Tag Archives: sea level rise

Matt Ridley needs to take some advice from Matt Ridley

Matt Ridley is a techno-optimist of the Lomborgian mold, with all of the cherry-picking and source misrepresentation that goes with it apparently. He gave a speech to the Royal College of Physicians of Edinburgh [corrected – see below] that has “skeptics” falling all over themselves in delight.

What groundbreaking evidence does Ridley marshal in defense of his rejection of mainstream science?

I was curious. Ridley ostensibly is a cut above the average denizen of WUWT. He was trained as a zoologist before taking up science writing. He has articles frequently published in the mainstream press, as the delicious-in-hindsight tweet by Andy Revkin reflects. He’s widely acclaimed for popularizing science concepts for mainstream reading audiences. So whatever Ridley had must be good, I thought. His arguments would reflect the best of the “skeptics'” best.

It turned out I was wrong. Or perhaps, I was right, and Ridley was bringing the best of the “skeptics'” best. Either way, it was an enormous disappointment. Ridley’s speech turned out to be a textbook Gish Gallop, full of false claims, logical fallacies, and trivially true but irrelevant “facts”. It was, as I put it at Keith Kloor’s blog, “skeptic” bingo.

  • Sea level rise is small and is decelerating!
  • Methane isn’t increasing!
  • Hockey Stick!
  • Etc.

I don’t think I will do a point by point rebuttal to every claim in Ridely’s speech at this time (maybe later, for sport, time permitting). But suffice it to say that while Ridley is being lauded by the denialosphere now, he’s actually done them a tremendous disservice. With this speech, he’s fully exposing himself as a crank, and has thus reduced the ever-dwindling list of “credible skeptics” one further.

And in case anyone is curious, while the year-to-year variability is significant,  on climate-relevant timescales, sea level rise is indeed accelerating (Church and White 2011; Rahmstorf and Vermeer 2011).

But more to the point, absent emissions stabilization, sea level rise is going to increase, reaching 1m or more by end of century (Vermeer and Rahmstorf 2009).

Failure to stabilize emissions will almost assuredly result in the eventual collapse of the Greenland and Antarctic ice sheets, committing the world to multimeter sea level rise that will be for all practical purposes irreversible. Many of Ridley’s claims similarly depend on falsely equivocating between concern over future climate changes absent emissions stabilization (and their relative irreversibility over human timescales) and what is happening at present. This couldn’t be more misleading.

As you might imagine, given the way this is going, Ridley’s claim that methane isn’t increasing is also false. Methane levels today are much higher than they’ve been over at least the past 800,000 years and continue to increase (Loulergue et al., 2008; NOAA AGGI).

The “hockey stick” nonsense has been done to death. And “skeptics” like Ridley inevitably fail to mention the main points: the “hockey stick” has basically nothing to do with either the attribution of recent warming to humans or the seriousness of future warming; the ostensible statistical problems in the original Mann et al. paper were overstated by its critics, and the actual problems it did have don’t tremendously affect its results (Huybers 2005; Wahl and Amman 2007); moreover, independent Northern Hemisphere reconstructions (including “skeptics'” own) show more or less the same results as Mann et al.’s recent work- the warming during the instrumental record exceeds peak Medieval temperatures (Ljunqvist 2010; Loehle and McCulloch 2008; Mann et al., 2008; Moberg, et al., 2005).

People like Ridley spend an awful lot of time listening to “skeptic” bloggers like Jo Nova and Bishop Hill, but seem to have no grasp of basic Earth systems science. And it shows. There is a total lack of coherence in Ridley’s claims. Ridley wants us to know that the climate changed rapidly in the past- but yet we’re also supposed to believe that climate sensitivity is very small. He also flubs basic concepts- equilibrium sensitivity is not the same thing as transient sensitivity (i.e. how much we will warm in response to a given increase in radiative forcing is larger than how much warming we’ll experience in the near term due to things like the thermal inertia of the ocean).

Perhaps Ridley can follow his own advice and “unlearn” the lies, fallacies, and nonsense he’s being cheered for regurgitating. Though let’s just say I’m a little skeptical of the prospect.

References:

  • Church, J.A., and N.J. White (2011): Sea-Level Rise from the Late 19th to the Early 21st Century. Surveys In Geophysics, 32, 4-5, 585-602, doi:10.1007/s10712-011-9119-1.
  • Huybers, P. (2005): Comment on “Hockey sticks, principal components, and spurious significance” by S. McIntyre and R. McKitrick. Geophysical Research Letters, 32, L20705, doi:10.1029/2005GL023395.Ljungqvist, F.C. (2010): A new reconstruction of temperature variability in the extra-tropical northern hemisphere during the last two millennia. Geografiska Annaler: Series A, 92, 3, 339-351, doi:10.1111/j.1468-0459.2010.00399.x.
  • Loehle, C. and J.H. McCulloch (2008): Correction to: A 2000-Year Global Temperature Reconstruction Based on Non-Tree Ring Proxies. Energy + Environment, 19, 1, 93-100.
  • Loulergue, L., et al. (2008): Orbital and millennial-scale features of atmospheric CH4 over the past 800,000 years. Nature, 453, 383-386, doi:10.1038/nature06950.
  • Mann, M.E., et al. (2008): Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia. Proceedings of the National Academy of Sciences (USA), 105, 36, 13252-13257, doi:10.1073/pnas.0805721105.
  • Moberg, A., et al. (2005): Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data. Nature, 433, 613-617, doi:10.1038/nature03265.
  • NOAA AGGI: The NOAA Annual Greenhouse Gas Index. URL: http://www.esrl.noaa.gov/gmd/aggi/
  • Rahmstorf, S., and M. Vermmer (2011): Discussion of: “Houston, J.R. and Dean, R.G., 2011. Sea-Level Acceleration Based on U.S. Tide Gauges and Extensions of Previous Global-Gauge Analyses”. Journal of Coastal Research, 27, 4, 784–787, doi:10.2112/JCOASTRES-D-11-00082.1.
  • Vermeer, M., and S. Rahmstorf (2009): Global sea level linked to global temperature. Proceedings of the National Academy of Sciences (USA), 106, 51, 21527-21532, doi:10.1073/pnas.0907765106.
  • Wahl, E.R., and C.M. Ammann (2007): Robustness of the Mann, Bradley, Hughes reconstruction of surface temperatures: Examination of criticisms based on the nature and processing of proxy climate evidence. Climatic Change, 85, 33-69, doi:10.1007/s10584-006-9105-7.

