Atlantic Circulation Changes
Posted by Stuart Staniford on November 30, 2005 - 7:37pm
The ocean current that gives western Europe its relatively balmy climate is stuttering, raising fears that it might fail entirely and plunge the continent into a mini ice age. The dramatic finding comes from a study of ocean circulation in the North Atlantic, which found a 30% reduction in the warm currents that carry water north from the Gulf Stream. The slow-down, which has long been predicted as a possible consequence of global warming, will give renewed urgency to intergovernmental talks in Montreal, Canada, this week on a successor to the Kyoto Protocol.The New Scientist is a UK publication, and this is scary stuff for a country that's running out of natural gas, oil, and coal. But let's just have a quick think about the implications for hurricanes and oil supply.
Sketch of the major surface currents in the North Atlantic. Values are transport in Sverdrups (106m3/s). From Sverdrup, Johnson, and Fleming (1942: fig. 187), via OceanWorld.
In addition, under the surface, deep cold waters which have sunk in the arctic are moving south and returning the net flow northwards on the surface. The total flow in the North Atlantic has to be roughly balanced because the amount of net transport through the Bering Strait is very small. So the deep cold currents make up the difference between the water the Gulf Stream carries north, and the water the subtropical gyre brings back south. Oceanographers measure the flow of water in currents in units of Sverdrups, with 1 Sverdrup = 106m3/s (one thousandth of a cubic kilometer/second). The flow through the Bering Strait is only 0.8 Sv, while the Gulf Stream through the Florida Straits is 32.2 +- 1.1 Sv.
(As an amusing aside, I note that total global oil production of 30gb/year corresponds to only 0.00016 Sv of fluid flow. So as we will see, we're having a much bigger impact by burning it than we would if we just dumped it into the ocean).
Update [2006-1-25 16:59:21 by Stuart Staniford]: Stig Oye pointed out that I had an arithmetic slip of several orders of magnitude in the "amusing aside", which I've belatedly corrected.
Now the new Bryden et al. paper (which I recommend reading if you can: I found it readable with some work and background research after paying my $30 to Nature for it) concerns changes in these flows. In particular, it reports on the latest 2004 survey of flows along the 25 degree latitude line, which has been surveyed before: in 1957, 1981, 1992, and 1998. It's important to understand exactly how the survey line corresponds to the currents.
The Gulf Stream is very tightly concentrated and goes between Florida and the Bahamas:
Sketch of the position of the Gulf Stream, warm core, and cold core eddies observed in infrared images of the sea surface collected by the infrared radiometer on NOAA-5 in October and December 1978. From Tolmazin (1985: 91)., via OceanWorld.
And this is where it gets interesting. Exercising my fair use commentary rights, here's the picture from the Nature paper that gets at the point I want to make:
Vertical distribution of water transport across the survey line in Bryden et al.
Now, the main emphasis of the coverage has been on c). This shows a blow-up of the portions of the transport that are the cold return currents. Clearly, these have been reducing - the newer lines are moving steadily to the right. Less and less water is coming down from the Arctic. Climatologists believe this is because more fresh water is coming into the Arctic (from increased river flow and ice sheet melting) and making the water up there less salty and thus less able to sink. Since less water is coming down from the Arctic, less water must be going up there in that central piece of the Gulf Stream (as the overall flow is nearly balanced), and so the heat-pump that warms Europe is presumably being affected.
But look at b). That's the returning subtropical gyre (faster currents above 1000m in depth). It's getting stronger and stronger with each passing survey. That's the warm water that didn't go to Europe, and is now coming back into the tropics. Where's it going again?
Sketch of the major surface currents in the North Atlantic. Values are transport in Sverdrups (106m3/s). From Sverdrup, Johnson, and Fleming (1942: fig. 187), via OceanWorld.
So if this result holds up and these trends continue, I think we can expect to see plenty more of this in the future:
BP's Thunder Horse rig undergoing repairs after hurricane damage. Source: Minerals Management Service.
