Archive for the ‘ice shelf’ Category

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Rahmstorf (2009): Off the mark again (part 5), Variation of gamma

April 14, 2010

Another post on Vermeer’s and Rahmstorf’s 2009 PNAS paper, “Global sea level linked to global temperature.”   This time we consider the variation of gamma (γ) in equation 4 of part two.  The curious result will be that for γ>1 the temperature will continuously increase, while the sea level rise rate will continuously drop.

In Part 1, I laid out the basic problem.

In Part 2, I went into a little more detail on the math.

In Part 3, I gave a few examples that show some bizarre consequences that would result if equation were correct.

In Part 4, improbable parallel universes.

This is very simple. 

The plots below will show hypothetical temperatures that satisfy equation 4 of part 2, with all parameters equal, except γ.  But the fact that the temperature is derived from this equation is not really important.  The important thing is that the version with a faster increasing temperature has a decreasing sea level rise rate, and vice versa.

How can this be?

As before, these bizarre results are not my invention – they follow directly from Vermeer’s and Rahmstorf’s equation relating sea level rise rate to temperature.  The answer to the question is very simple:  Vermeer’s and Rahmstorf’s model does not make sense.  Their model causes realistic temperature scenarios to yield unrealistic sea level rise rates.

A future post will discuss Vermeer’s and Rahmstorf’s misguided concept of a “positive, but time-lagged, sea level response.”

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Rahmstorf (2009): Off the mark again (part 4): Parallel Universes

April 12, 2010

Let’s consider Vermeer and Rahmstorf’s equation that relates sea level rise rate to temperature again.

You can read Vermeer and Rahmstorf’s PNAS paper (referred to as VR2009 for the rest of this post), Global Sea Level Linked to Global Temperature,  here.

In Part 1, I laid out the basic problem.
In Part 2, I went into a little more detail on the math.
In Part 3, I gave a few examples that show some bizarre consequences that would result if equation were correct.

As a reminder, here is their equation


where…

  • H is the sea level, and dH/dt is the change in sea level per unit time (the sea level rise rate)
  • T is the temperature, and dT/dt is the change in temperature per unit time
  • a = 05.6+- 0.5 mm*a-1K-1
  • b = -49 +- 10 mm*K-1
  • To = -0.41 +- 0.03 K

Parallel Universes

Let’s think in terms of parallel universes, just for the fun of it.  Both Universes will be the same as the one we live in up to this point.  Starting in 2010 they will continue as the same universe with a hypothetical increasing temperature scenario for the planet earth.  I will choose a temperature scenario that satisfies equation 4, from part 2.

The advantage of this temperature scenario is that the increasing temperature yields a perfectly constant sea level rise rate when applied to VR2009’s equation (equation 1, above).  Other than that, there is nothing special about this scenario, but it is convenient to work with for illustrative purposes, and in and of itself uncovers some of the bizarre nature of VR2009’s model.

After another 30 years, our universe will bifurcate into two parallel universes.  One will continue to have an increasing temperature due to all the nasty undertakings of the human scum that occupies the planet.  The other will experience a divine halt to the temperature rise, probably due to the mercy of Gaia after receiving years or prayers of intercession from faithful environmentalists.  In this second universe, the temperature will become constant.

How will the sea level rises in these two universes compare?

Universe #1


Universe 1 Excel file link

Universe #2


Universe #2 Excel file link

Comparison

Look closely at what happens in 2040, when the two universes split.  In Universe #1, where the temperature keeps increasing, the sea level rise rate remains constant.  But in Universe #2, where the temperature becomes constant, there is a sudden rise in the sea level rise rate.

