Well, there is a new paper in press in the Journal of Climate:

Improved methods for PCA-based reconstructions: case study using the Steig et al. 2009 Antarctic temperature reconstruction by Ryan O’Donnell, Nicholas Lewis, Steve McIntyre, Jeff Condon

The abstract states:

A detailed analysis is presented of a recently published Antarctic temperature reconstruction that combines satellite and ground information using a regularized expectation-maximization algorithm. Though the general reconstruction concept has merit, it is susceptible to spurious results for both temperature trends and patterns. The deficiencies include: (a) improper calibration of satellite data; (b) improper determination of spatial structure during infilling; and (c) suboptimal determination of regularization parameters, particularly with respect to satellite principal component retention. We propose two methods to resolve these issues. One utilizes temporal relationships between the satellite and ground data; the other combines ground data with only the spatial component of the satellite data. Both improved methods yield similar results that disagree with the previous method in several aspects. Rather than finding warming concentrated in West Antarctica, we find warming over the period of 1957–2006 to be concentrated in the Peninsula (≈0.35°C decade−1). We also show average trends for the continent, East Antarctica, and West Antarctica that are half or less than that found using the unimproved method. Notably, though we find warming in West Antarctica to be smaller in magnitude, we find that statistically significant warming extends at least as far as Marie Byrd Land. We also find differences in the seasonal patterns of temperature change, with winter and fall showing the largest differences and spring and summer showing negligible differences outside of the Peninsula.

Meanwhile, Ross McKitrick writes:

“NEW PAPER ON CONTAMINATED SURFACE TEMPERATURE DATA: In 2007 I published a paper with Pat Michaels showing evidence that CRU global surface temperature data used by the IPCC are likely contaminated due to socioeconomic development and variations in data quality. In 2009 Gavin Schmidt published a paper in the International Journal of Climatology claiming our results, as well as those of de Laat and Maurellis who independently found the same things we did, were spurious. My rebuttal, coauthored with Nicolas Nierenberg, has been accepted at The Journal of Economic and Social Measurement.

McKitrick, Ross R. and Nicolas Nierenberg (2010) Socioeconomic Patterns in Climate Data. Journal of Economic and Social Measurement, forthcoming.

Data/Code archive here. The paper provides a complete and thorough refutation of Schmidt’s critique. Why JESM? First, because it is a journal that focuses on the critical evaluation of policy-relevant databases, and its editors and reviewers have considerable econometric depth, and this paper is fundamentally an application of econometrics to the evaluation of data quality. Second, we submitted the paper to the IJOC in April 2009, on the assumption that, having published Schmidt’s paper, they were interested in the topic. Evidently their interest only extends to analyses that support IPCC views. After 10 months we found out that IJOC was rejecting our paper on the basis of some inane referee reports to which Nico and I were not given a chance to reply. We did anyway, and if anyone thinks the rejection by IJOC amounts to a knock against our paper, please read our response letter for some perspective. Whether or not the IJOC editors read it, they refused to reconsider our paper. Interestingly, we learned from the Climategate release that Schmidt’s paper, which focuses on defending Phil Jones’ CRU data against its various critics, was sent by the IJOC Editors to be reviewed by Phil Jones of the CRU. As you can imagine his review was shallow and uncritical, but evidently impressed the editors of IJOC. They didn’t ask deLaat or me to supply a review, nor did they invite us to contribute a response. Every interaction I have had over the years with the IJOC has left me very unimpressed.”

Summary of McKitrick & Nierenberg (2010):

To generate a climate data set, temperature data collected at the Earth’s surface must be adjusted to remove non-climatic effects such as urbanization and measurement discontinuities. Some studies have shown that the post-1980 spatial pattern of temperature trends over land in prominent climate data sets is strongly correlated with the spatial pattern of socioeconomic development, implying that the adjustments are inadequate, leaving a residual warm bias. This evidence has been disputed on three grounds: spatial autocorrelation of the temperature field undermines significance of test results; counterfactual experiments using model generated data suggest such correlations have an innocuous interpretation; and different satellite covariates yield unstable results. Somewhat surprisingly, these claims have not been put into a coherent framework for the purpose of statistical testing. We combine economic and climatological data sets from various teams with trend estimates from global climate models and we use spatial regressions to test the competing hypotheses. Overall we find that the evidence for contamination of climatic data is robust across numerous data sets, it is not undermined by controlling for spatial autocorrelation, and the patterns are not explained by climate models. Consequently we conclude that important data products used for the analysis of climate change over global land surfaces may be contaminated with socioeconomic patterns related to urbanization and other socioeconomic processes.