Contact
- Content: editors at theoildrum dot com
- Tech support: support at theoildrum dot com
License
This work is licensed under a Creative Commons Attribution-Share Alike 3.0 United States License.
On the other hand, there's no end to bad news about the Arctic meltdown due to rising temperatures and positive feedbacks.
I agree that the climatic impact on Europe seems a little less clear right now.
and we have no idea what will happen as a result.
http://www.timesonline.co.uk/article/0,,2087-1602579,00.html
This means, of course, that the substantial flows of freshly melted ice water, diluting the heavy salt water, may have been enough to slow the Gulf Stream.
Woods Hole has been sending monitors through all levels of the Gulf Stream to check on what is happening.
If this slow-down is true, hurricanes will be the least of our worries.
...precisely
http://www.sciencedaily.com/releases/2005/11/051107080830.htm
In fact, 2005 looks to feature the greatest amount of melting of the edge of the ice sheet in Greenland in about 30 years (or more):
http://cires.colorado.edu/science/groups/steffen/greenland/melt2005/
There is a great book called the Two Mile Time Machine, by Richard Alley, that discusses the Greenland Ice Core Project, and the study of past failures of the ice sheet, and the ensuing almost instant climate change. This failure is thought to be one of the primary drivers in the disruption of the warm, salty conveyor belt that keeps Europe's western reaches so mild.
Oh, and if the ice sheet does melt, how long can you tread water?:
http://news.nationalgeographic.com/news/2004/04/0408_040408_greenlandicemelt.html
The least of our worries indeed!
I think the models are poor enough at the present time that making predictions is hazardous but we can see the trendlines. And the geologic record tells us that climate change happens fast (less than a decade). In fact, here's an article discussing the process that scientists went through in the 20th century as they came to grips with the evidence of abrupt climate change.
We simply do not know where we are on the trendline from warm age to the next ice age. And by pushing the climate rapidly into unstable states, we may be accelerating things into even less stable conditions.
Jonathan Gregory, a climatologist at the University of Reading, UK, says global warming could start runaway melting on Greenland within 50 years, and it will "probably be irreversible this side of a new ice age". The only good news is that it a total meltdown is likely to take at least 1000 years.
Hyperbole and exaggeration don't help. Do I think the models are weak enough that Greenland Ice might melt faster than predicted? Sure. But this guy isn't saying it will be "gone in 50 years tops"
Professor Slawek Tulaczyk and Ian Howat, of the Department of Earth Sciences at the University of California, Santa Cruz, say that new melt evidence could easily cut previous melt estimates in half.
Yet here, we have another team saying the melt time is in "thousands" of years.
And here are scientists who aren't even sure the Greenland cap is melting at all.
The estimates reported seem to have wide variance (though not as wide as I originally thought). And further, none of the existing global warming models of which I am aware accounted for the sudden increase in melt over the last 5 years. Most climatologists seem to have been taken by surprise, as I noted previously, by the rapid increase in melt rate which was not accounted for by existing models.
I think my point remains - our models are incomplete and at this stage inevitably subject to errors. Also, at this point, the errors have all been too cautious. Given the immense potential impacts of these changes, both now and in the future, I think we are being foolish to ignore the longer term trend. But hey! The economists assure us that the market will solve everything so be happy, and spend, spend, spend, right?
Gregory's model, the subject of the first two links and referred to in the third, suggests that as ice is lost, the ice cap in central Greenland, high enough today to cause appreciable snowfall, would end up at lower elevations where the air is warmer. A feedback mechanism ensues in which less snowfall and more rain would cause the ice to disappear more quickly than it was being replaced, leading in turn to further drops in elevation. A different approach (Mitrovica et al, Nature 409:1026,(2001)) suggests melting of the Greenland ice complex over the last century has already contributed the equivalent of 0.6 mm per year of sea-level rise.
http://www.mba.ac.uk/marclim/is_our_climate_changing.asp
"....Central England temperature rose by almost 1°C during the twentieth century and the 1990's was the warmest decade in central England since records began in the 1600's. This warming over land was also accompanied by warming of UK coastal waters [Source: UKCIP, 2002]. Analysis of other data has revealed the following changes in the UK climate:
>The thermal growing season for plants in central England has lengthened by about one month since 1900.
