[another_someone]

George, i did not intend to correct your spelling. I read your reply too fast and obviously read it wrong.

No problem []

You can not use the WMD issue as a good analogy, that was a politically motivated decision. Not one based on scientific facts. You may argue that the issues surrounding climate change are politically motivated, and to some degree they are. Vote for me and i will do this or that about climate change.

I was merely using that as a counter to your statement that "even the US now admits we are causing the problem" - I assume you are referring to American politicians, since the academics tended to have the same spectrum of views that exist on this side of the pond.

What action should they take? Well i am not in a position to know all the facts, so i will be happy to leave that up to the chief scientist advising the government.

You mean like the chief medical officer in the 1990 (and for half a decade thereafter) insisted that BSE was not a threat to human health (then, when they were shown to be wrong, went from the extreme of saying that it would effect nobody, to speculating about an epidemic that could affect thousands, or even hundreds of thousands, of victims).

I am not trying to say that these guys are the devil incarnate, only that they are as human as the rest of us, and get it wrong as often as they get it right (although, to be fair, since there are always far more possible wrong answers than right ones, so a 50% success rate is still beating the odds, but it is not enough to simply accept whatever they have to say as gospel).

You are correct that i have said "there was global warming prior to the industrial revolution, but we have accelerated the process." and "we are causing the problem". Why do you think these are two different things?

Because, if one assumes global warming to be a problem, then if global warming exists despite human activity, then we are not the initial cause of the problem, but merely (apparently in your view) a contributory factor.  It is therefore a contradiction to say we are the cause of global warming, only (by your argument) one of the causes of global warming.

The process of global warming is a natural one, hence my statement "there was global warming prior to the industrial revolution, but we have accelerated the process." We are causing the problem, we have changed the fine balance that nature has to regulate. Too much carbon and other products have been released in to the atmosphere and altered the balance.

I would argue there never has been a 'fine balance' in nature.  Nature has always been robust and fluid, constantly changing - furthermore, we are a part of that changing nature, not separate from it.

Why has the hole in the ozone layer not reduced? you ask. Well it is not getting any bigger, the reason it has not reduced is because the CFC's have a life span (in the atmosphere) of up to 100 years. How long is it since we stopped using CFC's? Only a matter of a few years, countries such as china still continue to produce CFC's...can you see the problem? There is not quick fix, you can not discount the evidence because the hole has not shrunk.

The Montreal Protocol is rapidly approaching the end of its second decade - so a bit more than a few years; but yes, I do know the arguments as to why it has not yet had an effect.  I was not saying that the efficacy of that experiment had been disproved, only that it had yet to be proven, which is a different matter; and that the CO₂ experiment is considerably  more complex, and considerably more uncertain, yet we are rushing into this second experiment without having yet had time to learn from the first experiment in global environment control.

I don't think anyone is saying that we can reverse climate change, simply by reducing our carbon emissions. But we can go some way to prolong the effects until we have a better idea of what needs to be done.

Firstly, the propaganda suggests that all the ill effects of climate change are horrendous, and by inference, if we do all the things asked, we can avoid all these ill effects.

If we are now saying that climate change will happen no matter what, then the argument moves away from simply saying we must pay whatever price it takes to avoid theses horrendous consequences to saying that we must balance the amount we pay with the likely different our actions will make.  To make such an assessment, we have to have a realistic assessment of exactly how much difference we can make.  My own belief is that we can in fact make very little practical difference, and that we will have to pay an enormous cost even in attempting to make that difference, and that effort would be better spent in trying to mitigate that which we have no control over than in concentrate on trying to play at being King Canute.

What is the harm in wanting or encouraging us to live a greener lifestyle? Walk the kids to school instead of driving them. less emissions and possibly healthier slimmer kids.

While I am not trying to say every green policy is bad, but one has to be realistic about the policies, and I certainly would not regard a policy as good simply because it is green.

Yes, having kids walk to school is good - but then we live in a society where parents can be prosecuted for leaving their kids alone for only a few hours, and where we are constantly reminded (again, excessive panic, but just another side of the same panic that is driving the concerns over CO₂) about the risks our children are placed under, and that they should be constantly supervised.  Beyond that, children (and I would sometimes do this myself, although not habitually) will play truant, and in the modern world parents can be imprisoned if their child plays truant - so another reason why parents may be reluctant to let their children go unaccompanied to school.

Ofcourse, in the old days, mothers did not work, and if they felt it was necessary to spend time walking their kids from one place to the other, then they would have the time to do so.  We no longer live in that era.

The biggest driving force in increased road use is a combination of greater distances that need to be travelled (big out of town supermarkets, large but remote hospitals, large and remote schools, and generally long commuting distances) combined with ever less time to do things in, so the only effective option is to use motor transport.  Ofcourse, one could say that the old small local hospitals, small local shops, and small local schools, were all less demanding of transport; but the reason we have them is because the people who run our shops, schools, and hospitals, think it is more efficient (economies of scale) to have large centralised facilities that lots of small local facilities.  This is not the fault of the people who use these facilities, but the fault of those who provide them (whether, in the end, these economies of scale do offset the increased transport burden they place on society is a decision society has to make).

I am all for efficiency (including efficiency of energy usage), but I am simply not convinced by the scare stories.

Recycle those aluminium cans and plastic bottles, why waste landfill when you can recycle?
There are many things we can do as an individual that do not cost you one penny, why not do it?

Landfill usage is a very different argument from the arguments about CO₂.  I am not saying that I agree with all the recycling issues, nor do I disagree with them (although from a purely emotional perspective, I must admit I react very negatively to what I perceive as emotional blackmail - which is how I perceive most of the green propaganda - so it sometimes takes me quite an effort to try and get over my revulsion at being emotionally blackmailed and try and look, as well as I humanly can, dispassionately at the facts behind them - and yes, I too am human).