Greenland and Antarctic ice sheet decay update

Image courtesy of Flickr user christine zenino (chrissy575)

[See previous posts here and here. I’ve been meaning to do a follow up for over a year. Has it been that long?]

First, a question in the comments a little more than a little while ago regarding an alleged contradiction between recent studies on increasing Antarctic ice sheet loss and a paper (Tedesco 2009) on recent reduction in Antarctic snowmelt (i.e. presumably, “if there’s less melting, surely there can’t be more ice loss”). This is a non sequitur- snowmelt extent and ice sheet mass balance being two distinct phenomena- although it’s easy to see why it sounds plausible at first blush. Of course it doesn’t help that the denialosphere confused the issue by falsely claiming a reduction in “ice melt” rather than snowmelt index. (Whether they do this stuff out of  a deliberate desire to mislead people or sheer incompetence, the end result is the same and both are indefensible.)

As I wrote then, the snowmelt index is defined as the number of days multiplied by the extent of surface melt (duration times area) rather than an actual “amount” (either volume or mass) of melting ice (Zwally 1994). In other words, there is no inherent contradiction between greater ice sheet decay and reduced surface snowmelt. Furthermore, rather than exculpate anthropogenic influence on Antarctica as the denialists suggest, the decreased snowmelt might actually be being driven at least in part by human activities. Tedesco and Monaghan finger couplings between positive summertime phases of the SAM with positive ENSOs. And of course anthropogenic ozone depletion and greenhouse gas emissions are suspected to at least partially contribute to the increasingly positive SAM (Arblaster 2006). And of course, we know that that the Antarctic ice sheet loss is accelerating, because we can measure it happening.

But wait! Didn’t a study (Bevis 2009) just show that ice sheet decay as measured by GRACE was exaggerated, contradicting GRACE findings of accelerating ice sheet decay? “Yes!” cried the denialosphere. “Not so fast,” warn the literate. 

The Bevis, et al. study was concerned with long term bias in GRACE measurements (due to underestimates of post-glacial rebound), which aren’t that significant on the timescales discussed in papers like Velicogna 2009.  Bevis et al. note:

any sudden increase in the rate of ice loss will be resolved unambiguously by GRACE since the mass rates associated with PGR [post-glacial rebound] do not change significantly over several years.

In other words, even if the GRACE data were systematically biased, such a bias would be relatively constant on short timescales and not meaningfully contribute to/contaminate measurements of large changes happening over interannual periods, especially changes in the rate of loss. So while the total amount of ice lost may be revised downward, the acceleration in recent/current decay is very much real.

And it’s not as though the GRACE data are the only method of establishing accelerating ice loss. In a recent paper in Science, van den Broeke 2009 calculate GrIS loss using a “mass budget method, which quantifies the individual components of ice sheet mass balance [surface mass balance (SMB) and ice discharge (D)”:

For SMB, we used the monthly output of a 51-year climate simulation (1958–2008) with the Regional Atmospheric Climate Model (RACMO2/GR) at high horizontal resolution (~11 km)… The modeled SMB from RACMO2/GR agrees very well with in situ observations [N = 265, correlation coefficient (r) = 0.95], without need for post-calibration . For D, we used ice flux data from 38 glacier drainage basins, covering 90% of the ice sheet… corrected for SMB between flux gate and grounding line and updated to include 2008

Van den Broeke, et al. compare their modeled/in situ data with GRACE, and found good agreement between the two:

The temporal evolution of the cumulative SMB-D anomaly was evaluated using monthly GRACE mass changes. The spatial distribution of GrIS mass changes was compared to a regionally distributed GRACE solution, updated to include 2008… The high correlation (r = 0.99) between the two fully independent time series and the similarity in trends support the consistency of the mass balance reconstruction. A linear regression on the SMB-D time series yields a 2003– 2008 GrIS mass loss rate of –237 ± 20 Gt year^−1.

Cumulative SMB-D anomaly (2003–2008) and comparison with GRACE data. Short horizontal lines indicate GRACE uncertainty, dashed lines the linear trends. GRACE values are not absolute numbers, and the curve has been vertically shifted for clarity. The scatter plot in the inset shows a direct linear regression between the monthly GRACE values as a function of the cumulative SMB-D anomaly, together with the linear regression coefficients. (van den Broeke 2009)

Recently, Rignot 2011 combined van den Broeke’s SMB-D method (which they call “mass budget method” or MBM) with GRACE data to reconstruct changes in GrIS and Antarctic mass balance over two decades, from 1992-2009.

