Tag Archives: Ice melt

Pre-history proof of climate’s see-saw sensitivity

The woolly rhinoceros once roamed wild on the plains of Europe Image: Public Library of Science via Wikimedia Commons
The woolly rhinoceros once roamed wild on the plains of Europe
Image: Public Library of Science via Wikimedia Commons

By Tim Radford

Computer simulations reaching back deep into the last Ice Age have enabled scientists to put a historic perspective on how even small variations in the climate system can lead to dramatic temperature change.

LONDON, 24 August, 2014 − It doesn’t take much to change a planet’s climate – just a little shift in the Northern hemisphere glacial ice sheet and a bit more carbon dioxide in the atmosphere. After that, the response is rapid. The tropical rain belt moves north and the southern hemisphere cools a bit, in some sort of bipolar see-saw response.

Sound familiar? It does, and it doesn’t. It all happened long before the internal combustion engine, or even the new Stone Age.

Researchers from the Alfred Wegener Institute’s Helmholtz Centre for Polar and Marine Research, Bremerhaven, the University of Bremen, Germany, and the University of Cardiff in the UK, report in Nature journal that they have made climate simulations that agree with observations of historical climate change that date back 800,000 years.

Long before the present alarms about global warming through the emission of carbon dioxide from fossil fuels, climate researchers were puzzled by the phenomenon of the Ice Ages and the “interglacials” that punctuated those long periods when the Arctic ice extended from the North Pole to the Atlantic coast of France, and over huge tracts of North America.

Vanished species

Mysteriously, and at great speed, the temperatures would rise by up to 10°C and the vast walls of ice would retreat. Lion, hyena and rhinoceros would invade the wild plains of what is now southern England, and now-vanished species of humans would hunt big game and gather fruit and seeds in the valleys and forests of Europe and America.

Since the end 10,000 years ago of the last ice age – itself a very rapid event – was the springboard for agriculture and civilisation, and eventually an Industrial Revolution based on fossil fuels, the story of climate change plays a powerful role in human history.

So any analysis of the tiny shifts in ice cover that seemed to trigger these dramatic, bygone events can be helpful in understanding the long story of the making of the modern world.

The researchers found a tentative scenario involving weak ocean currents, and prevailing winds that shifted the sea ice and allowed the oceans and atmosphere to exchange heat, pushing warmer water into the north-east Atlantic.

These changes precipitated a dramatic warming of the northern hemisphere in just a few decades, and the retreat of the glaciers for an extended period before the ice returned to claim much of the landmass again. But, overall, such changes tended to occur when sea levels reached a certain height.

“The rapid climate changes known in the scientific world as Dansgaard-Oeschger events were limited to a period of time from 110,000 to 23,000 years before the present,” said Xu Zhang, the report’s lead author.

“The abrupt climate changes did not take place at the extreme low sea levels, corresponding to the time of maximum glaciations 20,000 years ago, or at high sea levels such as those prevailing today. They occurred during periods of intermediate ice volume and intermediate sea levels”

Climate swings

Co-author Gerrit Lohmann, who leads the Wegener Institute’s palaeoclimate dynamics group, said: “Using the simulations performed with our climate model, we were able to demonstrate that the climate system can respond to small changes with abrupt climate swings.

“At medium sea levels, powerful forces − such as the dramatic acceleration of polar ice cap melting − are not necessary to result in abrupt climate shifts and associated drastic temperature changes.”

How much this tells anybody about modern climate change is open to debate. Right now, according to this line of evidence, the planet’s climate could be in one of its more stable phases of the Earth’s history.

But while the conditions for the kind of rapid change recorded in pre-history do not exist today, Prof Lohmann warns that “sudden climate changes cannot be excluded in the future”. – Climate News Network

Antarctic warming could accelerate sea level rise

Warming would cause more Antarctic ice to break off and melt Image: PIK/R.Winkelmann
Rising concern: warming would cause more Antarctic ice to break off and melt
Image: PIK (R.Winkelmann)

By Alex Kirby

An international study says warming is affecting not only the Arctic but also the Antarctic – and that could significantly raise global sea levels much faster than previously predicted.

LONDON, 20 August, 2014 − The effect of climate change on the world’s two polar regions looks like a stark contrast: the Arctic is warming faster than most of the rest of the Earth, while most of Antarctica appears to remain reassuringly locked in a frigid embrace.

