Introduction to global warming

I shouldn't be lifting it from a blog wholesale - but this is a wonderfully informed and data/information rich post on "catastrophic global warming". The original blog, which again is very useful.

Regards

Kundan

http://climateprogress.org/2009/03/22/an-introduction-to-global-warming-impacts-hell-and-high-water/

An introduction to global warming impacts: Hell and High Water

March 22, 2009

This is for readers who wanted one-stop, updatable introductory posts on various key topics.Please do add any key impacts you think I’ve missed — but focus on those with a scientific source.

In this post, I will examine the key impacts we face by 2100 if we stay anywhere near our current emissions path. I will focus primarily on:

• Staggeringly high temperature rise, especially over land — some 10°F over much of the United States
• Sea level rise of 5 feet, rising some 6 to 12 inches (or more) each decade thereafter
• Dust Bowls over the U.S. SW and many other heavily populated regions around the globe
• Massive species loss on land and sea — 50% or more of all life
• Unexpected impacts — the fearsome “unknown unknowns”
• More severe hurricanes — especially in the Gulf

Equally tragic, as a 2009 NOAA-led study found, these impacts be “largely irreversible for 1000 years.”

The single biggest failure of messaging by climate scientists (until very recently) has been the failure to explain to the public, opinion makers, and the media that business-as-usual warming results in impacts that are beyond catastrophic. For these impacts, terms like “global warming” and “climate change” are essentially euphemisms. That is why I prefer the term “Hell and High Water.”

Business-as-usual typically means continuing at recent growth rates of carbon dioxide emissions, which we now know would take us to atmospheric concentrations of carbon dioxide greater than 1000 ppm (see U.S. media largely ignores latest warning from climate scientists: “Recent observations confirm … the worst-case IPCC scenario trajectories (or even worse) are being realised” — 1000 ppm). We are at about 8.5 billion metric tons of carbon a year (GtC/yr) and, until the recent global economic recession, were rising about 3% per year.

What is less well understood is that even a very strong mitigation effort that kept carbon emissions this century to 11 GtC a year on average would still probably take us to 1000 ppm — a little noted conclusion of the 2007 Intergovernmental Panel on Climate Change (IPCC) report (see “Nature publishes my climate analysis and solution“).

The scientific community has spent little time modeling the impacts of a tripling (~830 ppm) or quadrupling (~1100 ppm) carbon dioxide concentrations from preindustrial levels. In part, I think, that’s because they never believed humanity would be so stupid as to ignore the warnings and simply continue on its self-destructive path. In part, they lowballed the difficult-to-model amplifying feedbacks in the carbon cycle.

So I pieced together those impacts from available studies and from discussions with leading climate scientists for my book, Hell and High Water. But now as climate scientists have sobered up to their painful role as modern-day Cassandra’s, the scientific literature on what we face is much richer. Let me review it here.

TEMPERATURE

Two of the best recent analyses of what we are headed towards can be found here:

• M.I.T. joins climate realists, doubles its projection of global warming by 2100 to 5.1°C
• Hadley Center: “Catastrophic” 5-7°C warming by 2100 on current emissions path

As Dr. Vicky Pope, Head of Climate Change Advice for the Met Office’s Hadley Centre explains on their website (here):

Contrast that with a world where no action is taken to curb global warming. Then,temperatures are likely to rise by 5.5 °C and could rise as high as 7 °C above pre-industrial values by the end of the century.

That likely rise corresponds to roughly 9°F globally and typically 40% higher than that over inland mid-latitudes (i.e. much of this country) — or well over 10°F.

[Note: The MIT rise is compared to 1980-1999 levels see study here). So you can add at least 0.5 C and 1.0°F for comparison with pre-industrial temperatures.]

Based on two studies in the last few years:

By century’s end, extreme temperatures of up to 122°F would threaten most of the central, southern, and western U.S. Even worse, Houston and Washington, DC could experience temperatures exceeding 98°F for some 60 days a year. Much of Arizona would be subjected to temperatures of 105°F or more for 98 days out of the year–14 full weeks.

Yet that conclusion is based on studies of only 700 ppm and 850 ppm, so it could get much hotter than that.

And the Hadley Center adds, “By the 2090s close to one-fifth of the world’s population will be exposed to ozone levels well above the World Health Organization recommended safe-health level.”

The Hadley Center has a huge but useful figure which I will reproduce here:

SEA LEVEL RISE

A 5.5°C warming would likely lead to the mid- to high-range of currently projected sea level rise — 5 feet or more by 2100, followed by 10 to 20 inches a decade for centuries. The best recent study is

• Startling new sea level rise research: “Most likely” 0.8 to 2.0 meters by 2100

Needless to say, a sea level rise of one meter by 2100 would be an unmitigated catastrophe for the planet, even if sea levels didn’t keep rising several inches a decade for centuries, which they inevitably would. The first meter of SLR would flood 17% of Bangladesh, displacing tens of millions of people, and reducing its rice-farming land by 50 percent. Globally, it would create more than 100 million environmental refugees and inundate over 13,000 square miles of this country. Southern Louisiana and South Florida would inevitably be abandoned. And salt water infiltration will only compound this impact (see “Rising sea salinates India’s Ganges“). As will hurricanes (see below).