Remember, this is a consequence of VR2009’s model, not my imagination.  How can this be possible?  It all comes down to VR2009’s model and the fact that they find the constant b in equation 1 to be negative.  They recognized the strangeness of this conclusion and attempted to explain away the counter-intuitive sign of b by saying that it points to a …

positive, but time-lagged, sea level response. That a negative b corresponds to a lag is easily seen… Several mechanisms could be envisaged for a delayed onset of sea-level rise after warming. For example, mass loss of ice can be caused by warm water penetrating underneath shelves, triggering their collapse and subsequent speed-up of outlet glaciers banked up behind the ice shelf. We cannot explore the causes of delay in more detail here, but note the statistical result is robust irrespective of causes.

So, in both universes, water was penetrating underneath the ice shelves.  Drop for drop, molecule for molecule, the water penetration was identical.  The condition of the ice shelves in the two universes were identical at the moment of bifurcation.  In the universe where the temperature continues to rise the ice shelves do not collapse, as evidenced by the fact that the sea level rise rate does not increase.  This is despite the fact that the increasing warmth would cause even more water to “penetrate underneath shelves.”   But in the universe where the temperature becomes constant, the ice shelf immediately starts to collapse, increasing the sea level rise rate.  OK, sure.

Conclusion (for now)

It’s too bad that VR2009 “cannot explore the causes of delay in more detail,” because I would love to hear how they explain the bizarre results that follow from their model.  My conclusion is that their model is bogus.  As such, it has no predictive power for sea level rise rates for the 21st century.

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The Thermohaline Circulation Only Stops for Extreme, Unrealistic Models

June 4, 2009

Return to Criticisms of Al Gore’s “An Inconvenient Truth”

Gore gives a cartoon description of the ocean circulation system when he explains what has become known as the thermohaline circulation, or the meridional overturning circulation.  In his simplistic scenario the surface ocean current that flows north in the Atlantic, bringing warmth to northern Europe will be halted by melting ice from Greenland, subsequently throwing Europe into an ice age. 

Here is Gore’s explanation in his own words from the Inconvenient Truth movie:

The Earth’s climate is like a big engine for redistributing heat from the equator to the poles.  And it does that by means of ocean currents and wind currents.  They tell us, the scientists do, that the Earth’s climate is an non-linear system – just a fancy way they have of saying that the changes are not all just gradual, some of them come suddenly, in big jumps… And so, all those wind and ocean currents that have formed since the last ice age and have been relatively stable – they’re all up in the air – they change. 

And one of the ones they’re most worried about, where they’ve spent a lot of time studying the problem is in the the North Atlantic where the gulf stream comes up and meets the cold winds coming off the Arctic over Greenland and that evaporates the heat out of the gulf stream and the steam is carried over to western Europe by the prevailing winds and the Earth’s rotation.  But isn’t it interesting that the whole ocean current system is all linked together in this loop, they call it the ocean conveyor.

vlcsnap-324533And the red are the warm surface currents, the Gulf Stream is the best known of them.  But the blue represent the cold currents running in the opposite direction…

vlcsnap-32114Up in the North Atlantic, after that heat is pulled out, what’s left behind is colder water, and saltier water, because the salt doesn’t go anywhere. And so, that makes it denser and heavier.  And so that cold heavy dense water sinks at the rate of 5 billion gallons per second.  And then that pulls that current back south.ani-21

At the end of the last ice age as the last glacier was receding from North America the ice melted and a giant pool of fresh water formed in North America, and the Great Lakes are the remnants of that huge lake.  An ice dam on the eastern border formed, and one day it broke, and all that fresh water came rushing out, ripping open the St. Lawrence there, and it diluted the salty dense cold water, made it fresher and lighter so it stopped sinking, and that pump shut off.

 vlcsnap-549956-smallAnd the heat transfer stopped.  And Europe went back into an ice age for another 900 to 1000 years.  And the change from conditions like we have here today to an ice age took place in perhaps as little as ten years time.  So that’s a sudden jump.  Now, of course, that’s not going to happen again because the glaciers of North America are not there… Is there any other big chunk of ice anywhere near there…?  Oh, yeah [Gore says ominously, as the image pans to ice covered Greenland] we’ll come back to that one…

Later in the movie Gore tells us that Greenland is rapidly melting.  The point being that it will provide a massive amount of fresh water that will stop the the thermohaline conveyor and  “would raise sea level almost 20 feet if it ‘went,'” Gore tells us.  He tells us about water seeping to the bottom of the ice sheets where it “lubricates where the ice meets the bedrock” causing the ice to slide toward the ocean.

