Climate Science // Current

Climate change is 'faster and more extreme' than feared

'Extreme weather events' such as the hot summer of 2003, which caused an extra 35,000 deaths across southern Europe from... more

JanforGore
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Wake Up, Freak Out - Then Get a Grip

This really isn’t about polar bears any more. At this very moment, the fate of civilization itself hangs in the balance. ... more

lmmesq
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Sea level rises could far exceed IPCC estimates: scientists

Could our coastlines disappear underwater much sooner than we think? The controversial view that sea levels could rise at a rate of more than 1 metre per century has found support from a new study of a long-melted ice sheet.

In reconstructing the events at the end of the last ice age, Anders Carlson of the University of Wisconsin-Madison and colleagues found that the Laurentide ice sheet, which covered most of North America between 95,000 and 7000 years ago, rapidly disintegrated.

The researchers began by studying beryllium isotopes in rocks to determine how the outer edges of the two final chunks of the Laurentide ice sheet retreated. They found that the ice retreated rapidly between 9000 and 8500 years ago, stabilised, and then made its final rapid retreat between 7600 and 6800 years ago.

The team calculated the volume of water that would have been released in each of these melting stages, and the rate at which it must have raised sea levels. They concluded that levels would have climbed 1.3 metres per century in the earlier period, and 0.7 metres per century in the final melt.

Carlson then used a sophisticated computer model – one that is used to forecast future climate change – to check the results. The model predicted an average sea level rise of 1.3 metres per century.

Different times
"The forces that led to the demise of the Laurentide ice sheet in a very rapid way are comparable to the forces the same computer models predict we will experience this century if we do not rapidly curb greenhouse gas emissions," says Gavin Schmidt of the NASA Goddard Institute for Space Studies, who collaborated with Carlson on the study.

For Mark Siddall of the University of Bristol, UK, and Michael Kaplan of the Lamont Doherty Earth Observatory in New York, however, there remain many differences between what happened nearly 10,000 years ago and the climate change Earth is currently experiencing.

"To what extent this dynamic response of the Laurentide ice sheet to past temperature change can be considered analogous to present and future reduction of the Greenland ice sheet remains unresolved," they say in an associated commentary. "But their work suggests that future reductions of the Greenland ice sheet on the order of one metre per century are not out of the question."

If Carlson's estimates are correct, they show that 2007 predictions made by the Intergovernmental Panel on Climate Change – a sea-level rise of between 18 centimetres and 59 cm by 2100 – are very conservative, as the IPCC acknowledged at the time.

Millions at risk
Sea-level rises of at least a metre per century were also predicted by the head of the NASA Goddard Institute for Space Studies, James Hansen. Hansen believes that our climate will soon hit tipping points – points of no return – beyond which the ice sheets will rapidly disintegrate.

Carlson says his team's findings are proof that large ice sheets can disintegrate very rapidly. What's more, he says the forces that caused the Laurentide ice sheet to disintegrate are equivalent to the ones that threaten the Greenland ice sheet today.
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Will the US and other industrialized nations then step up to the plate in Copenhagen next year? Will the US Congress do so as well? The way I feel today I would say it would have to take Greenland falling into the ocean before that happens. How irresponsible of them to not be making this the priority issue it must be.Could our coastlines disappear underwater much sooner than we think? The controversial view that sea levels could rise at a rate... more

JanforGore
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3 months ago

Global warming time bomb trapped in Arctic soil: study

Climate change could release unexpectedly huge stores of carbon dioxide from Arctic soils, which would in turn fuel a vicious... more

JanforGore
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26 responses

3 months ago

Purdue researcher identifies climate change hotspots

A study using one of the most complete climate modeling systems in the world points to southern California, northern Mexico and... more

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3 months ago

Seals helping humans unlock secrets of the frozen sea

Led by Dr Jean-Benoit Charrassin, a marine biologist at the Natural History Museum in Paris, researchers in France, the UK,... more

JanforGore
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20 responses

3 months ago

Climate change in action in Greenland

You can't see climate change in action, much to the disappointment of photographers and magazine art directors. Warming is a function of time, and we see it only as time passes. Years go by, we add more carbon dioxide to the atmosphere, temperatures rise, glaciers retreat and deserts expand. One of the essential facts about climate science is that unlike, say, weather forecasting, the farther ahead we look into the future, the more confident we can be of our predictions. So we know that burning enough fossil fuel to raise the concentration of CO2 in the atmosphere to 550 parts per million twice preindustrial levels will virtually guarantee a temperature increase of at least 3 F, with all the consequences that will carry. By contrast, we can't look at a hurricane, or at an iceberg melting, and say, "Yes, this is global warming, and we did this." Climate change is change, and change happens over time.

