Tropical and northern wetlands likely to blame for greenhouse gas increases

A press release from the University of Guelph: A surprising recent rise in atmospheric methane likely stems from wetland emissions, suggesting that much more of the potent greenhouse gas will be pumped into the atmosphere as northern wetlands continue to thaw and tropical ones to warm, according to a new international study led by a University of Guelph researcher.

The study supports calls for improved monitoring of wetlands and human changes to those ecosystems – a timely topic as the Intergovernmental Panel on Climate Change prepares to examine land use impacts on greenhouse gas emissions, says Prof. Merritt Turetsky, Department of Integrative Biology.

Turetsky is the lead author
of a paper published today in Global Change Biology based on one of the largest-ever analyses of global methane emissions. The team looked at almost 20,000 field data measurements collected from 70 sites across arctic, temperate and tropical regions. Agnieszka Kotowska, a former master’s student, and David Olefeldt, a post-doc at Guelph, also were among 19 study co-authors from Canada, the United States, the United Kingdom, Finland, Germany and Sweden.

One of the strongest greenhouse gases, methane comes from agriculture and fossil fuel use, as well as natural sources such as microbes in saturated wetland soils. The amount of atmospheric methane has remained relatively stable for about a decade, but concentrations began to rise again in 2007. Scientists believe this increase stems partly from more methane being released from thawing northern wetlands.

Scientists have assumed that wetland methane release is largest in the tropics, said Turetsky. “But our analyses show that northern fens, such as those created when permafrost thaws, can have emissions comparable to warm sites in the tropics, despite their cold temperatures. That’s very important when it comes to scaling methane release at a global scale.”....

US Fish and Wildlife Service photo of tundra in the Arctic

Research into carbon storage in arctic tundra reveals unexpected insight into ecosystem resiliency

Science Daily: When UC Santa Barbara doctoral student Seeta Sistla and her adviser, environmental studies professor Josh Schimel, went north not long ago to study how long-term warming in the Arctic affects carbon storage, they had made certain assumptions.

"We expected that because of the long-term warming, we would have lost carbon stored in the soil to the atmosphere," said Schimel. The gradual warming, he explained, would accelerate decomposition on the upper layers of what would have previously been frozen or near-frozen earth, releasing the greenhouse gas into the air. Because high latitudes contain nearly half of all global soil carbon in their ancient permafrost -- permanently frozen soil -- even a few degrees' rise in temperature could be enough to release massive quantities, turning a carbon repository into a carbon emitter.

"The Arctic is the most rapidly warming biome on Earth, so understanding how permafrost soils are reacting to this change is of major concern globally," Sistla said.

To test their hypothesis, the researchers visited the longest-running climate warming study in the tundra, the U.S. Arctic Long-Term Ecological Research site at Toolik Lake in northern Alaska. This ecosystem-warming greenhouse experiment was started in 1989 to observe the effects of sustained warming on the Arctic environment.

What they initially found was typical of Arctic warming: low-lying, shallow-rooted vegetation giving way to taller plants with deeper roots; greater wood shrub dominance; and increased thaw depth. What they weren't expecting was that two decades of slow and steady warming had not changed the amounts of carbon in the soil, despite changes in vegetation and even the soil food web.

The answer to that mystery, according to Sistla, might be found in the finer workings of the ecosystem: Increased plant growth appears to have facilitated stabilizing feedbacks to soil carbon loss. Their research is published in the recent edition of the journal Nature.

"We hypothesize that net soil carbon hasn't changed after 20 years because warming-accelerated decomposition has been offset by increased carbon inputs to the soil due to a combination of increased plant growth and changing soil conditions," Sistla said....

Alaskan tundra, shot by Maisotti, Wikimedia Commons, under the Creative Commons Attribution 3.0 Unported license

Global warming turns tundra to forest

Reuters: Plants and shrubs have colonised parts of the Arctic tundra in recent decades growing into small trees, a scientific study found, adding the change may lead to an increase in global warming pressures if replicated on a wider scale. Scientists from Finland and Oxford University investigated an area of 100,000 square km, roughly the size of Iceland, in the northwestern Eurasian tundra, stretching from western Siberia to Finland.

