Many of the effects of global warming have been well-documented. It is the precise extent that is difficult to predict.

Ministry of Climate and Energy of Denmark

Predicting the consequences of global warming is one of the really difficult tasks for the world’s climate researchers. Firstly, because the natural processes that cause precipitation, storms, increases in sea level and other expected effects of global warming are dependent on many different factors. Secondly, because it is difficult to predict the size of the emissions of greenhouse gases in the coming decades, as this is determined to a great extent by political decisions and technological breakthroughs.

Many of the effects of global warming have been well-documented, and observations from real life are very much consistent with earlier predictions. It is the precise extent that is difficult to predict. Among the effects that can be predicted are:

More droughts and more flooding:

When the weather gets warmer, evaporation from both land and sea increases. This can cause drought in areas of the world where the increased evaporation is not compensated for by more precipitation. The extra water vapor in the atmosphere has to fall again as extra precipitation, which can cause flooding other places in the world.

Less ice and snow:

Glaciers are shrinking rapidly at present. The trend is for the ice to melt faster than estimated in the IPCC’s latest report. In areas that are dependent on melt water from mountain areas, this can cause drought and a lack of drinking water. According to the IPCC, up to a sixth of the world’s population lives in areas that will be affected by this.

More extreme weather incidents:

The warmer climate will most probably cause more heatwaves, more cases of heavy rainfall and also possibly an increase in the number and/or severity of storms.

Rising sea level:

The sea level rises for two reasons. Partly because of the melting ice and snow, and partly because of the thermal expansion of the sea. Thermal expansion takes a long time, but even an increase in temperature of two degrees Celsius is expected, in due time, to cause a rise in the water level of almost a metre.

In order to get an idea of the extent of the consequences, researchers typically work with scenarios that show various possible developments.

credited to United Nations Climate Change Conference in Copenhagen official site

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Scientists expect some great travel spots to be altered or ruined by global climate change.

Some of the changes are already taking place. Others are expected to be seen in coming decades.

There are two ways to look at this: Either stay home (which might be less depressing and won't add more airline emissions) or get a move on it and see the hot spots you just can't miss.

For those who want to head out, CNN got advice on the best pre-warming travel destinations from Bob Henson, author of "The Rough Guide to Climate Change" and a writer at the University Corporation for Atmospheric Research in Boulder, Colorado.

Here are Henson's top five choices:

Great Barrier Reef, Australia

Warming temperatures can spell disaster for coral reefs, which depend on a delicate balance of ocean temperature and chemistry to bloom into colorful displays.

Many of the world's reefs already are experiencing "bleaching" in which algae living in the coral die and leave behind whitened skeletons.

The Great Barrier Reef -- which is composed of about 2,900 individual reefs and is off the northeast coast of Australia -- is seeing limited bleaching now, and the Great Barrier Reef Marine Park Authority expects the problem to grow in coming decades.

Henson said the reefs' colorful displays are not to be missed.

"It's a feast for the eyes in terms of color, texture variations -- it's just amazing to see," he said. "It's wonderful to be enveloped in the warm water and look down just a few feet below at this amazing spread of ocean life."

Boats of people with snorkels typically launch into the reefs from Cairns, Queensland. If you go, tread lightly, Henson said. Visitors can damage the reefs if they get too close.

New Orleans, Louisiana

How much sea levels will rise as the world warms is one of the trickiest parts of the climate change equation. If huge hunks of ice -- such as parts of Greenland and the western shelf of Antarctica -- melt, then the rise is expected to be more dramatic.

"Nobody knows whether they're going to completely melt or not, but we do know it's not going to happen in the next 10 years," Henson said.

But for cities near the coast such as New Orleans, which already sits below sea level, rising waters could spell trouble for tourists and residents alike, even in the relative near term.

"In the next several hundred years, life there may be difficult, and the cities may become impractical unless we can build large structures to keep the waters at bay," he said.

Henson doesn't expect New Orleans to be underwater anytime soon. But travel to the Louisiana city may become more difficult in the future, he said. Scientists expect floods to become more frequent.

"It's sobering to be in New Orleans and look up at the levees that sit above you and keep out the Mississippi River," he said. "You're standing below the level of the river, looking up."

Rocky Mountain National Park, Estes Park, Colorado

Herds of tiny pine beetles are munching away at Colorado's forests, turning the evergreens a sickly red and destroying large patches of trees.

Cold snaps -- which, in mountain terms, mean about five nights of minus-30 temperatures -- usually kill off the native beetles. But winters are warming, and Henson and others said they worry the beetles can't be stopped.

The beetle infestation "has reached epidemic proportions as a result of climate issues," said Kyle Patterson, spokeswoman for the Rocky Mountain National Park.

