Lets have a clean debate about AGW

[Old Rocks]

Weather and Climate Summit - Day 5, Jennifer Francis - YouTube

A presentation by Dr. Jennifer Francis about the effect of the Arctic Sea Ice melt on the jet stream and Rossby waves.

Did the same thing happen when the ice melted during the medieval warm period, the roman warm period, and the holocene maximum as well as all of the other times arctic ice has melted? Do you have any actual proof that the results of melting ice in the arctic happened during those times when we know that there was less ice than at present?

It is easy to stand in front of a camera and make claims...it is an entirely different matter to substantiate those claims.

Since Dr. Francis was speaking entirely of what the current affects are, she did not address the past periods. After all, there were not 7 billion people depending on agriculture for their daily bread at that time.

 

[SSDD]

Satellite data reveals extent of Andean glacier melt

Andean glaciers are also dissappearing with devastating consequences for the agriculture that depends on them.

Apply the same questions to the andean glaciers. I can't help but notice that you aren't answsering any of my questions. Why?

 

[Old Rocks]

How rapidly is permafrost changing - Romanovsky

And do you think that melting permafrost in the arctic is something new? Do you think it never happened before? Do you think that it never had carbon sequestered before? Do you think the permafrost was more stable than at present during the Medieval Warm period? How about during the Roman warm period? How about during the Holocene maximum? Do you think there has ever been a time in earth's history where temperatures were warmer and the permafrost less stable than now?

Now, since the geologists involved in the research have stated that this permafrost that is melting currently has existed as permafrost for thousands of years, I would have to assume that it did not melt during either the MWP or the so called Roman Warm Period.

 

[Old Rocks]

The American Geophyisical Union has more members that study the affects of the warming than any other scientific organization in the world. This is their statement on what is happening currently;

AGU Position Statement

Human Impacts on Climate

Adopted by Council December 2003
Revised and Reaffirmed December 2007

The Earth's climate is now clearly out of balance and is warming. Many components of the climate system—including the temperatures of the atmosphere, land and ocean, the extent of sea ice and mountain glaciers, the sea level, the distribution of precipitation, and the length of seasons—are now changing at rates and in patterns that are not natural and are best explained by the increased atmospheric abundances of greenhouse gases and aerosols generated by human activity during the 20th century. Global average surface temperatures increased on average by about 0.6°C over the period 1956–2006. As of 2006, eleven of the previous twelve years were warmer than any others since 1850. The observed rapid retreat of Arctic sea ice is expected to continue and lead to the disappearance of summertime ice within this century. Evidence from most oceans and all continents except Antarctica shows warming attributable to human activities. Recent changes in many physical and biological systems are linked with this regional climate change. A sustained research effort, involving many AGU members and summarized in the 2007 assessments of the Intergovernmental Panel on Climate Change, continues to improve our scientific understanding of the climate.

During recent millennia of relatively stable climate, civilization became established and populations have grown rapidly. In the next 50 years, even the lower limit of impending climate change—an additional global mean warming of 1°C above the last decade—is far beyond the range of climate variability experienced during the past thousand years and poses global problems in planning for and adapting to it. Warming greater than 2°C above 19th century levels is projected to be disruptive, reducing global agricultural productivity, causing widespread loss of biodiversity, and—if sustained over centuries—melting much of the Greenland ice sheet with ensuing rise in sea level of several meters. If this 2°C warming is to be avoided, then our net annual emissions of CO2 must be reduced by more than 50 percent within this century. With such projections, there are many sources of scientific uncertainty, but none are known that could make the impact of climate change inconsequential. Given the uncertainty in climate projections, there can be surprises that may cause more dramatic disruptions than anticipated from the most probable model projections.