Using data from satellite imaging, fieldwork and observations from local reindeer herders, they found that in 8-15 percent of the area willow and alder plants have grown to over 2 metres in the last 30-40 years. A report of the research is published on Sunday in the journal Nature Climate Change.

"It's a big surprise that these plants are reacting in this way," said Marc Macias-Fauria of Oxford University and lead author of the report. Scientists had thought that the colonisation of the warming Arctic would take centuries, he said.

"But what we've found is that the shrubs that are already there are transforming into trees in just a few decades." Previous studies suggested that the advance of forest into Arctic tundra could increase Arctic warming by an extra 1-2 degrees Celsius (1.8-3.6 Fahrenheit) by the late 21st Century.

Warming in the Arctic is happening about twice as fast as in the rest of the world. As reflective snow and ice recede, they expose soil or water which are a darker colour and so soak up more of the sun's heat....

Tundra near Svalbard in Norway, shot by Jerzy Strzelecki, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

More grasslands, less tundra in Alaska's future

Yereth Rosen in Reuters: Long-term climate shifts will mean the spread of prairie-like grasslands and the displacement of much of the tundra habitat in Alaska and neighboring parts of Canada, according to a report released this week by the University of Alaska.

The report predicts climate shifts through the end of the century in Alaska and Canada's Yukon and Northwestern Territories.

The two-year Alaska, Yukon and Northwestern Territories Climate-Biome Shift Projects, conducted by the university in collaboration with government agencies and nonprofit groups from the United States and Canada, maps out expected changes for the 18 identified sub-climates in the study area, ranging from sparsely vegetated northern Arctic tundra to rainforest and grasslands.

Some changes are expected to be drastic, the report said. While climates have evolved in the past, the predicted transformations will be "a lot more rapid than historical changes in climate," said Nancy Fresco, a University of Alaska Fairbanks research professor and project manager for the Alaska and Canadian studies....

A road dip caused by melting tundra near Barrow, Alaska. Shot by Dr. John Cloud of NOAA

As Arctic temperatures rise, tundra fires increase

Research.gov: Scientists have found evidence of unprecedented tundra burning on the North Slope of Alaska. Their research indicates that tundra burning increases dramatically when temperatures rise above a mean threshold.

Within the global carbon cycle, what is the fate of the enormous amount of organic carbon stored in tundra ecosystems? Scientists just aren't sure. But results from this study shed new light, indicating that tundra burning is sensitive to climate warming. Increased burning could cause sudden releases of carbon dioxide and accelerate climate warming, while also diminishing subsistence resources for Arctic indigenous people.

In September 2007, the Anaktuvuk River Fire burned more than 1,000 square kilometers of tundra on Alaska's North Slope. This burn area was twice the size of any measured since recordkeeping began in 1950. A team of scientists from multiple universities, led by Feng Sheng Hu at the University of Illinois, sought to answer a simple question: Was this seemingly historic fire an anomaly, or were large fires regular occurrences in the region? They analyzed the distribution of charcoal particles in lake-sediment cores and found no evidence of a fire of similar scale or intensity in the region over the past 5,000 years.

The researchers then developed a model relating the tundra area burned in Alaska each year to the mean temperature and precipitation in the warmest period of the year--June through September. They found a dramatic, nonlinear relationship between climate conditions and tundra fires. That is, once the temperature rises above a mean threshold--or what one may call a tipping point--of 10 degrees Celsius (50 degrees Fahrenheit), tundra burning increases dramatically...

A tundra fire in Northern Alaska, shot by the US National Park Service

Ignored tundra fires could have impact on global warming

International Business Times: The amount of soil-bound carbon released to atmosphere in the 2007 Anaktuvuk River fire was enough to impact the global climate, according to UF ecologist Michelle Mack and other scientists. "The 2007 fire was the canary in the coal mine," Mack said. "In this wilderness, hundreds of miles away from the nearest city or source of pollution, we're seeing the effects of a warming atmosphere. It's a wakeup call that the Arctic carbon cycle could change rapidly, and we need to know what the consequences will be."

The fire covered more than 400 square miles on the North Slope of Alaska's Brooks Range and 2.1 million metric tons of carbon was released in the fire. It was twice the size the amount of greenhouse gases generated by Miami in one year. The fire not only inserted greenhouse gases into the atmosphere but it also consumed 30 percent up of the insulating layer of the organic matter that protects moss covered landscape. Arctic tundra stores large amounts of carbon in cool, wet soils insulated by permafrost, a layer of permanently frozen ground.