The scientific literature has been moving in this direction for a couple of years now — too late for the IPCC to consider in its latest assessment. For instance, an important Science article from 2007 used empirical data from last century to project that sea levels could be up to 5 feet higher in 2100 and rising 6 inches a decade (see Inundated with Information on Sea Level Rise)!

Another 2007 study from Nature Geoscience came to the same conclusion (see “Sea levels may rise 5 feet by 2100“). Leading experts in the field have a similar view (see “Amazing AP article on sea level rise” and “Report from AGU meeting: One meter sea level rise by 2100 “very likely” even if warming stops?“).

Note: Since global warming deniers and delayers like to hide behind the IPCC’s 2007 sea level estimate — even though they really don’t believe most of what the IPCC says or most of the scientific literature on which it bases its conclusion — you’re going to be hearing the IPCC estimate for another several years, until the IPCC does a new report and puts in a more realistic estimate. That said, while the delayers never acknowledge it, even the 2007 IPCC report “was the first to acknowledge that the melting of the Greenland ice sheet from rising temperature [which would raise the oceans 23 feet] could result in sea-level rise over centuries rather than millennia,” as the NYT put it (see “Absolute MUST Read IPCC Report: Debate over, further delay fatal, action not costly“).

Yet even a major report signed off on by the Bush administration itself was forced to concede that the IPCC numbers are simply too out of date to be quoted anymore:

• US Geological Survey stunner: Sea-level rise in 2100 will likely “substantially exceed” IPCC projections

DESERTIFICATION

Then we have moderate drought over half the planet, plus the loss of all inland glaciers that provide water to a billion people.

“The unexpectedly rapid expansion of the tropical belt constitutes yet another signal that climate change is occurring sooner than expected,” noted one climate researcher in December 2007. A 2008 study led by NOAA noted, “A poleward expansion of the tropics is likely to bring even drier conditions to” the U.S. Southwest, Mexico, Australia and parts of Africa and South America.”

In 2007, Science (subs. req’d) published research that “predicted a permanent drought by 2050 throughout the Southwest” — levels of aridity comparable to the 1930s Dust Bowl would stretch from Kansas to California. And they were only looking at a 720 ppm case! The Dust Bowl was a sustained decrease in soil moisture of about 15% (”which is calculated by subtracting evaporation from precipitation”).

A NOAA-led study similary found permanent Dust Bowls in Southwest and around the globe on our current emissions trajectory (and irreversibly so for 1000 years). And as I have discussed, future droughts will be fundamentally different from all previous droughts that humanity has experienced because they will be very hot weather droughts (see Must-have PPT: The “global-change-type drought” and the future of extreme weather).

I should note that even the “moderate drought over half the planet″ scenario from the Hadley Center is only based on 850 ppm (in 2100). Princeton has done an analysis on “Century-scale change in water availability: CO2-quadrupling experiment,” which is to say 1100 ppm. The grim result: Most of the South and Southwest ultimately sees a 20% to 50% (!) decline in soil moisture.

SPECIES LOSS ON LAND AND SEA

In 2007, the IPCC warned that as global average temperature increase exceeds about 3.5°C [relative to 1980 to 1999], model projections suggest significant extinctions (40-70% of species assessed) around the globe. That is a temperature rise over pre-industrial levels of a bit more than 4.0°C. So a 5.5°C rise would likely put extinctions beyond the high end of that range.

And, of course, “When CO2 levels in the atmosphere reach about 500 parts per million, you put calcification out of business in the oceans.” There aren’t many studies of what happens to the oceans as we get toward 800 to 1000 ppm, but it appears likely that much of the world’s oceans, especially in the southern hemisphere, become inhospitable to many forms of marine life. A 2005 Nature study concluded these “detrimental” conditions “could develop within decades, not centuries as suggested previously.”

A 2009 study in Nature Geoscience warned that global warming may create “dead zones” in the ocean that would be devoid of fish and seafood and endure for up to two millennia (see Ocean dead zones to expand, “remain for thousands of years”).

UNEXPECTED IMPACTS

If we go to 800 ppm — let alone 1000 ppm or higher — we are far outside the bounds of simple linear projection. Some of the worst impacts may not be obvious — and there may be unexpected negative synergies. The best evidence that will happen is the fact that it is already happened with even a small amount of warming we have seen to date.

“The pine beetle infestation is the first major climate change crisis in Canada” notes Doug McArthur, a professor at Simon Fraser University in Vancouver. The pests are “projected to kill 80 per cent of merchantable and susceptible lodgepole pine” in parts of British Columbia within 10 years — and that’s why the harvest levels in the region have been “increased significantly.”

As quantified in the journal Nature, “Mountain pine beetle and forest carbon feedback to climate change,” (subs. req’d), while just looks at the current and future impact from the beetle’s warming-driven devastation in British Columbia:

… the cumulative impact of the beetle outbreak in the affected region during 2000–2020 will be 270 megatonnes (Mt) carbon (or 36 g carbon m^-2 yr^-1 on average over 374,000 km² of forest). This impact converted the forest from a small net carbon sink to a large net carbon source.