Then he shows a series of pictures purporting to show the amount of melting in Greenland.  Gore says…

ani-31

“In 1992 they measured this amount of melting in Greenland … Ten years later this is what happened…And here’s the melting from 2005”

 

Hosing Experiments

But what if…?  What if there were a huge amount of low density fresh water dumped into the North Atlantic where the high density water is supposed to be sinking, just like the giant Canadian lake crashing through the barrier of ice the Gore told us about?  This possibility is explored with computer models known as  “hosing experiments.”  In a hosing experiment a model that simulates the ocean and atmosphere circulation patterns is modified to artificially dump huge amounts of extra fresh water, as if from a giant hose, into some location in the ocean.   It has been found that when enough fresh water is forced in, the circulation can be slowed, but rarely stopped

How much fresh water do the hosing experiments use to nearly stop the thermohaline circulation?  Typically (or here), they use one million cubic meters of fresh water per second, for 100 years!!!  (One million cubic meters per second has its own unit name: One Sverdrup or 1 Sv).  How does 1 Sv compare to, say, the rate of water flowing over Niagara Falls?

Niagara falls168,000 cubic  meters of water fall over Niagara Falls every minute.  That is about 2,800 cubic meters of water per second.  So one Sverdrup of water is the same as about 350 Niagara Falls!  (1,000,000 / 2,800  = 357).  So, roughly speaking, if 350 Niagara Falls were dumped into the oceans around Greenland continuously for 100 years, then we could expect to see a significant slow down of the thermohaline circulation.

River systems discharging into the Arctic Ocean.

River systems discharging into the Arctic Ocean.

How does one Sverdrup compare to the freshwater discharge of ALL the rivers emptying into the arctic ocean?  One Sverdrup of fresh water amounts to nearly 32,000 km3 of water per year  (1 Sv  x 106 m3 s-1/sv x (86,400 s/day) x (365 day/year) = 31,536 km3/year).  The total fresh water discharge from all rivers into the arctic is only about 4,300 km3 per year.  So, typical hosing experiments that nearly stop the overturning circulation add a water volume about 7 times the amount of water from all rivers discharing into the Arctic Ocean combined.

What about Greenland?

Hosing copyGore ominously implies that the amount of fresh water needed to turn off the overturning circulation is just waiting to pour off of  Greenland, due of course (drum roll), to CO2 induced anthropogenic global warming.   His pictures of Greenland, shown above, imply that about half of Greenland’s 2.8 million cubic kilometers of ice have melted in the 13 years between 1992 and 2005.  This is wildly misleading.  Only a miniscule fraction of the area shown in Gore’s Greenland images actually melts every year.   This is evidenced by mass balance studies, which show Greenland loses on the order of hundred cubic kilometers of ice every year,  which translates into a measly 0.003 Sverdrups.

100 km3 /year= 1011 m3/year

(1011 m3/year) / (365 days/year) / (86,400 seconds/day)
             = 3 x 103 m3/second
             = 0.003 Sv

Put another way, one Sverdrup of fresh water is 86.4 km3/day.  So the hosing experiments pouring in one Sverdrup put about as much fresh water into the ocean each day (86.4 km3) as Greenland provides in a year (100 km3).

But if Greenland actually started melting, by some extraordinary circumstance,  300 times faster, then it would yield 1 Sverdrup, or 1,000,000 cubic meters, of fresh water every second.  What would happen after 100 years of melting at that rate?  Well, that’s a trick question, because at a melting rate that gives 1 Sverdrup of freshwater Greenland would run out of ice in about 90 years.  This is because Greenland has only 2.85 million cubic kilometers of ice, and one Sverdrup of water is the same as about 31,500 cubic kilometers of water per year.  Ignoring the difference in density between ice and water, then 2.85 million cubic kilometers divided by 31,500 cubic kilometers per year gives 90 years.

