Guest post by David Middleton
William D. Nordhaus is an economics professor at Yale University. He recently published this essay in the New York Review of Books…
Why the Global Warming Skeptics Are Wrong
The threat of climate change is an increasingly important environmental issue for the globe. Because the economic questions involved have received relatively little attention, I have been writing a nontechnical book for people who would like to see how market-based approaches could be used to formulate policy on climate change. When I showed an early draft to colleagues, their response was that I had left out the arguments of skeptics about climate change, and I accordingly addressed this at length.
But one of the difficulties I found in examining the views of climate skeptics is that they are scattered widely in blogs, talks, and pamphlets. Then, I saw an opinion piece in The Wall Street Journal of January 27, 2012, by a group of sixteen scientists, entitled “No Need to Panic About Global Warming.” This is useful because it contains many of the standard criticisms in a succinct statement. The basic message of the article is that the globe is not warming, that dissident voices are being suppressed, and that delaying policies to slow climate change for fifty years will have no serious economic or environment consequences.
My response is primarily designed to correct their misleading description of my own research; but it also is directed more broadly at their attempt to discredit scientists and scientific research on climate change.1 I have identified six key issues that are raised in the article, and I provide commentary about their substance and accuracy. They are:
• Is the planet in fact warming?
• Are human influences an important contributor to warming?
• Is carbon dioxide a pollutant?
• Are we seeing a regime of fear for skeptical climate scientists?
• Are the views of mainstream climate scientists driven primarily by the desire for financial gain?
• Is it true that more carbon dioxide and additional warming will be beneficial?
Professor Nordhaus then proceeds to
address his six strawmen answer his own questions.
Is the planet in fact warming?
First off, the “planet” hasn’t warmed. The atmosphere has warmed and cooled throughout the planet’s history. And, apparently, the ability to conjugate verbs is not a prerequisite for Ivy League economics professors. Professor Nordhaus’ answer is that the lower atmosphere (AKA planet) is warming because it did warm from 1978 to 1998…
It is easy to get lost in the tiniest details here. Most people will benefit from stepping back and looking at the record of actual temperature measurements. The figure below shows data from 1880 to 2011 on global mean temperature averaged from three different sources.2 We do not need any complicated statistical analysis to see that temperatures are rising, and furthermore that they are higher in the last decade than they were in earlier decades.3
One of the reasons that drawing conclusions on temperature trends is tricky is that the historical temperature series is highly volatile, as can be seen in the figure. The presence of short-term volatility requires looking at long-term trends.
Yes! By all means, let’s have a look at some long-term trends. Let’s take the long-term trend back to a time when mankind wasn’t burning much fossil fuel…
From Ljungqvist, 2010…
The amplitude of the reconstructed temperature variability on centennial time-scales exceeds 0.6°C. This reconstruction is the first to show a distinct Roman Warm Period c. AD 1-300, reaching up to the 1961-1990 mean temperature level, followed by the Dark Age Cold Period c. AD 300-800. The Medieval Warm Period is seen c. AD 800–1300 and the Little Ice Age is clearly visible c. AD 1300-1900, followed by a rapid temperature increase in the twentieth century. The highest average temperatures in the reconstruction are encountered in the mid to late tenth century and the lowest in the late seventeenth century. Decadal mean temperatures seem to have reached or exceeded the 1961-1990 mean temperature level during substantial parts of the Roman Warm Period and the Medieval Warm Period. The temperature of the last two decades, however, is possibly higher than during any previous time in the past two millennia, although this is only seen in the instrumental temperature data and not in the multi-proxy reconstruction itself.
The proxy reconstruction itself does not show such an unprecedented warming but we must consider that only a few records used in the reconstruction extend into the 1990s. Nevertheless, a very cautious interpretation of the level of warmth since AD 1990 compared to that of the peak warming during the Roman Warm Period and the Medieval Warm Period is strongly suggested.
The amplitude of the temperature variability on multi-decadal to centennial time-scales reconstructed here should presumably be considered to be the minimum of the true variability on those time-scales.
Ljungqvist is recommending caution in comparing the modern instrumental reconstruction to the older proxy reconstructions because the proxy data are of much lower resolution. The proxy data are showing the “minimum of the true variability on those time-scales.” The instrumental data are depicting something closer to actual variability.