No wonder the carbon sinks are saturating faster than we thought (see here) — unmodeled impacts of climate change are destroying them:

Insect outbreaks such as this represent an important mechanism by which climate change may undermine the ability of northern forests to take up and store atmospheric carbon, and such impacts should be accounted for in large-scale modelling analyses.

And the bark beetle is slamming the Western U.S. and Alaska, too (see “Oldest Utah newspaper: Bark-beetle driven wildfires are a vicious climate cycle“).

The key point is this catastrophic climate change impact and its carbon-cycle feedback were not foreseen even a decade ago — which suggests future climate impacts will bring other equally unpleasant surprises, especially as we continue on our path of no resistance.

HURRICANES

Even if we don’t see an increase in the worst hurricanes hurricanes, the rising sea levels alone would put a growing number of coastal cities below sea level. Such cities are particularly hard to protect from major hurricanes as we saw with New Orleans. And that suggests in the second half of this century, we will be increasingly reluctant to rebuild cities devastated by major hurricanes.

That said, the literature suggests we will see an increase in severe hurricanes (see “ Hurricanes ARE getting fiercer — and it’s going to get much worse“). A 2008 Nature studied concluded:

The team calculates that a 1 ºC increase in sea-surface temperatures would result in a 31% increase in the global frequency of category 4 and 5 storms per year: from 13 of those storms to 17. Since 1970, the tropical oceans have warmed on average by around 0.5 ºC. Computer models suggest they may warm by a further 2 ºC by 2100.

Well, actually, those are the old computer models running old scenarios of emissions without much consideration of amplifying carbon cycle feedbacks. On our current emissions path, key parts of the tropical oceans are likely to warm considerably more than 2°C by century’s end.

For a longer discussion of why future hurricanes in the Gulf of Mexico are likely to become far more dangerous in the future, see (Why global warming means killer storms worse than Katrina and Gustav, Part 1 and Part 2).

CONCLUSION

We can’t let this happen. We must pay any price or bear any burden to stop it.

And let me make one final point. I think it is increasinly clear the “middle ground” scenarios are unstable in that once you hit 500 ppm (or possibly lower), the amplifying feedbacks kick in: These feedbacks include:

• The defrosting of the permafrost
• The drying of the Northern peatlands (bogs, moors, and mires).
• The destruction of the tropical wetlands
• Decelerating growth in tropical forest trees — thanks to accelerating carbon dioxide
• Wildfires and Climate-Driven forest destruction by pests
• The desertification-global warming feedback
• The saturation of the ocean carbon sink

As Dr. Pope puts it, “If the climate turns out to be particularly sensitive to increases in greenhouse gases and the Earth’s biological systems cannot absorb very much carbon then temperature rises could be even higher.”

Indeed, some of the best research on this has come from the Hadley Center, since it has one of the few models that incorporates many of the major carbon cycle feedbacks. In a 2003Geophysical Research Letters (subs. req’d) paper, “Strong carbon cycle feedbacks in a climate model with interactive CO2 and sulphate aerosols,” the Hadley Center, the U.K.’s official center for climate change research, finds that the world would hit 1000 ppm in 2100 even in a scenario that, absent those feedbacks, we would only have hit 700 ppm in 2100. I would note that the Hadley Center, though more inclusive of carbon cycle feedbacks than most other models, still does not model most of the feedbacks above or any feedbacks from the melting of the tundra even though it is probably the most serious of those amplifying feedbacks.

So we must stabilize at 450 ppm or below — or risk what can only be called humanity’s self-destruction. Since the cost is maybe 0.11% of GDP per year — or probably a bit higher than that if we shoot for 350 ppm — the choice would seem clear. Now if only the scientific community and environmentalists and progressives could start articulating this reality cogently.

Six degrees to a hotter Planet

Please find this very interesting article. It is again written from a westerner's perspective, but note that our nemesis (i.e. for people from the developing world) is very close if no drastic action is taken.

http://www.marklynas.org/2007/4/23/six-steps-to-hell-summary-of-six-degrees-as-published-in-the-guardian

'Six steps to hell' - summary of Six Degrees as published in the Guardian 23 April 07

By the end of the century, the Earth could be more than 6C hotter than it is today, according to the Intergovernmental Panel on Climate Change. We know that would be bad news - but just how bad? How big a rise will it take for the Alps to melt, the oceans to die and desert to conquer Europe and the Americas? Mark Lynas sifted through thousands of scientific papers for his new book on global warming. This is what the research told him...

The following is an article by Mark Lynas based on his book Six Degrees: Our Future on a Hotter Planet. It was published in the Guardian on 23 April 2007. The original version is available here.

1ºC

Nebraska isn’t at the top of most tourists’ to-do lists. However, this dreary expanse of impossibly flat plains sits in the middle of one of the most productive agricultural systems on Earth. Beef and corn dominate the economy, and the Sand Hills region – where low, grassy hillocks rise up from the flatlands – has some of the best cattle ranching in the whole US. But scratch beneath the grass and you will find, as the name suggests, not soil but sand. These innocuous-looking hills were once desert, part of an immense system of sand dunes that spread across the Great Plains from Texas in the south to the Canadian prairies in the north. Six thousand years ago, when temperatures were about 1C warmer than today in the US, these deserts may have looked much as the Sahara does today. As global warming bites, the western US could once again be plagued by perennial drought – devastating agriculture and driving out human inhabitants on a scale far larger than the 1930s “Dustbowl” exodus.