Conclusion

You don’t hear as much about the threat of the collapse to the thermohaline circulation today as you did a few years ago.  This is because it has become recognized as being a very far fetched possibility, even by most alarmists who want to maintain a shred of dignity.  But I have a feeling we will not see this wildly exaggerated threat removed from new editions of Gore’s “An Inconvenient Truth” anytime soon.

Return to Criticisms of Al Gore’s “An Inconvenient Truth”

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Reply to John Mashey

May 27, 2009

I recently had an exchange of comments with some folks at Millard Filmore’s Bathtub concerning one of my previous posts about sea level rise near Boston.  The discussion seemed to really strike a nerve with alarmist nag John Mashey.  He scolded me with the following comment- you can almost see him wagging his finger:

Mashey’s comment

Mr Moriarity’s views on SLR at this time are simply not worth reading, for reasons I will explain.

NOAA collects the data, but the past is not the future. For very good scientific reasons, NOBODY serious about climate science does a simple linear projection of last century’s trendline into the next one, unlike Mr. Moriarty’s suggestion.

That would be about as silly as claiming solar PV [invented where I used to work] scientists should already be getting 100% efficiency.

Within ~30 minutes’ of Tom’s NRELare places thick with expert climate scientists, which makes him one of the lucky people who can easily go talk to experts:

NCAR
UC Boulder
USGS-Denver

I’m a AAASmember: I did a quick search of Science (An adequately prestigious journal) for “sea level rise”, and from the first hit page picked out a few recent SLR articles by Colorado authors, all of which I’d already read, along with the relevant IPCC TAR and AR4 chapters, etc, etc. (*I’m* no SLR expert, but I often talk to people who are. )

Mr. Moriarty has strong views on SLR, and surely is a AAAS member and has read these papers, all of whom think SLR will be a serious (acclerating) problem. He *could* write an article for Science showing them wrong, which would make him (properly) famous, given the mass of physics that would haveto be overturned to preserve a simple linear trend.

See How Much More Global Warming and Sea Level Rise?, 2005, 8 authors from NCAR.

See Paleoclimatic Evidence for Future Ice-Sheet Instability and Rapid Sea-Level Rise”, 2006, of whose 6 authors, 2 are at NCAR,1 at UC-Boulder, and 1 at USGS-Denver.

See Glaciers Dominate Eustatic Sea-Level Rise in the 21st Century”>,2007, of whose 8 authors, 5 are at UC Boulder.Kinematic Constraints on Glacier Contributions to 21st-Century Sea-Level Rise, 2008, of whose 3 authors one is at UC-Boulder.

See “On the basis of calculations presented here, we suggest that an improved estimate of the range of SLR to 2100 including increased ice dynamics lies between 0.8 and 2.0 m.”

(That’s probably as good a single estimate as you get right now. People are trying to model melt dynamics for places that have been frozen through recorded human history, complexified by various nonlinear effects, tipping points, etc. Ice-sheet issues are *hard*.)

NCAR says Community Ice Sheet Model Will Aid Understanding of Sea Level Rise.

“Scientists think that this mechanism might trigger the rapid retreat of the West Antarctic Ice Sheet – which could raise sea level by a meter or more within a century or less.”

See Dan Cayan (SCRIPPS)talk @ SFBCDCconference a year ago. This was not news,but right in line with mainstream science.

Specifically, see p 18-19, noting that some of the models are from NCAR. I used to sell supercomputers to NCAR and talk to their scientists. They are quite competent.

NCAR and USGS (and some of UCBoulder) are Federally-funded to do good science for us all. If Mr. Moriarty denigrates *their* work, he might want to think about the fact that most of *his* career has been supported by *Federal* tax money.