The beetles are causing problems all over America's mountainous west, but the issue is particularly visible at Patterson's park, northwest of Denver. Henson recommends visiting the park this decade to ensure you can still see the dense forests in decent shape. Some of the reddened forests look beautiful in a strange way, Henson said, but visitors should note that the color isn't natural for pine trees.

"Come soon. It's happening quickly," he said.

Visit in the summer or early fall and take a breathtaking drive to 12,183 feet, Patterson said. Or, come in the winter and enjoy snowshoeing and nearby skiing. Many of the park's 355 miles of hiking trails are open year-round.

Alpine Glaciers, Switzerland

The European Alps sit at a lower altitude than the Rocky Mountains, and their glaciers and ski resorts are therefore more susceptible to melting, Henson said.

A climate expert in Austria recently told National Geographic that the Alps' famed glaciers will disappear entirely between 2030 and 2050. A 2006 report had said they would melt by the end of the century.

Henson said he once took a train through the Alpine glaciers. They're worth seeing before they go -- whenever that happens, he said.

"They're beautiful; the light blue quality of the meltwater is really stunning," he said.

Amazon rain forest, Brazil

Deforestation continues to be the major environmental issue in the Amazon, the world's largest tropical rain forest. But as locals and corporations chop down the Amazon's rich forests to create farmland and to harvest biofuels, climate change may make things worse.

"The fear is that there will be kind of a feedback where trees are cut down, and it gets warmer and drier" in the forest until it can't grow back, Henson said.

The best way to visit the forest is by boat, Henson said. That way, you'll leave less of a mark on the struggling ecosystem.

Of course, getting to a boat on the Amazon is not simple, and the long trip can create a lot of heat-trapping pollution. Henson said the destination might be one of those better left alone by tourists.

credited to CNN

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When it comes to global warming, the canary in the coal mine isn't a canary at all. It's a purple finch.

As the temperature across the U.S. has gotten warmer, the purple finch has been spending its winters more than 400 miles farther north than it used to.

And it's not alone.

An Audubon Society study to be released Tuesday found that more than half of 305 birds species in North America, a hodgepodge that includes robins, gulls, chickadees and owls, are spending the winter about 35 miles farther north than they did 40 years ago.

The purple finch was the biggest northward mover. Its wintering grounds are now more along the latitude of Milwaukee, Wis., instead of Springfield, Mo.

Bird ranges can expand and shift for many reasons, among them urban sprawl, deforestation and the supplemental diet provided by backyard feeders. But researchers say the only explanation for why so many birds over such a broad area are wintering in more northern locales is global warming.

Over the 40 years covered by the study, the average January temperature in the United States climbed by about 5 degrees Fahrenheit. That warming was most pronounced in northern states, which have already recorded an influx of more southern species and could see some northern species retreat into Canada as ranges shift.

"This is as close as science at this scale gets to proof," said Greg Butcher, the lead scientist on the study and the director of bird conservation at the Audubon Society. "It is not what each of these individual birds did. It is the wide diversity of birds that suggests it has something to do with temperature, rather than ecology."

The study provides compelling evidence for what many birders across the country have long recognized -- that many birds are responding to climate change by shifting farther north.

Previous studies of breeding birds in Great Britain and the eastern U.S. have detected similar trends. But the Audubon study covers a broader area and includes many more species.

The study of migration habits from 1966 through 2005 found about one-fourth of the species have moved farther south. But the number moving northward -- 177 species -- is twice that.

The study "shows a very, very large fraction of the wintering birds are shifting" northward, said Terry Root, a biologist at Stanford University. "We don't know for a fact that it is warming. But when one keeps finding the same thing over and over ... we know it is not just a figment of our imagination."

The research is based on data collected during the Audubon Society's Christmas Bird Count in early winter. At that time of year, temperature is the primary driver for where birds go and whether they live or die. To survive the cold, birds need to eat enough during the day to have the energy needed to shiver throughout the night.

Milder winters mean the birds don't need to expend as much energy shivering, and can get by eating less food in the day.

General biology aside, the research can't explain why particular species are moving. That's because changes in temperature affect different birds in different ways.

Some birds will expand their range farther north. For example, the Carolina wren -- the state bird of South Carolina -- has turned into a Yankee, based on Audubon's calculations. It is now commonly seen in the winter well into New England, as well as its namesake state of South Carolina.

"Twenty years ago, I remember people driving hours to see the one Carolina wren in the state," said Jeff Wells, an ornithologist based in southern Maine. "Now, every year I get two or three just in my area," he said. "Obviously, things have changed."

Other species, such as the purple finch and boreal chickadee, spend their summers in the forests of Canada and fly south into the U.S. for the winter. Climate change could be playing a role in why they are not flying as far south as they used to, and are no longer as common as they were in states like Maine, Vermont and Wisconsin.