"When the permafrost warms, microbes will begin to decompose that organic matter and could release even more carbon that's been stored in the permafrost for hundreds or thousands of years into the atmosphere," Mack said. "If that huge stock of carbon is released, it could increase atmospheric carbon dioxide drastically."

The study revealed how isolated fires can have massive impact, said University of Alaska biology professor Terry Chapin. "When you think about the massive carbon stocks and massive area of tundra throughout the world, and its increasing vulnerability to fire as climate warms, it suggests that fire may become the dominant factor that governs the future carbon balance of this biome," Chapin said....

The village of Anaktuvuk Pass in 1969

Russian boreal forests undergoing vegetation change

Fariss Samarrai in University of Virginia Today: Russia's boreal forest – the largest continuous expanse of forest in the world, found in the country's cold northern regions – is undergoing an accelerating large-scale shift in vegetation types as a result of globally and regionally warming climate. That in turn is creating an even warmer climate in the region, according to a new study published in the journal Global Change Biology and highlighted in the April issue of Nature Climate Change.

…"We've identified that the boreal forest, particularly in Siberia, is converting from predominantly needle-shedding larch trees to evergreen conifers in response to warming climate," said the study's lead author, Jacquelyn Shuman, a post-doctoral research associate in environmental sciences in U.Va.'s Graduate School of Arts & Sciences. "This will promote additional warming and vegetation change, particularly in areas with low species diversity."

…The researchers used a climate model to assess what would happen if evergreens continued to expand their range farther north and larch species declined. The "positive feedback" cycle of warming promoting warming showed an increase of absorbed surface warming. The model takes into account detailed information about tree growth rates, and the results agree with actual field studies documenting changes in cone production and movement of evergreen treelines northward.

…The Russian boreal forest sits over a tremendous repository of carbon-rich soil frozen in the permafrost. As the forest changes in species distribution from larch to evergreens, warming of the ground surface would cause decomposition of the soil, releasing huge quantities of carbon dioxide into the atmosphere – possibly as much as 15 percent of the carbon dioxide currently in the atmosphere. "This is not the scenario one would want to see," Shugart said. "It potentially would increase warming on a global scale."…

Jack London Lake near Kolyma in Siberia, shot by Bartoshd, Bartosh Dmytro, Ukraine, Kiev, http://fotostudio.com.ua, Wikimedia Commons, under the Creative Commons Attribution 3.0 Unported license

Shrinking tundra, advancing forests: how the Arctic will look by century's end

EurekAlert: Imagine the vast, empty tundra in Alaska and Canada giving way to trees, shrubs and plants typical of more southerly climates. Imagine similar changes in large parts of Eastern Europe, northern Asia and Scandinavia, as needle-leaf and broadleaf forests push northward into areas once unable to support them. Imagine part of Greenland's ice cover, once thought permanent, receding and leaving new tundra in its wake.

Those changes are part of a reorganization of Arctic climates anticipated to occur by the end of the 21st century, as projected by a team of University of Nebraska-Lincoln and South Korean climatologists. In an article to be published in a forthcoming issue of the scientific journal Climate Dynamics, the research team analyzed 16 global climate models from 1950 to 2099 and combined it with more than 100 years of observational data to evaluate what climate change might mean to the Arctic's sensitive ecosystems by the dawn of the 22nd century.

The study is one of the first to apply a specific climate classification system to a comprehensive examination of climate changes throughout the Arctic by using both observations and a collection of projected future climate changes, said Song Feng, research assistant professor in UNL's School of Natural Resources and the study's lead author.

Based on the climate projections, the new study shows that the areas of the Arctic now dominated by polar and sub-polar climate types will decline and will be replaced by more temperate climates – changes that could affect a quarter to nearly half of the Arctic, depending on future greenhouse gas emission scenarios, by the year 2099.

Changes to Arctic vegetation will naturally follow shifts in the region's climates: Tundra coverage would shrink by 33 to 44 percent by the end of the century, while temperate climate types that support coniferous forests and needle-leaf trees would push northward into the breach, the study shows.