That’s money from me and the companies I’ve worked for. My home state (CA) since 1983 is far and away the biggest *net* contributor to the Federal budget, and none of NCAR, NREL, Fermilab, or Argonne are here, but we helped pay for them. [And this is OK with me, since I like to think America is a *country*, not just a collection of independent states; all those labs have made good contributions.]

LOOKING AHEAD
NCAR has regular lectures. So does UC-BOulder’s NSIDC.

If Mr. Moriarty actually wants to learn about the science, he has *real* experts nearby to visit, often.

I’m done.

My reply

John thanks for the thoughtful comment.  I hope you have had a chance to wind down get off your high horse during the holiday weekend.

Congratulations on being a AAAS member.  So am I.  And so are 120,000 other people.  For those of you who are impressed by John’s membership in the AAAS, let me fill you in on the strict requirements for membership.  Send a check – then you are a member. 

Oh, by the way, thanks for inventing solar PV, I guess without you I wouldn’t have a job.

Let’s talk about the papers you cited: 

#1  How Much More Global Warming and Sea Level Rise?  Science 18 March 2005: Vol. 307. no. 5716, pp. 1769 – 1772. 

John, did you actually read this paper?  Meehl, et. al., consider three possible scenarios from the Special Report for Emissions Scenarios (SRES).  Specifically, scenarios B1, A1B, and A2.  They ran two models on each of these scenarios. Here is what they found for 21st century steric sea level rise:

Low range scenario B1, model PCM: 13 cm

Low range scenario B1, model CCSM3: 18 cm

Low range scenario A1B, model PCM: 18 cm

Low range scenario A1B, model CCSM3: 25 cm

Low range scenario A2, model PCM: 19 cm

Low range scenario A2, model CCSM3: 30 cm

Let me translate that:  Under their worst case scenario and their most sensitive model you get 30 cm (12 inches) by 2100  Wow – pretty scary.  Note that the map at  “Impacts of Sea Level Rise on the California Coast,” which I mentioned in my earlier comment to alleviate your fear of the west coast going under water, and in which you need to zoom way, way in to even find the affected areas, were based on a much greater 140 cm (56 inch) sea level rise by 2100.

So John, why did you cite this paper.  Let me guess: You read the abstract and saw the words “additional 320% sea level rise.”  But you didn’t actually read the article, did you? These numbers don’t exactly fit the alarmists’ (Gore and Hansen for example) picture of cities under water by the end of the century.

#2  Paleoclimatic Evidence for Future Ice-Sheet Instability and Rapid Sea-Level Rise , 24 March 2006: Vol. 311. no. 5768, pp. 1747 – 1750

This paper has a preposterous flaw.  It assumes a 1% yearly increase in atmospheric CO2 levels for the 21st century.  That sounds pretty innocuous – “What’s the problem with the assumption of a 1% increase?”, you might ask.  The problem is that the actual increase is about 0.5% per year.  Check this yourself here.  (By the way, John, that’s a NOAA website.  NOAAis one of those entities with labs in Boulder that you imply I have never heard of.)  This 0.5% trend has been fairly consistent for decades.  You can get the raw data from Mauna Loa, take the derivative, even take the second derivative, and see that 1% is preposterous. 

You might say “Big deal, 0.5% or 1%, what’s the difference.”  This is like a compound interest problem.  Take 1.005 to the 100th power (0.5% increase for 100 years) on one of your super computers, then take 1.01 to the 100th power (1% increase for 100 years).  The rest of you readers can simply try this on your desktop scientific calculator.  See the difference?  Pretty big, isn’t it?

Here is a paper that you seem to have overlooked in your comprehensive literature search: An overview of results from the Coupled Model Intercomparison Project, Covey, et. al., Global and Planetary Change, Vol 37, 2003. 