“Only by playing with data can scientists come up with the infamous ‘hockey stick’ graph of global warming.”

Read the excellent summary of the ‘hockey stick’ saga in the National Post: Ross McKitrick: Defects in key climate data are uncovered

1. In a 1995 Nature paper by Briffa, Schweingruber et al., they reported that 1032 was the coldest year of the millennium – right in the middle of the Medieval Warm Period. But the reconstruction depended on 3 short tree ring cores from the Polar Urals whose dating was very problematic. http://www.climateaudit.org/?p=877.

2. In the 1990s, Schweingruber obtained new Polar Urals data with more securely-dated cores for the MWP. Neither Briffa nor Schweingruber published a new Polar Urals chronology using this data. An updated chronology with this data would have yielded a very different picture, namely a warm medieval era and no anomalous 20th century. Rather than using the updated Polar Urals series, Briffa calculated a new chronology from Yamal – one which had an enormous hockey stick shape. After its publication, in virtually every study, Hockey Team members dropped Polar Urals altogether and substituted Briffa’s Yamal series in its place.
http://www.climateaudit.org/?p=528. PS: The exception to this pattern was Esper et al (Science) 2002, which used the combined Polar Urals data. But Esper refused to provide his data. Steve got it in 2006 after extensive quasi-litigation with Science (over 30 email requests and demands).

3. Subsequently, countless studies appeared from the Team that not only used the Yamal data in place of the Polar Urals, but where Yamal had a critical impact on the relative ranking of the 20th century versus the medieval era.
http://www.climateaudit.org/?p=3099

4. Meanwhile Briffa repeatedly refused to release the Yamal measurement data used inhis calculation despite multiple uses of this series at journals that claimed to require data archiving. E.g. http://www.climateaudit.org/?p=542

5. Then one day Briffa et al. published a paper in 2008 using the Yamal series, again without archiving it. However they published in a Phil Tran Royal Soc journal which has strict data sharing rules. Steve got on the case. http://www.climateaudit.org/?p=3266

6. A short time ago, with the help of the journal editors, the data was pried loose and appeared at the CRU web site. http://www.climateaudit.org/?p=7142

7. It turns out that the late 20th century in the Yamal series has only 10 tree ring chronologies after 1990 (5 after 1995), making it too thin a sample to use (according to conventional rules). But the real problem wasn’t that there were only 5-10 late 20th century cores- there must have been a lot more. They were only using a subset of 10 cores as of 1990, but there was no reason to use a small subset. (Had these been randomly selected, this would be a thin sample, but perhaps passable. But it appears that they weren’t randomly selected.)
http://www.climateaudit.org/?p=7142

8. Faced with a sample in the Taymir chronology that likely had 3-4 times as many series as the Yamal chronology, Briffa added in data from other researchers’ samples taken at the Avam site, some 400 km away. He also used data from the Schweingruber sampling program circa 1990, also taken about 400 km from Taymir. Regardless of the merits or otherwise of pooling samples from such disparate locations, this establishes a precedent where Briffa added a Schweingruber site to provide additional samples. This, incidentally, ramped up the hockey-stickness of the (now Avam-) Taymir chronology.
http://www.climateaudit.org/?p=7158

9. Steve thus looked for data from other samples at or near the Yamal site that could have been used to increase the sample size in the Briffa Yamal chronology. He quickly discovered a large set of 34 Schweingruber samples from living trees. Using these instead of the 12 trees in the Briffa (CRU) group that extend to the present yields Figure 2, showing a complete divergence in the 20th century. Thus the Schweingruber data completely contradicts the CRU series. Bear in mind the close collaboration of Schweingruber and Briffa all this time, and their habit of using one another’s data as needed.