>Heatwaves have become more frequent in summer, while there are now fewer frosts and winter cold spells.
>Winters over the last 200 years have become wetter relative to summers throughout the UK.
>A larger proportion of winter precipitation in all regions now falls on heavy rainfall days than was the case 50 years ago.... "
This could explain what is being observed in this case, afterall, this part of the coneyor has not yet shut down, simply slowed.
So, it might take more than the current state to begin cooling in Europe noticably. But, when it happens, it can happen quickly.
This is facinating (maybe like a slow-motion train wreck). I would not have expected to see changes occur so quickly.
So perhaps it's a self-correcting system. Slowing the warm water flow may ultimately cause more ice to form again.
There is little doubt now that England will soon be covered with ice a mile deep, once again turning that hardy race into wandering tribes of gardeners, as they were during Victoria's reign (may she rest in peace).
I used to have a good winter Firewood business in North Texas.No more by a log shot.I longed for cold air this fall and now it arrives.But what ice sheet is melting to heat the warmer air arriving at the North Pole where this air came from ?
In May 05, the prediction was 12 to 15 tropical storms, about little more half of those to hurricanes, and about a little over half of those hurricanes would be intense. as mentioned here
Today is the official end of hurricane season 2005. But the new season starts 01June06. Thats only 6 months away.
"But Richard Wood, chief oceanographer at the UK Met Office's Hadley Centre for climate research in Exeter, says the Southampton team's findings leave a lot unexplained. The changes are so big they should have cut oceanic heating of Europe by about one-fifth - enough to cool the British Isles by 1°C and Scandinavia by 2°C. "We haven't seen it yet," he points out.
"Though unseasonably cold weather last month briefly blanketed parts of the UK in snow, average European temperatures have been rising, Wood says. Measurements of surface temperatures in the North Atlantic indicate a strong warming trend during the 1990s, which seems now to have halted.
"Bryden speculates that the warming may have been part of a global temperature increase brought about by man-made greenhouse warming, and that this is now being counteracted by a decrease in the northward flow of warm water."
I guess now we know why the forecast of the possibility of a colder than usual winter in Britain.
Of course they are related and oil use harms the climate - but if you want to convict a single energy source for crimes against the climate, look at coal.
Sahara November 2000 (left), September 2003 (right)
Another reason for Algeria to be the land of opportunity. Hmmm. Maybe we should all go buy some land over there - got to be a better investment than buying a house here in California :-) At any rate, the issue of rapid climate change in the past is increasingly well attested now.
This makes it 5 storms past the (W)ilma which is the last letter in the English alphabet that is used for naming storms. This was the first year they ever ran out of letters. This year had two storms that broke records for being the lowest in central pressure.
I do wonder what next year will bring.
Ocean temperatures also affect sea life. Push them to far out of the norm and we could lose fish stocks even more than we have from over fishing.
I read a report earlier in the year that spoke of birds off the north coast the British Isles that had lost their normal food, due to temperature changes moving the fish away from their feeding grounds and nesting sites.
Watch for folks to scream that we just don't know what we are thinking, that it is all in our heads, THE WORLD IS JUST FINE, keep on driving nothing to worry about.
Isn't the weather getting interesting?
http://www.fortune.com/fortune/print/0,15935,582584,00.html
CLIMATE COLLAPSE
The Pentagon's Weather Nightmare
The climate could change radically, and fast. That would be the mother of all national security issues.