[paul.fr]

Oh my god, i will have to have a sleep before i attemp to read, let alone reply to that one George.

[paul.fr]

I think we are getting slightly off track (that and i lost the reply i was going to post), i think we should get back to the actual topic, that being the film and the data it presented.

Well, i think most of us know that the film contained a few errors, but that should not distract us from the overall messsage. What about those errors, how wrong was Gore?

I don't have much time during the week for long responces so i will try and add something daily.

One or the errors was: global warming "shutting down the ocean conveyor" - the  process by which the gulf stream is carried over the north Atlantic to  western Europe. The judge said that, according to the Intergovernmental  Panel on Climate Change, it was "very unlikely" that the conveyor would  shut down in the future, though it might slow down.

So lets start with that one.

According to the Woods Hole Oceanographic Institution (the largest non-profit oceanographic institution in the world.)

Does Earth's climate system have an 'Achilles' heel'?
Here is a simplified description of some basic ocean-atmosphere dynamics that regulate Earth’s climate:

The equatorial sun warms the ocean surface and enhances evaporation in the tropics. This leaves the tropical ocean saltier. The Gulf Stream, a limb of the Ocean Conveyor, carries an enormous volume of heat-laden, salty water up the East Coast of the United States, and then northeast toward Europe.

This oceanic heat pump is an important mechanism for reducing equator-to-pole temperature differences. It moderates Earth’s climate, particularly in the North Atlantic region. Conveyor circulation increases the northward transport of warmer waters in the Gulf Stream by about 50 percent. At colder northern latitudes, the ocean releases this heat to the atmosphere—especially in winter when the atmosphere is colder than the ocean and ocean-atmosphere temperature gradients increase. The Conveyor warms North Atlantic regions by as much as 5° Celsius and significantly tempers average winter temperatures.

But records of past climates—from a variety of sources such as deep-sea sediments and ice-sheet cores—show that the Conveyor has slowed and shut down several times in the past. This shutdown curtailed heat delivery to the North Atlantic and caused substantial cooling throughout the region. One earth scientist has called the Conveyor “the Achilles’ heel of our climate system.”3


What can disrupt the Ocean Conveyor?
Solving this puzzle requires an understanding of what launches and drives the Conveyor in the first place. The answer, to a large degree, is salt.

For a variety of reasons, North Atlantic waters are relatively salty compared with other parts of the world ocean. Salty water is denser than fresh water. Cold water is denser than warm water. When the warm, salty waters of the North Atlantic release heat to the atmosphere, they become colder and begin to sink.

In the seas that ring the northern fringe of the Atlantic—the Labrador, Irminger, and Greenland Seas—the ocean releases large amounts of heat to the atmosphere and then a great volume of cold, salty water sinks to the abyss. This water flows slowly at great depths into the South Atlantic and eventually throughout the world’s oceans.

Thus, the North Atlantic is the source of the deep limb of the Ocean Conveyor. The plunge of this great mass of cold, salty water propels the global ocean’s conveyor-like circulation system. It also helps draw warm, salty tropical surface waters northward to replace the sinking waters. This process is called “thermohaline circulation,” from the Greek words “thermos” (heat) and “halos” (salt).

If cold, salty North Atlantic waters did not sink, a primary force driving global ocean circulation could slacken and cease. Existing currents could weaken or be redirected. The resulting reorganization of the ocean’s circulation would reconfigure Earth’s climate patterns.

Computer models simulating ocean-atmosphere climate dynamics indicate that the North Atlantic region would cool 3° to 5° Celsius if Conveyor circulation were totally disrupted. It would produce winters twice as cold as the worst winters on record in the eastern United States in the past century. In addition, previous Conveyor shutdowns have been linked with widespread droughts throughout the globe.

It is crucial to remember two points: 1) If thermohaline circulation shuts down and induces a climate transition, severe winters in the North Atlantic region would likely persist for decades to centuries—until conditions reached another threshold at which thermohaline circulation might resume. 2) Abrupt regional cooling may occur even as the earth, on average, continues to warm.

[paul.fr]

Are worrisome signals developing in the ocean?
If the climate system’s Achilles’ heel is the Conveyor, the Conveyor’s Achilles’ heel is the North Atlantic. An influx of fresh water into the North Atlantic’s surface could create a lid of more buoyant fresh water, lying atop denser, saltier water. This fresh water would effectively cap and insulate the surface of the North Atlantic, curtailing the ocean’s transfer of heat to the atmosphere.

An influx of fresh water would also dilute the North Atlantic’s salinity. At a critical but unknown threshold, when North Atlantic waters are no longer sufficiently salty and dense, they may stop sinking. An important force driving the Conveyor could quickly diminish, with climate impacts resulting within a decade.

In an important paper published in 2002 in Nature, oceanographers monitoring and analyzing conditions in the North Atlantic concluded that the North Atlantic has been freshening dramatically—continuously for the past 40 years but especially in the past decade.4 The new data show that since the mid-1960s, the subpolar seas feeding the North Atlantic have steadily and noticeably become less salty to depths of 1,000 to 4,000 meters. This is the largest and most dramatic oceanic change ever measured in the era of modern instruments.

At present the influx of fresher water has been distributed throughout the water column. But at some point, fresh water may begin to pile up at the surface of the North Atlantic. When that occurs, the Conveyor could slow down or cease operating.

Signs of a possible slowdown already exist. A 2001 report in Nature indicates that the flow of cold, dense water from the Norwegian and Greenland Seas into the North Atlantic has diminished by at least 20 percent since 1950.5


At what threshold will the Conveyor cease?
The short answer is: We do not know. Nor have scientists determined the relative contributions of a variety of sources that may be adding fresh water to the North Atlantic. Among the suspects are melting glaciers or Arctic sea ice, or increased precipitation falling directly into the ocean or entering via the great rivers that discharge into the Arctic Ocean.6 Global warming may be an exacerbating factor.