But an international scientific team says the reality is quite different. The Antarctic is warming too, it says, and the southern ice could become the main cause of global sea level rise during this century − far sooner than previously thought.

The study, led by the Potsdam Institute for Climate Impact Research (PIK) in Germany, found that ice discharge from Antarctica could contribute up to 37 centimetres to global sea levels by 2100.

Computer simulations

The study is the first comprehensive estimate of the full range of Antarctica’s potential contribution to global sea level rise based on physical computer simulations. It combines state-of-the-art climate models and observational data with various ice models.

The results of the study − published in the European Geosciences Union’s journal, Earth System Dynamics − reproduce Antarctica’s recent contribution to sea level rise, as observed by satellites over the last two decades.

“If greenhouse gases continue to rise as before, ice discharge from Antarctica could raise the global ocean by an additional 1 to 37 centimetres this century,” says the study’s lead author, Anders Levermann, PIK professor of dynamics of the climate system.

“Science needs to be clear about the uncertainty,
so that decision-makers can consider the potential implications . . .”

“This is a big range – which is exactly why we call it a risk. Science needs to be clear about the uncertainty, so that decision-makers on the coast and in coastal mega-cities like Shanghai or New York can consider the potential implications in their planning processes.”

The scientists analysed how rising global average temperatures resulted in a warming of the ocean around Antarctica, influencing the melting of the Antarctic ice shelves.

Antarctica currently contributes less than 10% to global sea level rise and is a relatively minor player in comparison with the impact of the oceans’ increasing thermal expansion and the melting of glaciers.

But the major contributors to future long-term sea level rise are expected to be the huge volumes of ice locked up in Greenland and the Antarctic ice sheets. The marine ice sheets in West Antarctica alone could raise sea level by several metres over a period of several centuries.

The study’s computed projections for this century’s sea level contribution are significantly higher than the upper end of the latest projections by the Intergovernmental Panel on Climate Change. These suggest a probable rise by 2100 of around 60cm, although other estimates put the figure almost twice as high.

Even if governments can agree and enforce strict climate policies limiting global warming below the international target level of a maximum 2°C increase, Antarctica’s contribution to global sea level rise is expected still to range from 0 to 23cm this century.

Critical input

A co-author of the study, Robert Bindschadler, from the NASA Goddard Space Flight Center, said: “This paper is a critical input to projections of possible future contributions of diminishing ice sheets to sea level by a rigorous consideration of uncertainty of not only the results of ice sheet models themselves but also the climate and ocean forcing driving the ice sheet models.

“Billions of dollars, euros, yuan, etc, are at stake, and wise and cost-effective decision-makers require this type of useful information from the scientific experts.”

But major modeling challenges still remain. Datasets of Antarctic bedrock topography, for instance, are still inadequate, and some physical processes of interaction between ice and ocean cannot yet be sufficiently simulated.

The team also emphasises that the study’s results are limited to this century, while all 19 of the comprehensive climate models used show that the impacts of atmospheric warming on Antarctic ice shelf cavities will hit with a time delay of several decades.

However, Levermann says: “Earlier research indicated that Antarctica would become important in the long term. But pulling together all the evidence, it seems that Antarctica could become the dominant cause of sea level rise much sooner.” − Climate News Network

Human factor speeds up glacial melting

Glaciers such as Artesonraju in the Peruvian Andes are melting at record rates Image: Edubucher via Wikimedia Commons
Glaciers such as Artesonraju in the Peruvian Andes are melting at record rates
Image: Edubucher via Wikimedia Commons

By Tim Radford

Scientists simulating changes in mountain glaciers over the last century and a half have established that rates of melting have increased greatly in recent years – and that humans are the main culprits.

LONDON, 17 August, 2014 – The impact of human activity is melting the glaciers in the world’s mountain regions, and is doing so at an accelerating rate.

Ben Marzeion, a climate scientist at the University of Innsbruck’s Institute of Meteorology and Geophysics, Austria, reports with colleagues in the journal Science that they used computer models to simulate changes in the world’s slow-flowing frozen rivers between the years 1851 and 2010. The study embraced all the world’s glaciers except those in Antarctica.

This kind of manipulation allows researchers to play with the possibilities and see, for instance, how much changes in the sunlight patterns, high-level atmospheric changes because of volcanic eruptions, or simply slow cycles of natural weather patterns might be at work in the ice record.