By David Stipp
Summary from Union of Concerned Scientists:
http://www.ucsusa.org/global_warming/science/abrupt-climate-change-faq.html
"Two high-profile events are putting the issue of "abrupt climate change" squarely in the public eye. The first is a February 2004 Fortune Magazine article that broke the news of a report prepared for the Pentagon on abrupt climate change and its implications for U.S. national security. The Pentagon report describes a scenario in which human-caused global warming leads to a near-term collapse of the ocean's thermohaline circulation, which brings warm surface waters from the tropics to the North Atlantic, warming parts of Western Europe. The authors propose dramatic impacts, including rapid cooling in Europe, greatly diminished rainfall in many important agricultural and urban centers and consequent disruptions in food supply and water supply with enormous geopolitical and security implications."
BTW, Sturart, you've done some excellent work on this subject.
Probably, the best guide for us regarding Europe is the "Little Ice Age" (LIA), which actually lasted all the way into the 19th Century. During the worst of the LIA, there were reports of glaciers moving out of the Alps at the rate of a "musket shot per day" obliterating everything in their paths. Recent research has shown that these rapid climate changes are like flipping a switch. So, recent warming patterns in Europe are irrelevant.
In the Fortune article, the author noted that given a choice between starving to death in the cold or waging war, humans have traditionally chosen war, which is why the Pentagon has expressed so much interest in the subject. I was particularly taken by implications regarding the recent spike in U.K. natural gas prices to the equivalent of almost $180 per barrel. There were some very nasty comments being made by the Brits regarding their European cousins, basically because utilities on the continent were refusing to sell the U.K. additional gas at any price--they wanted to hold on to it for their own citizens. This is only the beginning to what could truly be a long winter of our discontent.
That's a link to the report that the Fortune article summarized. I dug it up when it first came out. Interesting read.
What's a little uncanny is how accurate the prediction has been so far. Here in North Texas we are going through the worst drought since the Fifties.
- The ash is confined to the gasifier and is removed as solidified slag.
- Sulfur is easily removed from the syngas with standard scrubbing techniques.
- The desulfurized fuel gas can be further scrubbed of mercury and other heavy metals using activated carbon.
- If carbon dioxide and hydrogen sulfide are co-captured at the gasifier outlet, they can be co-stored and sequestered at lower cost than the standard practice of conversion of H2S to solids.
If we're going to use coal at all, IGCC is the way to do it.we find the Western Antarctic Ice Shelf- WAIS,
4. There is evidence that these peripheral changes are having a strong effect on glaciers of the inland Antarctic ice due to ice dynamics. The glaciers that used to feed Larsen A ice shelf have accelerated threefold after the collapse of the ice shelf, suggesting that the ice shelves have a critical role in restraining the flow of the inland ice. A similar behaviour might be occurring on the Amundsen Sea sector of the west Antarctic Ice Sheet (WAIS), where Pine Island and Thwaites glaciers have lost significant portions of their fringing ice shelves, and show signs of recent acceleration. This ice sheet is a fraction of the size of the dominating east Antarctic ice sheet, but its mass is still great enough to raise global sea-level by five meters.
http://www.environmenttimes.net/article.cfm?pageID=4
And-
British scientists have discovered a new threat to the world which may be a result of global warming. Researchers from the Cambridge-based British Antarctic Survey (BAS) have discovered that a massive Antarctic ice sheet previously assumed to be stable may be starting to disintegrate, a conference on climate change heard yesterday-
He added: "The previous view was that WAIS would not collapse before the year 2100. We now have to revise that judgement. We cannot be so sanguine." Collapse of the WAIS would be a disaster, putting enormous chunks of low-lying, desperately poor countries such as Bangladesh under water - not to mention much of southern England.
http://www.mindfully.org/Air/2005/WAIS-Sea-Levels2feb05.htm
We've been living on Geological Borrowed Time-
If anything, our current interglacial is most remarkable for its brevity. If it ended this week and the glaciers returned, it would be marked as the shorter side of normal.
http://anthropik.com/2005/11/thesis-17-environmental-problems-may-lead-to-collapse/
Margaret Beckett (Again, from Mindfully.org), the Environment Secretary, who opened the conference, added another ominous prediction when she said that major global warming impacts on the world in the next 20 to 30 years could not be avoided. Whatever we do, potentially disastrous world temperature rises will take place because they are already "built into the system," she said.