Though we have invested in, and now rely on, a global network of meteorological stations to monitor fast-changing atmospheric conditions, at present we do not have a system in place for monitoring slower-developing, but critical, ocean circulation changes.

The great majority of oceanographic measurements was taken throughout the years by research ships and ships of opportunity—especially during the Cold War era for anti-submarine warfare purposes. Many were taken incidentally by Ocean Weather Stations—a network of ships stationed in the ocean after World War II, whose primary duty was to guide transoceanic airplane flights. Starting in the 1970s, satellite technology superseded these weather ships. The demise of the OWS network and the end of the Cold War have left oceanographers with access to far fewer data in recent years.

Initial efforts to remedy this deficit are under way,7 but these efforts are nascent and time is of the essence. Satellites can measure wind stress and ocean circulation globally, but only at the ocean surface. Also recently launched (but not nearly fully funded) is the Argo program—an international program to seed the global ocean with an armada of some 3,000 free-floating buoys that measure upper ocean temperature and salinity. Measuring deep ocean currents is critical for observing Conveyor behavior, but it is more difficult. Efforts have just begun to measure deep ocean water properties and currents at strategic locations with long-term moored buoy arrays, but vast ocean voids remain unmonitored.

New ocean-based instruments also offer the potential to reveal the ocean’s essential, but poorly understood, role in the hydrological cycle—which establishes global rainfall and snowfall patterns. Global warming affects the hydrological cycle because a warmer atmosphere carries more water. This, in turn, has implications for greenhouse warming, since water vapor itself is the most abundant, and often overlooked, greenhouse gas.

[paul.fr]

What can the past teach us about the future?
Revealing the past behavior of Earth’s climate system provides powerful insight into what it may do in the future. Geological records confirm the potential for abrupt thermohaline-induced climate transitions that would generate severe winters in the North Atlantic region. A bad winter or two brings inconvenience that societies can adapt to with small, temporary adjustments. But a persistent string of severe winters, lasting decades to a century, can cause glaciers to advance, rivers to freeze, and sea ice to grow and spread. It can render prime agricultural lands unfarmable.

About 12,700 years ago, as Earth emerged from the most recent ice age and began to warm, the Conveyor was disrupted. Within a decade, average temperatures in the North Atlantic region plummeted nearly 5° Celsius.

This cold period, known as the Younger Dryas, lasted 1,300 years. It is named after an Arctic wildflower. Scientists have found substantial evidence that cold-loving dryas plants thrived during this era in European and US regions that today are too warm. Deep-sea sediment cores show that icebergs extended as far south as the coast of Portugal. The Younger Dryas ended as abruptly as it began. Within a decade, North Atlantic waters and the regional climate warmed again to pre-Younger Dryas levels.

A similar cooling occurred 8,200 years ago. It lasted only about a century—a blip in geological time, but a catastrophe if such a cooling occurred today.


Are 'little ice ages' and 'megadroughts' possible?
Scientists are investigating whether changes in ocean circulation may have played a role in causing or amplifying the “Little Ice Age” between 1300 and 1850. This period of abruptly shifting climate regimes and more severe winters had profound agricultural, economic, and political impacts in Europe and North America and changed the course of history.

During this era, the Norse abruptly abandoned their settlements in Greenland. The era is captured in the frozen landscapes of Pieter Bruegel’s 16th-century paintings and in the famous painting of George Washington’s 1776 crossing of an icebound Delaware River, which rarely freezes today. But the era is also marked by persistent crop failures, famine, disease, and mass migrations. “The Little Ice Age,” wrote one historian, “is a chronicle of human vulnerability in the face of sudden climate change.”8

Societies are similarly vulnerable to abrupt climate changes that can turn a year or two of diminished rainfall into prolonged, severe, widespread droughts. A growing body of evidence from joint archaeological and paleoclimatological studies is demonstrating linkages among ocean-related climate shifts, “megadroughts,” and precipitous collapses of civilizations, including the Akkadian empire in Mesopotamia 4,200 years ago, the Mayan empire in central America 1,500 years ago, and the Anasazi in the American Southwest in the late 13th century.9

Rapid changes in ocean circulation associated with the abrupt North Atlantic cooling event 8,200 years ago have been linked with simultaneous, widespread drying in the American West, Africa, and Asia.10 Regional cooling events also have been linked with changes in the Southwest Asian monsoon, whose rains are probably the most critical factor supporting civilizations from Africa to India to China.11


What future climate scenarios should we consider?
The debate on global change has largely failed to factor in the inherently chaotic, sensitively balanced, and threshold-laden nature of Earth’s climate system and the increased likelihood of abrupt climate change. Our current speculations about future climate and its impacts have focused on the Intergovernmental Panel on Climate Change, which has forecast gradual global warming of 1.4° to 5.8° Celsius over the next century.

It is prudent to superimpose on this forecast the potential for abrupt climate change induced by thermohaline shutdown. Such a change could cool down selective areas of the globe by 3° to 5° Celsius, while simultaneously causing drought in many parts of the world. These climate changes would occur quickly, even as other regions continue to warm slowly. It is critical to consider the economic and political ramifications of this geographically selective climate change. Specifically, the region most affected by a shutdown—the countries bordering the North Atlantic—is also one of the world’s most developed.

The key component of this analysis is when a shutdown of the Conveyor occurs. Two scenarios are useful to contemplate:

[paul.fr]

Scenario 1: Conveyor slows down within next two decades.
Such a scenario could quickly and markedly cool the North Atlantic region, causing disruptions in global economic activity. These disruptions may be exacerbated because the climate changes occur in a direction opposite to what is commonly expected, and they occur at a pace that makes adaptation difficult.