The answers were unequivocal about human impact on the environment. “In our data, we find unambiguous evidence of anthropogenic contribution to glacier mass loss,” Dr Marzeion says.

In retreat

That glaciers are losing mass − retreating uphill, and melting at a faster rate − is not in doubt. A year ago, one group established without any doubt that worldwide, and overall, glaciers are in retreat.

In South America, some glaciers in the Andes are melting at a record rate, while satellite measurements show that the Jakobshavn glacier in Greenland doubled its flow speed between 1997 and 2003, and has doubled it again since 2003.

In Europe, 19th-century landscape painters, pioneer photographers and mountain guides unwittingly made permanent, easily-accessible records of Alpine glacier geography. These now set a baseline for all modern measurements, and researchers have established that the melt is getting faster.

The challenge is to determine how much of this is due to natural causes, and how much to changes in human land use, and the emission of greenhouse gases.

Higher proportion

The Innsbruck team has calculated that around a quarter of all the melting between 1851 and 2010 can be put down to human activity. But that is the overall picture: the proportion gets higher with time. Between 1991 and 2010, the fraction of melting due to human activity rose to two-thirds.

“In the 19th century and first half of the 20th century we observed that glacier mass loss attributable to human activity is barely noticeable, but since then has steadily increased,” Dr Marzeion says. – Climate News Network

Arctic warming blamed for dangerous heat waves

Feeling the heat: a wildfire rages in New Mexico during the 2012 heat wave in the US Image: Kari Greer/USFS Gila National Forest via Wikimedia Commons
Feeling the heat: a wildfire rages in New Mexico during the 2012 heat wave
Image: Kari Greer/USFS Gila National Forest via Wikimedia Commons

By Paul Brown

Giant waves in the jet stream that often governs our weather are changing as the Arctic warms more rapidly − leading to long periods of soaring temperatures that pose major threats to economies and human health.

LONDON, 16 August, 2014 − Few people have heard of Rossby waves and even less understand them, but if you are sweltering in an uncomfortably long heat wave, then they could be to blame.

New discoveries about what is going on in the atmosphere are helping to explain why heat waves are lasting longer and causing serious damage to humans and the natural world. These events have doubled in frequency this century, and the cause is believed to be the warming of the Arctic.

The weather at the Earth’s surface is often governed by high winds in the atmosphere, known as jet streams. In 1939, Carl-Gustaf Arvid Rossby, a Swedish-born America meteorologist, discovered waves in the northern jet stream that were associated with the high and low pressure systems at ground level that form daily weather patterns.

Jet streams travel at up to 200 kilometres an hour, frequently wandering north and south − with cold Arctic air to the north, and warmer air to the south.

Rapid variations

When the jet stream develops Rossby waves and they swing north, they suck warm air from the tropics to Europe, Russia or the US. And when they swing south, they do the same thing with cold air from the Arctic. The waves constantly change shape, and so cause rapid variations in the weather.

But new research, published in the Proceedings of the National Academy of Sciences of the USA, has discovered a tendency for these waves in the jet stream to get much bigger and to get stuck – particularly in July and August. This causes heat waves that last not just for a few days but for weeks.

This is a serious health and economic threat. A recent example is the record heat wave in the US that hit corn farmers and worsened wildfires in 2012.

Close study of records shows that, from 1980 to 2003, there were two such heat wave events every four years on average. From 2004-07, there were three events, and between 2008-11 there were five.

Ice shrinking

Theory and the new data both suggest a link to processes in the Arctic. Since 2000, the Arctic has been warming about twice as fast as the rest of the globe. One reason for this is that ice is rapidly shrinking in the White Sea − a southern inlet of the Barents Sea on the north-west coast of Russia – and so less sunlight gets reflected back into space, while the open ocean is dark and hence warms more.

“This melting of ice and snow is actually due to our lifestyle of churning out unprecedented amounts of greenhouse gases from fossil fuels,” says Hans Joachim Schellnhuber, co-author of the study and founding director of the Potsdam Institute for Climate Impact Research.

As the Arctic warms more rapidly, the temperature difference to other regions decreases. Yet temperature differences are a major driver of the atmospheric circulation patterns that in turn rule our weather.