"The expansion of forest may amplify global warming, because the newly forested areas can reduce the surface reflectivity, thereby further warming the Arctic," Feng said. "The shrinkage of tundra and expansion of forest may also impact the habitat for wildlife and local residents."…

Area of the Arctic National Wildlife Refuge coastal plain, looking south toward the Brooks Range mountains. US Fish and Wildlife Service photo

Biomes in Alaska shifting due to climate change

Woods Hole Research Center: A new study released today in the EarlyView of Ecology Letters addresses forest productivity trends in Alaska, highlighting a shift in biomes caused by a warming climate. The findings, conducted by scientists at the Woods Hole Research Center and three other institutions based in Alaska and France, linked satellite observations with an extensive and unique tree-ring data set. Patterns observed support current hypotheses regarding increased growth of evergreen forest at the margins of present tundra and declining productivity at the margins of temperate forest to the south. This study provides a regional picture of forest productivity which did not previously exist.

According to lead author Pieter Beck, a post-doctoral fellow at WHRC, “The results provide evidence for the initiation of a biome shift in response to climate change, and indicate that some ecosystem models may be missing fundamental changes taking place in the circumpolar region.” He adds that “while the findings contrast with some recent model predictions of increased high latitude vegetation productivity, they are consistent with longer-term projections of global vegetation models.”

Scott Goetz, a senior scientist at WHRC, proposed the study and co-authored the manuscript. He says, “Most people don’t think of high latitudes forests as being drought stressed - and they are not in the traditional sense of having soils dry up and blow away - but their growth is negatively impacted by hot dry air masses and those have increased in recent years. This paper shows those drought impacts are captured in both the satellite and the tree ring record. Of course the tree rings go back in time much further than the satellite observations, which only extend about 30 years, but the changes that we observe from satellites are clearly supported not only by the tree rings but also by carbon isotope analysis of the wood.”

Beck adds that climate driven changes in the disturbance regime, which can rapidly alter forest dynamics and the ability of boreal forests to migrate into current tundra areas, will most likely shape the biome shift in the future….

These maps show trends in remotely sensed gross productivity (Prs) between 1982 and 2008 and trends in spruce growth since 1982 in Alaska (left) and the area around Fairbanks (right). White shading indicates sparsely vegetated or human modified land cover. Light gray shading indicates the trend in Prs from 1982 to 2008 was non-deterministic based on a Vogelsang significance test (a = 0.05), and dark gray areas had wildfires anywhere between 1982 and 2007. Green and brown shading in the symbols indicate increasing and decreasing ring widths, respectively, in unburned stands from 1982 to the year of sampling which ranged from 1994 to 2008. Map from the Woods Hole Research Center website

Thawing permafrost likely will accelerate global warming in coming decades

University of Colorado at Boulder News: Up to two-thirds of Earth's permafrost likely will disappear by 2200 as a result of warming temperatures, unleashing vast quantities of carbon into the atmosphere, says a new study by the University of Colorado Boulder's Cooperative Institute for Research in Environmental Sciences.

The carbon resides in permanently frozen ground that is beginning to thaw in high latitudes from warming temperatures, which will impact not only the climate but also international strategies to reduce fossil fuel emissions, said CU-Boulder's Kevin Schaefer, lead study author. "If we want to hit a target carbon dioxide concentration, then we have to reduce fossil fuel emissions that much lower than previously thought to account for this additional carbon from the permafrost," he said. "Otherwise we will end up with a warmer Earth than we want."

…While other studies have shown carbon has begun to leak out of permafrost in Alaska and Siberia, the study by Schaefer and his colleagues is the first to make actual estimates of future carbon release from permafrost. "This gives us a starting point, and something more solid to work from in future studies," he said. "We now have some estimated numbers and dates to work with."

…Schaefer and his team ran multiple Arctic simulations assuming different rates of temperature increases to forecast how much carbon may be released globally from permafrost in the next two centuries. They estimate a release of roughly 190 billion tons of carbon, most of it in the next 100 years. The team used Intergovernmental Panel on Climate Change scenarios and land-surface models for the study.

"The amount we expect to be released by permafrost is equivalent to half of the amount of carbon released since the dawn of the Industrial Age," said Schaefer. The amount of carbon predicted for release between now and 2200 is about one-fifth of the total amount of carbon in the atmosphere today, according to the study….