10. Combining the CRU and Schweingruber data yields the green line in the 3rd figure above. While it doesn’t go down at the end, neither does it go up, and it yields a medieval era warmer than the present, on the standard interpretation. Thus the key ingredient in a lot of the studies that have been invoked to support the Hockey Stick, namely the Briffa Yamal series (red line above) depends on the influence of a thin subsample of post-1990 chronologies and the exclusion of the (much larger) collection of readily-available Schweingruber data for the same area.

Ross McKitrick commenting on Steve McIntyre’s Climate Audit blog post entitled: ‘Yamal: A “Divergence” Problem’

Recent Warming Reverses Long-Term Arctic Cooling
Darrell S. Kaufman et al, Science 4 September 2009:
Vol. 325. no. 5945, pp. 1236 – 1239
DOI: 10.1126/science.1173983

Abstract: The temperature history of the first millennium C.E. is sparsely documented, especially in the Arctic. We present a synthesis of decadally resolved proxy temperature records from poleward of 60°N covering the past 2000 years, which indicates that a pervasive cooling in progress 2000 years ago continued through the Middle Ages and into the Little Ice Age. A 2000-year transient climate simulation with the Community Climate System Model shows the same temperature sensitivity to changes in insolation as does our proxy reconstruction, supporting the inference that this long-term trend was caused by the steady orbitally driven reduction in summer insolation. The cooling trend was reversed during the 20th century, with four of the five warmest decades of our 2000-year-long reconstruction occurring between 1950 and 2000.

Marc Morano has a nice summary over at Climate Depot:

Not Again! Media Promoting Arctic ‘Hockey Stick’ – Claim Temps Warmest in 2000 Years – But Scientists Already Rebuking Latest Study. Temperature claims ‘contradict numerous previous Arctic studies.’

The study has also amused Steve McIntyre of Climate Audit:

“Amusingly, the [Arctic study's lead author] Kaufman Team perpetuates Mann’s upside down use of the Tiljander proxy,” McIntyre wrote on September 3, 2009. “You can readily see that this closely matches the Mann version,” McIntyre noted. “The most cursory examination [of the study] shows the usual problem of seemingly biased picking of proxies without any attempt to reconcile proxy conflicts,” McIntryre wrote.

Climate Audit: Kaufman and Upside-Down Mann

We present a chironomid-based reconstruction of late-Holocene temperature from Lake Anterne (2060 m a.s.l.) in the northern French Alps. Chironomid assemblages were studied in 49 samples along an 8 m long sediment core covering the last 1800 years. July air temperatures were inferred using an inference model based on the distribution of chironomid assemblages in 100 Swiss lakes. The transfer function has a leave-one-out cross-validated coefficient of determination (r ) of 0.88, a root mean square error of prediction (RMSEP) of 1.40°C. Despite possible biases induced by methodological aspects and the ecological complexity of the chironomid response to both climate and environmental changes, the concordance of the Lake Anterne temperature reconstruction with other Alpine records suggests that the transfer function has successfully reconstructed past summer temperature during the last two millennia. The twentieth century is the only section of the record which shows a poor agreement with other climate reconstructions and the distinct warming found in most instrumental records for this period is not apparent in the Lake Anterne record. Stocking of the lake with fish from the early twentieth century onwards was found to be a possible cause of changes in the chironomid fauna and subsequent distortion in the inferred climate signal. Evidence was found of a cold phase at Lake Anterne between AD 400 and 680, a warm episode between AD 680 and 1350, and another cold phase between AD 1350 and 1900. These events were possibly correlated to the so-called `Dark Age Cold Period’ (DACP), the `Mediaeval Warm Period’ (MWP) and the `Little Ice Age’ (LIA). The chironomid-based inference model reconstructed a July air temperature decrease of c. 0.7°C for the DACP and 1.3°C for the LIA compared with the temperature prevailing during the MWP.

Key Words: Climate reconstruction • late Holocene • July air temperature • chironomids • northern French Alps.

CO2 Science.org’s take on this paper is here:

Background
The authors write that “among biological proxies from lake sediments, chironomid [non-biting midge] assemblages are viewed as one of the most promising climatic indicators,” and that “the accuracy of chironomid assemblages for the reconstruction of Lateglacial temperatures is now broadly demonstrated.”