On the other side of the Atlantic, today’s hottest desert could be seeing a wetter future in the one-degree world. At the same time as sand dunes were blowing across the western US, the central Sahara was a veritable Garden of Eden as rock paintings of elephants, giraffes and buffalo, also dating from 6,000 years ago, attest. On the borders of what is today Chad, Nigeria and Cameroon, the prehistoric Lake Mega-Chad spread over an area only slightly smaller than the Caspian Sea does now. Could a resurgent north African monsoon drive rainfall back into the Sahara in a one-degree world? Models suggest it could.

Also in Africa, Mount Kilimanjaro will be losing the last of its snow and ice as temperatures rise, leaving the entire continent ice-free for the first time in at least 11,000 years. The Alps, too, will be melting, releasing deadly giant landslides as thawing permafrost removes the “glue” that holds the peaks together. In the Arctic, temperatures will rise far higher than the one-degree global average, continuing the rapid decline in sea ice that scientists have already observed. This spells bad news for polar bears, walruses and ringed seals – species that are effectively pushed off the top of the planet as warming shrinks cold areas closer and closer to the pole.

Indeed, it is the ecological effects of warming that may be most apparent at one degree. Critically, this temperature rise may wipe out the majority of the world’s tropical coral reefs, devastating marine biodiversity. Most of the Great Barrier Reef will be dead.

2ºC

In the highly unlikely event that global warming deniers prove to be right, we will still have to worry about carbon dioxide, because it dissolves in the oceans and makes them more acidic. Even with relatively low emissions, large areas of the southern oceans and parts of the Pacific will within a few decades become toxic to organisms with calcium carbonate shells, for the simple reason that the acidic seawater will dissolve them. Many species of plankton – the basis of the marine food chain and essential for the sustenance of higher creatures, from mackerel to baleen whales – will be wiped out, and the more acidic seawater may be the knockout blow for what remains of the world’s coral reefs. The oceans may become the new deserts as the world’s temperatures reach 2C above today’s.

Two degrees may not sound like much, but it is enough to make every European summer as hot as 2003, when 30,000 people died from heatstroke. That means extreme summers will be much hotter still. As Middle East-style temperatures sweep across Europe, the death toll may reach into the hundreds of thousands. The Mediterranean area can expect six more weeks of heatwave conditions, with wildfire risk also growing. Water worries will be aggravated as the southern Med loses a fifth of its rainfall, and the tourism industry could collapse as people move north outside the zones of extreme heat.

Two degrees is also enough to cause the eventual complete melting of the Greenland ice sheet, which would raise global sea levels by seven metres. Much of the ice-cap disappeared 125,000 years ago, when global temperatures were 1-2C higher than now. Because of the sheer size of the ice sheet, no one expects this full seven metres to come before the end of the century, but a top Nasa climate scientist, James Hansen, is warning that the mainstream projections of sea level rise (of 50cm or so by 2100) could be dangerously conservative. As if to underline Hansen’s warning, the rate of ice loss from Greenland has tripled since 2004.

This melting will also continue to affect the world’s mountain ranges, and in Peru all the glaciers will disappear from the Andean peaks that currently supply Lima with water. In California, the loss of snowpack from the Sierra Nevada – three-quarters of which could disappear in the two-degree world – will leave cities such as Los Angeles increasingly thirsty during the summer. Global food supplies, especially in the tropics, will also be affected but while two degrees of warming will be survivable for most humans, a third of all species alive today may be driven to extinction as climate change wipes out their habitat.

3ºC

Scientists estimate that we have at best 10 years to bring down global carbon emissions if we are to stabilise world temperatures within two degrees of their present levels. The impacts of two degrees warming are bad enough, but far worse is in store if emissions continue to rise. Most importantly, 3C may be the “tipping point” where global warming could run out of control, leaving us powerless to intervene as planetary temperatures soar. The centre of this predicted disaster is the Amazon, where the tropical rainforest, which today extends over millions of square kilometres, would burn down in a firestorm of epic proportions. Computer model projections show worsening droughts making Amazonian trees, which have no evolved resistance to fire, much more susceptible to burning. Once this drying trend passes a critical threshold, any spark could light the firestorm which destroys almost the entire rainforest ecosystem. Once the trees have gone, desert will appear and the carbon released by the forests’ burning will be joined by still more from the world’s soils. This could boost global temperatures by a further 1.5ºC – tippping us straight into the four-degree world.

Three degrees alone would see increasing areas of the planet being rendered essentially uninhabitable by drought and heat. In southern Africa, a huge expanse centred on Botswana could see a remobilisation of old sand dunes, much as is projected to happen earlier in the US west. This would wipe out agriculture and drive tens of millions of climate refugees out of the area. The same situation could also occur in Australia, where most of the continent will now fall outside the belts of regular rainfall.

