Archive for the ‘James Hansen’ Category

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More on Thermohaline Circulation

June 16, 2009

In a previous post “The Thermohaline Circulation Only Stops for Extreme, Unrealistic Models,” I compared the amount of fresh water used in “hosing experiment” models to drastically reduce the thermohaline circulation (THC, or Meridional Overturning Circulation, MOC) to the amount of water flowing over Niagara Falls, or flowing from all rivers into the Arctic,  or coming off of Greenland due to melting ice.

The key number was one Sverdrup, or 1 million cubic meters of fresh water per second.  One Sverdrup of fresh water artificially dumped into the Labrador sea, for 100 years would have the feared effect.  But it turns out that one Sverdrup of fresh water is 350 times the amount of water flowing over Niagara falls, and about 300 times the amount of water from melting ice that flows off of Greenland.  It was seen that there is not plausible source for this amount of extra fresh water to be dumped into the arctic.

An interesting letter that appeared in Science a year ago gives a little more perspective,  So I have reproduced it in full here:

Freshwater Forcing: Will History Repeat Itself?

IN THEIR RESEARCH ARTICLE “REDUCED North Atlantic deep water coeval with the glacial Lake Agassiz freshwater outburst” (4 January, p. 60), H. F. Kleiven et al. present compelling evidence for an abrupt deep-ocean response to the release of freshwater from glacial Lake Agassiz into the northwest Atlantic about 8400 years ago. Such data are particularly important in evaluating the response in ocean models of the Atlantic Meridional Overturning Circulation (MOC) to freshwater forcing. For this event, the freshwater forcing was likely large but short; Clarke et al. (1) estimate that the flood had a freshwater flux of 4 to 9 Sv [Sverdrups] released in 0.5 years.

In this context, we are aware of no possible mechanism that might reproduce such a forcing in response to global warming, and all available model simulations, including those with estimates of maximum Greenland Ice Sheet (GIS) melting rates, indicate that it is very unlikely that the MOC will undergo an abrupt transition during the course of the 21st century (2). Multimodel ensemble averages under Special Report on Emissions Scenario (SRES) A1B suggest a best estimate of 25 to 30% reduction in the overall MOC strength (2). In one example, 14 coupled models simulated a 100-year 0.1-Sv freshwater perturbation to the northern North Atlantic Ocean—17 times the recently estimated melt rates from the GIS [Greenland Ice Sheet]—and the MOC weakened by a multimodel mean of 30% after 100 years; none of the models simulated a shutdown (3). Another model simulated greenhouse gas levels that increased to four times preindustrial values and then remained fixed; the resulting GIS displayed a peak melting rate of about 0.1 Sv, with little effect on the MOC (4). One model simulation uses the SRES  freshwater forcing as an upper-bound estimate of potential GIS melting. In this case, the MOC weakened but subsequently recovered its strength, indicating that GIS melting would not cause abrupt climate change in the 21st century (5). Accordingly, we urge caution in drawing comparisons of the abrupt change 8400 years ago to future scenarios involving, for example, the melting of the GIS and its relevance to human societies.

PETER U. CLARK1, THOMAS L. DELWORTH2, ANDREW J. WEAVER1
1Department of Geosciences, Oregon State University, Corvallis, OR 97331, USA.
2Geophysical Fluid Dynamics Laboratory/NOAA, Princeton, NJ 08542, USA.
3School of Earth and Ocean Sciences, University of Victoria, Victoria, BC V8W 3P6, Canada.

References
1. G. K. C. Clarke, D. W. Leverington, J. T. Teller, A. S. Dyke, Quat. Sci. Rev. 23, 389 (2004).
2. G. A Meehl et al., in Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, S. Solomon et al., Eds. (Cambridge Univ. Press, New York, 2007), pp. 747–845.
3. R. J. Stouffer et al., J. Clim. 19, 1365 (2006).
4. J. K. Ridley, P. Huybrechts, J. M. Gregory, J. A. Lowe, J. Clim. 17, 3409 (2005).
5. J. H. Jungclaus, H. Haak, M. Esch, E. Roeckner, J. Marotzke, Geophys. Res. Lett. 33, 10.1029/2006GL026815 (2006).

So, the event that occurred 8400 years ago involved 4 to 9 Sverdrups of fresh water.  This is THOUSANDS of times greater than the flow of the Niagara Falls today.  It is THOUSANDS of times greater than the amount of fresh water flowing from melting Greenland ice today. It is multiples bigger than the entire fresh water budget into the Arctic.

Note that in my previous post I referred to hosing experiments that pumped up to one Sverdrup of fresh water into the oceans.   The authors of the above letter refer to hosing experiments that used only 0.1 Sverdrups – yet they still point out how gigantic this is compared to actual sources of fresh water in the Arctic today.

So, when Al Gore ominously implies that that the Greenland Ice Sheet [GIS] is going to melt down and dump enough fresh water into the Atlantic Ocean to shut down the Thermohaline Circulation, remember the works of Clarke, et.al., in the above letter: “we urge caution in drawing comparisons of the abrupt change 8400 years ago to future scenarios involving, for example, the melting of the GIS [Greenland Ice Sheet] and its relevance to human societies.”

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Impure thoughts about sea level rise

June 5, 2009

There has been some back and forth about the magnitude, consequences and proper response to sea level rise here, here, herehere and here. The alarmists would like to dismiss the evidence of man’s ability to cope. I have wondered why they think the history of free and motivated people pushing back against the ocean is irrelevant. But now this comment by Ed Darrell (from here) puts the alarmists’ mindset into clear focus.