In some places of the world, that change is happening more quickly than in others, so quickly that our "fast-thinking human mind," as the University of Copenhagen geologist Minik Rosing says, can almost catch it. One of those places is the coastal town of Ilulissat, the last stop on our climate tour of Greenland. It's home to the Ilulissat ice fjord, a basin-shaped wound in the rocky coast, through which the massive Sermeq Kujalleq glacier churns toward the sea. As the glacier moves at the hardly glacial speed of over 100 ft. a day the ice melts and cracks into cathedrals of blue and white that bob in the harbor beyond the isfledsbanken, or iceberg bank. Sermeq Kujalleq, which is fed by the 1.8 million cubic miles of solid ice that cover central Greenland, is the most productive glacier on the island, calving icebergs with dramatic regularity. The iceberg that sank the Titanic may well have come from Sermeq, and looking upon Ilulissat's harbor, choked with sheer cliffs of ice that dwarf even the stately cruise liners, I can believe it.

We take a boat out for a tour amid the ice. In the Arctic summer Ilulissat is cool but not cold, maybe 65 F, but as we near the ice fjord, the temperature drops, as if cold is emanating from the icebergs themselves. As we leave the port, at first we encounter a slurry of ice in the water, which is sapphire blue because of the cold. But soon we near the giants, and they are easily over 100 ft. tall and that's just above the water. (More than 80% of an iceberg's mass is beneath the surface, and the water in Ilulissat's port is more than a mile deep.) We can't get too close to the big icebergs as they melt all the time in the salty sea, without warning, they can crack and cave in, loosing waves big enough to topple or even crush small boats. But even from a distance, they are breathtaking: natural cathedrals of white, lined by unmappable crevices, leaking pure glacial meltwater that pours into the sea as if from a fountain. It's easy to see why UNESCO made Ilulissat a World Heritage site and why tourist numbers have been growing steadily.

But we're not here as tourists. After the boat docks, our group boards a helicopter piloted by a sprite of a Greenlandic woman for a tour of the fjord and glacier, which is retreating fast. Before we leave, we are shown a map of the glacier. As pressure from the central ice cap builds up behind the glacier, it pushes its way to the sea through the ice fjord. The glacier ends where melting causes icebergs to calve off, and we see that each year the glacier has retreated farther and farther away from the sea. Sermeq Kujalleq is shrinking so fast (on a geological scale) that we can almost see it.

This is global warming as close as we can get to it in action. There's no doubt here, no room for skeptics: temperatures have warmed in Greenland, and as they have warmed, the ice has melted. It is as simple as that.You can't see climate change in action, much to the disappointment of photographers and magazine art directors. Warming is a... more

JanforGore
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3 months ago

Climate Change Equals Stronger Rains

As the globe continues to warm, the rainiest parts of the world are very likely to get wetter, according to a new study in Science. Desert dwellers, however, are likely to see what little rain they receive dry up, as the rain becomes even more concentrated in high-precipitation areas.

Atmospheric scientists Richard Allan of the University of Reading in England and Brian Soden of the University of Miami looked at satellite records of daily rainfall stretching back to 1987 to see how warmer temperatures had affected precipitation. That's one of the key climate changes expected from rising greenhouse gas levels in the atmosphere. The researchers specifically focused on El Niño, the warming of the waters of the tropical Pacific that raises air pressure, changes winds, and recurs every few years.

The weather pattern causes floods in some areas and droughts in others while changing climate across the globe over time—and thus is a pretty good stand-in for global warming.

"For the period we examined, 1987 to 2004, there was a clear relationship between warm El Niño events and increased occurrence of heavy precipitation," Soden says. Such "events will certainly become more frequent in a warmer climate."

For example, other research has shown that monsoon storms that dump six inches (150 millimeters) or more of rain on India have become more common since the 1950s.

The satellite observations agree with the predictions of various computer models. The U.N. Intergovernmental Panel on Climate Change expects that such changes will wreak havoc on agriculture, human health and the natural environment.

But the Science study also reveals that the computer projections may be underestimating how severe such downpours may become. Warmer seas resulted in three times as many heavy rainstorms as the models would have predicted—and other studies have shown that such models fail to account for the rapid increase in water vapor in the atmosphere.

"It is very likely that heavy rainfall will become more common and more intense in a warming world," Allan says. "It is too early to say by how much real world changes in rainfall will surpass projections from the climate models."

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The effects of this will have devastating effects on agriculture in areas that need rain but do not receive it, and areas that will receive heavier rains. This will also bring with it health risks such as disease carrying insects and waterborne diseases as well as many more displaced people. It is studies like this that must be taken into account in any new global climate treaty.
As the globe continues to warm, the rainiest parts of the world are very likely to get wetter, according to a new study in... more

JanforGore
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3 months ago

Despite sceptics' noise on climate change, scientific consensus is growing

Anyone keeping up with current affairs could be forgiven for thinking scientists are riven with doubt over climate change. Climate sceptics have enjoyed a resurgence as the federal Coalition danced around the introduction of carbon trading and heavy-polluting industries began an intensive lobbying effort to convince the Federal Government of their special needs.