With extreme weather continuing to bite – hurricanes may increase in power by half a category above today’s top-level Category Five – world food supplies will be critically endangered. This could mean hundreds of millions – or even billions – of refugees moving out from areas of famine and drought in the sub-tropics towards the mid-latitudes. In Pakistan, for example, food supplies will crash as the waters of the Indus decline to a trickle because of the melting of the Karakoram glaciers that form the river’s source. Conflicts may erupt with neighbouring India over water use from dams on Indus tributaries that cross the border.

In northern Europe and the UK, summer drought will alternate with extreme winter flooding as torrential rainstorms sweep in from the Atlantic – perhaps bringing storm surge flooding to vulnerable low-lying coastlines as sea levels continue to rise. Those areas still able to grow crops and feed themselves, however, may become some of the most valuable real estate on the planet, besieged by millions of climate refugees from the south.

4ºC

At four degrees another tipping point is almost certain to be crossed; indeed, it could happen much earlier. (This reinforces the determination of many environmental groups, and indeed the entire EU, to bring us in within the two degrees target.) This moment comes as the hundreds of billions of tonnes of carbon locked up in Arctic permafrost – particularly in Siberia – enter the melt zone, releasing globally warming methane and carbon dioxide in immense quantities. No one knows how rapidly this might happen, or what its effect might be on global temperatures, but this scientific uncertainty is surely cause for concern and not complacency. The whole Arctic Ocean ice cap will also disappear, leaving the North Pole as open water for the first time in at least three million years. Extinction for polar bears and other ice-dependent species will now be a certainty.

The south polar ice cap may also be badly affected – the West Antarctic ice sheet could lift loose from its bedrock and collapse as warming ocean waters nibble away at its base, much of which is anchored below current sea levels. This would eventually add another 5m to global sea levels – again, the timescale is uncertain, but as sea level rise accelerates coastlines will be in a constant state of flux. Whole areas, and indeed whole island nations, will be submerged.

In Europe, new deserts will be spreading in Italy, Spain, Greece and Turkey: the Sahara will have effectively leapt the Straits of Gibraltar. In Switzerland, summer temperatures may hit 48C, more reminiscent of Baghdad than Basel. The Alps will be so denuded of snow and ice that they resemble the rocky moonscapes of today’s High Atlas – glaciers will only persist on the highest peaks such as Mont Blanc. The sort of climate experienced today in Marrakech will be experienced in southern England, with summer temperatures in the home counties reaching a searing 45C. Europe’s population may be forced into a “great trek” north.

5ºC

To find out what the planet would look like with five degrees of warming, one must largely abandon the models and venture far back into geological time, to the beginning of a period known as the Eocene. Fossils of sub-tropical species such as crocodiles and turtles have all been found in the Canadian high Arctic dating from the early Eocene, 55 million years ago, when the Earth experienced a sudden and dramatic global warming. These fossils even show that breadfruit trees were growing on the coast of Greenland, while the Arctic Ocean saw water temperatures of 20C within 200km of the North Pole itself. There was no ice at either pole; forests were probably growing in central Antarctica.

The Eocene greenhouse event fascinates scientists not just because of its effects, which also saw a major mass extinction in the seas, but also because of its likely cause: methane hydrates. This unlikely substance, a sort of ice-like combination of methane and water that is only stable at low temperatures and high pressure, may have burst into the atmosphere from the seabed in an immense “ocean burp”, sparking a surge in global temperatures (methane is even more powerful as a greenhouse gas than carbon dioxide). Today vast amounts of these same methane hydrates still sit on subsea continental shelves. As the oceans warm, they could be released once more in a terrifying echo of that methane belch of 55 million years ago. In the process, moreover, the seafloor could slump as the gas is released, sparking massive tsunamis that would further devastate the coasts.

Again, no one knows how likely this apocalyptic scenario is to unfold in today’s world. The good news is that it could take centuries for warmer water to penetrate down to the bottom of the oceans and release the stored methane. The bad news is that it could happen much sooner in shallower seas that see a stronger heating effect (and contain lots of methane hydrate) such as in the Arctic. It is also important to realise that the early Eocene greenhouse took at least 10,000 years to come about. Today we could accomplish the same feat in less than a century.

6ºC

If there is one episode in the Earth’s history that we should try above all not to repeat, it is surely the catastrophe that befell the planet at the end of the Permian period, 251 million years ago. By the end of this calamity, up to 95% of species were extinct. The end-Permian wipeout is the nearest this planet has ever come to becoming just another lifeless rock drifting through space. The precise cause remains unclear, but what is undeniable is that the end-Permian mass extinction was associated with a super-greenhouse event. Oxygen isotopes in rocks dating from the time suggest that temperatures rose by six degrees, perhaps because of an even bigger methane belch than happened 200 million years later in the Eocene.

Sedimentary layers show that most of the world’s plant cover was removed in a catastrophic bout of soil erosion. Rocks also show a “fungal spike” as plants and animals rotted in situ. Still more corpses were washed into the oceans, helping to turn them stagnant and anoxic. Deserts invaded central Europe, and may even have reached close to the Arctic Circle.