For other species, global warming may not be a major factor in the movements measured by Audubon at all. The wild turkey was second only to the purple finch in miles moved north -- about 400. But it's likely due to efforts by hunters and state wildlife managers to boost its population.

In other cases, the range shifts are prompting calls to cull some bird populations.

The sandhill crane, a large gray bird that migrates to the southern U.S. for the winter, has a range that expanded about 40 miles north in the last 40 years. This small movement has likely contributed to the bird's population explosion in Tennessee. The sandhill population has grown to a point that state wildlife officials are considering allowing the bird to be hunted.

"You are seeing it all across the state," said Richard Connors, president of the Tennessee Ornithological Society. "As it increases, there is going to be pressure to hunt it. The bird watchers of Tennessee don't want that."

credited to discovery.com

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Phil Koperberg knows bushfires.

He’s spent his whole life fighting them.For 10 years he was on the front line as NSW Rural Fire Service Commissioner.

Before that, he was the Director-General of the NSW Bush Fire Service

And now he represents some of our most bushfire-vulnerable countrymen in as the member for the Blue Mountains.

So when he comes out and says firefighters are going to have to adjust what they do because of global warming - it’s worth listening to.

This morning, in the face of the worst bushfires ever experienced by this nation, he stated categorically that fires are now behaving in different ways because of global warming.

“There will be a revision now (due to) climate change,” he said on Sydney radio.

“Fires are behaving differently in many, many ways. The fuel conditions change according to the amount of rainfall, according to the amount of moisture content in the fuel.

“And these are the challenges ahead of fire authorities in the next 20 to 30 years.”

These simple words are something those who make a living out of denying the existence of climate change should read very carefully. Even with all our technology more people than any other bushfire episode in our history, 130, have died.

The Andrew Bolts, the John Howards and the Piers Akermans of this world should feel very nervous.

It is them who will be condemned over the next 30 years as we start to see such events more and more.

(Keep in mind on Saturday Melbourne had it’s hottest day ever, at 46.4, since records were first kept in 1850 and has experienced a heatwave without precedent in 100 years.)

In fact, I’ve got a great idea so we don’t fail to forget all those people who - as of 2009 - are still denying humans are beginning to irreversibly change our only home.

The people who are the public mouth pieces for big business and vested interest who are making too much money to want to change their ways.

The Bolts and the Akermans and their ilk should have their names carved in stone – which cannot be scorched by any fire. And I’ll put my name in stone too.

A stone we can consult in say, 30 years time, when all the evidence is in.

Because where as if I’m wrong I’ll look like a fool, if they’re wrong by then we’ll be headed down a road – to paraphrase Kevin Rudd – to hell.

credited to livenews.com.au

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Satellite images show Papua New Guinea's Gulf Province rain forest intact in 1988 (left) and laid bare by logging in 2002. The images were released this week as part of a new study.

At the current rate of destruction, 53 percent of the country's rain forest—said to be the world's third largest—will disappear by 2021, according to the study of three decades of satellite imagery. Between 1972 and 2002 alone, 19.8 million acres (8 million hectares) were lost.

"It was previously thought that PNG had a very low or nonexistent rate of deforestation and degradation," study co-author Phil Shearman, of the University of Papua New Guinea, told Britain's Telegraph newspaper.

"Our study is making it reasonably clear that's not the case—indeed PNG is losing its rain forest at rates comparable to that of the Congo and to that of the Amazon."

Along with trees, unique animals and plants are expected to vanish. And because trees absorb the greenhouse gas carbon dioxide, the deforestation could encourage global warming.

Twenty-two million tons of carbon will be released from Papua New Guinea's forests this year as a result of logging-industry action—approximately the equivalent of the annual output of all carbon from the cars in Australia, the report's authors said.

Lee Tan of the Australian Conservation Foundation, said, "We can very confidently predict that if more of the forests are cut, there will be erosion, there will be landslides, lives lost and other calamities"—not to mention the potential loss of species diversity.

"We fear logging and other forms of degradation are wiping out the forests before we even know what is there," Tan said.

Papua New Guinean officials have proposed that the international community pay the country for preserving the forest and that loggers plant three trees for every one they remove.

credited to Associated Press

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More than 2 trillion tons of land ice in Greenland, Antarctica and Alaska have melted since 2003, according to new NASA satellite data that show the latest signs of what scientists say is global warming.

More than half of the loss of landlocked ice in the past five years has occurred in Greenland, based on measurements of ice weight by NASA's GRACE satellite, said NASA geophysicist Scott Luthcke. The water melting from Greenland in the past five years would fill up about 11 Chesapeake Bays, he said, and the Greenland melt seems to be accelerating.