Even then, the instrumental record doesn’t exceed the margin of error for the proxy data during the peak of the Medieval Warm Period…
Since someone is bound to chime in with, “But Ljungqvist isn’t a real climate scientist!”… Let’s compare Mann et al., 2008 (EIV) and Ljungqvist, 2010…
Apart from the 20th century hockey stick, they are very similar. Here’s a blow up of the above from 1950 with HadCRUT3 (NH)…
The entire blade of the hockey stick is post-1995.
Now, on to the verb conjugation. The lower atmosphere is not currently warming, irrespective of what it did from 1978-1998, or what it has done since the 1850’s, or what it has done since 1600 AD…
There has been no global warming for more than a decade. To paraphrase Paul Revere, “None if by land”…
“None if by sea”…
All of the anomalous warming occurred between 1995 and 1998. This, amazingly, is what the satellite data indicate…
Are human influences an important contributor to warming?
Maybe. Urban heat islands are “human influences.” Most other land-use changes are “human influences.” Anthropogenic greenhouse gas emissions are “human influences.” Are they important? It all depends on the model.
This model says, “Not very important”…
Although, the authors seem to have concluded that “human influences” related to global cooling were masking the “human influences” related to global warming.
Models are great heuristic tools; but they cannot and should never be used as substitutes for observation and correlation. I can build a valid computer model that tells me that an overpressured Cibicides opima sandstone at depth of 15,000′ should exhibit a Class 3 AVO response. If I drill a Class 3 AVO anomaly in that neighborhood, I will drill a dry hole. A little bit of observation and correlation would quickly tell me that productive overpressured Cibicides opima sandstones at depth of 15,000′ don’t exhibit Class 3 AVO anomalies.
Is carbon dioxide a pollutant?
I thought about answering with a treatise on plant stomata, but this was “easier”…
JPL-Developed Clean Energy Technology Moves ForwardA team of scientists at NASA’s Jet Propulsion Laboratory originally developed this 300-watt engineering prototype of a Direct Methanol Fuel Cell system for defense applications. Image credit: NASA/JPL-Caltech
May 26, 2011
A team of scientists at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., in partnership with the University of Southern California in Los Angeles, developed a Direct Methanol Fuel Cell technology for future Department of Defense and commercial applications. Recently, USC and the California Institute of Technology in Pasadena, which manages JPL for NASA, awarded a license to SFC Energy, Inc., the U.S. affiliate of SFC Energy AG. The non-exclusive license for the technology will facilitate the expansion of the company’s methanol fuel cell products into the U.S. market.
This novel fuel cell technology uses liquid methanol as a fuel to produce electrical energy, and does not require any fuel processing. Pure water and carbon dioxide are the only byproducts of the fuel cell, and no pollutants are emitted.
If NASA and the JPL say carbon dioxide is not a pollutant, that’s good enough for me. The plant stomata treatise will follow along shortly.
Are we seeing a regime of fear for skeptical climate scientists?
“Fear” is probably not the right word. However, this kind of attitude from government officials is somewhat disconcerting…
“When you are in that kind of position, as the CEO of one the primary players who have been putting out misinformation even via organisations that affect what gets into school textbooks, then I think that’s a crime.”
It’s of particular concern when the self-appointed inquisitor takes pride in influencing “the nature of the measurements obtained, so that the key information can be obtained” (AKA “Torturing the data until it confesses”…
It’s also a bit disconcerting when the people who make our laws are threatening skeptics with tobacco-style inquisitions. The recent Fakegate shows that the Warmists are quite willing to engage in fraud in order to bring about such an inquisition. Concerned: yes. Afraid: no.
Are the views of mainstream climate scientists driven primarily by the desire for financial gain?
No, all “mainstream climate scientists” are unpaid volunteers. (/Sarcasm).
Is it true that more carbon dioxide and additional warming will be beneficial?
Yes, Professor Nordhaus, more carbon dioxide and additional warming will be beneficial…
The Little Ice Age was quite possibly the coldest part of the Holocene since the 8.2 KYA Cooling Event…
The climate has oscillated between warming and cooling throughout the Holocene with a period of ~1,000 years, with an underlying secular cooling trend. This millennial-scale cycle is clearly present in the Greenland ice cores…
The millennial-scale cycle is also painfully obvious in non-hockey stick climate reconstructions…
The polynomial trend line simulates a Gaussian filter. It is not intended to be predictive of the magnitude of future climate changes. Its purpose is to highlight the cyclical nature of the climate reconstruction.