One scientific paper investigating “kill mechanisms” during the end-Permian suggests that methane hydrate explosions “could destroy terrestrial life almost entirely”. Acting much like today’s fuel-air explosives (or “vacuum bombs”), major oceanic methane eruptions could release energy equivalent to 10,000 times the world’s stockpile of nuclear weapons.

Whatever happened back then to wipe out 95% of life on Earth must have been pretty serious. And while it would be wrong to imagine that history will ever straightforwardly repeat itself, we should certainly try and learn the lessons of the distant past. If they tell us one thing above all, it is this: that we mess with the climatic thermostat of this planet at our extreme – and growing – peril.

Zaroori Khwab

A song on Dongarias and Niyamgiri by Milli Bhagat.

Catastrophic Climate Change: What will be Orissa's fate?

Please an article from Guardian on climate change. One of them talks about rise in sea level because of melting glaciers. Predictions of sea level rise of upto 150 cm. by century end have been made by USA's Geological Survey- and some scientists say that this may be an underestimate.

Has someone done a detailed analysis of the impact of sea level rise on coastal Orissa- what will be the zones of submergence with different levels of rise, and which habitations and areas wll get submerged in the next couple of decades.

Kundan

http://www.guardian.co.uk/environment/2009/sep/01/sermilik-fjord-greenland-global-warming

The Sermilik fjord in Greenland: a chilling view of a warming world

'We all live on the Greenland ice sheet now. Its fate is our fate'

• 
• • Patrick Barkham at Sermilik fjord, Greenland
  • The Guardian, Tuesday 1 September 2009
  • Article history

The Sermilik fjord, where hundreds of icebergs are calving from Greenland's vast ice sheets. Photograph: Philippe Roy/Getty

It is calving season in the Arctic. A flotilla of icebergs, some as jagged as fairytale castles and others as smooth as dinosaur eggs, calve from the ice sheet that smothers Greenland and sail down the fjords. The journey of these sculptures of ice from glaciers to ocean is eerily beautiful and utterly terrifying.

The wall of ice that rises behind Sermilik fjord stretches for 1,500 miles (2,400km) from north to south and smothers 80% of this country. It has been frozen for 3m years. Now it is melting, far faster than the climate models predicted and far more decisively than any political action to combat our changing climate. If the Greenland ice sheet disappearedsea levels around the world would rise by seven metres, as 10% of the world's fresh water is currently frozen here.

This is also the season for science in Greenland. Glaciologists, seismologists and climatologists from around the world are landing on the ice sheet in helicopters, taking ice-breakers up its inaccessible coastline and measuring glaciers in a race against time to discover why the ice in Greenland is vanishing so much faster than expected.

Gordon Hamilton, a Scottish-born glaciologist from the University of Maine's Climate Change Institute, is packing up equipment at his base camp in Tasiilaq, a tiny, remote east coast settlement only accessible by helicopter and where huskies howl all night.

With his spiky hair and ripped T-shirt, Hamilton could be a rugged glaciologist straight from central casting. Four years ago he hit upon the daring idea of landing on a moving glacier in a helicopter to measure its speed.

The glaciers of Greenland are the fat, restless fingers of its vast ice sheet, constantly moving, stretching down into fjords and pushing ice from the sheet into the ocean, in the form of melt water and icebergs.

Before their first expedition, Hamilton and his colleague Leigh Stearns, from the University of Kansas, used satellite data to plan exactly where they would land on a glacier.

"When we arrived there was no glacier to be seen. It was way up the fjord," he says. "We thought we'd made some stupid goof with the co-ordinates, but we were where we were supposed to be." It was the glacier that was in the wrong place. A vast expanse had melted away.

When Hamilton and Stearns processed their first measurements of the glacier's speed, they thought they had made another mistake. They found it was marching forwards at a greater pace than a glacier had ever been observed to flow before. "We were blown away because we realised that the glaciers had accelerated not just by a little bit but by a lot," he says. The three glaciers they studied had abruptly increased the speed by which they were transmitting ice from the ice sheet into the ocean.

Raw power

Standing before a glacier in Greenland as it calves icebergs into the dark waters of a cavernous fjord is to witness the raw power of a natural process we have accelerated but will now struggle to control.

Greenland's glaciers make those in the Alps look like toys. Grubby white and blue crystal towers, cliffs and crevasses soar up from the water, dispatching millenniums of compacted snow in the shape of seals, water lilies and bishops' mitres.

I take a small boat to see the calving with Dines Mikaelsen, an Inuit guide, who in the winter will cross the ice sheet in his five-metre sled pulled by 16 huskies.

It is not freezing but even in summer the wind is bitingly cold and we can smell the bad breath of a humpback whale as it groans past our bows on Sermilik Fjord. Above its heavy breathing, all you can hear in this wilderness is the drip-drip of melting ice and a crash as icebergs cleave into even smaller lumps, called growlers.

Mikaelsen stops his boat beside Hann glacier and points out how it was twice as wide and stretched 300 metres further into the fjord just 10 years ago. He also shows off a spectacular electric blue iceberg.

Locals have nicknamed it "blue diamond"; its colour comes from being cleaved from centuries-old compressed ice at the ancient heart of the glacier. Bobbing in warming waters, this ancient ice fossil will be gone in a couple of weeks.