With climate change, as with ozone depletion, the human footprint on Earth is apparent. The cause of disruptive climate change, unlike ozone depletion, is tied to energy use and runs through modern society. Solutions will necessarily involve all aspects of society. Mitigation strategies and adaptation responses will call for collaborations across science, technology, industry, and government. Members of the AGU, as part of the scientific community, collectively have special responsibilities: to pursue research needed to understand it; to educate the public on the causes, risks, and hazards; and to communicate clearly and objectively with those who can implement policies to shape future climate.

 

[SSDD]

Since that is an hour long lecture, which I posted at 6:25, and you answered at 6:33, stating that you had watched it all the way through, something is amiss in your statement.

Like I said on another thread, people like you just never learned critical thinking and as a result, you will always be behind the curve and subject to being taken advantage of by huxters.

You have posted that idiot video no less than 70 times dating back to 12/22/2009. Hell you have posted it 3 times since the beginning of the year.

Now, how about posting the time stamps where you believe anything that might be construed as proof might be viewed.

 

[Old Rocks]

The Geological Society of America also has a unequivacal statement concerning climate change;

The Geological Society of America - Position Statement on Global Climate Change

Rationale
Scientific advances in the first decade of the 21st century have greatly reduced previous uncertainties about the amplitude and causes of recent global warming. Ground-station measurements have shown a warming trend of ~0.7 °C since the mid-1800s, a trend consistent with (1) retreat of northern hemisphere snow and Arctic sea ice in the last 40 years; (2) greater heat storage in the ocean over the last 50 years; (3) retreat of most mountain glaciers since 1850; (4) an ongoing rise of global sea level for more than a century; and (5) proxy reconstructions of temperature change over past centuries from ice cores, tree rings, lake sediments, boreholes, cave deposits and corals. Both instrumental records and proxy indices from geologic sources show that global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries (National Research Council, 2006).

Measurements from satellites, which began in 1979, initially did not show a warming trend, but later studies (Mears and Wentz, 2005; Santer et al., 2008) found that the satellite data had not been fully adjusted for losses of satellite elevation through time, differences in time of arrival over a given location, and removal of higher-elevation effects on the lower tropospheric signal. With these factors taken into account, the satellite data are now in basic agreement with ground-station data and confirm a warming trend since 1979. In a related study, Sherwood et al. (2005) found problems with corrections of tropical daytime radiosonde measurements and largely resolved a previous discrepancy with ground-station trends. With instrumental discrepancies having been resolved, recent warming of Earth’s surface is now consistently supported by a wide range of measurements and proxies and is no longer open to serious challenge.

The geologic record contains unequivocal evidence of former climate change, including periods of greater warmth with limited polar ice, and colder intervals with more widespread glaciation. These and other changes were accompanied by major shifts in species and ecosystems. Paleoclimatic research has demonstrated that these major changes in climate and biota are associated with significant changes in climate forcing such as continental positions and topography, patterns of ocean circulation, the greenhouse gas composition of the atmosphere, and the distribution and amount of solar energy at the top of the atmosphere caused by changes in Earth's orbit and the evolution of the sun as a main sequence star. Cyclic changes in ice volume during glacial periods over the last three million years have been correlated to orbital cycles and changes in greenhouse gas concentrations, but may also reflect internal responses generated by large ice sheets. This rich history of Earth's climate has been used as one of several key sources of information for assessing the predictive capabilities of modern climate models. The testing of increasingly sophisticated climate models by comparison to geologic proxies is continuing, leading to refinement of hypotheses and improved understanding of the drivers of past and current climate change.

Given the knowledge gained from paleoclimatic studies, several long-term causes of the current warming trend can be eliminated. Changes in Earth’s tectonism and its orbit are far too slow to have played a significant role in a rapidly changing 150-year trend. At the other extreme, large volcanic eruptions have cooled global climate for a year or two, and El Niño episodes have warmed it for about a year, but neither factor dominates longer-term trends.