NASA scientists planned to present their findings Thursday at the American Geophysical Union conference in San Francisco. Luthcke said Greenland figures for the summer of 2008 aren't complete yet, but this year's ice loss, while still significant, won't be as severe as 2007.

The news was better for Alaska. After a precipitous drop in 2005, land ice increased slightly in 2008 because of large winter snowfalls, Luthcke said. Since 2003, when the NASA satellite started taking measurements, Alaska has lost 400 billion tons of land ice.

In assessing climate change, scientists generally look at several years to determine the overall trend.

Melting of land ice, unlike sea ice, increases sea levels very slightly. In the 1990s, Greenland didn't add to world sea level rise; now that island is adding about half a millimeter of sea level rise a year, NASA ice scientist Jay Zwally said in a telephone interview from the conference.

Between Greenland, Antarctica and Alaska, melting land ice has raised global sea levels about one-fifth of an inch in the past five years, Luthcke said. Sea levels also rise from water expanding as it warms.

Other research, being presented this week at the geophysical meeting point to more melting concerns from global warming, especially with sea ice.

credited to link

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Summer Arctic sea-ice is shrinking rapidly. 2007, saw record lows and 2008 followed a similar pattern. Sinhue Torres-Valdes and Richard Sanders describe the work of a major new consortium called ASBO - but not a delinquent scientist in sight.

The Arctic is a very beautiful place to work. The forces of nature are such that they make you wonder about your own role and place within the whole ecosystem. It is a privilege to sit in a laboratory on a research ship and catch sight of seabirds soaring in conditions we would struggle with for more than a few seconds.

The Arctic Ocean is central to the Earth's system. It supports life ranging from microscopic plants to fish and top predators such as polar bears. It is home to many indigenous cultures, and it is of particular importance to the global ocean circulation and the planet's climate. Each winter, tens of thousands of square kilometres of sea-ice form. This melts again in summer.

But something odd is happening. Rising global temperatures are changing the polar regions. The Arctic is one of the fastest warming regions on the planet. During the last few decades this annual cycle of freezing and melting has been gradually shifting out of balance. In autumn 2007, sea-ice reached its lowest point ever recorded. 2008 came close to surpassing this record. Computer models predict the Arctic may be ice-free in summer by 2030.

The decreasing summer ice cover has huge implications, not least geopolitical. The fall in surface area means a massive drop in available habitat for much life in the region, with a knock-on effect on ecosystem functioning.

The amount of freshwater entering the Arctic is changing. Glaciers are melting and the global water cycle is shifting as a result of human-induced climate change. More rain at northern latitudes means more water entering the Arctic from rivers in North America, Asia and Europe.

Freshwater floats on the dense salty water beneath. Salinity and temperature differences help drive the major ocean circulations that bring warm waters into the Arctic and push cold deep waters southwards towards the tropics. Sea ice has a role to play because it removes huge volumes of fresh water from the oceans.

But is has another role in the global climate system. Its white surface effectively reflects heat from the sun back out to space. Less ice means more dark-coloured water. Instead of reflecting heat, water effectively absorbs heat from the sun.

In 2007, NERC funded the the Arctic Synoptic Basin-wide Oceanography (ASBO) programme. ASBO is part of a huge international research effort in the polar regions over the period 2007-09 known as International Polar Year (IPY). Over 60,000 scientists from 50 nations are involved and NERC is the main funder of the international offices based at the British Antarctic Survey in Cambridge.

An important part of IPY is a complete survey of Arctic oceanography over two seasons to assess the state of the Arctic in the face of environmental change. This has been a large logistical operation.

In 2007, scientists from the Scottish Association for Marine Science joined a Canadian research ship to mount weather instruments on Arctic ice floes. Over the two years, the International Arctic Research Institute at the University of Alaska In Fairbanks coordinated the large international field expeditions on two Russian research ships. All this field work will be backed up by mathematical models and data analyses. We want to know what happens to sea ice as it melts, in particular the poorly-understood 'melt pond formation' which is crucial in determining the rate of ice loss.

In the ASBO consortium, we're measuring the changes in the Arctic Ocean's freshwater content. We also want to estimate how heat moves around the Arctic, both within the ocean and between ocean and atmosphere and to look at how all these factors will influence the ocean circulation over the entire Arctic basin.

We sailed along the remote rarely-sampled northern coast of Russia deploying scientific buoys and moorings that, among other things, continuously record temperature and salinity.

The 2007 expedition was significant because it happened during the historic sea-ice low. We left from Kirkenes in northern Norway and headed straight towards the Laptev and the East Siberian Seas onboard the small Russian research vessel Viktor Buynitskiy with colleagues from Fairbanks. Here we mapped the relatively warm Atlantic waters as they travel into the Arctic Ocean along the Eurasian continental shelf.