Covey et. al. write about the same 1% per year CO2 increase, but warned “The rate of radiative forcing increase implied by 1% per year increasing CO2 is nearly a factor of two greater than the actual anthropogenic forcing in recent decades, even if non-CO2 greenhouse gases are added in as part of an “equivalent CO2 forcing” and anthropogenic aerosols are ignored.”  They conclude that this 1% “ increasing-CO2 scenario cannot be considered as realistic for purposes of comparing predicted and observed climate changes during the past century.”

#3  Glaciers Dominate Eustatic Sea-Level Rise in the 21st Century, Meier, et. al., Science, 24 August, 2007, Vol 317, 1064-1067

Meier, et. al, calculated a 560 mm rise in sea level due to melting ice by 2100 based on an accelerating rate of global ice melting.   They managed to concluded that the amount of ice melting each year had been, on the average, 32 Gigatonnes (Gt) greater than the previous year from 1995 to 2005.  They simply extrapolated this yearly 32 Gt increase out to 2100.   A 32 Gt yearly increase in the amount of global ice that melts each year, over the 10 year period from 1995 to 2005, would mean 320 Gt more ice was melting in 2005 that in 1995.  That translates into a sea level rise rate in 2005 that must have been 0.9 mm greater than the sea level rise rate in 1995 (320 Gt/year x  2.7 microns/Gt  = 0.9 mm/year).

But we have very good sea level rise data that covers the period from 1995 to 2005.  And John, you will be delighted to know that this data is maintained by the University of Colorado, in Boulder.

sea level rise

Take a good look.  Note that the sea level rises a rate of 3.2 mm per year from 1995 to 2005 as indicated by the line fit and the notation in the bottom right corner.  It does not start out at 3.2 mm per year in 1995 and go to 4.1 mm per year (3.2 mm/year + 0.9 mm/year) by 2005.  The rise rate clearly does not increase by 0.9 mm per year over that period of time. 

What should have happened by 2009?  Well, according to Meier the global rate at which water was added to the oceans should have continued increasing by an additional 32 Gt/year and therefore there should be 448 Gt { (2009 – 1995) x 32 Gt/year = 448 Gt/year) } more water added to the oceans per year in 2009 than in 1995.  That translates into a rise rate that is 1.2 mm/year greater in 2005 than in 1995.  If the slope of the line fit in the above graph were actually 3.2 mm/year in 1995, then by Meier’s logic it should have been 4.4 mm/year by 2009.  However, the graph clearly shows that, if anything, the rise rate is less in 2009 than in 1995.

Please feel free to actually read the paper by Meier, et. al.  Please examine their source of data and their data reduction.  Here is a nice sample of how they determined that the amount of ice melting from glaciers and ice caps (as opposed to ice melting form the Greenland or Antarctic ice sheets) is increasing:

 Figure 1 from Meier

They took a scattered set of Meier’s own data, showing the melting rate of glaciers and ice caps, and fit it to a line.  It is traditional to give some numerical indication of the quality of a line fit.  In this case Meier chose not to provide such an indication.  So I digitized his data and did it for him: the r-squared value of this data is less than a dismal 0.1.  They found the slope of the line to be 11.9 Gt/year/year and thus concluded that for each year between 1995 and 2005 the glaciers and ice caps were losing 11.9 Gt more ice than the previous year.  Then they extrapolated that rate out another 95 years.  To extrapolate a function out 10 times the actual data’s domain is risky under any circumstances.  When the data is this scattered as this, it is just plain silly. 

They then undertook equally rigorous analysis of ice changes from the Greenland ice sheet, the West Antarctic ice sheet and the East Antarctic ice sheet, added the results together and came up with their 32 Gt/year/year acceleration rate.

#4.  Kinematic Constraints on Glacier Contributions to 21st-Century Sea-Level Rise, Pfeffer, et. al., Science, 5 September 2008, Vol. 321. no. 5894, pp. 1340 – 1343

To their credit, Pfeffer et. al., work in this paper to put an upper limit on the sea level rise by 2100.  This immediately separates them from the wildest alarmists like Al Gore and James Hansen.  Their conclusion is the maximum sea level rise by 2100 is 2 meters.  But they say in the abstract “More plausible but still accelerated conditions lead to total sea-level rise by 2100 of about 0.8 meter.”  This is still quite high and apparently caught your eye, right John?