 

[Old Rocks]

The Geological Society of America - Position Statement on Global Climate Change

As a result, greenhouse gas concentrations, which can be influenced by human activities, and solar fluctuations are the principal remaining factors that could have changed rapidly enough and lasted long enough to explain the observed changes in global temperature. Although the 3rd IPCC report allowed that solar fluctuations might have contributed as much as 30% of the warming since 1850, subsequent observations of Sun-like stars (Foukal et al., 2004) and new simulations of the evolution of solar sources of irradiance variations (Wang et al., 2005) have reduced these estimates. The 4th (2007) IPCC report concluded that changes in solar irradiance, continuously measured by satellites since 1979, account for less than 10% of the last 150 years of warming.

Greenhouse gases remain as the major explanation. Climate model assessments of the natural and anthropogenic factors responsible for this warming conclude that rising anthropogenic emissions of greenhouse gases have been an increasingly important contributor since the mid-1800s and the major factor since the mid-1900s (Meehl et al., 2004). The CO2 concentration in the atmosphere is now ~30% higher than peak levels that have been measured in ice cores spanning 800,000 years of age, and the methane concentration is 2.5 times higher. About half of Earth’s warming has occurred through the basic heat-trapping effect of the gases in the absence of any feedback processes. This “clear-sky” response to climate is known with high certainty. The other half of the estimated warming results from the net effect of feedbacks in the climate system: a very large positive feedback from water vapor; a smaller positive feedback from snow and ice albedo; and sizeable, but still uncertain, negative feedbacks from clouds and aerosols. The vertical structure of observed changes in temperature and water vapor in the troposphere is consistent with the anthropogenic greenhouse-gas “fingerprint” simulated by climate models (Santer et al., 2008). Considered in isolation, the greenhouse-gas increases during the last 150 years would have caused a warming larger than that actually measured, but negative feedback from clouds and aerosols has offset part of the warming. In addition, because the oceans take decades to centuries to respond fully to climatic forcing, the climate system has yet to register the full effect of gas increases in recent decades.

These advances in scientific understanding of recent warming form the basis for projections of future changes. If greenhouse-gas emissions follow the current trajectory, by 2100 atmospheric CO2 concentrations will reach two to four times pre-industrial levels, for a total warming of less than 2 °C to more than 5 °C compared to 1850. This range of changes in greenhouse gas concentrations and temperature would substantially alter the functioning of the planet in many ways. The projected changes involve risk to humans and other species: (1) continued shrinking of Arctic sea ice with effects on native cultures and ice-dependent biota; (2) less snow accumulation and earlier melt in mountains, with reductions in spring and summer runoff for agricultural and municipal water; (3) disappearance of mountain glaciers and their late-summer runoff; (4) increased evaporation from farmland soils and stress on crops; (5) greater soil erosion due to increases in heavy convective summer rainfall; (6) longer fire seasons and increases in fire frequency; (7) severe insect outbreaks in vulnerable forests; (8) acidification of the global ocean; and (9) fundamental changes in the composition, functioning, and biodiversity of many terrestrial and marine ecosystems. In addition, melting of Greenland and West Antarctic ice (still highly uncertain as to amount), along with thermal expansion of seawater and melting of mountain glaciers and small ice caps, will cause substantial future sea-level rise along densely populated coastal regions, inundating farmland and dislocating large populations. Because large, abrupt climatic changes occurred within spans of just decades during previous ice-sheet fluctuations, the possibility exists for rapid future changes as ice sheets become vulnerable to large greenhouse-gas increases. Finally, carbon-climate model simulations indicate that 10–20% of the anthropogenic CO2 “pulse” could stay in the atmosphere for thousands of years, extending the duration of fossil-fuel warming and its effects on humans and other species. The acidification of the global ocean and its effects on ocean life are projected to last for tens of thousands of years.

 

[SSDD]

Now, since the geologists involved in the research have stated that this permafrost that is melting currently has existed as permafrost for thousands of years, I would have to assume that it did not melt during either the MWP or the so called Roman Warm Period.

So how do you think it survived those temperatures that were warmer than the present with no melting?