The blue diamond is one vivid pointer to the antiquity of the Greenland ice sheet. A relic of the last Ice Age, this is one of three great ice sheets in the world. Up to two miles thick, the other two lie in Antarctica.

While similar melting effects are being measured in the southern hemisphere, the Greenland sheet may be uniquely vulnerable, lying much further from the chill of the pole than Antarctica's sheets. The southern end of the Greenland sheet is almost on the same latitude as the Shetlands and stroked by the warm waters of the Gulf Stream.

Driven by the loss of ice, Arctic temperatures are warming more quickly than other parts of the world: last autumn air temperatures in the Arctic stood at a record 5C above normal. For centuries, the ice sheets maintained an equilibrium: glaciers calved off icebergs and sent melt water into the oceans every summer; in winter, the ice sheet was then replenished with more frozen snow. Scientists believe the world's great ice sheets will not completely disappear for many more centuries, but the Greenland ice sheet is now shedding more ice than it is accumulating.

The melting has been recorded since 1979; scientists put the annual net loss of ice and water from the ice sheet at 300-400 gigatonnes (equivalent to a billion elephants being dropped in the ocean), which could hasten a sea level rise of catastrophic proportions.

As Hamilton has found, Greenland's glaciers have increased the speed at which they shift ice from the sheet into the ocean. Helheim, an enormous tower of ice that calves into Sermilik Fjord, used to move at 7km (4.4 miles) a year. In 2005, in less than a year, it speeded up to nearly 12km a year. Kangerdlugssuaq, another glacier that Hamilton measured, tripled its speed between 1988 and 2005. Its movement – an inch every minute – could be seen with the naked eye.

The three glaciers that Hamilton and Stearns measured account for about a fifth of the discharge from the entire Greenland ice sheet. The implications of their acceleration are profound: "If they all start to speed up, you could have quite a large rise in sea level in the near term, much larger than the official estimate by the Intergovernmental Panel on Climate Change (IPCC) would project," says Hamilton.

The scientific labours in the chill winds and high seas of the Arctic summer seem wrapped in an unusual sense of urgency this year. The scientists working in Greenland are keen to communicate their new, emerging understanding of the dynamics of the declining ice sheet to the wider world. Several point out that any international agreement forged at the UN climate change conference in Copenhagen in December will be based on the IPCC's fourth assessment report from 2007. Its estimates of climate change and sea-level rise were based on scientific research submitted up to 2005; the scientists say this is already significantly out of date.

The 2007 report predicted a sea level rise of 30cm-60cm by 2100, but did not account for the impact of glaciers breaking into the sea from areas such as the Greenland ice sheet. Most scientists working at the poles predict a one metre rise by 2100. The US Geological Survey has predicted a 1.5 metre rise. As Hamilton points out: "It is only the first metre that matters".

Record temperatures

A one metre rise – with the risk of higher storm surges – would requirenew defences for New York, London, Mumbai and Shanghai, and imperil swaths of low-lying land from Bangladesh to Florida. Vulnerable areas accommodate 10%of the world's population – 600 million.

The Greenland ice sheet is not merely being melted from above by warmer air temperatures. As the oceans of the Arctic waters reach record high temperatures, the role of warmer water lapping against these great glaciers is one of several factors shaping the loss of the ice sheet that has been overlooked until recently.

Fiamma Straneo, an Italian-born oceanographer, is laboriously winding recording equipment the size of a fire extinguisher from the deck of a small Greenpeace icebreaker caught in huge swells at the mouth of Sermilik fjord.

In previous decades the Arctic Sunrise has been used in taking direct action against whalers; now it offers itself as a floating research station for independent scientists to reach remote parts of the ice sheet. It is tough work for the multinational crew of 30 in this rough-and-ready little boat, prettified below deck with posters of orang-utans and sunflowers painted in the toilets.

Before I succumb to vomiting below deck – another journalist is so seasick they are airlifted off the boat – I examine the navigational charts used by the captain, Pete Willcox, a survivor of the sinking of theRainbow Warrior in 1985. He shows how they are dotted with measurements showing the depth of the ocean but here, close to the east coast of Greenland, the map is blank: this part of the North Atlantic was once covered by sea ice for so much of the year that its waters are still uncharted.

Earlier in the expedition, the crew believe, they became the first boat to travel through the Nares Strait west of Greenland to the Arctic Ocean in June, once impassable because of sea ice at that time of year. The predicted year when summers in the Arctic would be free of sea ice has fallen from 2100 to 2050 to 2030 in a couple of years.

Jay Zwally, a Nasa scientist, recently suggested it could be virtually ice-free by late summer 2012. Between 2004 and 2008 the area of "multiyear" Arctic sea ice (ice that has formed over more than one winter and survived the summer melt) shrank by 595,000 sq miles, an area larger than France, Germany and the United Kingdom combined.

Undaunted by the sickening swell of the ocean and wrapped up against the chilly wind, Straneo, of Woods Hole Oceanographic Institution, one of the world's leading oceanographic research centres, continues to take measurements from the waters as the long Arctic dusk falls.

According to Straneo, the rapid changes to the ice sheet have taken glaciologists by surprise. "One of the possible mechanisms which we think may have triggered these changes is melting driven by changing ocean temperatures and currents at the margins of the ice sheet."

