist Haewon McJeon at Pacific Northwest National Laboratory have investigated how nonlinear climate and economic uncertainties interact with one another, to affect the costs of different climate policies.

The pair began with a model of the energy system and the economy, and input 380 different technology scenarios – for instance, where there is a breakthrough in renewable energy or in nuclear power. For each of these scenarios, they figured out the best way, or policy, to keep carbon dioxide emissions beneath a certain concentration. This defined the cost of the policy, so that the researchers could then determine how much damage climate change would have to inflict to make that policy more economically sensible than doing nothing.

One result was that, under a wide range of scenarios, a carbon dioxide target of 500 parts per million (ppm) was most sensible; a lower target of 450 ppm was cost-effective only if the future sees major breakthroughs in low-carbon technology, or if high warming causes exceptional damage. (The current carbon dioxide concentration in the atmosphere is just over 400 ppm.)

By doing their analysis, however, Lemoine and McJeon could see which assumptions most strongly affected whether or not a policy was economically sensible. Contrary to popular belief, they found that the uncertainty in future technology, and the uncertainty in damage caused by warming, are more important economic parameters than the uncertainty in the amount of predicted warming....

A 2009 flood in the UK, shot by Patrick Mackie, Wikimedia Commons via Geograph UK, under the Creative Commons Attribution-Share Alike 2.0 Generic license

Siberia could experience widespread permafrost thaw due to global warming

Lee Rannals in RedOrbit: More evidence is pointing to the nightmare scenario that global warming is taking a toll on our planet. Oxford University scientists say that a global temperature rise of 2.7 degrees Fahrenheit could thaw the ground over a large area of Siberia, threatening the release of carbon from soil.

If the thawing of Siberia’s permafrost occurs, it could see that over 1,000 gigatons of the greenhouse gases carbon dioxide and methane are dished out into the atmosphere, adding an even larger global warming threat.

The scientists studied stalactites and stalagmites from caves located along the permafrost frontier in Siberia, where the ground stays permanently frozen in a layer of tens to hundreds of feet thick. Because these cave features only grow when liquid rainwater and snow melt drips into the caves, these formations record 500,00 years of changing permafrost conditions.

Records from 400,000 years ago show that a global warming of 2.7 degrees Fahrenheit is enough to cause substantial thawing of permafrost far north from its present-day southern limit.

“The stalactites and stalagmites from these caves are a way of looking back in time to see how warm periods similar to our modern climate affect how far permafrost extends across Siberia,” lead author Dr Anton Vaks of Oxford University’s Department of Earth Sciences, said in a statement. “As permafrost covers 24 percent of the land surface of the Northern hemisphere significant thawing could affect vast areas and release gigatonnes of carbon.”...

Permafrost in South Gydan, Siberia, shot by Skonstantinov09, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license 

Birds may need a hand to weather climate change

Durham University News: Birds in Asia may need a helping hand to adapt to climate change, according to scientists. A new study led by Durham University and BirdLife International, shows that many bird species are likely to suffer under future climate change, and will require enhanced protection of important sites, better management of the wider countryside, and in some of the most extreme cases may need to be physically moved to climatically suitable areas to help them survive.

The priority, the researchers say, is for stronger protection and effective management of networks of important sites for conservation which currently support priority species and could offer new habitat for birds forced to shift their distribution in future.

The research, published in the journal Global Change Biology, examined the potential future distributions of suitable climate within conservation sites (Important Bird Areas) for 370 Asian bird species of conservation concern across the Eastern Himalaya and Lower Mekong regions.

According to the scientists, the findings demonstrate how climate change could affect birdlife and conservation policy across the globe. The researchers say that adapting the way that conservation sites are managed, and facilitating the movement of species to suitable areas, will be critical to future conservation.

Projections show that at least 45% and possibly up to 88% of the 370 species studied will experience declines in suitable climate, leading to changing species composition at individual sites.

The study considered almost 500 scenarios of each bird species’ response to future climate change and showed, for the first time, that despite uncertainty in future climate projections, it was extremely likely that these changes in bird communities would occur. However, the site network as a whole is still likely to retain suitable climate for all species in future, meaning that current conservation efforts should be strengthened, but also adapted....

A red-crowned crane in flight in Hokkaido, Japan, shot by Alastair Rae, Wikimedia Commons via Flickr, under the Creative Commons Attribution-Share Alike 2.0 Generic license

Are we heading for 6° temperature rise?

Liz Kalaugher in Environmental Research Web: Climate scientist Kevin Anderson believes scientists at the interface of climate and policy may have used naive assumptions when modelling for a 2°C target.

They say never judge a book by its cover, but chances are a lecture entitled "Real clothes for the emperor: facing the challenges of climate change" will be fairly down-to-earth. That proved to be the case when Kevin Anderson of the Tyndall Centre for Climate Change Research at the University of Manchester, UK, gave the Cabot Annual Lecture 2012 in Bristol, UK, in November 2012.

In response to an audience member who commented that most climate scientists were simply trying to pay their bills, Anderson said "I don't think it's OK to walk past a mugging on the way to pay the mortgage. Climate scientists need to be good citizens too. Our science tells us we are killing people in poor parts of the world by putting our lights on and we need to make people think about that. Scientists need to start standing up for what they believe in. By staying quiet we are legitimizing it."

Back in 2011, Anderson published a paper in the Philosophical Transactions of the Royal Society A on how he felt today's integrated assessment models, which combine climate data with economic data, are dangerously flawed. Why? Because they are based on "naive" assumptions for factors such as emission growth rates and the date of emission peaks, they limit annual energy-emission reduction rates to between 2 and 4%, and assume uptake of geoengineering as well as a high penetration of nuclear power alongside untested carbon-capture and storage technologies.

"Because integrated assessment models typically use similar and inappropriate sets of assumptions, they repeatedly come up with the same narrow and fundamentally flawed answers," Anderson told environmentalresearchweb at the time. In his November talk, on the topic of emission growth rates used in models that were lower than real-world growth rates, he said "We've always underplayed everything we possibly can – we've done exactly what the sceptics said but in reverse."

..."With few exceptions the scenarios out there hide or massage historical emissions and emission trends," said Anderson. "So they change the framing of where we are today. They underestimate short-term growth out to the peak of emissions. The peak choice is Machiavellian at best. No-one thinks that we're going to peak in 2016 and yet virtually every model will peak in 2016, which gives you a nice answer for your policymaker."...

This map shows the average of a set of climate model experiments projecting changes in surface temperature for the period 2050-2059, relative to the period from 1971-1999. Future greenhouse gas emissions were fed into the climate models to project future temperature changes. In this temperature projection, emissions are based on the Intergovernmental Panel on Climate Change's emissions scenario "A2" (see Special Report on Emissions Scenarios for more information on the A2 scenario). Public domain