Scenario 2: Conveyor slows down a century from now.
In such a scenario, cooling of the North Atlantic region may partially or totally offset the major effects of global warming in this region. Thus, the climate of the North Atlantic region may rapidly return to one that more resembles today’s—even as other parts of the world, particularly less-developed regions, experience the unmitigated brunt of global warming. If the Conveyor subsequently turns on again, the “deferred” warming may be delivered in a decade.


What can we do to improve our future security?
Ignoring or downplaying the probability of abrupt climate change could prove costly. Ecosystems, economies, and societies can adapt more easily to gradual, anticipated changes. Some current policies and practices may be ill-advised and may prove inadequate in a world of rapid and unforeseen climate change. The challenge to world leaders is to reduce vulnerabilities by enhancing society’s ability to monitor, plan for, and adapt to rapid change.

All human endeavor hinges on the vicissitudes of climate. Thus, the potential for abrupt climate change should prompt us to re-examine possible impacts on many climate-affected sectors. They include: agriculture; water resources; energy resources; forest and timber management; fisheries; coastal land management; transportation; insurance; recreation and tourism; disaster relief; and public health (associated with climate-related, vector-borne diseases such as malaria and cholera).

Developing countries lacking scientific resources and economic infrastructures are especially vulnerable to the social and economic impacts of abrupt climate change. However, with growing globalization of economies, adverse impacts (although likely to vary from region to region) are likely to spill across national boundaries, through human and biotic migration, economic shocks, and political aftershocks, the National Academy of Sciences (NAS) report stated.

The key is to reduce our uncertainty about future climate change, and to improve our ability to predict what could happen and when. A first step is to establish the oceanic equivalent of our land-based meteorological instrument network. Such a network would begin to reveal climate-influencing oceanic processes that have been beyond our ability to grasp. These instruments, monitoring critical present-day conditions, can be coupled with enhanced computer modeling, which can project how Earth’s climate system may react in the future. Considerably more research is also required to learn more about the complex ocean-air processes that induced rapid climate changes in the past, and thus how our climate system may behave in the future.

 The NAS report is titled Abrupt Climate Change: Inevitable Surprises.  Climate change may be inevitable. But it is not inevitable for society to be surprised or ill-prepared.

References:
1 “Are We on the Brink of a New Little Ice Age?”—testimony to the US Commission on Ocean Policy, September 25, 2002, by T. Joyce and L. Keigwin (Woods Hole Oceanographic Institution).

2 Abrupt Climate Change: Inevitable Surprises, US National Academy of Sciences, National Research Council Committee on Abrupt Climate Change, National Academy Press, 2002.

3 “Thermohaline Circulation, the Achilles’ Heel of Our Climate System: Will Man-Made CO2 Upset the Current Balance?” in Science, Vol. 278, November 28, 1997, by W. S. Broecker (Lamont-Doherty Earth Observatory, Columbia University).

4 “Rapid Freshening of the Deep North Atlantic Ocean Over the Past Four Decades,” in Nature, Vol. 416, April 25, 2002, by B. Dickson (Centre for Environment, Fisheries, and Aquaculture Science, Lowestoft, UK), I. Yashayaev, J. Meincke, B. Turrell, S. Dye, and J. Hoffort.

5 “Decreasing Overflow from the Nordic Seas into the Atlantic Ocean Through the Faroe Bank Channel Since 1950,” in Nature, Vol. 411, June 21, 2001, by B. Hansen (Faroe Fisheries Laboratory, Faroe Islands), W. Turrell, and S. østerhus.

6 “Increasing River Discharge to the Arctic Ocean,” in Science, Vol. 298, December 13, 2002, by B. J. Peterson (Marine Biological Laboratory), R. M. Holmes, J. W. McClelland, C. J. Vörösmarty, R. B. Lammers, A. I. Shiklomanov, I. A. Shiklomanov, and S. Rahmstorf.

7 “Ocean Observatories,” in Oceanus, Vol. 42, No. 1, 2000, published by the Woods Hole Oceanographic Institution.

8 The Little Ice Age: How Climate Made History 1300-1850, by Brian Fagan (University of California, Santa Barbara), Basic Books, 2000.

9 “Cultural Responses to Climate Change During the Late Holocene,” in Science, Vol. 292, April 27, 2001, by P. B. deMenocal (Lamont-Doherty Earth Observatory, Columbia University).

10 “Holocene Climate Instability: A Prominent, Widespread Event 8,200 Years Ago,” in Geology, Vol. 26, No. 6, 1997, by R. B. Alley and T. Sowers (Pennsylvania State University), P. A. Mayewski, M. Stuiver, K. C. Taylor, and P. U. Clark.

11 “A High-Resolution Absolute-Dated Late Pleistocene Monsoon Record From Hulu Cave, China,” in Science, Vol. 294, December 14, 2001, by Y. J. Wang (Nanjing Normal University, China), H. Cheng, R. L. Edwards, Z. S. An, J. Y. Wu, C. C. Shen, and J. A. Dorale.



ROBERT B. GAGOSIAN is President and Director of Woods Hole Oceanographic Institution in Woods Hole, Massachusetts. He was appointed Director in 1994 and President in 2001, following a distinguished career as a marine geochemist. He has served as Chairman of the Board of Governors for the 52-institution Consortium for Oceanographic Research and Education and as a member of the Ocean Research Advisory Panel of the US National Oceanographic Partnership Program. In 2002, he was appointed to the Science Advisory Panel of the US Commission on Ocean Policy and the US National Oceanic and Atmospheric Administration’s Science Advisory Board, and was elected a Fellow of the American Academy of Arts & Sciences.

http://www.whoi.edu/page.do?pid=12455&tid=282&cid=9986

[JimBob]

Also

Ice Retreating Faster Than Computer Models Project

Arctic sea ice is melting at a significantly faster rate than projected by even the most advanced computer models, a new study concludes. The research, by scientists at the National Center for Atmospheric Research (NCAR) and the University of Colorado's National Snow and Ice Data Center (NSIDC), shows that the Arctic's ice cover is retreating more rapidly than estimated by any of the 18 computer models used by the Intergovernmental Panel on Climate Change (IPCC) in preparing its 2007 assessments.