“The planetary waves topic illustrates how delicately interlinked components in the Earth system are,” Schellnhuber concludes: “And it shows how disproportionately the system might react to our perturbations.” – Climate News Network

Canada puts oil exploitation before forests

A plane drops a water bomb on a forest fire in Ontario, Canada Image: {Per via Wikimedia Commons
A plane drops a water bomb on a forest fire in Ontario, Canada
Image: Per via Wikimedia Commons

By Paul Brown

Having repudiated the Kyoto Protocol on reducing fossil fuel use, Canada is still exploiting tar sands for oil − despite accepting that climate change is destroying its forests.

LONDON, 9 August, 2014 − Detailed evidence that Canada’s vast natural areas are undergoing major changes because of climate change is produced in a new report by Natural Resources Canada.

The government body describes problems with disappearing glaciers, sea level rise, melting permafrost and changing snow and rainfall patterns. One of the country’s most important natural resources, the forests that cover more than 50% of its land area, is under pressure because of pests, fire and drought.

There may, the reports says, be some pluses for Canada in climate change − at least in the short term − because some staple cereal crops will also be able to be grown further north because of warmer weather, assuming that the soil is suitable.

The report, Canada in a Changing Climate, concentrates on impacts and adaptation, but does not mention the causes, or the fact that Canada is now an international pariah in the environmental community because of its exploitation of tar sands for oil.

The country does attempt, for economic reasons, to be more energy efficient, but has repudiated the Kyoto Protocol and international efforts to curb fossil fuel use. The country had accepted a target of cutting emissions on 1990 levels by 5% by 2012, but the government backed out in 2011.

Highest emissions

Average greenhouse gas emissions for oil sands extraction and upgrading are estimated to be 3.2 to 4.5 times as intensive per barrel as for conventional crude oil produced in Canada or the US. If Alberta, where the oil is produced from tar sands, was a country and not a merely a province of Canada, it would have the highest per capita greenhouse gas emissions in the world.

The only mention the report makes of tar sands extraction is the problem caused by its large use of water, and it makes the point that the industry is recycling as much as possible.

A tar sands mine at Mildred Lake, Alberta Image: TastCakes/Janitzky via Wikimedia Commons
A tar sands mine at Mildred Lake, Alberta
Image: TastyCakes/Janitzky via Wikimedia Commons

Mitigation is not on the agenda, as the country’s politicians are intent on exploiting as much of the country’s oil and gas as possible.

A study of forests says that 224,410 people are directly employed in the sector, although it makes up only 1.1% of GDP. About 5% of the forests are damaged annually because of outbreaks of pests and fire. Temperatures in the forest areas have risen far more sharply than on the rest of the planet, with far-reaching consequences for the future, the report says.

In 2009, over three million hectares of forest were destroyed by fire in a single year. The number of fires is expected to increase, with the area being burned being three to five times as much in Western Canada by the end of the century. Large fires are raging again this year, but the quantity of the damage has yet to be assessed.

Severe outbreaks

One of the pests moving north and devastating mature trees is the mountain pine beetle. The beetle is endemic, but is killed by winter temperatures below minus 35˚C, thus limiting its numbers from year to year. However, winter temperatures in many areas now fail to drop below this level, leading to larger and more severe outbreaks of the pest.

A report in 2012 concluded that 18.1 million hectares of forest dominated by mature Lodgepole pine (Pinus contorta) had been affected. Scientists conclude that productivity of the forests will decline rapidly in British Columbia, and thousands of jobs will be lost. Meanwhile, the beetle is continuing to move north and east.

One advantage of the increased temperatures in Canada is that trees can grow further north and higher up mountains than previously, and there is a longer growing season.

Trees that live 100 years cannot migrate fast enough to take advantage, so local governments are going in for assisted migration.

This involves planting the seeds of suitable species 100 to 200 metres above the existing tree line on mountains, and in some cases two degrees of latitude northwards (about 100 miles) of the existing forests into what is currently tundra or scrub. – Climate News Network

Lakes raise new question on Arctic warming

Thermokarst lakes formed in melting permafrost in Alaska. Image: 16Terezka via Wikimedia Commons
Thermokarst lakes formed in melting permafrost in Alaska.
Image: 16Terezka via Wikimedia Commons

By Alex Kirby

Research into the lakes that form when permafrost melts challenges the widely-held view that they are contributing to Arctic temperature rise by releasing carbon into the atmosphere.

