Naturen røber at verden varmer op

Evidence that the world's water cycle has already intensified is contained in new research to be published in the American Journal of Climate.

The stronger water cycle means arid regions have become drier and high rainfall regions wetter as atmospheric temperature increases.

The paper also confirms that surface warming of the world's oceans over the past 50 years has penetrated into the oceans' interior changing deep-ocean salinity patterns.

"This is further confirmation from the global ocean that the Earth's water cycle has accelerated....These broad-scale patterns of change are qualitatively consistent with simulations reported by the Intergovernmental Panel on Climate Change (IPCC)....While such changes in salinity would be expected at the ocean surface (where about 80 per cent of surface water exchange occurs), sub-surface measurements indicate much broader, warming-driven changes are extending into the deep ocean"

Based on historical records and data provided by the Argo Program's world-wide network of ocean profilers – robotic submersible buoys which record and report ocean salinity levels and temperatures to depths of two kilometres.....

Vegetation around the world is on the move, and climate change is the culprit, according to a new analysis of global vegetation shifts led by a University of California, Berkeley, ecologist in collaboration with researchers from the U.S. Department of Agriculture Forest Service.

The researchers calculated that from 1901 to 2002, mean temperatures significantly increased on 76 percent of global land, with the greatest warming in boreal, or subarctic, regions. The most substantial biome shifts occurred where temperature or precipitation changed by one-half to two standard deviations from 20th century mean values.

Some examples of biome shifts that occurred include woodlands giving way to grasslands in the African Sahel, and shrublands encroaching onto tundra in the Arctic.

Vi har hørt varslerne. Klokken tikker....Informerede valg

De seneste 4-5 år har vi oplevet, at der er kommet flere eksotiske arter til her i farvandet rundt om Nordjylland. Det er usædvanligt, og det kan jo hænge sammen med at havtemperaturen stiger, siger Peter Gregersen fra Nordsøen Oceanarium til TV2/VEJRET.

..for at hævde at opvarmningen 1900-2010 er helt helt speciel..

Gennem de sidste 50 år er det sandsynligt, at solpåvirkning og
vulkansk påvirkning tilsammen ville have medført afkøling. De
observerede opvarmningsmønstre og deres ændringer simuleres
kun af modeller, der også indeholder menneskeskabte påvirkninger.

The Greenland and Antarctic ice sheets are losing mass at an accelerating pace....The findings of the study -- the longest to date of changes in polar ice sheet mass -- suggest these ice sheets are overtaking ice loss from Earth's mountain glaciers and ice caps to become the dominant contributor to global sea level rise, much sooner than model forecasts have predicted.
....the Greenland and Antarctic ice sheets lost a combined mass of 475 gigatonnes a year on average. That's enough to raise global sea level by an average of 1.3 millimeters a year...

The pace at which the polar ice sheets are losing mass was found to be accelerating rapidly. Each year over the course of the study, the two ice sheets lost a combined average of 36.3 gigatonnes more than they did the year before.

...lead author Eric Rignot, of NASA's Jet Propulsion Laboratory, Pasadena, California, and the University of California, Irvine: "What is surprising is this increased contribution by the ice sheets is already happening. If present trends continue, sea level is likely to be significantly higher than levels projected by the United Nations Intergovernmental Panel on Climate Change in 2007. Our study helps reduce uncertainties in near-term projections of sea level rise."

The team found that for each year over the 18-year study, the Greenland ice sheet lost mass faster than it did the year before, by an average of 21.9 gigatonnes a year. In Antarctica, the year-over-year speedup in ice mass lost averaged 14.5 gigatonnes.

rick_uk skrev:
SCIENCE DAILY: Melting Ice Sheets Now Largest Contributor to Sea Level Rise (8/3-11)

...så må verdenshavene have aftagende temperaturer, da de stiger med aftagende hastighed.