The study, "Arctic Sea Ice Decline: Faster Than Forecast?" will appear tomorrow in the online edition of Geophysical Research Letters. It was led by Julienne Stroeve of the NSIDC and funded by the National Science Foundation, which is NCAR's principal sponsor, and by NASA.

"While the ice is disappearing faster than the computer models indicate, both observations and the models point in the same direction: the Arctic is losing ice at an increasingly rapid pace and the impact of greenhouse gases is growing," says NCAR scientist Marika Holland, one of the study’s co-authors.

The authors compared model simulations of past climate with observations by satellites and other instruments. They found that, on average, the models simulated a loss in September ice cover of 2.5 percent per decade from 1953 to 2006. The fastest rate of September retreat in any individual model was 5.4 percent per decade. (September marks the yearly minimum of sea ice in the Arctic.) But newly available data sets, blending early aircraft and ship reports with more recent satellite measurements that are considered more reliable than the earlier records, show that the September ice actually declined at a rate of about 7.8 percent per decade during the 1953-2006 period.

"This suggests that current model projections may in fact provide a conservative estimate of future Arctic change, and that the summer Arctic sea ice may disappear considerably earlier than IPCC projections," says Stroeve.

Thirty years ahead of schedule

The study indicates that, because of the disparity between the computer models and actual observations, the shrinking of summertime ice is about 30 years ahead of the climate model projections. As a result, the Arctic could be seasonally free of sea ice earlier than the IPCC- projected timeframe of any time from 2050 to well beyond 2100.

The authors speculate that the computer models may fail to capture the full impact of increased carbon dioxide and other greenhouse gases in the atmosphere. Whereas the models indicate that about half of the ice loss from 1979 to 2006 was due to increased greenhouse gases, and the other half due to natural variations in the climate system, the new study indicates that greenhouse gases may be playing a significantly greater role.

There are a number of factors that may lead to the low rates of simulated sea ice loss. Several models overestimate the thickness of the present-day sea ice and the models may also fail to fully capture changes in atmospheric and oceanic circulation that transport heat to polar regions.

March ice

Although the loss of ice for March is far less dramatic than the September loss, the models underestimate it by a wide margin as well. The study concludes that the actual rate of sea ice loss in March, which averaged about 1.8 percent per decade in the 1953 -2006 period, was three times larger than the mean from the computer models. March is typically the month when Arctic sea ice is at its most extensive.

The Arctic is especially sensitive to climate change partly because regions of sea ice, which reflect sunlight back into space and provide a cooling impact, are disappearing. In contrast, darker areas of open water, which are expanding, absorb sunlight and increase temperatures. This feedback loop has played a role in the increasingly rapid loss of ice in recent years, which accelerated to 9.1 percent per decade from 1979 to 2006 according to satellite observations.

Walt Meier, Ted Scambos, and Mark Serreze, all at NSIDC, also co-authored the study.

http://www.scienceblog.com/cms/ice-retreating-faster-computer-models-project-13118.html

[another_someone]

OK, I am not going to try and compete on length with your replies - I thought I was doing well enough at the length I was using.

As you say, climate has changed substantially in the past - without any human interaction.

The argument that we can at least slow down the inevitable, and that change at a slower rate is less expensive than change at a faster rate is not necessarily the case.

Assuming we do slow down the inevitable - what price will we have to pay to achieve this end?  This is always a factor that the environmentalist lobby just ignores, and assumes that all the options come at minimal or zero cost, and we only need to worry about the cost of outcome, not the cost of investment.

Nor is it inevitable that rapid change is more expensive than slow change - it depends on various factors.  Certainly, slow change will allow us to spread cost better (all other factors being ignored), but it may also require us to adapt to interim situations that in a rapid change may happen too fast to allow for adaptation, and hence incur limited cost.  As a possibly not very comparable example, but example nonetheless, over the last 30 years, my waistline has gradually increased by over 40% in size.  If all of this increase had happened in a single year, then in that year I would have had to buy a new set of clothes, but those clothes would then have lasted me for the next 30 years.  The fact that in each year there was only a slight increase in waistline meant that every few years I had to throw away my old clothes and buy new ones, which was more expensive that a single set of new clothes that would have allowed for the change in waistline in a single step.  As I said, there are many reasons why this is an unrealistic comparison to make, and I am not trying to say that this comparison alone is an argument for rapid change, only an indication that one has to look at the precise nature of a situation rather than simply assume that slow change is cheaper than fast change.

One particular factor one has to take account of is that if you are correct in assuming that the long term effect of global warming would be cooler temperatures in the mid and high latitudes, after an interim period of warmer temperatures in those same latitudes; then a more rapid change would cause a shorter period of time for that switchback to happen, and so less need to make substantial adaptations to the interim warm period before the temperature switches back to colder temperatures.

The other factor to take into account is that if there is an increase in ice cover, then it should increase the albedo of the Earth, and so limit the warming.  Other effects concerning increased aridity are complex, since the reduced cloud cover would reduce the albedo, but reduced humidity would also reduce the greenhouse effect of water vapour (if the converse happens, and we have increased rainfall, as some other projections suggest - then the contrary issues have to be considered).