Greenland

Initial concerns over accelerating Greenland ice loss arose when dramatic loss was recorded in the early to mid-2000s. However, this regional melting appeared to taper off around 2005, which lead to predictable crowing from climate contrarians who sought to portray this change as a reason to stop worrying about Greenland ice sheet decay.

Pritchard 2009 noted, however, that the extent of dynamic melt was more widespread than has been previously assessed- especially in the northwest- and has penetrated in some areas more than 100km inland and to altitudes as high as 2000m. 81 out of 111 Greenland glaciers surveyed showed melt rates more than twice as fast as nearby flowing ice.

Additional research- using data from GPS in addition to GRACE-  further supported this overall behavior, noting melt had again accelerated in some areas around 2005, especially in the northwest (Kahn 2010).

Rignot, et al. have confirmed that the long term trend for the GrIS is not just one of melt, but one of accelerating mass balance loss:

Total ice sheet mass balance, dM/dt, between 1992 and 2009 for Greenland, in Gt/yr from the Mass Budget Method (MBM) (solid black circle) and GRACE time-variable gravity (solid red triangle), with associated error bars. The acceleration rate in ice sheet mass balance, in gigatons per year squared, is determined from a linear fit of MBM over 18 yr (black line) and GRACE over 8 yr (red line). (Rignot 2011)

Rignot, et al.:

The mass losses estimated from MBM and GRACE are within ± 20 Gt/yr, or within their respective errors of ± 51 Gt/yr and ± 33 Gt/yr. The acceleration in mass loss is 19.3 ± 4 Gt/yr^2 for MBM [ed: 21.9 ± 1 Gt/yr^2 over 1992-2009] and 17.0 ± 8 Gt/yr^2 for GRACE. The GRACE-derived acceleration is independent of the GIA reconstruction, a constant signal during the observational period.

That last part is consistent with the earlier discussion of Bevis 2009- an adjustment to total mass balance loss numbers in GRACE due to glacial isostatic adjustment does not contradict the reality that Greenland is melting, and it’s melting at an accelerating pace.

Antarctica

Once upon a time, discussion of significant melting of Antarctic ice was restricted to the West Antarctic Ice Sheet (WAIS). The East Antarctic Ice Sheet (EAIS) was believed to be much more stable, and in much less danger of melting. A sense of complacency regarding the state of EAIS melt might be furthered in the public’s perception due to conflicting estimates of surface warming in that region. Ice sheet decay in Antarctica is not driven primarily by surface warming, however, and the Southern Ocean is warming significantly. And indeed, recent analysis of GRACE data has shown that the EAIS- long thought to be the more “safe” (e.g. less affected by warming) of the two Antarctic ice sheets- has been shown to be melting as well. (Chen 2009).

Additionally, concerns over Antarctic contribution to sea level rise have increasingly focused on the  Pine Island Glacier- e.g., according to Wiki, “The Pine Island and Thwaites Glaciers are two of Antarctica’s five largest ice streams. Scientists have found that the flow of these ice streams has accelerated in recent years, and suggested that if they were to melt, global sea levels would rise by 0.9–1.9 m (1–2 yards), destabilizing the entire West Antarctic Ice Sheet and perhaps sections of the East Antarctic Ice Sheet.”

Recent modeling results have suggested that Pine Island Glacier might already have crossed a threshold of stability (Katz 2010):

[O]ur results suggest that, in contrast to earlier assessments, the scenario of unstable grounding-line recession on retrograde beds in West Antarctica is likely. Indeed, in the case of the Pine Island glacier, it may be presently occurring.

Some had hoped that an increase in precipitation over Antarctica could result in an off-setting increase in surface mass balance. Unfortunately, Rignot, et al. note:

In Antarctica, Pine Island Glacier accelerated exponentially over the last 30 years: 0.8% in the 1980s, 2.4% in the 1990s, 6% in 2006 and 16% in 2007-2008 (Rignot, 2008), and quadrupled its thinning rate in 1992-2008 (Wingham et al., 2009). Simple model projections predict a tripling in glacier speed once the grounding line retreats to a deeper and smoother bed (Thomas et al., 2003). Dynamic losses are therefore likely to persist and spread farther inland in this critical sector. A small positive increase in Antarctic SMB could offset these coastal losses, but this effect has not yet been observed.

For the Antarctic continent as a whole, Rignot, et al. find:

an acceleration in mass loss from the GRACE data of 13.2 ± 10 Gt/yr^2…  [and for] the same time period, the acceleration in mass loss from the MBM data is 15.1 ± 12 Gt/yr^2 [ed: and 14.5 ± 2 Gt/yr^2 over 1992-2009].

Total ice sheet mass balance, dM/dt, between 1992 and 2009 for Antarctica, in Gt/yr from the Mass Budget Method (MBM) (solid black circle) and GRACE time-variable gravity (solid red triangle), with associated error bars. The acceleration rate in ice sheet mass balance, in gigatons per year squared, is determined from a linear fit of MBM over 18 yr (black line) and GRACE over 8 yr (red line). (Rignot 2011)

OVERALL

The take home message from Rignot, et al. is stark.