She has been surprised by early results measuring sea water close to the melting glaciers: one probe recovered from last year recorded a relatively balmy 2C at 60 metres in the fjord in the middle of winter. Straneo said: "This warm and salty water is of subtropical origin – it's carried by the Gulf Stream. In recent years a lot more of this warm water has been found around the coastal region of Greenland. We think this is one of the mechanisms that has caused these glaciers to accelerate and shed more ice."

Straneo's research is looking at what scientists call the "dynamic effects" of the Greenland ice sheet. It is not simply that the ice sheet is melting steadily as global temperatures rise. Rather, the melting triggers dynamic new effects, which in turn accelerate the melt.

"It's quite likely that these dynamic effects are more important in generating a near-term rapid rise in sea level than the traditional melt," says Hamilton. Another example of these dynamic effects is when the ice sheet melts to expose dirty layers of old snow laced with black carbon from forest fires and even cosmic dust. These dark particles absorb more heat and so further speed up the melt.

After Straneo gathers her final measurements, the Arctic Sunrise heads for the tranquillity of the sole berth at Tasiilaq, which has a population of fewer than 3,000 but is still the largest settlement on Greenland's vast east coast. Here another scientist is gathering her final provisions before taking her team camping on a remote glacier.

Invisible earthquakes

Several years ago Meredith Nettles, a seismologist from Colombia University, and two colleagues made a remarkable discovery: they identified a new kind of earthquake. These quakes were substantial – measuring magnitude five – but had been invisible because they did not show up on seismographs. (While orthodox tremors registered for a couple of seconds, these occurred rather more slowly, over a minute.)

The new earthquakes were traced almost exclusively to Greenland, where they were found to be specifically associated with large, fast-flowing outlet glaciers. There have been 200 of them in the last dozen years; in 2005 there were six times as many as in 1993.

Nettles nimbly explains the science as she heaves bags of equipment on to a helicopter, which will fly her to study Kangerdlugssuaq glacier. "It's quite a dramatic increase, and that increase happened at the same time as we were seeing dramatic retreats in the location of the calving fronts of the glaciers, and an increase in their flow speed," she says. "The earthquakes are very closely associated with large-scale ice loss events."

In other words, the huge chunks of ice breaking off from the glaciers and entering the oceans are large enough to generate a seismic signal that is sent through the Earth. They are happening more regularly and, when they occur, it appears that the glacier speeds up even more.

The scientists rightly wrap their latest observations in caution. Their studies are still in their infancy. Some of the effects they are observing may be short-term.

The Greenland ice sheet has survived natural warmer periods in history, the last about 120,000 years ago, although it was much smaller then than it is now. Those still sceptical of the scientific consensus over climate change should perhaps listen to the voices of those who could not be accused of having anything to gain from talking up climate change.

Inuit warnings

Arne Sorensen, a specialist ice navigator on Arctic Sunrise, began sailing the Arctic in the 1970s. Journeys around Greenland's coast that would take three weeks in the 1970s because of sea ice now take a day. He pays heed to the observations of the Inuit. "If you talk to people who live close to nature and they tell you this is unusual and this is not something they have noticed before, then I really put emphasis on that," he says. Paakkanna Ignatiussen, 52, has been hunting seals since he was 13. His grandparents travelled less than a mile to hunt; he must go more than 60 miles because the sea ice disappears earlier – and with it the seals. "It's hard to see the ice go back. In the old days when we got ice it was only ice. Today it is more like slush," he says. "In 10 years there will be no traditional hunting. The weather is the reason."

The stench of rotting seal flesh wafts from a bag in the porch of his house in Tasiilaq as Ignatiussen's wife, Ane, remarks that, "the seasons are upside down".

Local people are acutely aware of how the weather is changing animal behaviour. Browsing the guns for sale in the supermarket in Tasiilaq (you don't need a licence for a gun here), Axel Hansen says more hungry polar bears prowl around the town these days. Like the hunters, the bears can't find seals when there is so little sea ice. And the fjords are filled with so many icebergs that local people find it hard to hunt whales there.

Westerners may shrug at the decline of traditional hunting but, in a sense, we all live on the Greenland ice sheet now. Its fate is our fate. The scientists swarming over this ancient mass of ice, trying to understand how it will be transformed in a warming world, and how it will transform us, are wary of making political comments about how our leaders should plan for one metre of sea level rise, and what drastic steps must be taken to cut carbon emissions. But some scientists are so astounded by the changes they are recording that they are moved to speak out.

What, I ask Hamilton, would he say to Barack Obama if he could spend10 minutes with the US president standing on Helheim glacier?

"Without knowing anything about what is going on, you just have to look at the glacier to know something huge is happening here," says the glaciologist. "We can't as a scientific community keep up with the pace of changes, let alone explain why they are happening.

"If I was, God forbid, the leader of the free world, I would implement some changes to deal with the maximum risk that we might reasonably expect to encounter, rather than always planning for the minimum. We won't know the consequences of not doing that until it's way too late. Even as a politician on a four-year elected cycle, you can't morally leave someone with that problem."