LONDON, 4 August, 2014 − Scientists say there is uncertainty over a previously unquestioned assumption about the way in which temperatures are rising in the Arctic.

New research, supported by the US National Science Foundation (NSF), suggests that a rethink is required on the widely-held scientific view that thawing permafrost uniformly accelerates atmospheric warming.

Instead, the scientists say, their findings show that one type of Arctic lake stores more greenhouse gases (GHGs) than it emits into the atmosphere.

But they say the effect is unlikely to be permanent, because increasing Arctic warmth will probably lead to the renewed release of the gases stored in the lakes.

Melted fresh water

The study, published in the journal Nature, focuses on thermokarst lakes, which appear as permafrost thaws and create surface depressions that fill with melted fresh water, converting previously frozen land into lakes.

The research suggests that Arctic thermokarst lakes are “net climate coolers” when observed over millennial timescales.

The Arctic is one of the fastest-warming regions on Earth. Sea ice has been retreating in the last 30 years or so by 12% a decade, NASA says, and spring and autumn on the Greenland icecap have warmed by more than 3°C.

But the new research suggests the lakes have not been contributing to this recent warmth, although thousands of years ago they did release GHGs.

“Until now, we’ve only thought of thermokarst lakes as positive contributors to climate warming,” said lead researcher Katey Walter Anthony, who is associate research professor at the University of Alaska Fairbanks Institute of Northern Engineering.

“It is true that they do warm climate by strong methane emissions when they first form, but on a longer-term scale they switch to become climate coolers because they ultimately soak up more carbon from the atmosphere than they ever release.”

The team found, thermokarst lakes in ice-rich regions of North Siberia and Alaska began cooling about 5,000 years ago. They stopped emitting methane and carbon dioxide, and instead started storing CO2 from peat-rich sediments.

The researchers used published data, their own field observations of Siberian permafrost and thermokarsts, radiocarbon dating, atmospheric modelling and spatial analyses to study how thawing permafrost is affecting climate change and GHG emissions.

Over the millennia, they say, several factors stimulated high rates of carbon deposits in lake sediments. These included thermokarst erosion and accumulations of organic matter, nutrient release from thawing permafrost, and slow decomposition in cold lake bottoms that lacked oxygen.

Carbon uptake

The study’s co-author, Miriam Jones, of the US Geological Survey, said: “These lakes are being fertilized by thawing yedoma permafrost [a type of permafrost rich in organic material]. So mosses and other plants flourish in these lakes, leading to carbon uptake rates that are among the highest in the world, even compared to carbon-rich peatlands.”

The study also found that when the lakes drain, previously thawed organic-rich lake sediments freeze again, storing a large amount of carbon processed in and under thermokarst lakes.

But the researchers say the new carbon storage will not last indefinitely. Future warming will probably start re-thawing some of the permafrost and release some of the carbon it contains.

Roughly 30% of global permafrost carbon is concentrated within 7% of the permafrost region in Alaska, Canada and Siberia. The study has expanded estimates of how much carbon the circumpolar peat stores in permafrost regions by more than 50%.

And it leaves scientists puzzling over a further question. The thermokarst lakes, according to this study, have been storing GHGs, not emitting them. So what else, despite that, is continuing to warm the Arctic faster than most of the rest of the planet? − Climate News Network

Ignoring climate risks could sink US economy

Flood devastation after Hurricane Katrina hit Louisiana in 2005 Image: Infrogmation via Wikimedia Commons
Harsh reminder: devastation after Hurricane Katrina hit Louisiana in 2005
Image: Infrogmation via Wikimedia Commons

By Alex Kirby

Failure to factor immediate action on climate change into American policies and business plans aimed at economic prosperity will lead to havoc, warns former US Treasury Secretary.

LONDON, 3 August, 2014 − For the second time in a month, Americans have been warned that the economic cost of not acting on climate change is likely to be calamitous.

Robert Rubin, the co-chairman of the influential, non-partisan Council on Foreign Relations, says the price of inaction could be the US economy itself.

Writing in the Washington Post, Rubin, a former US Treasury Secretary, argues: “When it comes to the economy, much of the debate about climate change − and reducing the greenhouse gas emissions that are fuelling it − is framed as a trade-off between environmental protection and economic prosperity,

“But from an economic perspective, that’s precisely the wrong way to look at it. The real question should be: ‘What is the cost of inaction?’”