But what must happen for this 0.8 meter sea level rise?  Pfeffer et. al., use the following logic:

“Rapid, dynamically unstable discharge of ice through calving is restricted to glaciers with beds based below sea level. We identified and calculated the aggregate cross-sectionalarea of Greenland’s marine- terminating outletglaciers by using surface and bed topography (16) and measured ice velocities (5) to identify all potential pathways for rapid discharge, including channels presently flowing rapidly as well as potentially unstable channels (Fig. 1 and table S1). Cross-sectionalareas (gates) for each outlet were calculated at the point of greatest lateral constriction by bedrock in the glacier’s marine-based reach. Ice stream widths in Antarctica can vary in time, but for Greenland outlet glaciers cross-sectional areas are constrained almost entirely by bedrock topography. Of the 290 km2 total aggregate gate cross-sectional area, we identified 170 km2 as the aggregate marine based gate area where drainage to the ocean is not blocked by near coastalsills standing above present day sea level. All dynamic discharge (Table 2) must pass through these gates by 2100 to meet2- to 5-m SLR targets. We considered four scenarios: velocities were calculated for both the “marine based” gate (170 km2) and the “total aggregate” gate (290 km2) given both projected SMB and 10× inflated SMB losses. We then considered whether those velocities are realistic.”

They note that “The present-day average velocity of all Greenland outlet glaciers is 0.56 km/year when weighted by drainage basin area or 1.23 km/year when weighted by gate cross-sectional area.”  For the large sea level rises that they consider, these velocities must increase.  If we just look at the case that requires the smallest velocity increase to reach 2 meters of sea level rise by 2100 (i.e. the case that most favors your argument), then Pfeffer reports that the velocity for the discharge gates must go up to at least 26.8 km/year.

And they don’t say that this velocity must be achieved after 100 years of a slow acceleration.  Rather, they say “These velocities must be achieved immediately on all outlets considered and held at that level until 2100. Delays in the onset of rapid motion increase the required velocity further”

As you can see, the 2 meter rise requires the glacier velocity at the discharge gates to increase by at least a factor of 22. Right Now. Today. And then remain at that extraordinary velocity until 2100, winter, spring, summer and fall.

Here are some statements from the paper concerning their own velocity calculations: “The scenario velocities far exceed the fastest motion exhibited by any Greenland outlet glacier.”  “A comparison of calculated (Table 2) and observed (1.23 km/year) average velocities shows that calculated values for a 2-m SLR [sea level rise] exceed observations by a factor of 22 when considering all gates and inflated SMB and by a factor of 40 for the marine gates without inflated SMB [surface mass balance], which we consider to be the more likely scenario.”  “Although no physicalproof is offered that the velocities given in Table 2 cannot be reached or maintained over century time scales, such behavior lies far beyond the range of observations and at the least should not be adopted as a central working hypothesis.”

By extension, the glaciers would have to increase velocity by a factor of 9, today, right now,  and continue at that rate until 2100 to achieve the 0.8 meters. 

What would cause the glaciers to increase their velocity to such an extent?  The going theory at the time the Pfeffer paper was written was that melting water would make its way to the bottom of the glaciers and lubricate their motion to the sea.  Even Al Gore talks about this in his famous “An Inconvenient Truth.”  But data subsequent to the Pfeffer paper have shown that not to be the case. “Large and Rapid Melt-Induced Velocity Changes in the Ablation Zone of the Greenland Ice Sheet,”  R. S. W. van de Wal, et al., Science 321, 111 (2008).