Helicopter view of crack patterns in the permafrost, shot by Mila Zinkova , Wikimedia Commons,under the Creative Commons Attribution-Share Alike 3.0 Unported license

Soil microbes define dangerous rates of climate change

Seed Daily: The rate of global warming could lead to a rapid release of carbon from peatlands that would further accelerate global warming. Two recent studies published by the Mathematics Research Institute at the University of Exeter highlight the risk that this 'compost bomb' instability could pose, and calculate the conditions under which it could occur.

…The first paper by Catherine Luke and Professor Peter Cox describes the basic phenomenon. When soil microbes decompose organic matter they release heat - this is why compost heaps are often warmer than the air around them.

The compost bomb instability is a runaway feedback that occurs when the heat is generated by microbes more quickly than it can escape to the atmosphere. This in turn requires that the active decomposing soil layer is thermally-insulated from the atmosphere. Catherine Luke explains: "The compost bomb instability is most likely to occur in drying organic soils covered by an insulating lichen or moss layer".

The second paper led by Dr Sebastian Wieczorek and Professor Peter Ashwin, also of the University of Exeter, proves there is a dangerous rate of global warming beyond which the compost bomb instability occurs. This is in contrast to the general belief that tipping points correspond to dangerous levels of global warming....

Càrn na Ceàrdaich. A flat and boggy summit with views across the peatlands towards Ben More. Shot by Richard Webb, Wikimedia Commons via Geograph UK, under the Creative Commons Attribution-Share Alike 2.0 Generic license

As Arctic temperatures rise, tundra fires increase

University of Illinois News Bureau: In September, 2007, the Anaktuvuk River Fire burned more than 1,000 square kilometers of tundra on Alaska's North Slope, doubling the area burned in that region since record keeping began in 1950. A new analysis of sediment cores from the burned area revealed that this was the most destructive tundra fire at that site for at least 5,000 years. Models built on 60 years of climate and fire data found that even moderate increases in warm-season temperatures in the region dramatically increase the likelihood of such fires. The study was published this October in the Journal of Geophysical Research.

After the Anaktuvuk fire, University of Illinois plant biology professor Feng Sheng Hu sought to answer a simple question: Was this seemingly historic fire an anomaly, or were large fires a regular occurrence in the region? … "If such fires occur every 200 years or every 500 years, it's a natural event," Hu said. "But another possibility is that these are truly unprecedented events caused by, say, greenhouse warming."

On a trip to Alaska in 2008, Hu chartered a helicopter to the region of the Anaktuvuk fire and collected sediment cores from two affected lakes. He and his colleagues analyzed the distribution of charcoal particles in these cores and used established techniques to determine the approximate ages of different sediment layers. The team found no evidence of a fire of similar scale and intensity in sediments representing roughly 5,000 years at that locale.

The researchers then analyzed 60 years of fire, temperature and precipitation records from the Alaskan tundra to determine whether specific climate conditions prevailed in years with significant tundra fires. They developed a model relating the tundra area burned in Alaska each year to the mean temperature and precipitation in the warmest period of the year: June through September.

This analysis uncovered a striking pattern, Hu said. "There is a dramatic, nonlinear relationship between climate conditions and tundra fires, and what one may call a tipping point," he said. Once the temperature rises above a mean threshold of 10 degrees Celsius (50 degrees Fahrenheit) in the June-through-September time period, he said, "the tundra is just going to burn more frequently."…

The 2007 Anaktuvuk River Fire burned more than 1,000 square kilometers of tundra on Alaska's North Slope. It was the largest fire in the region since 1950, when record-keeping began. Photo courtesy Department of Land Management

Study finds permafrost warming

Terra Daily: Permafrost warming continues throughout a wide swath of the Northern Hemisphere, according to a team of scientists assembled during the recent International Polar Year. Their extensive findings, published in the April-June 2010 edition of Permafrost and Periglacial Processes, describe the thermal state of high-latitude permafrost during the International Polar Year, 2007-2009.

Vladimir Romanovsky, a professor with the snow, ice and permafrost group at the University of Alaska Fairbanks Geophysical Institute, is the lead author of the paper, which also details the significant expansion of Northern Hemisphere permafrost monitoring. "This paper is actually pretty unique," Romanovsky said, "because it's the first time such a large geographical area has been involved in one paper."