But all of this is a side issue to my major concern - which is not about what will or will not happen, but what degree of certainty we have that we can make the slightest difference to this outcome, and how much is it going to cost us to be proven to fail in this experiment in human climate control (we have so far failed even to manage local weather, with things like cloud seeding, which has had very mixed outcomes - but we are ignoring those failures, and going for the big one -  seeking to control global temperature).

[another_someone]

Ice Retreating Faster Than Computer Models Project

Arctic sea ice is melting at a significantly faster rate than projected by even the most advanced computer models, a new study concludes. The research, by scientists at the National Center for Atmospheric Research (NCAR) and the University of Colorado's National Snow and Ice Data Center (NSIDC), shows that the Arctic's ice cover is retreating more rapidly than estimated by any of the 18 computer models used by the Intergovernmental Panel on Climate Change (IPCC) in preparing its 2007 assessments.

The study, "Arctic Sea Ice Decline: Faster Than Forecast?" will appear tomorrow in the online edition of Geophysical Research Letters. It was led by Julienne Stroeve of the NSIDC and funded by the National Science Foundation, which is NCAR's principal sponsor, and by NASA.

"While the ice is disappearing faster than the computer models indicate, both observations and the models point in the same direction: the Arctic is losing ice at an increasingly rapid pace and the impact of greenhouse gases is growing," says NCAR scientist Marika Holland, one of the study’s co-authors.

But this is exemplifying what I have been saying - the models do not explain observations.

I have not doubted that global warming is, and has since before the industrial revolution, been a fact of current climate trends - the debate is not about what, but about why.

What the environmentalists are saying here is they have a theory why things are happening, when they test that theory against reality the two do not match up, but they use that mismatch as a proof that their theory was correct.

When they start to get the numbers consistently right, rather than when they get them wrong, it will begin to sound more plausible.

[Andrew K Fletcher]

I remember watching this scenario a long time ago with James burkes brilliant film titled after the warming.

It of course got ridiculed by the majority of scientists, but I could not help believing that the Atlantic Conveyor system could again be slowed down by a sudden influx of fresh water running in from thawing ice around the North Pole regions. Well in the words of Burke; ‘That’s just  what was about to happen when global warming caused the ice to melt around the poles’. I still have the film in my collection and have asked repeatedly if I can show a small clip from it, but alas never did get a reply. Have just wrote again asking if it is possible to use it.

Series Price:  $185.00
(2 videos in series)
Sale Price:  $20.00 
(Public Performance Rights Included)   

This was included on the website, As I have already purchased a copy does this give me permission to show a small clip and provide a link back to the video source?

By the way, Burkes version is far more comprehensive.

Andrew

[Andrew K Fletcher]

http://video.google.com/videoplay?docid=6514270139930450081

After The Warming Online Video from Google:

ENJOY Fantastic video!

Andrew

[JimBob]

George,

This does say the models are wrong. The effects of global warming are happening FASTER than anyone thought they would. So, get out your survival gear.

[another_someone]

George,

This does say the models are wrong. The effects of global warming are happening FASTER than anyone thought they would. So, get out your survival gear.

With the caveat that in fact no-one has (to my knowledge) been able to work out how much ice is melting, only how much ice we see melting in the places we look (I know satellites give us a lot more coverage, but one also has to look at ice thickness, etc.).  Nonetheless, I am willing to believe that even if the measures are imprecise and subject to error, I am willing to believe the figures to be plausible.

Yes, it does mean we have to look at how we cope with the consequences - not something I questioned.  All I have said is we do not have the models that would allow us to take control of the atmosphere.

[JimBob]

I think "control" falls under fantasy until we can build domes for cities. We can however, make as much effore tas we can to try to influence the climate. It is doable. What has happened to the greasy black atmosphere of Londonin the 1800's until humans took it in their hands to change it?

[another_someone]

I think "control" falls under fantasy until we can build domes for cities. We can however, make as much effore tas we can to try to influence the climate. It is doable. What has happened to the greasy black atmosphere of Londonin the 1800's until humans took it in their hands to change it?

I don't think it is at all comparable.

The clean air act of 1956, aside from being on a far more local scale, was about making a concious attempt to control the contents of the air, over which we did have direct control, not over controlling weather.  It would be wrong to say it had no effect on the weather, since removal of particulates in the air actually increased local temperatures, but that was not the intended effect of the legislation, nor could we at the time have predicted that outcome.

[paul.fr]

Another "error" by Gore was that he attributed hurricane Kartina to global warming. Whilst this may be an error, in the fact that we can not be positive Katrina was a direct result of global warming> There is good evidence that it just may be.

On Monday August 29, Hurricane Katrina ravaged New Orleans, Louisiana and Missisippi, leaving a trail of destruction in her wake. It will be some time until the full toll of this hurricane can be assessed, but the devastating human and environmental impacts are already obvious.

Katrina was the most feared of all meteorological events, a major hurricane making landfall in a highly-populated low-lying region. In the wake of this devastation, many have questioned whether global warming may have contributed to this disaster. Could New Orleans be the first major U.S. city ravaged by human-caused climate change?

The correct answer–the one we have indeed provided in previous posts (Storms & Global Warming II, Some recent updates and Storms and Climate Change) –is that there is no way to prove that Katrina either was, or was not, affected by global warming. For a single event, regardless of how extreme, such attribution is fundamentally impossible. We only have one Earth, and it will follow only one of an infinite number of possible weather sequences. It is impossible to know whether or not this event would have taken place if we had not increased the concentration of greenhouse gases in the atmosphere as much as we have. Weather events will always result from a combination of deterministic factors (including greenhouse gas forcing or slow natural climate cycles) and stochastic factors (pure chance).

Due to this semi-random nature of weather, it is wrong to blame any one event such as Katrina specifically on global warming - and of course it is just as indefensible to blame Katrina on a long-term natural cycle in the climate.