When we use the extended time period 1992-2009, the significance of the trend improves considerably. The MBM record indicates an acceleration in mass loss of 21.9 ± 1 Gt/yr^2 for Greenland and 14.5 ± 2 Gt/yr^2 for Antarctica…  When the mass changes from both ice sheets are combined together…, the data reveal an increase in ice sheet mass loss of 36.3 ± 2 Gt/yr^2.

Total ice sheet mass balance, dM/dt, between 1992 and 2009 for the sum of Greenland and Antarctica, in Gt/yr from the Mass Budget Method (MBM) (solid black circle), with associated error bars. The acceleration rate in ice sheet mass balance, in gigatons per year squared, is determined from a linear fit of MBM over 18 yr (black line). (Rignot 2011)

Greenland and Antarctica are melting. Moreover, they’re melting at an accelerating rate. This is not an artifact of instrumental bias in GRACE, or due to an insufficiently short time period.

Rignot, et al. conclude:

This study reconciles two totally independent methods for estimating ice sheet mass balance, in Greenland and Antarctica, for the first time: the MBM method comparing influx and outflux of ice, and the GRACE method based on time-variable gravity data. The two records agree in terms of mass, M(t), mass change, dM(t)/dt, and acceleration in mass change, d2M/dt2. The results illustrate the major impact of monthly-to-annual variations in SMB on ice sheet mass balance. Using the two-decade long MBM observation record, we determine that ice sheet loss is accelerating by 36.3 2 Gt/yr2, or 3 times larger than from mountain glaciers and ice caps (GIC). The magnitude of the acceleration suggests that ice sheets will be the dominant contributors to sea level rise in forthcoming decades, and will likely exceed the IPCC projections for the contribution of ice sheets to sea level rise in the 21st century.

This last finding will come as no surprise to those who know that the IPCC AR4 sea level rise estimates didn’t account for nonlinear ice sheet decay, but rather assumed a contribution from Greenland and Antarctica at the observed linear rate from 1993-2003. Using semi-empirical methods (that still don’t explicitly account for catastrophic ice sheet collapse) provides an additional line of evidence for accelerating ice sheet contribution to SLR (e.g. Vermeer 2009).

Projection of sea-level rise from 1990 to 2100, based on IPCC temperature projections for three different emission. The sea-level range projected in the IPCC AR4 for these scenarios is shown for comparison in the bars on the bottom right. Also shown is the observations-based annual global sea-level data (red) including artificial reservoir correction. (Vermeer 2009)

References:

  • Arblaster, J.M. and G.A. Meehl (2006): Contributions of External Forcings to Southern Annular Mode Trends. Journal of Climate, 19, 12, 2896-2905, doi:10.1175/JCLI3774.1
  • Bevis, M., et al. (2009): Geodetic measurements of vertical crustal velocity in West Antarctica and the implications for ice mass balance. Geochemistry, Geophysics, Geosystems, 10, Q10005, doi:10.1029/2009GC002642.
  • Chen, J.L., et al. (2009): Accelerated Antarctic ice loss from satellite gravity measurements. Nature Geoscience, 2, 859 – 862, doi:10.1038/ngeo694.
  • Katz, F.A. and M.G. Worster (2010): Stability of ice-sheet grounding lines. Proceedings of the Royal Society: A, 466, 1597–1620, doi:10.1098/rspa.2009.0434.
  • Khan, S. A., et al. (2010): Spread of ice mass loss into northwest Greenland observed by GRACE and GPS. Geophysical Research Letters, 37, L06501, doi:10.1029/2010GL042460.
  • Rignot, E., et al. (2011): Acceleration of the contribution of the Greenland and Antarctic Ice Sheets to sea level rise. Geophysical Research Letters, in press, doi:10.1029/2011GL046583.
  • Tedesco, M., and A. J. Monaghan (2009): An updated Antarctic melt record through 2009 and its linkages to high-latitude and tropical climate variability. Geophysical Research Letters, 36, L18502, doi:10.1029/2009GL039186.
  • van den Broeke, M., et al. (2009): Partitioning Recent Greenland Mass Loss. Science, 326, 5955, 984-986, doi:10.1126/science.1178176.
  • Velicogna, I. (2009): Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets revealed by GRACE. Geophysical Research Letters, 36, L19503, doi:10.1029/2009GL040222.
  • Vermeer, M., and S. Rahmstorf (2009): Global sea level linked to global temperature. Proceedings of the National Academies of Science (USA), 106, 51, 21527-21532, doi:10.1073/pnas.0907765106.
  • Zwally, H.J., and S. Fiegles (1994): Extent and duration of Antarctic surface melting. Journal of Glaciology, 40, 136, 463-476.

A test for establishment climate journalists

Image courtesy of Flickr user just.Luc

Over at Keith Kloor’s blog, I wrote:

Keith, respectfully- either you can acknowledge that [Bjorn Lomborg] engages in blatant misrepresentation of key indicators of climate change like [sea level rise] and [temperature] trends, or you cannot.

If you can’t, I’m not particularly interested in whether it’s a refusal to do so due to adherence to some imagined journalistic allegiance to neutrality or out of a lack of ability to understand that he’s doing it.

If climate journalists either can’t see what he’s doing or refuse to acknowledge it, then we’re in far worse trouble than I ever imagined.

I’ve submitted a similar question to Dot Earth. Can establishment climate journalists acknowledge what Lomborg does? If not, what hope is there that the general public can make an informed assessment of his credibility?