During the International Polar Year, Romanovsky and his colleagues launched a field campaign to improve the existing permafrost-monitoring network. The permafrost thermal state is monitored with borehole sensors, which gather data from holes drilled deep into the permafrost.

The researchers established nearly 300 borehole sites that serve as permafrost observatories across the polar and sub-polar regions in the Northern Hemisphere. Their work more than doubled the size of the previously existing network… Having data from across the circumpolar North allows scientists to analyze trends affecting permafrost. The article notes that permafrost temperatures have warmed as much as two degrees Celsius from 20 to 30 years ago….

Permafrost in Svalbard, Norway, shot by Hannes Grobe, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 2.5 Generic license

Permafrost thaw threatens Russia oil and gas complex

Energy Daily via Agence France-Presse: Thawing permafrost caused by global warming is costing Russian energy firms billions of dollars annually in damage control and shrinking Russia's territory, Greenpeace warned in a new study Friday. According to the report by the environmental watchdog, up to 55 billion roubles (1.9 billion dollars) a year is spent on repairs to infrastructure and pipelines damaged by changes in the permafrost in western Siberia.

"For Russia, the biggest threat of the permafrost melt is to oil and gas company infrastructure," said Vladimir Chuprov, who heads Greenpeace's energy programme in Russia. He said that the group had consulted with experts at gas giant Gazprom in writing its report, which detailed the destruction to infrastructure such as pipelines caused by rising temperatures and resulting melt water.

"These are people who see what is happening and are already feeling the economic consequences of it," he told reporters in Moscow…. The permafrost thaw has accelerated in recent years and Russia is now shrinking by 30 square kilometres (12 square miles) per year as icey territory disappears from the coastline, one of the authors of the report, Oleg Anisimov, warned….

Zapadno-Kluchevskoe oil in the Tomsk region of Siberia, shot by Ivan Petrov / Иван Петров, Wikimedia Commons, under the Creative Commons Attribution ShareAlike 3.0 License

Warming peat could release megatonnes of carbon

Environmental Research Web: A one-degree warming of the world's northern peatlands could increase respiration enough to release 38–100 megatonnes of carbon each year. Such a rise is much higher than previously believed and would offset much of the European Union's target for greenhouse gas emissions cuts under the Kyoto Protocol, which is currently 92 megatonnes of carbon per year.

"Northern peatland soils store about one-third of the world's total amount of soil carbon, which has accumulated during centuries to millennia owing to the strongly adverse conditions for the breakdown of organic plant remains," Ellen Dorrepaal of the VU University Amsterdam in the Netherlands told environmentalresearchweb. This storage is equivalent to more than half the carbon in the atmosphere.

Together with colleagues from the Royal Swedish Academy of Sciences and the University of Sheffield, UK, Dorrepaal found that an increase in spring and summer temperature of around 1 °C stimulated ecosystem respiration rates by as much as 52–60%. "One of the striking results was that this strong stimulation was sustained for at least eight years (which was the last time we performed these measurements)," she said, "and therefore did not decline as has been observed in warming studies in other ecosystem types."...

A peat bog in Ireland, shot by Amos, Wikimedia Commons via Flickr, under Creative Commons Attribution 2.0 License

Alaska's biggest tundra fire sparks climate warning

Tracey Logan in New Scientist: The fire that raged north of Alaska's Brooks mountain range in 2007 left a 1000-square-kilometre scorched patch of earth – an area larger than the sum of all known fires on Alaska's North Slope since 1950.

Now scientists studying the ecological impact of the fire report that the blaze dumped 1.3 million tonnes of carbon dioxide into the atmosphere – about the amount that Barbados puts out in a year. What's more, at next week's meeting of the Ecological Society of America in Albuquerque, New Mexico, two teams will warn that as climate change takes hold tundra fires across the Arctic will become more frequent.

Tundra fires only take off once certain thresholds are reached, says Adrian Rocha of the Marine Biological Laboratory, Woods Hole, Massachusetts. "But projected changes in climate over the next century – increased aridity, thunderstorms, and warming in the Arctic – will increase the likelihood that these thresholds will be crossed and thus result in more larger and frequent fires."…

Brooks Range Mountains, Arctic National Wildlife Refuge, US Fish and Wildlife Service