What was done
Millet et al. (1) “present a new chironomid-based temperature record from Lake Anterne (northern French Alps) covering the past two millennia,” (2) “compare this reconstruction with other late-Holocene temperature records from Central Europe,” and (3) “address the question of whether previously described centennial-scale climate events such as the ‘Medieval Warm Period’ [MWP] or the ‘Little Ice Age’ [LIA] can be detected in this new summer temperature record,” noting that “at a hemispheric or global scale the existence of the LIA and MWP have been questioned.”

What was learned
The six scientists report that “evidence was found of a cold phase at Lake Anterne between AD 400 and 680, a warm episode between AD 680 and 1350, and another cold phase between AD 1350 and 1900,” and they say that these events were “correlated to the so-called ‘Dark Age Cold Period’ (DACP), the ‘Medieval Warm Period’ and the ‘Little Ice Age’.” In addition, they say that “many other climate reconstructions across western Europe confirm the existence of several significant climatic changes during the last 1800 years in Central Europe and more specifically the DACP, the MWP and the LIA.” Last of all, they report that the reconstructed temperatures of the 20th century failed to show a return to MWP levels of warmth, which failure they attributed to a breakdown of the chironomid-temperature relationship over the final century of their 1800-year history.

What it means
Ever more evidence continues to indicate that the Medieval Warm Period was a real and global phenomenon (see our Medieval Warm Period Project). It also continues to indicate that the MWP was likely warmer than the Current Warm Period (CWP) has been to date. Such could also be said about the new evidence provided by the study of Millet et al., although we tend to agree that there was indeed a breakdown of their chironomid-temperature relationship when it mattered most and disallowed a valid (apples-to-apples) comparison to be made between the warmth of the MWP and the CWP. However, the fact that Millet et al.’s reconstructed summer temperature dropped by about 1.3°C during the MWP to LIA transition would indeed suggest that the MWP was warmer than the CWP has yet been, since post-LIA warming is generally considered to have been somewhat less than 1.3°C … even when comparing apples to oranges!

The IPCC on a heterogeneous Medieval Warm Period

Jan Esper and David Frank

Climatic Change (2009) 94:267–273
DOI 10.1007/s10584-008-9492-z

Full paper available here.

CO2 Science.org’s take is here:

In an important paper recently published in the peer-reviewed journal Climatic Change, Swiss scientists Jan Esper (of the Swiss Federal Research Institute) and David Frank (of the Oeschger Centre for Climate Change Research) take the Intergovernmental Panel on Climate Change (IPCC) to task for concluding in their fourth assessment report (AR4) that, relative to modern times, there was “an increased heterogeneity of climate during medieval times about 1000 years ago.”

This finding, if true, would be of great significance to the ongoing debate over the cause of 20th-century global warming, because, in the words of Esper and Frank, “heterogeneity alone is often used as a distinguishing attribute to contrast with present anthropogenic warming.” On the other hand, if the IPCC’s contention is false, it would mean that the warmth of the Current Warm Period is not materially different from that of the Medieval Warm Period (MWP), suggesting there is no need to invoke anything extraordinary (such as anthropogenic CO2 emissions) as the cause of earth’s current warmth, which does not yet appear to have reached the level experienced a thousand years ago (when there was much less CO2 in the air than there is today), as is indicated by the materials archived in our Medieval Warm Period Project. And, of course, this outcome would also be of great significance.

So what did the two Swiss scientists find? By means of various mathematical procedures and statistical tests, Esper and Frank were able to demonstrate that the records reproduced in the AR4 “do not exhibit systematic changes in coherence, and thus cannot be used as evidence for long-term homogeneity changes.” And even if they could be thus used, they say “there is no increased spread of values during the MWP,” and that the standard error of the component data sets “is actually largest during recent decades.” Consequently, the researchers concluded that their “quantification of proxy data coherence suggests that it was erroneous [for the IPCC] to conclude that the records displayed in AR4 are indicative of a heterogeneous climate during the MWP.”

Nevertheless, the homogeneity issue remains unresolved, for as Esper and Frank also note, “an estimation of long-term spatial homogeneity changes is premature based on the smattering of data currently available.” And that is why we continue to post the results of one new study each and every week that provides additional data on the Medieval Warm Period. We are determined to see this question — and others associated with it — clearly resolved, one way or the other. And as may be seen from the ever-expanding results of our Interactive Map and Time Domain Plot, the MWP is looking ever more global and substantial with every passing week.