Untold gallons of figurative ink have been spilled over the efforts of climate “skeptics” to discredit Michael Mann and colleagues’ paleoclimatic reconstructions on the grounds of bad statistics. Republicans even went so far as to get “statistics expert” Ed Wegman to put an official seal on the supposed discrediting, and we can see how that’s all working out for them. Meanwhile, the overall conclusions of the Mann et al. papers have been upheld by independent reviews, other multiproxy reconstructions, and independent lines of paleoclimatic evidence, even though some of Mann’s initial statistical choices could have been better.

By contrast Lomborg takes a metric like temperature or sea level rise and then cherry-picks an interval to get the lowest possible trend out of it. If it’s an interval of two years at the time of press, so be it. If he needs to write another article and using the same interval no longer gives the lowest possible trend, he’ll use four. It’s inarguable that using his own intervals from previous claims completely contradicts his current ones, and that there is no physical, statistical, or logical justification for doing so. He is just cherry-picking. Period.

But you’d never know it reading Andy Revkin’s or Keith Kloor’s blogs. Why not? What good is climate journalism if it must slavishly attend to largely unfounded claims of “skeptics” but can’t identify clear-cut cases of misrepresentation by people like Bjorn Lomborg?

“Cool It” yourselves

Since it looks like it’s going to be wall-to-wall Lomborg in the press for a while, it’s probably worth reviewing why he is not only not taken seriously by many people actually concerned about climate change, but why a great many people actively dislike him. It’s not that he proposes “alternatives” to mitigation efforts like cap-and-trade, although he would certainly love for people to believe that.

It’s because he presents himself as someone credible, someone who isn’t a climate denialist- i.e. he proclaims to accept the reality of anthropogenic warming and to consider it a serious threat. But as anyone who has dealt with denialism knows, few if any people in the grips of denialism actually consider themselves to be denialists. There are plenty of “intelligent design” proponents who claim not to reject biology but rather believe that key aspects of evolution are overstated (e.g. irreducible complexity). Many anti-vax denialists claim to support vaccines but only want to “make them safer/greener”.

It’s not so much what someone professes to believe that determines whether or not they’re engaging in denialism, but the way they misrepresent evidence.

And Lomborg has quite a history of doing just that. Let’s take a look at just three such cases:

On polar bears:

Lomborg has frequently and grossly misrepresented scientific data and literature on polar bears and other aspects of climate change.

He has claimed that the Arctic Climate Impact Assessment says polar bears have nothing to worry about, they’ll just devolve into brown bears:

The Arctic Climate Impact Assessment finds it likely that disappearing ice will make polar bears take up “a terrestrial summer lifestyle similar to that of brown bears, from which they evolved.”

The implication is that polar bears aren’t actually threatened by (anthropogenic warming-induced) sea ice decline, because they can just go back to acting like brown bears and everything will be fine. It sounds ludicrous, so much so that an an interviewer for Salon.com asked Lomborg if that is actually what he was claiming. Lomborg made it crystal clear that it was, and that it was his genuine understanding of the Impact Assessment report:

Salon: Are you saying that polar bears will be OK, that the species will survive if they evolve backward?

Lomborg: Yes, that’s certainly how I read it.

But the Impact Assessment said no such thing. Sea ice decline presents a dire, possibly fatal threat to polar bears. In a summer ice-free Arctic, there is no “okay” scenario. Polar bears face demise or might eke out a grim survival among threats from other species of bears and humans. The Impact Assessment states:

It is difficult to envisage the survival of polar bears as a species given a zero summer sea-ice scenario. Their only option would be a terrestrial summer lifestyle similar to that of brown bears, from which they evolved. In such a case, competition, risk of hybridization with brown bears and grizzly bears, and increased interactions with people would then number among the threats to polar bears.

Far from representing a scenario in which polar bears are “okay” living like brown bears, the Impact Assessment presented it as a last hope, fraught with major threats of its own.

In good company with many other climate denialists, Lomborg has also tried to give the impression that polar bears aren’t really in danger from anthropogenic warming because their populations are increasing, not decreasing.

He does by citing historic population levels at 5,000 in the 1960s and present numbers at 25,000. He conveniently omits population estimates that put historic numbers at 18,000-20,000 and the present numbers as low as 20,000. In other words, given the spread of the estimates, it’s possible to cherry-pick numbers that give you anything from no increase whatsoever, to a modest increase, to a monstrous increase of 20,000 bears. Lomborg chooses the latter, without justification for doing so or informing his audience of the full range of estimates.

But suppose we ignore this blatant cherry picking. According to Lomborg’s numbers, had polar bears been recovering from a low brought about by unregulated hunting? Yes. Does this recovery mean that they aren’t threatened by global warming? No.

Or, characterized this way by UCN/SSC Polar Bear Specialist Group Chair, Andrew Derocher:

The various presentations of biased reporting ignore, or are ignorant of, the different reasons for changes in populations. If I thought that there were more bears now than 50 years ago and a reasonable basis to assume this would not change, then no worries. This is not the case.

The bottom line here is that it is an apples and oranges issue. The early estimates of polar bear abundance are a guess. There is no data at all for the 1950-60s. Nothing but guesses. We are sure the populations were being negatively affected by excess harvest (e.g., aircraft hunting, ship hunting,self-killing guns, traps, and no harvest limits). The harvest levels were huge and growing. The resulting low numbers of bears were due only to excess harvest but, again, it was simply a guess as to the number of bears….

Comparing declines caused by harvest followed by recovery from harvest controls to declines from loss of habitat and climate warming are apples and oranges. Ignorant people write ignorant things.