Jeg kan ikke får det til at hænge sammen med daterne. Hav stigning fra 1870-2000 var i gennemsnit 1,7mm / år. Stigningen fra 1993-nu har været 3,27mm / år

Lodgepole pine, a hardy tree species that can thrive in cold temperatures and plays a key role in many western ecosystems, is already shrinking in range as a result of climate change – and may almost disappear from most of the Pacific Northwest by 2080, a new study concludes.

Lodgepole pine ecosystems occupy large areas following major fires where extreme cold temperatures, poor soils and heavy, branch-breaking snows make it difficult for other tree species to compete. This includes large parts of higher elevation sites in Oregon, Washington, the Rocky Mountains and western Canada. Yellowstone National Park is dominated by this tree species.

However, warming temperatures, less winter precipitation, earlier loss of snowpack and more summer drought already appear to be affecting the range of lodgepole pine, at the same time increasing the infestations of bark beetles that attack this tree species.

The researchers concluded that some of these forces have been at work since at least 1980, and by around 2020 will have decreased the Pacific Northwest range of lodgepole pine by 8 percent. After that, continued climatic changes are expected to accelerate the species' demise. By 2080, it is projected to be almost absent from Oregon, Washington and Idaho, some of the areas facing the most dramatic changes.

"For skeptics of climate change, it's worth noting that the increase in vulnerability of lodgepole pine we've seen in recent decades is made from comparisons with real climatic data, and is backed up with satellite-observations showing major changes on the ground," said Richard Waring, an OSU distinguished professor emeritus of forest science.

"This is already happening in some places," Waring said. "Bark beetles in lodgepole pine used to be more selective, leaving the younger and healthier trees alone.

"Now their populations and pheromone levels are getting so high they can more easily reach epidemic levels and kill almost all adult trees," he said. "Less frost, combined with less snow favors heavier levels of bark beetle infestation. We're already seeing more insect attack, and we project that it will get worse."

Abstract
Analyses of remote sensing data, surface observations and output from a regional atmosphere model point to new records in 2010 for surface melt and albedo, runoff, the number of days when bare ice is exposed and surface mass balance of the Greenland ice sheet, especially over its west and southwest regions. Early melt onset in spring, triggered by above-normal near-surface air temperatures, contributed to accelerated snowpack metamorphism and premature bare ice exposure, rapidly reducing the surface albedo. Warm conditions persisted through summer, with the positive albedo feedback mechanism being a major contributor to
large negative surface mass balance anomalies. Summer snowfall was below average. This helped to maintain low albedo through the 2010 melting season, which also lasted longer than usual.

4. Conclusions
Our analysis of remote sensing data, surface glaciological observations and model outputs paints a portrait of strongly negative surface mass balance during 2010 promoted by a strong warmth and enhanced by large negative anomalies of albedo and accumulation and large positive anomalies of days when bare ice was exposed. Our results clearly indicate that, beside near-surface temperature, other factors must be considered to properly analyze extreme events such as the one that occurred in 2010. The melt season started in mid April, after a warm and dry winter. Early melt onset, triggered by large positive near-surface temperature anomalies during May 2010 (up to +4 ◦C above the mean) contributed to accelerated snowpack metamorphism and premature bare ice exposure, with the consequence of rapidly reducing the surface albedo. Reduced accumulation in 2010, and the positive albedo feedback mechanism are likely responsible for the premature exposure of bare ice. While June and July temperature anomalies were not exceptional, being +1.5 ◦C above the 1979–2009 average, anomalously warm conditions persisted with the positive albedo feedback mechanism contributing to large negative SMB anomalies. Summer snowfall, which helps to increase surface albedo, was below average. Melt during August and September was also exceptional, consistent with low surface albedos and near-surface temperature anomalies of up to +3 ◦C, yielding a long ablation season. The surface melt time series from the combined passive microwave record, 1979–present, is characterized by an upward trend, with considerable year-to-year variability primarily related to atmospheric conditions. Viewed in this context, the unusually warm conditions over the Greenland ice sheet in 2010 and reduced snowfall can be related to persistence of a 500 hPa high ridge from late spring through summer. Averaged for May–August, 500 hPa heights were above normal over all of Greenland, with the largest anomalies of up to 80 m over the south-central ice sheet. This anomalous ridge was associated with 700 hPa temperature anomalies over south-central Greenland of up to +3 ◦C. The ridge and associated 700 hPa temperature anomaly was best expressed in May and August, coinciding with near-surface air temperature records.