Sherwood, Keith and Craig Idso

Reference
Esper, J. and Frank, D. 2009. The IPCC on a heterogeneous Medieval Warm Period. Climatic Change 94: 267-273.

Of course, Steve McIntyre is giving the paper a thorough examination over at Climate Audit. Craig Loehle has this amusing comment on the CA thread: “It is hilarious that the same people who dismissed my reconstruction as only having 18 proxies are quite happy to make a bold statement about the MWP based on 4. It also stretches my credulity that the NAO was stuck in one mode that long.”

Talking of the NAO, as CRN has reported previously, Tsonis et al name the NAO as the ‘pacemaker’ of the climate shifts that can explain all the 20th century temperature changes. Alarmists ‘scuppered?’

Wang, Swanson and Tsonis, GRL (2009): ‘The pacemaker of major climate shifts.’

The Abstract states:

Models and data suggest that the interplay of major climate modes may result in climate shifts [Tsonis et al., 2007]. More specifically it has been shown that when the network of North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), El Nino/Southern Oscillation (ENSO) and North Pacific Index (NPI) synchronizes, an increase in the coupling between these oscillations destroys the synchronous state and leads the climate system to a new state. These shifts are associated with significant changes in global temperature trend and in ENSO variability. Here we probe the details of this network’s dynamics to investigate if a certain oscillation is the culprit in these shifts. From a total of 12 synchronization events observed in three climate simulations and in observations we find that the instigator of these shifts is NAO. Without exception only when NAO’s coupling with the Pacific increases a shift will occur. Our results suggest a dynamical sequence of events in the evolution of climate shifts which is consistent with recent independent empirical and modeling studies.

The paper concludes:

Many studies have in the past dealt with the origin and mechanisms of climate oscillations as well as with the consequences of their interactions. Our study with the help of a novel approach identifies for the first time which may be the most significant of these oscillations. In a dynamical scenario where the major modes of variability in the northern hemisphere are synchronized, an increase in the coupling strength destroys the synchronous state and causes climate to shift to a new state. Here we were able to identify that the major participant in this coupling strength increase is NAO, which we found to be behind all climate shifts observed in observations as well as in three climate simulations. Understanding variability of our extremely complex climate system is far from complete as new and often contradicting views are proposed. In this realm we hope that our results will provide some direction and focus to this perpetual quest for understanding climate variability.

Kyle Swanson and Anastasios Tsonis GRL (2009):‘Has the climate recently shifted?’

The Abstract states:

This paper provides an update to an earlier work that showed specific changes in the aggregate time evolution of major Northern Hemispheric atmospheric and oceanic modes of variability serve as a harbinger of climate shifts. Specifically, when the major modes of Northern Hemisphere climate variability are synchronized, or resonate, and the coupling between those modes simultaneously increases, the climate system appears to be thrown into a new state, marked by a break in the global mean temperature trend and in the character of El Ni˜no/Southern Oscillation variability. Here, a new and improved means to quantify the coupling between climate modes confirms that another synchronization of these modes, followed by an increase in coupling occurred in 2001/02. This suggests that a break in the global mean temperature trend from the consistent warming over the 1976/77–2001/02 period may have occurred.

The paper concludes:

If as suggested here, a dynamically driven climate shift has occurred, the duration of similar shifts during the 20th century suggests the new global mean temperature trend may persist for several decades. Of course, it is purely speculative to presume that the global mean temperature will remain near current levels for such an extended period of time. Moreover, we caution that the shifts described here are presumably superimposed upon a long term warming trend due to anthropogenic forcing. However, the nature of these past shifts in climate state suggests the possibility of near constant temperature lasting a decade or more into the future must at least be entertained. The apparent lack of a proximate cause behind the halt in warming post 2001/02 challenges our understanding of the climate system, specifically the physical reasoning and causal links between longer time-scale modes of internal climate variability and the impact of such modes upon global temperature. Fortunately, climate science is rapidly developing the tools to meet this challenge, as in the near future it will be possible to attribute cause and effect in decadal scale climate variability within the context of a seamless climate forecast system [Palmer et al. 2008]. Doing so is vital, as the future evolution of the global mean temperature may hold surprises on both the warm and cold ends of the spectrum due entirely to internal variability that lie well outside the envelope of a steadily increasing global mean temperature.