Derocher is saying that such claims (even granting their numbers) are at heart a combination of two forms of fallacious reasoning, the cherry pick (polar bear populations are increasing during a certain interval) and the non sequitur (therefore they are not threatened by anthropogenic warming). The claim that polar bear populations are rising only holds true because the period is selected to begin at a low point brought about by unregulated hunting. Once hunting restrictions were put in place, populations had begun returning to their historic norms.

However, that does not mean that polar bear populations are increasing across the board. The IUCN Polar Bear Specialist Group found in 2005 (well before the 2007 publication of “Cool It!”) that of the 19 polar bear subpopulations, only 2 were increasing, while 5 were flat and 5 more were actually in decline (there were insufficient data for the remaining 7). Relative to their historic levels, only 6 subpopulations were believed to be “not reduced” while 6 were “reduced” or “severely reduced” (there were insufficient data for the remaining 7).

(In case anyone is curious, in 2009 the IUCN Polar Bear Specialist Group found that only “1 of 19 subpopulations is currently increasing” while “3 are stable and 8 are declining” with insufficient data for the remaining 7.)

Lomborg does not appear to have corrected or retracted his claims.

[Edited to add: this of course doesn’t even get into the discrepancies between Lomborg’s “don’t worry” attitude and the scientific literature on projected polar bear population trends as sea ice declines. I may add that in later.]

On sea level rise:

Lomborg also has a nasty habit of claiming that sea level isn’t rising as fast (or at all!) as mainstream climate science believes. To do so, he picks whichever start and end points he can to get the smallest trend in sea level rise.

Writing in the Guardian in March 2009, Stefan Rahmstorf exposed Lomborg’s cherry-picking as the dishonest misrepresentation that it was:

Why does Lomborg cite the trend [2005-2008 1.6mm/year]? Last October, he cited that of the previous two years. Why now four years? Because the trend of the past two years (2007-2008) is now + 3.7 mm/year? It is even worse. The trend since the beginning of any year of the data series varies between 1.6 mm/year and 9.0 mm/year, depending on the start year chosen. Using 2005, Lomborg cherry-picked the by far lowest.

Sound familiar? This kind of dishonesty is all the more reprehensible because Lomborg is (was?) an associate professor of statistics! This isn’t the naive error of someone acting in good faith, it’s entirely, despicably deliberate.

On Global Temperatures:

In much the same way that Lomborg is fond of misrepresenting polar population dynamics and sea level rise, he also enjoys misleading the public about global warming’s most well-known symptom: rising temperatures. It’s occasionally claimed that while there is political disagreement about what to do about global warming, no credible scientist or policy wonk actually doubts that the planet is warming. Judging by surveys of scientists and statements by various governmental organizations, that’s probably broadly true.

And then, there’s Lomborg:

It is hard to keep up the climate panic as reality diverges from the alarmist predictions more than ever before: the global temperature has not risen over the past ten years, it has declined precipitously in the last year and a half, and studies show that it might not rise again before the middle of the next decade.

This was Lomborg writing about cooling back in 2008, as we were experiencing a fairly strong La Niña. Cooling! No warming since 1998! Claims at home in the comments section of the most ignorant and paranoid of climate denialist blogs (or George Will columns).

Most people relatively conversant with major features of the climate system, let alone “climate experts” holding international conferences and writing books on the subject, are aware that La Niñas don’t equal global cooling. In case there was some confusion about the La Niña and the appearance of a lack of warming among the general public, climate institutions like Met Hadley and others had handy pages explaining that, no we weren’t cooling several months prior to Lomborg’s claim.

Lomborg (like other denialists) was simply taking one slice of time (1998-2008) out of a much larger data set- without any attempt at justification- to get the results he wanted- results in complete opposition to what a serious examination of the data would show, requiring an ignorance of basic physics, meteorology, and statistics to believe.

A Question for Journalists:

What is it about Lomborg that allows you to engage in collective amnesia about his dishonesty? Have you forgotten that people like Kåre Fog and Howard Friel (not to mention the blogosphere) have exposed him for what he is?

Videobreak: Rob Dunbar – The threat of ocean acidification

Tom Fuller’s climate misdirection at WattsUpWithThat, Part II

Previously, Tom Fuller demonstrated why he isn’t a serious journalist by making a fool of himself on the issue of polar bears.Today, Fuller mixes it up with a little sea level rise (SLR) malarkey. I do love the little “Reality Wikipedia has a liberal climate alarmist bias” preface:

Wikipedia, which doesn’t always play fair when climate issues are discussed, has the chart everyone needs to see to provide perspective on sea level rise. Titled ‘Post Glacial Sea Level Rise, it shows a dramatic rise in sea levels that stopped dead 6,000 years ago and a very flat line since. You could balance a glass of water on the last 6,000 years of that graph.

So what? This means nothing without looking at the drivers of SLR over the same period. Assuming the best of Fuller and choosing to believe that he isn’t trying to be deliberately misleading, this is just a shocking demonstration of laziness or ignorance. SLR doesn’t just magically happen. The clear implication of Fuller’s reference in light of the rest of the post is: “SLR has basically flatlined since we melted out of the Last Glacial Maximum- what’s the big deal?” Of course, the big deal is that radiative forcing isn’t (and certainly won’t in the near future be) flat enough to “balance a glass of water on”. There is no reason to expect SLR to be either.