Simply getting to these remote places was challenging. Small channels between islands choked with ice requiring large icebreakers to smash through these straits. Our small ship trailed in their wake. Ice clogged the winches we use to lower instruments and retrieve water samples. The ice must be scraped off by hand, a very time consuming and energy demanding task.

In rough seas work was often difficult and even dangerous. If the captain so decided, work stopped until conditions improve. This can be frustrating because sea time is precious. Collecting water samples with temperatures close to or below zero degrees numbs your hands and working around the clock in stormy weather, under rain, snow and freezing winds is exhausting. Each bit of data was hard won against the ocean and doubly valuable for this reason.

All the efforts we made while at sea were worthwhile once we returned to land and we could analyse samples and process data. We traced the origins of the waters in the area we sampled. Our techniques meant that we could identify waters from the Atlantic and Pacific oceans and fresh water from rivers and melting sea-ice.

When we compared our new data with data from the past we found that the main body Atlantic Ocean water entering the Arctic appears to be thicker and warmer than the long term average for the same time of year. Also, ASBO members from the British Antarctic Survey found larger amounts of rainwater water compared with previous years and colleagues from Bangor University measured the extent of water from the Atlantic in the Arctic Ocean and patterns of heat movement into the Arctic.

As this article goes to press we have just returned from our second expedition to the same region on board the large diesel-powered icebreaker Kapitan Dranitsyn (See link to expedition blog in right column). Because we were later in the season, ice conditions were much worse than 2007 with the ship having to break through ice three to four metres thick in places.

Our work will provide information and answers to questions of global importance that have relevance to all creatures living on the planet, including ourselves. Surely you will be hearing from us in the near future.

credited to link

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Plants closer to the equator are more likely to have larger seeds, a fact that could help predict the risk that climate change poses to native plants, according to an Australian researcher.

Evolutionary biologist Angela Moles of the University of New South Wales will this week receive an Australian Institute of Policy and Science Tall Poppy award for her research, which looks at how climate and other factors influence plant traits across the world.

Moles argues a better understanding of the impact of climate on plant traits will help pinpoint which plants have traits that will be an advantage or disadvantage under future climate changes.

"A lot of the time we just protect them in national parks and hope for the best but with all of these changes happening it's not clear that is going to work," she said.

Moles and colleagues searched the literature on more than 11,000 species of native plants from around the world to identify what factors influence the size of their seeds.

They found tropical plants had overall bigger seeds.

"Seeds are 320 times bigger at the equator than at 60 degree latitude," said Moles.

She says this is largely because trees have bigger seeds than shrubs or herbs, and make up a larger proportion of plant life in the tropics.

These seeds are typically found in fleshy fruits and are dispersed by big animals, ranging from monkeys to giant birds, which are also more plentiful in the tropics.

By contrast in the Arctic, seeds tend to be small and wind-dispersed.

Moles said the largest seeds are those of the double coconut, which weigh up to 27 kilograms (60 pounds) each and "look like giant bums."

The smallest seeds are those of orchids, which look like little bits of dust, and weigh less than a millionth of a gram, she said.

As part of her research Moles spent two years backpacking her way through 75 study sites around the world including China, Patagonia, the Republic of Congo and Greenland collecting other information to feed into a large database on native plant traits.

During this trip she recorded plant height, how the plants were being eaten by insects and other animals and information on plant defence mechanisms.

Moles said this project was carried out on a "shoestring" and relied on hiring local field assistants, "everything from an Argentinian goat-herder to a villager from Kabo in the Congo."

She trained the local field assistants to tag leaves and come back regularly to see how much they'd been eaten over time, and to send photographs of the leaves to her.

"We've now got about 500,000 pictures of leaves with holes that we're working through," she said.

Last week, Moles received an Australian Research Council grant to study plant traits in weeds, which may one day be useful in weed management.

Earlier this year she also received a 2008 L'Oreal Australia For Women in Science Fellowship for her research.

credited to link

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Arctic sea ice extent during the 2008 melt season dropped to the second-lowest level since satellite measurements began in 1979, reaching the lowest point in its annual cycle of melt and growth on Sept. 14, according to researchers at the University of Colorado at Boulder's National Snow and Ice Data Center.

Preliminary data also indicate 2008 may represent the lowest volume of Arctic sea ice on record, according to the researchers. The declining Arctic sea ice is due to rising concentrations of greenhouse gases that have elevated temperatures across the Arctic and strong natural variability in Arctic sea ice, according to scientists.