If “more carbon dioxide and additional warming” prevent the next “Little Ice Age” from being as cold as the last “Little Ice Age,” it will be very beneficial. If it slows our inevitable transition into the next Quaternary glacial stage by a few hundred years, it will be very beneficial. Although, elevated CO2 levels didn’t make much difference in the Eemian. If CO2 was such a potent forcing mechanism, this shouldn’t be possible…
Sangamonian CO2 levels didn’t start falling (and possibly kept rising) until the cooling into the most recent glaciation had progressed 20,000 years.
The models can’t account for any of the observed cyclicity using only solar forcing. So they assume that CO2 forcing must be about 3-6 times greater than the instrumental data suggest. Funny thing: recent papers have concluded that solar forcing has been underestimated by a factor of six and CO2 forcing is much lower than the so-called consensus estimate.
As promised: A plant stomata treatise!
The so-called consensus will continue overestimating CO2 forcing until they accept the fact that ice core temperature estimates are at least an order of magnitude of higher resolution than ice core CO2 estimates. The ever-growing volume of peer-reviewed research on the relationship between plant stomata and CO2 will eventually force a paradigm shift.
Wagner et al., 1999. Century-Scale Shifts in Early Holocene Atmospheric CO2 Concentration. Science 18 June 1999: Vol. 284 no. 5422 pp. 1971-1973…
In contrast to conventional ice core estimates of 270 to 280 parts per million by volume (ppmv), the stomatal frequency signal suggests that early Holocene carbon dioxide concentrations were well above 300 ppmv.
Most of the Holocene ice core records from Antarctica do not have adequate temporal resolution.
Our results falsify the concept of relatively stabilized Holocene CO2 concentrations of 270 to 280 ppmv until the industrial revolution. SI-based CO2 reconstructions may even suggest that, during the early Holocene, atmospheric CO2 concentrations that were .300 ppmv could have been the rule rather than the exception.
The ice cores cannot resolve CO2 shifts that occur over periods of time shorter than twice the bubble enclosure period. This is basic signal theory. The assertion of a stable pre-industrial 270-280 ppmv is flat-out wrong.
McElwain et al., 2001. Stomatal evidence for a decline in atmospheric CO2 concentration during the Younger Dryas stadial: a comparison with Antarctic ice core records. J. Quaternary Sci., Vol. 17 pp. 21–29. ISSN 0267-8179…
It is possible that a number of the short-term fluctuations recorded using the stomatal methods cannot be detected in ice cores, such as Dome Concordia, with low ice accumulation rates. According to Neftel et al. (1988), CO2 fluctuation with a duration of less than twice the bubble enclosure time (equivalent to approximately 134 calendar yr in the case of Byrd ice and up to 550 calendar yr in Dome Concordia) cannot be detected in the ice or reconstructed by deconvolution.
Not even the highest resolution ice cores, like Law Dome, have adequate resolution to correctly image the MLO instrumental record.
Kouwenberg et al., 2005. Atmospheric CO2 fluctuations during the last millennium reconstructed by stomatal frequency analysis o fTsuga heterophylla needles . Geology; January 2005; v. 33; no. 1; p. 33–36…
The discrepancies between the ice-core and stomatal reconstructions may partially be explained by varying age distributions of the air in the bubbles because of the enclosure time in the firn-ice transition zone. This effect creates a site-specific smoothing of the signal (decades for Dome Summit South [DSS], Law Dome, even more for ice cores at low accumulation sites), as well as a difference in age between the air and surrounding ice, hampering the construction of well-constrained time scales (Trudinger et al., 2003).
Stomatal reconstructions are reproducible over at least the Northern Hemisphere, throughout the Holocene and consistently demonstrate that the pre-industrial natural carbon flux was far more variable than indicated by the ice cores.
Wagner et al., 2004. Reproducibility of Holocene atmospheric CO2 records based on stomatal frequency. Quaternary Science Reviews. 23 (2004) 1947–1954…
The majority of the stomatal frequency-based estimates of CO 2 for the Holocene do not support the widely accepted concept of comparably stable CO2 concentrations throughout the past 11,500 years. To address the critique that these stomatal frequency variations result from local environmental change or methodological insufficiencies, multiple stomatal frequency records were compared for three climatic key periods during the Holocene, namely the Preboreal oscillation, the 8.2 kyr cooling event and the Little Ice Age. The highly comparable fluctuations in the paleo-atmospheric CO2 records, which were obtained from different continents and plant species (deciduous angiosperms as well as conifers) using varying calibration approaches, provide strong evidence for the integrity of leaf-based CO2 quantification.