Widespread disruption

He backed the Risky Business Project, a research initiative chaired by a bi-partisan panel and supported by him and several other former Treasury Secretaries. It reported in June that the American economy could face significant and widespread disruption from climate change unless US businesses and policymakers take immediate action.

In his opinion article in the Washington Post, Rubin argues that, in economic terms, taking action on climate change will prove far less expensive than inaction. He wrote: “By 2050, for example, between $48 billion and $68 billion worth of current property in Louisiana and Florida is likely to be at risk of flooding because it will be below sea level. And that’s just a baseline estimate; there are other scenarios that could be catastrophic.

“Then, of course, there is the unpredictable damage from superstorms yet to come. Hurricane Katrina and Hurricane Sandy caused a combined $193 billion in economic losses; the congressional aid packages that followed both storms cost more than $122 billion.

“And dramatically rising temperatures in much of the country will make it far too hot for people to work outside during parts of the day for several months each year − reducing employment and economic output, and causing as many as 65,200 additional heat-related deaths every year.”

Rubin believes a fundamental problem with tackling climate change is that the methods used to gauge economic realities do not take climate change into consideration. He wants climate-change risks reflected accurately, and companies required to be transparent in reporting vulnerabilities tied to climate.

“If companies were required to highlight their exposure to climate-related risks, it would change investor behaviour, which in turn would prod those companies to change their behaviour,” he argues.

Flawed picture

“Good economic decisions require good data. And to get good data, we must account for all relevant variables. But we’re not doing this when it comes to climate change − and that means we’re making decisions based on a flawed picture of future risks.

“While we can’t define future climate-change risks with precision, they should be included in economic policy, fiscal and business decisions, because of their potential magnitude.”

Rubin says the scientific community is “all but unanimous” in agreeing that climate change is a serious threat. He insists that it is a present danger, not something that can be left to future generations to tackle.

“What we already know is frightening, but what we don’t know is more frightening still,” he writes. “For example, we know that melting polar ice sheets will cause sea levels to rise, but we don’t know how negative feedback loops will accelerate the process. . . And the polar ice sheets have already started to melt.”

He concludes: “We do not face a choice between protecting our environment or protecting our economy. We face a choice between protecting our economy by protecting our environment − or allowing environmental havoc to create economic havoc.”

The White House’s Council of Economic Advisers  has estimated that the eventual cost of cutting greenhouse gas emissions will increase by about 40% for every decade of delay, because measures to restrict them will be more stringent and costlier as atmospheric concentrations grow. − Climate News Network

Data adds to confusion over polar sea ice

The expansion of Antarctic sea ice may have been overestimated. Image: Jason Auch via Wikimedia Commons
The expansion of Antarctic sea ice may have been overestimated.
Image: Jason Auch via Wikimedia Commons

By Tim Radford

Possible errors in the interpretation of satellite data may help to explain scientists’ puzzlement over indications that sea ice cover is apparently increasing in the Antarctic, but is shrinking visibly in the Arctic.

LONDON, 26 July, 2014 − Scientists believe they may have found explanations for two inconsistencies in their understanding of global warming.

One cause for head scratching is in the Antarctic, where the sea ice seems to be getting bigger when it ought to be shrinking, and another has been the apparent slowdown overall in the rate of global warming for the last decade.

Climate scientists around the world have been picking away at both puzzles, and not just because climate sceptics and energy industry lobbyists use them as ammunition to argue that global warming is not a problem at all. Scientists are naturally unhappy when data doesn’t match their predictions − and they want to know the reason why.

The Antarctic problem is hard to miss. The Arctic Ocean sea ice is shrinking visibly, and the entire sea could be ice-free most summers in a few decades. But even though there is clear evidence from separate sources that West Antarctica is responding to climate change, the southern hemisphere ice cover, overall, has been increasing.

Or has it? Ian Eisenman, a climatologist at the Scripps Institution of Oceanography at the University of California San Diego, begs to differ. He and colleagues report, in The Cryosphere journal, that it could be due to an error in the way satellite data is processed.

Spliced together

Scientists have been using satellite data to check sea ice cover for 35 years. But the data does not come from one instrument on just one satellite: observations transmitted from a series of satellites have been spliced together.