Average sea ice extent during September, a benchmark measurement in the scientific study of Arctic sea ice, was 1.8 million square miles. The record monthly low, set in 2007, was 1.65 million square miles. The third lowest monthly low was 2.15 square miles in 2005, according researchers at the center.

The 2008 low strongly reinforces the 30-year downward trend in Arctic sea ice extent, said CU-Boulder Research Professor Mark Serreze, an NSIDC senior scientist. The 2008 September low was 34 percent below the long-term average from 1979 to 2000 and only 9 percent greater than the 2007 record. Because the 2008 low was so far below the September average, the negative trend in the September extent has been pulled downward, from a minus 10.7 percent per decade to a minus 11.7 percent per decade, he said.

"When you look at the sharp decline we have seen over the past 30 years, a recovery from lowest to second lowest is no recovery at all," Serreze said. "Both within and beyond the Arctic, the implications of the decline are enormous."

Conditions in the spring, at the end of the growth season, played an important role in the outcome of this year's melt, the researchers said. In March 2008, thin first-year ice covered a record high 73 percent of the Arctic basin. While it may appear to be a recovery of the sea ice, the large extent masked an important aspect of sea ice health since thin ice is more prone to melting during the summer. The widespread thin ice in spring 2008 set the stage for extensive ice loss during the melt season, according to the NSIDC researchers.

Through the 2008 melt season, a race developed between the melting of thin ice and gradually waning sunlight, said CU-Boulder Research Associate Walt Meier, a research scientist at NSIDC. Summer ice losses allowed significant solar energy to enter the ocean and heat up the water, melting even more ice from the bottom and sides. Warm oceans store heat longer than the atmosphere does, contributing to melt long after the sunlight has begun to wane, Meier said. In August 2008, the Arctic Ocean lost more ice than any previous August on record.

"Warm ocean waters helped contribute to ice losses this year, pushing the already thin ice pack over the edge," said Meier. "In fact, preliminary data indicate that 2008 probably represents the lowest volume of Arctic sea ice on record, partly because less multiyear ice is surviving now and the remaining ice is so thin."

In 2008, summer conditions worked together to save some first-year ice from melting and to "cushion" the thin ice pack from the effects of sunlight and warm ocean waters, preventing the "perfect storm" for ice loss seen in 2007, according to the researchers. Temperatures in 2008 were cooler than in 2007, although still warmer than average.

Cloudier skies also protected the ice from some melt, and wind patterns spread the ice pack out, leading to higher extent numbers, according to CU-Boulder Research Associate Julienne Stroeve, an NSIDC research scientist. The end result was the natural variability of short-term weather patterns provided enough of a "brake" to prevent a new record-low ice extent from occurring, she said.

"I find it incredible that we came so close to beating the 2007 record, without the especially warm and clear conditions we saw last summer," said Stroeve. "I hate to think what 2008 might have looked like if the weather patterns had set up in a more extreme way."

The melt season of 2008 reinforces the decline of Arctic sea ice documented over the past 30 years, said CU-Boulder Senior Research Associate Ted Scambos, NSIDC lead scientist. "The trend of decline in the Arctic continues, despite this year's slightly greater extent of sea ice," said Scambos. "The Arctic is more vulnerable than ever."

credit: University of Colorado at Boulder (2008, October 3). Arctic Sea Ice Hits Second-lowest Recorded Extent, Likely Lowest Volume. ScienceDaily. Retrieved October 3, 2008, from http://www.sciencedaily.com­ /releases/2008/10/081002172436.htm

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The theory that global warming may be contributing to stronger hurricanes in the Atlantic over the past 30 years is bolstered by a new study led by a Florida State University researcher. The study will be published in the Sept. 4 edition of the journal Nature.

Using global satellite data, FSU geography Professor James B. Elsner, University of Wisconsin-Madison Professor James P. Kossin and FSU postdoctoral researcher Thomas H. Jagger found that the strongest tropical cyclones are, in fact, getting stronger -- and that ocean temperatures play a role in driving this trend. This is consistent with the "heat-engine" theory of cyclone intensity.

"As seas warm, the ocean has more energy that can be converted to tropical cyclone wind," Elsner said. "Our results do not prove the heat-engine theory. We just show that the data are quite consistent with it."

Kerry Emanuel of the Massachusetts Institute of Technology first suggested the possible connection between global warming and increases in tropical cyclone intensity in a 2005 paper. He linked the increased intensity of storms to the heating of the oceans, which has been attributed to global warming.

Critics argued that the data were not reliable enough to make assertions about the relationship between climate change and hurricanes. Moreover, when scientists looked at the mean tropical cyclone statistics, they did not see an upward trend.

Elsner's team addressed both issues by using globally consistent, satellite-derived tropical cyclone wind speeds as opposed to the observational record and by focusing on the highest wind speeds of the strongest tropical cyclones each year.