The Antarctic ice cores lack adequate resolution because the firn densification process acts like a low-pass filter.
Van Hoof et al., 2005. Atmospheric CO2 during the 13th century AD: reconciliation of data from ice core measurements and stomatal frequency analysis. Tellus 57B (2005), 4…
AtmosphericCO2 reconstructions are currently available from direct measurements of air enclosures in Antarctic ice and, alternatively, from stomatal frequency analysis performed on fossil leaves. A period where both methods consistently provide evidence for natural CO2 changes is during the 13th century AD. The results of the two independent methods differ significantly in the amplitude of the estimated CO2 changes (10 ppmv ice versus 34 ppmv stomatal frequency). Here, we compare the stomatal frequency and ice core results by using a firn diffusion model in order to assess the potential influence of smoothing during enclosure on the temporal resolution as well as the amplitude of the CO2 changes. The seemingly large discrepancies between the amplitudes estimated by the contrasting methods diminish when the raw stomatal data are smoothed in an analogous way to the natural smoothing which occurs in the firn.
The derivation of equilibrium climate sensitivity (ECS) to atmospheric CO2 is largely based on Antarctic ice cores. The problem is that the temperature estimates are based on oxygen isotope ratios in the ice itself; while the CO2 estimates are based on gas bubbles trapped in the ice.
The temperature data are of very high resolution. The oxygen isotope ratios are functions of the temperature at the time of snow deposition. The CO2 data are of very low and variable resolution because it takes decades to centuries for the gas bubbles to form. The CO2 values from the ice cores represent average values over many decades to centuries. The temperature values have annual to decadal resolution.
The highest resolution Antarctic ice core is the DE08 core from Law Dome.
The IPCC and so-called scientific consensus assume that it can resolve annual changes in CO2. But it can’t. Each CO2 value represents a roughly 30-yr average and not an annual value.
If you smooth the Mauna Loa instrumental record (red curve) and plant stomata-derived pre-instrumental CO2 (green curve) with a 30-yr filter, they tie into the Law Dome DE08 ice core (light blue curve) quite nicely…
The deeper DSS core (dark blue curve)has a much lower temporal resolution due to its much lower accumulation rate and compaction effects. It is totally useless in resolving century scale shifts, much less decadal shifts.
The IPCC and so-called scientific consensus correctly assume that resolution is dictated by the bubble enclosure period. However, they are incorrect in limiting the bubble enclosure period to the sealing zone. In the case of the core DE08 they assume that they are looking at a signal with a 1 cycle/1 yr frequency, sampled once every 8-10 years. The actual signal has a 1 cycle/30-40 yr frequency, sampled once every 8-10 years.
30-40 ppmv shifts in CO2 over periods less than ~60 years cannot be accurately resolved in the DE08 core. That’s dictated by basic signal theory. Wagner et al., 1999 drew a very hostile response from the so-called scientific consensus. All Dr. Wagner-Cremer did to them, was to falsify one little hypothesis…
In contrast to conventional ice core estimates of 270 to 280 parts per million by volume (ppmv), the stomatal frequency signal suggests that early Holocene carbon dioxide concentrations were well above 300 ppmv.
Our results falsify the concept of relatively stabilized Holocene CO2 concentrations of 270 to 280 ppmv until the industrial revolution. SI-based CO2 reconstructions may even suggest that, during the early Holocene, atmospheric CO2concentrations that were >300 ppmv could have been the rule rather than the exception (23).
I merged the data from six peer-reviewed papers on stomata-derived CO2 to build this Holocene reconstruction…
The plant stomata pretty well prove that Holocene CO2 levels have frequently been in the 300-350 ppmv range and occasionally above 400 ppmv over the last 10,000 years.
The incorrect estimation of a 3°C ECS to CO2 is almost entirely driven the assumption that preindustrial CO2 levels were in the 270-280 ppmv range, as indicated by the Antarctic ice cores.
The plant stomata data clearly show that preindustrial atmospheric CO2 levels were much higher and far more variable than indicated by Antarctic ice cores. Which means that the rise in atmospheric CO2 since the 1800’s is not particularly anomalous and at least half of it is due to oceanic and biosphere responses to the warm-up from the Little Ice Age.
As the Earth’s climate continues to not cooperate with their models, the so-called consensus will eventually recognize and acknowledge their fundamental error. Hopefully we won’t have allowed decarbonization zealotry to bankrupt us beforehand.