One report from the Intergovernmental Panel on Climate Change said the sea ice cover was more or less constant, but a later report said it had grown by 16,500 square kilometers a year between 1979 and 2012.

“When we looked at how the numbers reported for the trend had changed, and we looked at the time series of Antarctic sea ice, it didn’t look right,” Dr Eisenman said.

The researchers think that the difference between the two datasets might be linked to a change in satellite sensors in 1991, and the way the data collected by the two instruments was calibrated. What the Scripps team has done is identify a source of possible error, but it hasn’t settled the question one way or the other.

Since the Arctic and Antarctic are very different places, it would be unrealistic to expect the patterns of melting to be the same. And it may still be that southern hemisphere sea ice is growing.

However, while that question remains open, there is less doubt about the long slowdown in the rate of average global warming during the 21st century.

Missing heat

Separate teams of researchers have proposed a series of possible explanations for the failure of the climate to keep up with the projections of the climate scientists. These have included the suggestion that the missing heat may be “concealed” in the deep oceans, and that a pause in warming was going to happen anyway, but it just happened earlier than anyone expected.

Shaun Lovejoy, professor of physics at McGill University in Canada, reports in Geophysical Research Letters that there is yet another explanation. He argues, from statistical analysis, that coincidentally with the increase in man-made emissions of greenhouse gases, there has been a natural cycle at work, and that the most recent human impact on climate has been damped down by a cooling phase.

He had already ruled out with 99% certainty the possibility that natural variation could explain all the ups and downs of global average temperatures since 1800. This time he used the same statistical approach to the data for the 15 years from 1998 to the present.

His research suggests that there has been a natural cooling of 0.28°C to 0.37°C since 1998, which is in line with natural variations that occur every 20 to 50 years. “The pause has a convincing statistical explanation,” Lovejoy says. – Climate News Network

Climate data shows clear signs of warming

Wreckage caused by Super Typhoon Haiyan in the Philippines last year Image: Eoghan Rice, Trócaire/Caritas via Wikimedia Commons
Wreckage caused by Super Typhoon Haiyan in the Philippines last year
Image: Eoghan Rice, Trócaire/Caritas via Wikimedia Commons

By Alex Kirby

Hundreds of scientists from 57 countries have fed evidence into a new report that provides a clear picture of how patterns, changes, and trends of the global climate system show that our planet is becoming a warmer place.

LONDON, 24 July, 2014 − However you view the evidence, whatever set of measurements you examine, the picture that emerges is consistent: the Earth is heating up.

The US National Oceanic and Atmospheric Administration (NOAA) reports: “In 2013, the vast majority of worldwide climate indicators − greenhouse gases, sea levels, global temperatures, etc − continued to reflect trends of a warmer planet.”

This, NOAA says, is the picture painted by the indicators assessed in a report, State of the Climate in 2013, published online by the American Meteorological Society.

Scientists from NOAA’s National Climatic Data Center were the lead editors of the report, compiled by 425 scientists from 57 countries. It provides a detailed update on data collected by monitoring stations and instruments on air, land, sea and ice.

“These findings reinforce what scientists for decades have observed: that our planet is becoming a warmer place,” said the NOAA‘s administrator, Dr Kathryn Sullivan.

Changes tracked

The report tracks patterns, changes, and trends of the global climate system, including: greenhouse gases; temperatures throughout the atmosphere, ocean, and land; cloud cover; sea level; ocean salinity; sea ice extent; and snow cover.

It says greenhouse gases continued to climb, with concentrations of major gases − including carbon dioxide (CO2), methane and nitrous oxide − once again reaching historically high levels. Atmospheric CO2 concentrations rose by 2.8 parts per million (ppm) in 2013 and reached a global average of 395.3 ppm for the year.

Many scientists argue that once CO2 concentrations reach 450 ppm it will be difficult to prevent global average temperatures from rising more than 2°C above their level for most of human history. The present rate of increase suggests that, without drastic emission cuts, that threshold will be reached before mid-century.

Four major independent datasets show that 2013 was among the warmest years on record, ranking between second and sixth, depending upon the dataset used. Sea surface temperatures increased to place 2013 among the 10 warmest on record.

Sea level also continued to rise, in step with a trend of 3.2 ± 0.4 mm per year over the past two decades.