Emanuel's theory is that the intake of warm air near the ocean surface and the exhaust of colder air above the cyclone is what drives a hurricane. Other factors being equal, the warmer the ocean, the warmer the intake of air. This heat-engine theory of how hurricanes increase their intensity is well accepted, but there are many environmental factors, such as wind shear, that might prevent a hurricane from strengthening, Elsner said.

To address that problem, Elsner's team looked at a subset of hurricanes that are closest to their maximum possible intensity (MPI). Under the heat-engine theory, every storm will lose some energy through inefficiency, and that loss will limit the storm's potential. The MPI represents the storm's maximum potential under ideal environmental conditions.

"We speculated that you might not see a trend in the intensity of typical hurricanes due to environmental factors, but if the heat-engine theory is correct, you should see a trend in the intensity of hurricanes at or near their MPI," Elsner said. "On average, the strongest storms are closest to their MPI."

The researchers created a data set from satellite observations of hurricane intensity of all tropical cyclones around the globe and looked at the maximum wind speeds for each one during a 25-year period. Tropical cyclones, which include hurricanes, typhoons and tropical storms, occur on average about 90 times per year worldwide.

The researchers found that the strongest tropical cyclones are getting stronger, particularly over the North Atlantic and Indian oceans. Wind speeds for the strongest tropical storms increased from an average of 140 mph in 1981 to 156 mph in 2006, while the ocean temperature, averaged globally over the all regions where tropical cyclones form, increased from 28.2 degrees Celsius to 28.5 degrees Celsius during this period.

"By creating a better, more consistent historical data set, we've been able to weed out quality issues that introduce a lot of uncertainty," Kossin said. "Then, by looking only at the strongest tropical cyclones, where the relationship between storms and climate is most pronounced, we are able to observe the increasing trends in storm intensity that both the theory and models say should be there."

While Elsner said the heat-engine theory might explain how tropical cyclones intensify given that everything else is the same, he noted, "We still do not have a complete understanding of why some cyclones intensify, sometimes quite rapidly, and others don't."

The research is supported by the National Science Foundation and the Risk Prediction Initiative of the Bermuda Institute for Ocean Studies.

credited to Florida State University (2008, September 4). Global Warming: Warmer Seas Linked To Strengthening Hurricanes, According to New Research. ScienceDaily. Retrieved September 4, 2008, from http://www.sciencedaily.com­ /releases/2008/09/080903134323.htm

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The ice shelves in Canada's High Arctic have lost a colossal area this year, scientists report.

The floating tongues of ice attached to Ellesmere Island have seen almost a quarter of their cover break away.

Researchers say reduced sea-ice conditions and warm air temperatures have assisted the break-up.

"These substantial calving events underscore the rapidity of changes taking place in the Arctic," said Trent University's Dr Derek Mueller.

A rapid ice retreat is being experienced across the Arctic again this year, affecting both the ice attached to the coast and floating in the open ocean.

The floating sea-ice, which would normally keep the shelves hemmed in, has shrunk to just under five million sq km. This is the second lowest extent recorded since the era of satellite measurement began about 30 years ago.

Scientists reported in July that substantial slabs of ice had calved from Ward Hunt Ice Shelf, the largest of the Ellesmere shelves.

Similar changes have been seen in the other four shelves, with the entire 50 sq km (20 sq miles) Markham shelf now said to be floating free in the Arctic Ocean.

The shelves themselves are merely remnants of a much larger feature that was once bounded to Ellesmere Island and covered almost 10,000 sq km (3,500 sq miles).

Over the past 100 years, this expanse of ice has retreated by 90%, and at the start of this summer season covered just under 1,000 sq km (400 sq miles).

Much of the area was lost during a warm period in the 1930s and 1940s.

Temperatures in the Arctic are now even higher than they were then, and a period of renewed ice shelf break-up has ensued since 2002.

Unlike much of the floating sea-ice which comes and goes, the shelves contain ice that is up to 4,500 years old.

Loss of ice in the Arctic, and in particular the extensive sea-ice, has global implications. The "white parasol" at the top of the planet reflects energy from the Sun straight back out into space, helping to cool the Earth.

Further loss of Arctic ice will see radiation absorbed by darker seawater and snow-free land, potentially warming the Earth's climate at an even faster rate than current observational data indicates.

credited to BBC - news.bbc.co.uk/2/hi/science/nature/7595441.stm

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Climate models have long predicted that global warming will increase the intensity of extreme precipitation events. A new study conducted at the University of Miami and the University of Reading (U.K.) provides the first observational evidence to confirm the link between a warmer climate and more powerful rainstorms.