Tsonis et al, GRL (2007): ‘A new dynamical mechanism for major climate shifts’

In the mid-1970s, a climate shift cooled sea surface temperatures in the central Pacific Ocean and warmed the coast of western North America, bringing long-range changes to the northern hemisphere. After this climate shift waned, an era of frequent El Ninos and rising global temperatures began.

Tsonis et al. have investigated the collective behavior of known climate cycles such as the Pacific Decadal Oscillation, the North Atlantic Oscillation, the El Nino/Southern Oscillation, and the North Pacific Oscillation. By studying the last 100 years of these cycles’ patterns, they find that the systems synchronized several times.

Further, in cases where the synchronous state was followed by an increase in the coupling strength among the cycles, the synchronous state was destroyed. Then. a new climate state emerged, associated with global temperature changes and El Nino/Southern Oscillation variability.

The authors show that this mechanism explains all global temperature tendency changes and El Nino variability in the 20th century.

Major climate shifts have occurred or will occur around 1913, 1942, 1978, 2033, and 2072 according to the authors of this recent paper, who also predict a 0.2 Celsius cooling between 2005 and 2020 which should be followed by a 0.3 Celsius warming until 2045 or so – then cooling for the rest of the 21st century.

Modellers Remove Evidence of Cooling and Editor Removes Comment by Climate Sceptic

Is Antarctic Warming Real or “Mann”-Made? A Note from Fred Singer

Climate Science:

Follow Up On Today’s AP Article By Seth Bornenstein Entitled “Study: Antarctica Joins Rest Of Globe In Warming”

Prometheus:

Consistent With Chronicles, Antarctic Edition

More on Antarctica and “Consistent With”

Climate Audit:

Antarctic RegEM

Steig’s Silence

Climate Observations:

Recent Antarctic Warming Attribution Complicated By ENSO Events?

The Telegraph: Christopher Booker:

Despite the hot air, the Antarctic is not warming up

The Inhofe EPW Press Blog:

Scientists, Data Challenge New Antarctic ‘Warming’ Study

Flashback to 20th January 2008, Nature Geoscience: A recent volcanic eruption beneath the West Antarctic ice sheet

Abstract:

Indirect evidence suggests that volcanic activity occurring beneath the West Antarctic ice sheet influences ice flow and sheet stability. However, only volcanoes that protrude through the ice sheet4 and those inferred from geophysical techniques have been mapped so far. Here we analyse radar data from the Hudson Mountains, West Antarctica, that contain reflections from within the ice that had previously been interpreted erroneously as the ice-sheet bed. We show that the reflections are present within an elliptical area of about 23,000 km2 that contains tephra from an explosive volcanic eruption. The tephra layer is thickest at a subglacial topographic high, which we term the Hudson Mountains Subglacial Volcano. The layer depth dates the eruption at 207 BCplusminus240 years, which matches exceptionally strong but previously unattributed conductivity signals in nearby ice cores. The layer contains 0.019–0.31 km3 of tephra, which implies a volcanic explosive index of 3–4. Production and episodic release of water from the volcano probably affected ice flow at the time of the eruption. Ongoing volcanic heat production may have implications for contemporary ice dynamics in this glacial system.

Dennis Ambler on Junkscience.com:

Here is what Ellen and Lonnie Thompson said about Antarctic Temperature records in 2003:

ICE CORE PALEOCLIMATE HISTORIES FROM THE ANTARCTIC PENINSULA: WHERE DO WE GO FROM HERE?
Ellen Mosley-Thompson, Lonnie G. Thompson, Byrd Polar Research Center, Department of Geological Sciences, The Ohio State University, Columbus, Ohio.

It is essential to determine whether the strong 20th century warming in the Antarctic Peninsula (AP) reflects, in part, a response to anthropogenically driven, globally averaged warming or if it is consistent with past climate variability in the region. The necessary time perspective may be reconstructed from chemical and physical properties preserved in the regional ice cover and ocean sediments. Only three multi-century climate histories derived from ice cores in the AP region have been annually dated with good precision (± 2 years per century). The longest record contains only 1200 years and the three histories do not provide a coherent picture of 20th century climate variability.