Yet this is not the right way to frame the question. As we have also pointed out in previous posts, we can indeed draw some important conclusions about the links between hurricane activity and global warming in a statistical sense. The situation is analogous to rolling loaded dice: one could, if one was so inclined, construct a set of dice where sixes occur twice as often as normal. But if you were to roll a six using these dice, you could not blame it specifically on the fact that the dice had been loaded. Half of the sixes would have occurred anyway, even with normal dice. Loading the dice simply doubled the odds. In the same manner, while we cannot draw firm conclusions about one single hurricane, we can draw some conclusions about hurricanes more generally. In particular, the available scientific evidence indicates that it is likely that global warming will make - and possibly already is making - those hurricanes that form more destructive than they otherwise would have been.

The key connection is that between sea surface temperatures (we abbreviate this as SST) and the power of hurricanes. Without going into technical details about the dynamics and thermodynamics involved in tropical storms and hurricanes (an excellent discussion of this can be found here), the basic connection between the two is actually fairly simple: warm water, and the instability in the lower atmosphere that is created by it, is the energy source of hurricanes. This is why they only arise in the tropics and during the season when SSTs are highest (June to November in the tropical North Atlantic).

SST is not the only influence on hurricane formation. Strong shear in atmospheric winds (that is, changes in wind strength and direction with height in the atmosphere above the surface), for example, inhibits development of the highly organized structure that is required for a hurricane to form. In the case of Atlantic hurricanes, the El Nino/Southern Oscillation tends to influence the vertical wind shear, and thus, in turn, the number of hurricanes that tend to form in a given year. Many other features of the process of hurricane development and strengthening, however, are closely linked to SST.

Hurricane forecast models (the same ones that were used to predict Katrina's path) indicate a tendency for more intense (but not overall more frequent) hurricanes when they are run for climate change scenarios (Fig. 1).

Figure 1. Model Simulation of Trend in Hurricanes (from Knutson et al, 2004)

In the particular simulation shown above, the frequency of the strongest (category 5) hurricanes roughly triples in the anthropogenic climate change scenario relative to the control. This suggests that hurricanes may indeed become more destructive (1) as tropical SSTs warm due to anthropogenic impacts.

But what about the past? What do the observations of the last century actually show? Some past studies (e.g. Goldenberg et al, 2001) assert that there is no evidence of any long-term increase in statistical measures of tropical Atlantic hurricane activity, despite the ongoing global warming. These studies, however, have focused on the frequency of all tropical storms and hurricanes (lumping the weak ones in with the strong ones) rather than a measure of changes in the intensity of the storms. As we have discussed elsewhere on this site, statistical measures that focus on trends in the strongest category storms, maximum hurricane winds, and changes in minimum central pressures, suggest a systematic increase in the intensities of those storms that form. This finding is consistent with the model simulations.

A recent study in Nature by Emanuel (2005) examined, for the first time, a statistical measure of the power dissipation associated with past hurricane activity (i.e., the "Power Dissipation Index" or "PDI"–Fig. 2). Emanuel found a close correlation between increases in this measure of hurricane activity (which is likely a better measure of the destructive potential of the storms than previously used measures) and rising tropical North Atlantic SST, consistent with basic theoretical expectations. As tropical SSTs have increased in past decades, so has the intrinsic destructive potential of hurricanes.

Figure 2. Measure of total power dissipated annually by tropical cyclones in the North Atlantic (the power dissipation index "PDI") compared to September tropical North Atlantic SST (from Emanuel, 2005)

The key question then becomes this: Why has SST increased in the tropics? Is this increase due to global warming (which is almost certainly in large part due to human impacts on climate)? Or is this increase part of a natural cycle?

It has been asserted (for example, by the NOAA National Hurricane Center) that the recent upturn in hurricane activity is due to a natural cycle, e.g. the so-called Atlantic Multidecadal Oscillation ("AMO"). The new results by Emanuel (Fig. 2) argue against this hypothesis being the sole explanation: the recent increase in SST (at least for September as shown in the Figure) is well outside the range of any past oscillations. Emanuel therefore concludes in his paper that "the large upswing in the last decade is unprecedented, and probably reflects the effect of global warming." However, caution is always warranted with very new scientific results until they have been thoroughly discussed by the community and either supported or challenged by further analyses. Previous analysis of the AMO and natural oscillation modes in the Atlantic (Delworth and Mann, 2000; Kerr, 2000) suggest that the amplitude of natural SST variations averaged over the tropics is about 0.1-0.2 ºC, so a swing from the coldest to warmest phase could explain up to ~0.4 ºC warming.

What about the alternative hypothesis: the contribution of anthropogenic greenhouse gases to tropical SST warming? How strong do we expect this to be? One way to estimate this is to use climate models. Driven by anthropogenic forcings, these show a warming of tropical SST in the Atlantic of about 0.2 - 0.5 ºC. Globally, SST has increased by ~0.6 ºC in the past hundred years. This mostly reflects the response to global radiative forcings, which are dominated by anthropogenic forcing over the 20th Century. Regional modes of variability, such as the AMO, largely cancel out and make a very small contribution in the global mean SST changes.

Thus, we can conclude that both a natural cycle (the AMO) and anthropogenic forcing could have made roughly equally large contributions to the warming of the tropical Atlantic over the past decades, with an exact attribution impossible so far. The observed warming is likely the result of a combined effect: data strongly suggest that the AMO has been in a warming phase for the past two or three decades, and we also know that at the same time anthropogenic global warming is ongoing.