Ed Darrel said:

Yeah, I saw the chart that said sea level is rising in Boston. It’s been rising as long as it’s been measured there, hasn’t it?

Not once did the harbormaster get together with the Brahmins of Boston to say, “We need to make Boston Neck thicker because of rising sea level.”

I didn’t say sea level didn’t rise. I said none of the landfills was done in response to rising sea level. The land was filled out for commercial needs, for commercial wants, and because when the weather created a bunch of new land, it could be used. Not once was any part of the harborscape built out to meet rising ocean levels.

So, to claim that Boston illustrates that the world can cope, is simply in error. Of course the world can cope in major harbors where there is plenty of commercial activity to combat a modest increase in ocean level.

What was your point?

So, apparently, Boston’s experience doesn’t count as evidence of man’s ability to push back against the ocean. Why? Because their actions were motivated by impure thoughts.

If I have properly deciphered Ed’s logic, then the following scenario does not show man’s ability to cope with the ocean:

Land in the Boston area is crowded and valuable. Engineers and the ‘Brahmins of Boston’ say “We could boost commerce by making Boston Neck thicker and recovering land from the sea.” Engineers design ways to push back the ocean and follow through on their plans.

But the following scenario would demonstrate man’s ability to cope with the ocean:

Land in the Boston area is crowded and valuable. Engineers and the ‘Brahmins of Boston’ say “We could fight against global warming by making Boston Neck thicker and recovering land from the sea.” Engineers design ways to push back the ocean and follow through on their plans.

Why would the second scenario illustrate man’s ability to cope with the ocean, but the first does not? In both cases they have the same problem and the same outcome. Here’s why: in the first scenario the engineers’ and brahmins’ motivations are impure, in the second scenario the engineers’ and brahmins’ motivations are pure.

Well, at least we have found some common ground. That is, we agree that the sea level has been rising near Boston, and we agree that Boston has been successful in pushing back the ocean.  But Ed can’t seem to understand that even if the ocean had not been rising near Boston for the last hundred years, their experience shows that they have the ability to cope if it started rising now.

Just Plain NutsVell, Mr. Darrell, I think vee have made some veal progress.  At our next session vee vill analyze your repression of impure thoughts concerning sea level vise.

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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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Let’s Build a Seawall

May 17, 2009

I read with great surprise and pleasure that ClimateSanity has been added to the blogroll at  WattsUpWithThat.  Anthony, thank you, it is an honor!

The thing that brought this on was one of my previous posts about the effect of sea level rise on Boston, which Anthony was kind enough to share with his huge readership.

Just to stir the pot a little, here is a simple back of the envelope calculation that may serve as a response to some of the comments at WUWT:

Click to enlarge

Click to enlarge

Suppose you felt the need to build a sea wall three meters high and three meters thick to protect the Boston area from the rising sea.  Lets say you built it from Lynn in the North to Quincy in the south.  These two communities are about 25 kilometers apart in a straight line.  But let’s say when you account for the curviness of the coastline its really 100 km.  So,this sea wall will be 3 meters high, 3 meters thick, and 100 kilometers long.  That means the volume of the sea wall will be 900,000 cubic meters, or about 1,000,000 cubic meters. 

Since the ocean is rising quite slowly, we can allow ourselves 100 years to build this sea wall.

The population of the greater Boston area is about 4 million. Let’s assume that the population remains unchanged for the next hundred years (of course, it will probably grow a lot).

Then the volume of seawall that needs to be built per person per year is:  0.0025 cubic meters per person per year.  Oh my,  how will you every do it?

But if you manage to get it done in 100 years you will be able to look at the accomplishment with pride.  And assuming that the sea level keeps rising at its current rate of about 2.5 mm per year, you will know that the 3 meter tall seawall will keep you safe for another 1000 years.

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Boston Underwater?

March 24, 2009

Boston, you have been warned. Sea levels are rising , and if one of the IPCC’s five scenarios is correct, the world’s oceans will rise somewhere between 18 and 59 cm (7 to 23 inches) by 2100. If that isn’t terrifying enough for the people living on the New England coast, the Boston Globe now tells us that the ocean near Boston will rise 8 inches more than the world average. How will the hapless rubes of Boston cope with this onslaught of Atlantic water?

I wouldn’t lose to much sleep worrying about the folks in Boston when it comes to pushing back against the ocean. Excerpts from the following maps were used to make an animation of the changing coastline in Boston:

  • A 1775 map showing the Boston area with the rebel military works. Note especially the isthmus, known as Boston Neck< that connects the town of Boston to the mainland.
  • An 1838 George W. Boynton engraving of Boston area from a Thomas G. Bradford atlas.
  • USGS map of Boston area.
  • A 2009 satellite image from Google Earth

The top of the animation shows the maps after photoshopping to make the land and water more obvious. The bottom of the animation shows the unaltered excerpts of the maps or images.

animation-5I

The panic prone will argue that our Bostonian ancestors dealt with a static ocean, not a rising ocean. Not so fast. Check out the NOAA graph below (click inside graph to see it in context at NOAA site). It shows a sea level rise rate of 2.63 mm/yr for the last 100 years in Boston. At that rate it will rise 23.9 cm (9.4 inches) by 2100.

Boston sea level rise

Boston sea level rise data from NOAA. Click in image fro view in context.

Anyone who panics over the IPCCs 100 year projections of rising sea levels does not understand the perseverance and ingenuity of free people. Then there are others, like James Hansen, who enjoy the feeling of panic so much that that they exagerate the probable sea level rise for this century to get their thrills. But that is a story for another day…

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