The Arctic went on warming , marking its seventh warmest year since records began in the early 20th century. Record high temperatures were measured at a depth of 20 metres at permafrost stations in Alaska.

The Arctic sea ice extent was the sixth lowest since satellite observations began in 1979. All seven lowest sea ice extents on record have occurred in the past seven years.

Contradictory trends

The Antarctic, too, was consistent, even if only in the apparently contradictory trends it showed. The extent of the sea ice reached a record high for the second year in a row, of 7.56 million square miles on October 1 −  0.7% higher than the previous record high of 7.51 million sq miles in 2012 and 8.6% higher than the record low maximum of 6.96 million sq miles in 1986. But the South Pole station experienced its highest temperature since records began in 1957.

The number of tropical cyclones during 2013 was slightly above average, but the North Atlantic Basin had its quietest season since 1994. However, in the Western North Pacific Basin, Super Typhoon Haiyan had the highest wind speed ever known for a tropical cyclone, with one-minute sustained winds estimated at 196 miles per hour. − Climate News Network

  • State of the Climate in 2013 is the 24th edition in a peer-reviewed series published annually as a special supplement to the Bulletin of the American Meteorological Society.

Svalbard’s reindeer thrive as climate warms

Warm welcome: Svalbard's distinctive reindeer are increasing in numbers. Image: courtesy of Dr Jonathan Codd, University of Manchester
Warm welcome: Svalbard’s distinctive reindeer are increasing in numbers
Image: courtesy of Dr Jonathan Codd, University of Manchester

By Alex Kirby

The rising temperatures that have many negative impacts in the Arctic region are not a problem for a Norwegian subspecies of reindeer whose population increased by a remarkable 30% last year.

LONDON, 21 July, 2014 − There will be winners as well as losers as climate change intensifies, and scientists say they have just found one species that is prospering already.

Far from threatening the reindeer on the Norwegian high Arctic archipelago of Svalbard, rising temperatures appear to be driving a remarkable increase in the animals’ numbers.

Scientists from the University of Manchester, UK, and the Arctic University of Norway in Tromsø have found that the numbers of Svalbard reindeer, continuing a trend that has been observed over the last 36 years, increased by 30% in the last year.

Physically counted

The scientists established the population spurt by counting the reindeer in the valley of Adventdalen, in central Spitsbergen. They say their research is one of only very few studies on animal populations and climate change that involves animals being physically counted annually, rather than estimated.

The total number of animals − including all births and all deaths − in Adventdalen has been recorded annually since 1979 by a team led by Dr Nicholas Tyler, of the Arctic University of Norway.

Svalbard’s reindeer population had increased in close parallel with winter warming in the last 35 years, growing from an average of around 600 animals in the early 1980s to around 1,000 today.

Dr Tyler said: “Winter warming is widely held to be a major threat to reindeer across the Arctic, but, in Svalbard, global warming has had the opposite effect. Our data provides remarkable confirmation of this counter-intuitive observation.”

This summer, a team from Manchester, led by Jonathan Codd and Nathan Thavarajah, helped with the annual census of reindeer in Adventdalen.

Dr Codd, the programme director for zoology at the university, said: “The results revealed a remarkably successful year for Svalbard reindeer. Despite very high numbers in 2013, the population increased by almost 30% and reached a new record of just over 1,300 animals − more than three times the population size in 1979, when the present series of counts began.”

The team found very little winter mortality and very high calving. There were over 300 calves in the valley, the second highest number recorded.

Streets awash

“The substantial increase in the numbers of reindeer is linked with frequent and pronounced periods of warm weather last winter,” said Dr Codd. “In February, the temperature rose above freezing for six days, reaching a maximum of +4.2°C, and the streets of the Norwegian settlement at Longyearbyen were reported awash with melt water.”

Dr Codd told the Climate News Network: “We count the reindeer by walking the same set routes every day, and there is no possibility of any double counting.

“There are signs that Svalbard’s predators are in good shape. I think most of the polar bear populations are at least stable, and the Arctic foxes are doing pretty well too.

“But neither seems to be bothering the reindeer. The foxes will eat dead deer, but don’t attack live ones. And the main prey of the bears is seals.

“And the reindeer can move fast if they need to. I’ve heard reports that they have been known to reach a speed of 50 miles an hour (80 kph).” − Climate News Network