This hasn’t stopped the marketing gurus from trying to play to our ancestral horror stories and modern fears of flooding. Because there’s still enough ice left in Antarctica and Greenland to cause dramatic sea level rises, all they have to do is say that global warming will melt that ice and we’re in trouble. And so they do.

Fuller would have us believe that there is no actual basis for concern that the WAIS and GrIS could contribute to dramatic sea level rise. Any such claims are “hype” and not science:

Again, we are forced to separate the hype from the science. Remember that the IPCC projects sea level rise this century of 18-59 cm, unless dramatic loss of Greenland and/or Antarctic ice occurs. That’s from their AR4 report.

This isn’t actually what the AR4 says, though it’s not as screamingly wrong as some of Fuller’s other claims. The 18-59 cm range excludes any contribution from the GrIS and WAIS above the observed rate during 1993-2003. It doesn’t even assume a linear increase in their contribution alongside temperature increase- something that would increase the upper bound to 0.8m all by itself.

From the minute that AR4 was published, a string of papers, conferences, publicity events (such as parliamentary cabinet meetings held underwater) have been screaming from the headlines and news reports, drumming into us the message that dramatic loss of Greenland and/or Antarctic ice will in fact occur.

The audacity of researchers to continue working after the AR4! How dare they try to reduce the acknowledged uncertainty with regard to SLR by having conferences and publishing papers (a string of them even)? Have they no shame at all? And who do they think they’re fooling saying “that dramatic loss of Greenland and/or Antarctic ice will in fact occur”? Because this wasn’t explicitly included in the AR4 projections, we know that it can’t possibly occur- Q.E.D., no take-backs. Jeez!

Climate theory predicts that increased precipitation in the much larger middle of these ice caps will be in the form of snow, which will turn into ice and counterbalance some, most or all of the melt around the edges.

The “most or all” part is obviously where Fuller gets into trouble. This is a claim that he has made and failed to back up over at Michael Tobis’s, because a comprehensive look at the primary literature refutes it. There is a grain of truth to it, however. It was/is believed that Antarctica would accumulate snow in the interior due to increased precipitation. However, the possibility that Antarctica would still be a net source of SLR was certainly not ruled out. And moreover, the assertion that increased precipitation would result in an offset of “all” ice-sheet-related melt is simply, flatly unfounded.

It would take millenia [sic] to melt it all

Fuller picks up the goalposts of “dramatic loss of Greenland and/or Antarctic ice” and runs with them. Now we’re discussing melting every last bit of ice! My, oh my.

In the real world, nonlinear decay of ice sheets contributing to rapid, multimeter sea level rise on sub-millennial timescales is not only possible, it has already happened. Meltwater Pulse 1A (MWP-1A) is an event that took place ~14.6 thousand years ago involving sea level rise of ~20m in less than 500 years, with several meters of SLR coming from the Northern Hemisphere’s Laurentide Ice Sheet and the remainder from the Antarctic. The paleoclimatic evidence is unambiguous: dynamic ice sheet collapse is not a purely theoretical concern- it can and has happened. We have provisional observational evidence of the mechanisms that make such rapid collapses possible. As such they must be considered in any policy or economic analysis of mitigation. This isn’t environmentalist fearmongering, it’s how CBAs are done.

But even excluding hyper-abrupt events like MWP-1A, concern over 1 meter or more sea level rise is well-justified by the scientific evidence. Using a semiempirical approach to derive the relationship between SLR and temperature change, Vermeer and Rahmstorf find more realistic current (and in turn higher future) values than the IPCC numbers:

Projection of sea-level rise from 1990 to 2100, based on IPCC temperature projections for three different emission scenarios. The sea-level range projected in the IPCC AR4 for these scenarios is shown for comparison in the bars on the bottom right. Also shown is the observations-based annual global sea-level data (red) including artificial reservoir correction.

Fuller continues:

But, in a scenario that many will find sadly familiar, those with a political agenda have grabbed on to some straws, such as the GRACE studies we looked at yesterday, and are busy hyping possible mechanical changes to the ice sheets (which do happen) and are simultaneously trying to blame those mechanical changes on global warming. They hijacked the science and spun it. (It’s not the scientists–not in this case.)

Here Fuller refers to recent GRACE satellite studies showing that not only are the GrIS and WAIS showing net losses of ice, but that these losses are in fact accelerating- exhibiting exactly the kind of behavior that gives you SLR higher than the 18-59cm Fuller “believes in”. Predictably, Fuller doesn’t accept that evidence, despite its agreement with other sources of data, such as ICESat.

(While there has been no shortage of denialist keystrokes spent hyping a recent paper revising the net losses downward due to a revision in isostatic rebound numbers, the existence of the net negative mass balances and acceleration themselves remain unchallenged.)

In short, Fuller ignores the paleoclimatic and observational evidence that tells us that sea level rise under unchecked warming can receive significant contributions from the nonlinear decay of the Greenland and West Antarctic Ice Sheets- and exceed 1m or more- on sub-millennial timescales without either collapsing entirely.

When the evidence is alarming, to the uninformed those describing that evidence sound like alarmists.

On “constructive debate”

Or: My Response to Pielke’s Response – Hopefully NOT the first in a series

Roger Pielke Sr. has responded to a post where I addressed some misleading claims he had made that have been recently featured by the anti-science front group SPPI, courtesy of Marc “Swiftboat” Morano.