Until the paradigm shifts, all estimates of the pre-industrial relationship between atmospheric CO2 and temperature derived from Antarctic ice cores will be wrong… Because the ice core temperature and CO2 time series are of vastly different resolutions. And until the “so-called consensus” gets the signal processing right, Professor Nordhaus will continue to get it wrong.
Alley, R.B. 2000. The Younger Dryas cold interval as viewed from central Greenland. Quaternary Science Reviews 19:213-226.
Davis, J. C. and G. C. Bohling. The search for patterns in ice-core temperature curves. 2001. Geological Perspectives of Global Climate Change, AAPG Studies in Geology No. 47, Gerhard, L.C., W.E. Harrison,and B.M. Hanson.
Finsinger, W. and F. Wagner-Cremer. Stomatal-based inference models for reconstruction of atmospheric CO2 concentration: a method assessment using a calibration and validation approach. The Holocene 19,5 (2009) pp. 757–764
Fischer, H. A Short Primer on Ice Core Science. Climate and Environmental Physics, Physics Institute, University of Bern.
Garcıa-Amorena, I., F. Wagner-Cremer, F. Gomez Manzaneque, T. B. van Hoof, S. Garcıa Alvarez, and H. Visscher. 2008. CO2 radiative forcing during the Holocene Thermal Maximum revealed by stomatal frequency of Iberian oak leaves. Biogeosciences Discussions 5, 3945–3964, 2008.
Jessen, C. A., Rundgren, M., Bjorck, S. and Hammarlund, D. 2005. Abrupt climatic changes and an unstable transition into a late Holocene Thermal Decline: a multiproxy lacustrine record from southern Sweden. J. Quaternary Sci., Vol. 20 pp. 349–362. ISSN 0267-8179.
Kaufmann, R. K., H. Kauppi, M. L. Mann, and J. H. Stock (2011), Reconciling anthropogenic climate change with observed temperature 1998-2008, Proceedings of the National Academy of Sciences, PNAS 2011 : 1102467108v1-4.
Kouwenberg, LLR. 2004. Application of conifer needles in the reconstruction of Holocene CO2 levels. PhD Thesis. Laboratory of Palaeobotany and Palynology, University of Utrecht.
Kouwenberg, LLR, Wagner F, Kurschner WM, Visscher H (2005) Atmospheric CO2 fluctuations during the last millennium reconstructed by stomatal frequency analysis of Tsuga heterophylla needles. Geology 33:33–36
Ljungqvist, F.C.2009. Temperature proxy records covering the last two millennia: a tabular and visual overview. Geografiska Annaler: Physical Geography, Vol. 91A, pp. 11-29.
Ljungqvist, F.C. 2010. A new reconstruction of temperature variability in the extra-tropical Northern Hemisphere during the last two millennia. Geografiska Annaler: Physical Geography, Vol. 92 A(3), pp. 339-351, September 2010. DOI: 10.1111/j.1468-0459.2010.00399.x
Mann, M.E., Z. Zhang, M.K. Hughes, R.S. Bradley, S.K. Miller, S. Rutherford, and F. Ni. 2008. Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia. Proceedings of the National Academy of Sciences, Vol. 105, No. 36, September 9, 2008. doi:10.1073/pnas.0805721105
McElwain et al., 2001. Stomatal evidence for a decline in atmospheric CO2 concentration during the Younger Dryas stadial: a comparison with Antarctic ice core records. J. Quaternary Sci., Vol. 17 pp. 21–29. ISSN 0267-8179
Rundgren et al., 2005. Last interglacial atmospheric CO2 changes from stomatal index data and their relation to climate variations. Global and Planetary Change 49 (2005) 47–62.
Van Hoof et al., 2005. Atmospheric CO2 during the 13th century AD: reconciliation of data from ice core measurements and stomatal frequency analysis. Tellus 57B (2005), 4
Wagner F, et al., 1999. Century-scale shifts in Early Holocene CO2 concentration. Science 284:1971–1973.
Wagner F, Aaby B, Visscher H, 2002. Rapid atmospheric CO2 changes associated with the 8200-years-B.P. cooling event. Proc Natl Acad Sci USA 99:12011–12014.
Wagner F, Kouwenberg LLR, van Hoof TB, Visscher H, 2004. Reproducibility of Holocene atmospheric CO2 records based on stomatal frequency. Quat Sci Rev 23:1947–1954