Beavers are among the unwelcome changes associated with climate change.....

It was in 1985 that Apa Sherpa, who scaled Mount Everest for the 21st time in May 2011, came face to face with climate change. His entire village Thame was washed away in a massive glacial lake outburst flood (GLOF) of the Dig Tsho (Tsho-lake), in the western section of the Sagarmatha (Mt. Everest) National Park, Khumbu Himal, on August 4, 1985.

The veteran mountaineer, who dropped out of school at 12 to work as a porter for expeditions to support his family, told The Hindu that the lake burst at 2 a.m. and he had a narrow escape. Now his worry is another glacial lake in the Everest region, Imja, which is growing bigger. "Imja Khola is a threat to the entire region and I can't say if it is as safe as is made out to be. We have to do something before it bursts." Imja, located in the Khumbu region close to the Everest base camp, did not exist in photographs taken in the 1950s, but now has rapidly expanded to 1.012 sq km.

Since 2007 the ice pinnacles in the Everest area have reduced in height and at the advanced base camp, there has been flowing water in the climbing season, a clear indication that ice is melting. "You no longer have to melt ice to drink water," says Dawa Steven Sherpa. He too noted that the Imja lake was growing bigger. It is upstream of the Everest Base Camp and above major village settlements. "Imja and its potential threat are in the forefront of everyone's mind since the devastation could be huge," he fears.

Divyesh Muni, who has been climbing the mountain for over two decades, has noticed dramatic changes in terrain in the entire Himalayan region and the eastern Karakoram area since 2005. "In one of my expeditions in 2007 to Chong Kumdan, we had a tough time reaching the base camp. The glacier was deeply crevassed and the route had to be changed. It was a sorry state of affairs. In Saser La, a trade route famous for snow, there was none in 2007 making it a simple crossing."

There are few places mountaineer Harish Kapadia has not gone to and he has been observing changes in the Garhwal and Kumaon regions. "The last five years have been marked by receding glaciers and even walking is difficult. The uncertainty for climbers and trekkers is increasing in the Himalayan region."

The predator made her epic journey in the Beaufort Sea (see map), where sea ice is shrinking due to global warming, forcing mother bears to swim greater and greater distances to reach land—to the peril of their cubs.

The cub of the record-setting bear, for instance, died at some point between starting the swim and when the researchers next observed the mother on land. She also lost 22 percent of her body weight.

It's unknown whether the cubs are drowning at sea or whether the metabolically costly act of swimming long distances in nearly freezing water kills them after they reach land.

Until 1995, summer sea ice usually remained over along the continental shelf of the Beaufort Sea, a critical habitat for polar bears due to its rich seal population. Now the sea ice in the Beaufort and Chukchi Seas is retreating from the coast by hundreds of kilometers

In 2010, Arctic sea ice extent was the third lowest on record, part of a long-term trend of ice loss that will continue for decades to come, according to the National Snow and Ice Data Center in Boulder, Colorado.

"Although I knew what to expect in terms of ice loss from satellite imagery, I was still completely unprepared for the gob-smacking scale of the break-up, which rendered me speechless"

He said while sea glacier's "calving" of ice bergs was a natural process, they were witnessing something out of the ordinary.

"The break-off last year is bigger than anything seen for at least 150 years," Hubbard said.

"This region (northern Greenland) is experiencing temperatures which are abnormally warm ... I think the far northwest of Greenland is seeing a kind of new regime of climate," he added.

The Humbolt Glacier, the widest in the northern hemisphere, is also retreating, Hubbard said. He said he was not a climate scientist, but said the pattern of ice melting in the area was "a definite consequence of climate change and global warming."

Twice as many glaciers are retreating as the number that are advancing, and the area of ice lost was nine times the amount gained, the researchers found.