Her forecast that we are powerless to prevent major damage from climate change is accepted by scientists but it is rare for such a frank admission from a politician. It reflects the concern at a high level.
Get ready for Cascading Systems Failure.
But one of these days it will no longer be abstract, and I cannot help but feel that day is coming sooner rather than later - and there seem to be quite a few serious problems lining up at the same time.
Good observation. I face the same problem and I'll bet many others do too.
Two Cat 5's hitting the Gulf coats in the same year. Well that's pretty new (as a former Houston resident in the 1980's and early '90's I can attest).
How about unprecidented heat waves in northern latitudes of recent years, I was in the UK for one, Londoners sunbathing in the parks because must have seemed unsual for many there.
Major Ice sheets breaking away from Antarctica. That's pretty atypical.
How about the poor island of Tuvalu, which is being regularly inundated by high tides that heretofore had not bothered these fine atoll dwellers. A whole society will need to be evacuated...not so typical for canoe building Ocean dwellers.
It's the spikes that people notice, because we are prepared by evolution to notice them. These spikey events seem more frequent, particularly in the past few decades as exponential changes in global warming finally have reached a tipping point.
We may not notice them in our own back yard each and every day, but we do on occasion notice them, and with increasing frequency. Of course, depending on where your back yard is, or was, the amount of shock and personal disruption experienced will vary about as wildly as do annual peaks and trophs in temperature. As any former resident of NO, soon to be kicked out of FEMA supported housing (just in times for the holidays!!!) will not so happily attest.
Also, I was not aware of the Tuvalu situation, but it's not like you can expect to find out about it on the news or anything!
Maybe it's just due to reading about these issues on a daily basis, you start to expect something new to happen every day too. Can you be impatient for a bad thing to happen?
Pfft. Just a fluke. Call me back when we've lost three or four...
:-)
Courtesy EnergyBulletin-
http://energyBulletin.net/11370.html
1. North Sea-Concerning the North Sea the IEO2001 states:
"In the IEO2001 forecast, North Sea production reaches a peak
in 2006, at almost 6.6 million barrels/day (mb.d). Production
from Norway, Western Europe's largest producer, is expected to
peak at about 3.7 mb/d in 2004 and then gradually decline to
about 3.1 mb/d by the end of the forecast period with the
maturing of some of its large and older fields. The United
Kingdom is expected to produce about 3.1 mb/d by the middle
of this decade, followed by a decline to 2.7 mb/d by 2020."
The facts are that the North Sea was already post peak when
these words were written. The North sea peaked in 1999 at
5.947 mb/d. For the first nine months of 2005 the North Sea
has averaged 4.787 mb/d, 1.16 mb/d below the average for all
of 1999, the peak year. And that is over 1.8 mb/d below what
they expected the production to be next year. It is almost
a lead pipe cinch that by then the North sea will be producing
at least 2 mb/d below their predicted 6.6 mb/d, and declining fast.
Hurricane Epsilon-who woulda thought.
Please save your money for some country oil report from some overpaid analyst.
The nukes are coming.
Do LNG tankers still accomplish en-route cooling of their cargo by allowing LNG to boil off? (I've seen numbers suggesting that 8-12% of the LNG boils off in this fashion, when evap cooling is used as a heat-sink for the cargo.)
If so, LNG tankers are far worse for global warming than burning coal for elctricity generation, since CH4 is one of the most potent greenhouse gasses.
There's a better way. Either use on-board methane-powered compressors for en-route cooling (i.e. burn it, don't release it), or - cheaper yet - use LN2 (liquified on shore) for evap cooling...
Les Lambert
The above linked site also has an erudite technical discussion thread concerning this week's report about the state of accuracy of understanding of central Atlantic water currents now reported as 1/3 less mobile than when last measured 50 years ago, with conjecture about possible climate interrelationships if the interpretation is verified; the beginning article is here and the full discussion thread here covering various parts of that ocean.