Van de Wal, et. al., note:

Here, we present ice velocity measurements from the major ablation area along the western of the ice sheet. The data set contains simultaneous measurements of ice velocity and ablation rates, which makes it possible to study the relation between ice velocity and meltwater input on longer (>5 years) and shorter (~1 day) time scales…

Annually averaged velocities are completely decorrelated to the annual mass balance, whereas a correlation might be expected if there is a strong feedback between velocities and melt rate, leading to enhanced flow, surface lowering, and increased melt rates…

In earlier work (4, 7), it has been suggested that the interaction between meltwater production and ice velocity provides a positive feedback, leading to a more rapid and stronger response of the ice sheet to climate warming than hitherto assumed. Our results are not quite in line with this view. We did not observe a correlation between annual ablation rate and annual ice velocities. Ice velocities respond fast to changes in ablation rate on a weekly time scale. However, on a longer time scale, the internal drainage system seems to adjust to the increased meltwater input in such a way that annual velocities remain fairly constant. In our view, the annual velocities in this part of the ice sheet respond slowly to changes in ice thickness and surface slope.

So, it looks like you will have to live with the disappointing news that the planet is not doomed by rapid sea level rise after all.  And your approval for grand plans to save places like Boston and San Francisco may not be needed.  Don’t lose hope though, with any luck the planet will be threatened by a giant meteor and the services of your brilliant mind will be needed after all.

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Beverly Cleary, Goosebumps and … Al Gore?!?

April 6, 2008

Resistance is futile. 

Our kids have brought book order forms from Scholastic home from school for years.  Over the years we have spent hundreds or thousands of dollars ordering books from them.  Like so many others, Scholastic has jumped on the global warming bandwagon. 

In a recent order form for the Scholastic Arrow Book Club (April 2008) that my 3rd grader brought home we found the usual fare of animal stories, adventure, fantasy, science fiction, history and historical fiction.  But lately, Scholastic has a new category, that I will call “green living.” 

On page three of this issue we find advertisements for the books “Fairy Dust and the Quest for the Egg” (“Can Prilla the fairy outwit Captain Hook…”), a variety of poetry books, including works by Carl Sandburg and Shel Silverstein, and the “Indiana Jones Set” (Three book set for $9.95 where “Indiana Jones finds action and adventure all over the world!”).  Oh, and let’s not forget Al Gore’s “An Inconvenient Truth”.

Figure 1.  Al Gore shares a page with “Fairy Dust and the Quest for the Egg,” Shel Silverstein, and Indiana Jones.  Click on the image for a larger version without my overlay.

 

Figure2.  Close-up of the ad for Gore’s book.

 

Scholastic/Orchard also publishes The Down-to-Earth Guide to Global Warming by Laurie David and Cambria Gordon.  David was the producer of Gore’s movie.  In a recent interview with Publisher’s Weekly, David said…

“Kids also are the number one influence on their parents, so if you want to reach the parents, go to the kids.”

David’s editor, Lisa Sandell, added..

“Kids are often attracted to numbers, because it makes an idea tangible and relatable,” she says. “If you say, ‘X number water bottles are thrown away every hour,’ that’s a number they can understand … Kids can often be the arbiters of change. They can come back to their parents and ask, ‘Why don’t you have an EnergyStar appliance?”

The fact is that children don’t really understand the issues as clearly as Sandell thinks they do.  Try asking your third grader this: “Suppose refrigerator A uses 400 kilowatt hours per year and costs $1000, and refrigerator B, which is EnergyStar rated, uses 320 kilowatt hours per year, but costs $1,200.  Which one will cost more if we keep the refrigerator for 10 years and the cost of electricity averages $0.09 per kilowatt hour over that time period?”

Kids are attracted to the “Gee Whiz” effect of big numbers precisely because they don’t understand them. Neither do many adults.  (For example, people are impressed by statements like “Seven times the size of Manhattan” when talking about a piece of collapsing ice shelf, until the numbers are put in perspective.) 

The climate change issue is more about politics than it is about science.  It bothers me, but does not surprise me, that climate change alarmist want to indoctrinate my children as their political tools.