There are really two separate issues to address with regards to Pielke’s response: A) whether or not my points are indeed correct; and B) what constitutes in Pielke’s words “constructive debate” about climate.

Assuming that most would prefer to look at issues relating to data, we’ll start there.

Part I

I took issue with claims by Pielke about the behavior of three (for better or worse) popular climate change “metrics”: sea level rise (SLR), Arctic sea ice extent (from here on just “sea ice” for ease of discussion), and ocean heat content (OHC).

SLR- Pielke concedes that sea levels are in fact rising- he could hardly do otherwise. He fails to acknowledge the ludicrousness of his claim- the reality of “rising sea levels” was in fact “NOT TRUE”- based on a comparison of a handful of years, anchoring on a temporary high point. A standard by which sea levels (or temperature, or any other noisy data set with an unambiguous trend) could be claimed to have “stopped” and “started” so many times as to divorce the words completely from their definitions. This entire premise is, as I noted before, a fairly common denialist gambit, and one that inevitably exposes its proponents as clueless- or worse, cynics of a rather inexcusable sort.

[One brief clarification I’d like to make- Pielke complains:

I never stated that sea levels are expected to fall. His statement “(therefore sea levels will fall incredibly in the future)” is incorrectly (deliberately) associated in his text to my statements on sea level rise.

Preserving the hyperlink to an XKCD comic satirizing poor extrapolation. I thought that the comic along with the phrasing “fall incredibly” was enough to convey an appropriate amount of hyperbole so that it was clear I was not quoting Pielke but rather mocking the implication many in his audience and the wider “skeptic” community take from such nonsensical claims. Indeed, I wrote “Presumably Pielke really isn’t so stupid as to believe that sea levels are in fact falling, and knows that 2006 as an outlier would inevitably be surpassed” Obviously some people including Pielke himself have read that parenthetical as being actually attributed to Pielke, which I did not intend. Not being one to let incorrect or even ambiguous comments exist on my site indefinitely *cough* I will make a note in the original post.]

Sea ice- Pielke acknowledges that sea ice extent is currently “well below average”. He (again) fails to acknowledge his deliberate cherry pick of a ridiculously short period, playing (again) on a temporary outlier. Pielke doubles down on his false claims about sea ice by claiming that there has been no decline since 2008 (“The trend since 2008 has been flat”), when in fact the linear trend is negative (I’ve not bothered to test whether or not it is statistically significant- though by Pielke’s apparent criteria (eyeballing?), this is certainly more than enough to claim that the trend from 2008 is actually one of decrease). This is of course all beside the original point- that the sea ice loss was occurring more rapidly than expectations- as evidenced by comparing the actual numbers to AR4 projections, something that is inarguable even momentarily stipulating the absurd period of “since 2008″. Pielke again illustrates the nonsensical frame he uses (after falsely claiming that there has been no decline since 2008), with the comical Newspeak “a further decline could again re-commence”.

OHC- Bear in mind that Pielke’s original claim concerned [emphasis mine]: “warming of the upper ocean since 2003“. Pielke’s defense here comes in two parts: First he attacks my statement that Argo data are problematic [emphasis mine]:

The Argo data since 2005 is recognized as quite robust by ocean scientists, who unlike the writer of the The Ways Things Break weblog,  are working with this data.

I sincerely hope Pielke didn’t strain anything moving those goal posts forward a full two years from 2003 to 2005. His reason for doing should be transparent for those (certainly not me, of course) passing familiar with Argo’s well-documented data problems. For those who might wonder why the quality of Argo data prior to 2005 is sidestepped by Pielke, even though his original criticism defines the period as “since 2003″: AchutaRao 2007; Willis 2008Leuliette 2009; etc. Or perhaps an email from Willis directly to Pielke himself:

The Agro Science Team continues to improve the accuracy of the float pressure data for the entire historical Argo dataset. As it strives to achieve the array-averaged accuracy of 1-2 db that is necessary for estimates of global sea level and ocean heat content, small but significant revisions in estimates based on Argo should be expected, partiularly in the early years of the array prior to 2005.

When I pointed out that if you expand the analysis of OHC from 0-700m to 0-2000m Pielke’s assertion no longer holds, Pielke responds citing a paper by Leuliette [emphasis mine]:

There clearly was not ocean heating during the time period 2005 to 2008, which is when accurate data is available to diagnose ocean heating.

Using data from 0-900m- thus “countering” my claim (that if you consider heat content since 2003 extending to 2000m the “pause” in warming vanishes) by ignoring it completely and once again addressing only the top most ocean from 2005 on. In the interest of moving his goal posts to what he believed was a more defensible position (from 2005), Pielke himself clearly illustrates upper ocean warming since 2003, and in the process cites a paper suggesting previous conclusions based on Argo data during that period may be biased cold. Additionally, Pielke himself acknowledges that the paper I cited is in good agreement with climate model predictions of ocean heat content.

All of which I’ll accept as concession that his claims are unsupportable/self-contradictory.

Rather than gloat that Pielke batted 0/3 on the non-opinion portion of the discussion, I’d like to once again reiterate (from my original post): “The goal here isn’t to say that my short term data are definitive while Pielke, Morano, and SPPI’s are not- but rather to draw attention to the cherry-picked nature of the claims. [After pointing this out, Pielke accuses me of cherry-picking. The irony is undoubtedly lost on him.] If your conclusions are so sensitive to their starting or ending points, or data sets used, etc., then chances are you’re not saying much of import.” Continue reading