The Page Research Centre, a think tank associated with the Nationals, last week hosted a forum that concluded that the science behind global warming was shaky. Backbench MPs in both major parties have reportedly questioned the science on which the Federal Government's recent green paper is based.

The noise has been loudest on the internet, where websites give voice to people who believe scientists are suppressing evidence to protect their careers.

Unfortunately for the sceptics, and for everyone else, the evidence for human-induced climate change is stronger than ever. Scientists the Herald spoke to were candid in their assessment that there was little room for doubt that global warming is happening and that the only changes in the past few months have been political changes.

"It looks as though the population believes climate change is serious and there seems to be momentum behind the issue, and there are some people who don't like that," says Chris Mitchell, head of the CSIRO's Climate, Weather and Ocean Prediction group. "There are still plenty of creationists around, and there are people who believe tobacco is not linked to serious health effects, and so there are still people who choose to ignore or doubt the amount of evidence for climate change."

Andy Pitman, an editor of the prestigious international Journal Of Climate, says there are good reasons why global warming sceptics cannot get a run in peer-reviewed scientific literature. "We would kill, literally kill, for a good paper that proved the science on global warming was wrong," Pitman says. "Then I could retire and accept my chair at Harvard. Unfortunately, that's not going to happen, and there's vast amounts of evidence why."

Pitman, who is also a lead author of the Intergovernmental Panel on Climate Change (ABC) and director of the Climate Change Research Centre at the University of NSW, says the reasons are simple: "In essence, the models we use to predict climate have been proven right." In the past decade, he says, refinements in computer simulations have allowed scientists to accurately predict climate in four dimensions: time, latitude, longitude and depth of the atmosphere.

"You feed in the greenhouse gas concentrations that we've seen, and the models predict extremely well the climate variations we've seen. If you don't do that, you get nothing. The mathematical probability of it being a chance mistake, or the wrong numbers, is astronomical."

The claim, often cited by sceptics, that atmospheric temperature did not appear to match the levels predicted by climate models was revised by a reassessment of the data last year. The research, partly carried out in Australia, ended up reinforcing the accuracy of existing climate models. Claims that solar activity may be causing recent global warming, reinforced in State Parliament by the Treasurer, Michael Costa, have been comprehensively demolished in peer-reviewed journals.

Anyone keeping up with current affairs could be forgiven for thinking scientists are riven with doubt over climate change. Climate... more

JanforGore
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4 months ago

Wintertime disintegration of Wilkins ice shelf

On the Antarctic Peninsula, the Wilkins Ice Shelf (roughly 70 degrees south and 75 degrees west) historically extended toward Charcot Island in the northwest and Latady Island in the southwest. By July 2008, the ice shelf’s connection to Charcot Island, which had helped to hold the shelf in place, was nearly gone.

The Advanced Synthetic Aperture Radar (ASAR) on the European Space Agency’s Envisat satellite observed the ice shelf between May 30 and July 17, 2008. These ASAR images show the eastern part of the ice shelf on July 17 (top), June 28 (middle), and May 30 (bottom). Not pictured, Charcot Island is in the northwest (upper left).

The image acquired on May 30, 2008, captured the ice shelf at the beginning of a disintegration event. In this image, large slices of the ice shelf appear in the lower left corner. These long, thin blocks have broken off the shelf and are moving away toward the southwest. To the northeast, in the middle of the image, is what glaciologists describe as mélange—a stuck-together mass of ice blocks, snow, and sea ice. This portion of the shelf actually disintegrated in 1998, but the ice remained frozen in place for a decade. Farther to the east, the ice is in larger blocks. To the north is a mixture of very thin sea ice, ice blocks from earlier rifting, and open water.

The image acquired on June 28, 2008, shows several changes. In the southwest, the large slices of ice visible on May 30 have moved away. The portion of the ice shelf connecting to Charcot Island has narrowed, assuming an almost hourglass shape. Immediately northeast of this skinny stretch of shelf, the darker parts of the ice mélange appear to be melting. Farther northeast, the large blocks of ice have begun to drift apart.

The image acquired on July 17, 2008, shows the continued breakup of the ice shelf. The ice mélange is even darker than it was in late June. Large, relatively intact plates of ice drift toward the northeast from the thin piece of shelf that still stretches toward the nearby island. The large blocks of ice in the northeast continue their northward drift, some separated by areas of open water.

These images focus on events in the eastern portion of the Wilkins Ice Shelf, The western portion of the shelf rapidly disintegrated between February 28 and March 6, 2008. That event had occurred during the Southern Hemisphere summer, when summertime warmth and sunshine can drive surface melt processes that lead to disintegration. In contrast, the events occurring from late May to early July 2008 occurred in the Southern Hemisphere winter.
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Look to the glaciers and the oceans for your signs of climate change. Will ten years even be enough time?On the Antarctic Peninsula, the Wilkins Ice Shelf (roughly 70 degrees south and 75 degrees west) historically extended toward... more