Finally, then, we come back to Katrina. This storm was a weak (category 1) hurricane when crossing Florida, and only gained force later over the warm waters of the Gulf of Mexico. So the question to ask here is: why is the Gulf of Mexico so hot at present - how much of this could be attributed to global warming, and how much to natural variability? More detailed analysis of the SST changes in the relevant regions, and comparisons with model predictions, will probably shed more light on this question in the future. At present, however, the available scientific evidence suggests that it would be premature to assert that the recent anomalous behavior can be attributed entirely to a natural cycle.

But ultimately the answer to what caused Katrina is of little practical value. Katrina is in the past. Far more important is learning something for the future, as this could help reduce the risk of further tragedies. Better protection against hurricanes will be an obvious discussion point over the coming months, to which as climatologists we are not particularly qualified to contribute. But climate science can help us understand how human actions influence climate. The current evidence strongly suggests that:
(a) hurricanes tend to become more destructive as ocean temperatures rise, and
(b) an unchecked rise in greenhouse gas concentrations will very likely increase ocean temperatures further, ultimately overwhelming any natural oscillations.
Scenarios for future global warming show tropical SST rising by a few degrees, not just tenths of a degree (see e.g. results from the Hadley Centre model and the implications for hurricanes shown in Fig. 1 above). That is the important message from science. What we need to discuss is not what caused Katrina, but the likelyhood that global warming will make hurricanes even worse in future.

_____________________
1. By 'destructive' we refer only to the intrinsic ability of the storm to do damage to its environment due to its strength. The potential increases that we discuss apply only to this intrinsic meteorological measure. We are not taking into account the potential for increased destruction (and cost) due to increasing population or human infrastructure.

References:

Delworth, T.L., Mann, M.E., Observed and Simulated Multidecadal Variability in the Northern Hemisphere, Climate Dynamics, 16, 661-676, 2000.

Emanuel, K. (2005), Increasing destructiveness of tropical cyclones over the past 30 years, Nature, online publication; published online 31 July 2005 | doi: 10.1038/nature03906

Goldenberg, S.B., C.W. Landsea, A.M. Mestas-Nuñez, and W.M. Gray. The recent increase in Atlantic hurricane activity. Causes and implications. Science, 293:474-479 (2001).

Kerr, R.A., 2000, A North Atlantic climate pacemaker for the centuries: Science, v. 288, p. 1984-1986.

Knutson, T. K., and R. E. Tuleya, 2004: Impact of CO2-induced warming on simulated hurricane intensity and precipitation: Sensitivity to the choice of climate model and convective parameterization. Journal of Climate, 17(18), 3477-3495.

http://www.realclimate.org/index.php?p=181

[paul.fr]

Figure 1



Figure 2

[another_someone]

Sorry it has taken a little while to respond to this.

There are three different issues:

1) The key issue regarding this thread is whether Al Gore's film is a reliable tool for education.

2) Whether global warming exists, and what is its likely social impact.

3) Can we do anything that will avert any social disaster that is cheaper than the disaster itself (and that has a predictable outcome - otherwise we are simply gambling, and then the question becomes whether we can afford the gamble).

I have no disagreement with issue 2 - I have from the beginning agreed that we are, and have for over 3 centuries, been undergoing a period of global warming.

I have debated with Jim the issue of whether I believe we can intervene in a predictable and cost effective way to alter the rate of global warming - I don't believe we can (clearly others disagree with me on that, but have yet to convince me that they have either fully costed the issues, or that they have even provided adequate evidence that they can guarantee the outcome of the action they propose).

So the remaining issue is whether Al Gore's film is a reliable educational tool.  The primary argument in its favour seems to be that it is 'on message' - i.e. it may be propaganda, but it is politically acceptable propaganda.

What has happened is that while the judge has now said that some balance must be shown with Al Gore's film, it is yet to be seen what form such a balance will take - and will it be left to each school to implement that balance in the manner it chooses - which potentially can be a very week balance indeed.  Furthermore, whereas Al Gore's film has been provided to each school at no cost, there is no evidence that the schools have been allocated budgets to obtain balancing material of equivalent production values, and so they will be left with having to somehow source material that is also free of cost, but may not have the same production values (and most teachers are unlikely even to have the time to try and locate such material).

Some time ago there was a Channel 4 Documentary entitled "The Global Warming Swindle".  There is no evidence that the Government will be demanding that schools will be showing that documentary as a counterbalance to "The Inconvenient Truth" (it is unlikely to be collecting any Nobel Peace Prizes either).  I certainly would not regard the documentary as any better than Al Gore's film, but it does provide an appropriate balance of about equal quality.  I doubt it will happen.

[another_someone]

Another "error" by Gore was that he attributed hurricane Kartina to global warming. Whilst this may be an error, in the fact that we can not be positive Katrina was a direct result of global warming> There is good evidence that it just may be.

Lots of things 'may be' - but to state as fact that which 'may be' is incorrect.

More to the point, from what I have read of what you posted on the matter, it actually seems to be saying that there is no change in probability of a serious storm or hurricane hitting landfall at that point - it suggests that the change in probability is only in the strength of the storm, not the likelihood of its happening.

But since in any case, we are only playing with probabilities, it seems reasonable to say that if it is possible, then sooner or later it will happen - the only issue is the time-scale over which it will happen (i.e. will it happen once every 50 years, or once every 200 years - but sooner or later, it will happen).

[Bass]

3) Can we do anything that will avert any social disaster that is cheaper than the disaster itself (and that has a predictable outcome - otherwise we are simply gambling, and then the question becomes whether we can afford the gamble).

I have debated with Jim the issue of whether I believe we can intervene in a predictable and cost effective way to alter the rate of global warming - I don't believe we can (clearly others disagree with me on that, but have yet to convince me that they have either fully costed the issues, or that they have even provided adequate evidence that they can guarantee the outcome of the action they propose).

This also begs the question of opportunity costs- could we spend money elsewhere to better combat the effects of global warming vs. the cost of reducing carbon emmissions?