Temperature records for Antarctica are sparse and short with few extending prior to the International Geophysical Year (1957-58).

This is particularly true for the continental interior. The longest and most dense net­work of meteorological records is in the Antarctic Peninsula region where the temperature record at Orcadas (South Orkney Islands) extends to 1903.

King et al. [this volume] review the surface temperature records in the Peninsula that extend to the late 1940s and the upper air measurements that began in 1956. Their analy­ses demonstrate marked differences between the temper­ature trends in the AP and the rest of the continent (East and West Antarctica).

Jones et al. [1993] also noted that temperature variations in the AP region are poorly correlated with those on the main part of the continent and concluded that extending the Antarctic temperature record by using the longer temperature histories from the Peninsula would be inappropriate.

“The Plateau Remote (PR) record contains some longer-term (~century scale) oscillations with a brief (~3 decades), but strong cooling in the early 17th century.

Conditions remain at or above the long-term mean from 1660 to 1780 after which a gradual cooling trend persists until 1870 after which conditions warm rapidly, peaking at the turn of the 20th century. Since that time the δ18O record indicates a cooling trend to the present.

The PR δ18O record, like those from South Pole, does not show 20th century 18O enrichment (warming), [Mosley-Thompson, unpublished data]. Similarly, the recently published isotopic record from Berkner Island [Mulvaney et al., 2002] also does not show a 20th century warming.

Domack et al. [this volume] report their cores contain a Medieval Warm Period (1.15 ka to 0.7 ka), a Little Ice Age signal (0.7 ka to ~0.15 ka) and 200-year oscillations in the regional climate/oceanographic conditions.”

(Isn’t it strange then that we are told the LIA and MWP were confined to the N. Hemisphere and even disposed of altogether by Mann et al)

The pdf can be downloaded from this link.

Some names to conjure with there, including Rutherford and Mann who are part of the ‘Hockey Team’ involved in the infamous ‘Hockey Stick’ graph saga. So who better to call on when much of Antarctica isn’t playing ball with global warming. But wait! There is more fun to be had here – Real Climate, which includes Michael Mann, have previously said, “A cold Antarctica and Southern Ocean do not contradict our models of global warming.” You just can’t lose when playing the ‘consistent with climate models’ game can you!? Presumably, the findings of this new paper don’t contradict climate models either.

Moving on to the new Nature paper, the first paragraph states:

Assessments of Antarctic temperature change have emphasized the contrast between strong warming of the Antarctic Peninsula and slight cooling of the Antarctic continental interior in recent decades. This pattern of temperature change has been attributed to the increased strength of the circumpolar westerlies, largely in response to changes in stratospheric ozone. This picture, however, is substantially incomplete owing to the sparseness and short duration of the observations. Here we show that significant warming extends well beyond the Antarctic Peninsula to cover most of West Antarctica, an area of warming much larger than previously reported. West Antarctic warming exceeds 0.1 6C per decade over the past 50 years, and is strongest in winter and spring. Although this is partly offset by autumn cooling in East Antarctica, the continent-wide average near-surface temperature trend is positive. Simulations using a general circulation model reproduce the essential features of the spatial pattern and the long-term trend, and we suggest that neither can be attributed directly to increases in the strength of the westerlies. Instead, regional changes in atmospheric circulation and associated changes in sea surface temperature and sea ice are required to explain the enhanced warming in West Antarctica.

The paper concludes:

Mean surface temperature trends in both West and East Antarctica are positive for 1957–2006, and the mean continental warming is comparable to that for the Southern Hemisphere as a whole. This warming trend is difficult to explain without the radiative forcing associated with increasing greenhouse-gas concentrations. However, the future trajectory of Antarctic temperature change also depends on the extent to which changes in atmospheric composition (whether from greenhouse gases or stratospheric ozone) affect Southern Hemisphere sea ice and regional atmospheric circulation patterns. Improved representation in models of coupled atmosphere/sea-ice dynamics will be critical for forecasting Antarctic temperature change.