One of the most serious challenges humanity will face in response to global warming is adapting to changes in extreme weather events. Of utmost concern is that heavy rainstorms will become more common and more intense in a warmer climate due to the increased moisture available for condensation. More intense rain events increase the risk of flooding and can have substantial societal and economic impacts.

To understand how precipitation responds to a warmer climate, researchers in this study used naturally-driven changes associated with El Niño as a laboratory for testing their hypotheses. Based on 20 years of satellite observations, they found a distinct link between tropical rainfall extremes and temperature, with heavy rain events increasing during warm periods and decreasing during cold periods.

"A warmer atmosphere contains larger amounts of moisture which boosts the intensity of heavy downpours," said Dr. Brian J. Soden, associate professor at the University of Miami Rosenstiel School of Marine & Atmospheric Science.

The report, "Atmospheric Warming and the Amplification of Precipitation Extremes," previewed in Science Express this Thursday, August 7, and published in an upcoming issue of Science, found that both observations and models indicated an increase in heavy rainstorms in response to a warmer climate. However, the observed amplification of rainfall extremes was found to be substantially larger in the observations than what is predicted by current models.

"Comparing observations with results from computer models improves understanding of how rainfall responds to a warming world" said Dr. Richard P. Allan, NERC advance fellow at the University of Reading's Environmental Systems Science Centre. "Differences can relate to deficiencies in the measurements, or the models used to predict future climatic change"

credited to University of Miami Rosenstiel School of Marine & Atmospheric Science (2008, August 8). Climate Change: When It Rains It Really Pours. ScienceDaily. Retrieved August 9, 2008, from http://www.sciencedaily.com­ /releases/2008/08/080807144240.htm

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A report just released in the most recent issue of the Bulletin of the American Meteorological Society offers hope that a new high-resolution storm surge modeling system developed by scientists at Stony Brook University will better be able to predict flood levels and when flooding will occur in the New York metropolitan area, information crucial to emergency managers when planning for impending storms. The report also warns that flooding is dependent not just upon the intensity of the tropical storm, hurricane, or nor'easter, but also on the local phase of the tide at the time of the storm.

In a project funded by New York Sea Grant, Brian Colle, Associate Professor in the School of Marine and Atmospheric Science (SoMAS) at Stony Brook University, and colleagues tested the utility of coupling a state-of the art atmospheric model with an ocean model from the Stony Brook Storm Surge (SBSS) system in order to predict storm surges for the NYC metropolitan region. Colle and colleagues tested their combined model against Tropical Storm Floyd and a nor'easter from 11-12 December 1992, and found the model predicted peak water levels comparable (within 10 percent) to those measured during the storms at several water level gauges around the region.

"Ultimately, the goal is to provide emergency managers with a range of possibilities as to what may happen as the result of a storm, and this approach shows great promise," says Dr. Colle.

The modelers also performed simulations to assess the impact of parameters such as local tide level and wind intensity on flooding severity. Model simulations showed that if Tropical Storm Floyd had arrived in NYC a week earlier, coinciding with a spring (fortnightly) high tide, water levels would likely have been high enough for minor flooding to occur. Another simulation, which used wind levels of a Category 1 hurricane timed to arrive at spring high tide, predicted water levels likely to have caused significant flooding. These results suggest that the New York City metropolitan region was spared from flooding during Tropical Storm Floyd only because the storm's winds had weakened before reaching the region and because the strongest winds luckily occurred during local low tide.

"We're playing Russian roulette in some sense with these storms coming up the coast," says Colle. "If we have a high tide or spring high tide when we have one of these events, then we're in trouble."

If a category-3 hurricane hit NYC, the U.S. Army Corps of Engineers estimates that nearly 30% of the south side of Manhattan would be flooded. Storm surge flooding could threaten billions of dollars of property and have a grave impact on the lives of the millions of people who live in NYC. During the December 1992 nor'easter, storm tides over-topped some of the region's seawalls for only a few hours, but managed to flood the NYC subway and the PATH train systems at the train station in Hoboken New Jersey, shutting down these transportation systems for several days.

As sea level rises, NYC becomes even more vulnerable to storm surge flooding. It takes high water levels of only 1.5- 1.75 m (4.92 – 5.74 feet) above mean sea level to cause flooding over some of the southern Manhattan Island seawalls and global warming is expected to increase the rate at which sea level rises from 0.3 m (0.98 feet) per century to 0.5- .75 m (1.64 – 2.46 feet) per century.

"The vulnerability of the area speaks for itself as we've already had cases of flooding," says Colle. "When coupled with sea level rise, it's not going to take much of a storm to cause flooding as we go into the coming decades, so we are working to provide better forecasting of these events in the future."

credited to sciencedaily.com and iStockphoto/Klaas Lingbeek- Van Kranen

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