There is also an accompanying press release from Eric Steig:

New data show much of Antarctica is warming more than previously thought

Scientists studying climate change have long believed that while most of the rest of the globe has been getting steadily warmer, a large part of Antarctica – the East Antarctic Ice Sheet – has actually been getting colder.

But new research shows that for the last 50 years, much of Antarctica has been warming at a rate comparable to the rest of the world. In fact, the warming in West Antarctica is greater than the cooling in East Antarctica, meaning that on average the continent has gotten warmer, said Eric Steig, a University of Washington professor of Earth and space sciences and director of the Quaternary Research Center at the UW.

“West Antarctica is a very different place than East Antarctica, and there is a physical barrier, the Transantarctic Mountains, that separates the two,” said Steig, lead author of a paper documenting the warming published in the Jan. 22 edition of Nature.

For years it was believed that a relatively small area known as the Antarctic Peninsula was getting warmer, but that the rest of the continent – including West Antarctica, the ice sheet most susceptible to potential future collapse – was cooling.

Steig noted that the West Antarctic Ice Sheet, with an average elevation of about 6,000 feet above sea level, is substantially lower than East Antarctica, which has an average elevation of more than 10,000 feet. While the entire continent is essentially a desert, West Antarctica is subject to relatively warm, moist storms and receives much greater snowfall than East Antarctica.

The study found that warming in West Antarctica exceeded one-tenth of a degree Celsius per decade for the last 50 years and more than offset the cooling in East Antarctica.

Co-authors of the paper are David Schneider of the National Center for Atmospheric Research in Boulder, Colo., a former student of Steig’s; Scott Rutherford of Roger Williams University in Bristol, R.I.; Michael Mann of Pennsylvania State University; Josefino Comiso of NASA’s Goddard Space Flight Center in Greenbelt, Md.; and Drew Shindell of NASA’s Goddard Institute for Space Studies in New York City. The work was supported by grants from the National Science Foundation.

The researchers devised a statistical technique that uses data from satellites and from Antarctic weather stations to make a new estimate of temperature trends.

“People were calculating with their heads instead of actually doing the math,” Steig said. “What we did is interpolate carefully instead of just using the back of an envelope. While other interpolations had been done previously, no one had really taken advantage of the satellite data, which provide crucial information about spatial patterns of temperature change.”

Satellites calculate the surface temperature by measuring the intensity of infrared light radiated by the snowpack, and they have the advantage of covering the entire continent. However, they have only been in operation for 25 years. On the other hand, a number of Antarctic weather stations have been in place since 1957, the International Geophysical Year, but virtually all of them are within a short distance of the coast and so provide no direct information about conditions in the continent’s interior.

The scientists found temperature measurements from weather stations corresponded closely with satellite data for overlapping time periods. That allowed them to use the satellite data as a guide to deduce temperatures in areas of the continent without weather stations.

“Simple explanations don’t capture the complexity of climate,” Steig said. “The thing you hear all the time is that Antarctica is cooling and that’s not the case. If anything it’s the reverse, but it’s more complex than that. Antarctica isn’t warming at the same rate everywhere, and while some areas have been cooling for a long time the evidence shows the continent as a whole is getting warmer.”

A major reason most of Antarctica was thought to be cooling is because of a hole in the Earth’s protective ozone layer that appears during the spring months in the Southern Hemisphere’s polar region. Steig noted that it is well established that the ozone hole has contributed to cooling in East Antarctica.

“However, it seems to have been assumed that the ozone hole was affecting the entire continent when there wasn’t any evidence to support that idea, or even any theory to support it,” he said.

“In any case, efforts to repair the ozone layer eventually will begin taking effect and the hole could be eliminated by the middle of this century. If that happens, all of Antarctica could begin warming on a par with the rest of the world.”

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For more information, contact Steig at (206) 685-3715, (206) 543-6327 or steig@ess.washington.edu .

Climate Research News has previously mentioned an article that helps to confirm the divergent climate histrories for the East and West Antarctic ice sheets – a phenomenon that persists from 14 million years ago to modern times.

How do the authors of the new Nature paper find evidence for Antarctic warming? Using “statistical climate-field-reconstruction techniques to obtain a 50-year-long, spatially complete estimate of monthly Antarctic temperature anomalies.”

So there you have it Mr President – you apparently have 4 years to save the world and Antarctica from ‘global warming.’