And as to what scientists "say" that idiot Marcott claimed that an ice cap covering half of canada melted during a time when global temperatures were barely half a degree warmer than the present. The sort of science that would pass that sort of crap for publishing would pass anything wouldn't it?

 

[Old Rocks]

Since that is an hour long lecture, which I posted at 6:25, and you answered at 6:33, stating that you had watched it all the way through, something is amiss in your statement.

Like I said on another thread, people like you just never learned critical thinking and as a result, you will always be behind the curve and subject to being taken advantage of by huxters.

You have posted that idiot video no less than 70 times dating back to 12/22/2009. Hell you have posted it 3 times since the beginning of the year.

Now, how about posting the time stamps where you believe anything that might be construed as proof might be viewed.

I have, and will continue to post, the research done by reputable scientists.

 

[SSDD]

The American Geophyisical Union has more members that study the affects of the warming than any other scientific organization in the world. This is their statement on what is happening currently;

AGU Position Statement

Human Impacts on Climate

So you admit that neither you, nor your political heads of scientific organizations have any proof of the claims. You have a logical fallacy as support for your claims. Typical.

 

[Old Rocks]

Now, since the geologists involved in the research have stated that this permafrost that is melting currently has existed as permafrost for thousands of years, I would have to assume that it did not melt during either the MWP or the so called Roman Warm Period.

So how do you think it survived those temperatures that were warmer than the present with no melting?

And as to what scientists "say" that idiot Marcott claimed that an ice cap covering half of canada melted during a time when global temperatures were barely half a degree warmer than the present. The sort of science that would pass that sort of crap for publishing would pass anything wouldn't it?

Please post research that states those temperatures in where the permafrost is melting at present were warmer then than now.

 

[SSDD]

I have, and will continue to post, the research done by reputable scientists.

Reputable scientist...which you continually hold up as if it contains actual proof of something....and yet, you can't provide a time stamp for when the proof is presented.

You can't show any evidence that the consequences for melting arctic ice came to be at times in the not so distant past when the ice was even less than it is now. Doesn't it strike you as odd that she claims all these things will happen if the ice continues to melt, but those things didn't happen during the noted periods when temperatures up there were warmer than the present?

 

[Old Rocks]

The paper that this is based on was published in Nature. Do you have a peer reviewed study that states that their data and conclusions are not correct?

What the Hell is happening to the Arctic Sea Ice?

Everyone who studies the ice melt agrees that natural weather variation from year to year has played a role. Both 2007 and 2012 were unusually bad years for the ice, and would have been even if the planet's climate hadn't changed. Looking over the data from 1979 to 2011 (before this year's new record low), a team of scientists led by Julienne Stroeve at the National Snow and Ice Data Center found that those random variations accounted for around 40 percent of the change in ice cover to date, and that human activity accounted for around 60 percent of the change.

Other research points to an even greater human component. In 2011, a team led by Chilean scientist Christophe Kinnard published a paper in Nature that used data from 69 sites around the Arctic to reconstruct the extent of the ice over the last 1450 years – all the way back to the 6th century AD. What they found was that late summer ice coverage over that entire fourteen and a half century period stayed between 9 million and 11 million square kilometers, a little higher than it was before satellite observation started in 1979, or roughly three times the minimum that we hit this September.

Kinnard was kind enough to send me the team's underlying data. Combining it with satellite based observations from 1979 onward, the last few decades pop out. Ice coverage fluctuates for centuries, but stays in a narrow band, until suddenly, in the last few decades, the amount of ice left in late summer plunges.

 

[SSDD]

Please post research that states those temperatures in where the permafrost is melting at present were warmer then than now.

The fact that we find trees of species that can no longer survive buried in the permafrost should be enough to convince any idiot that it was warmer up there during the not so distant past, but if you want research, sure, here is some research.


Dahl-Jensen, D., Mosegaard, K., Gundestrup, N., Clow, G.D., Johnsen, S.J., Hansen, A.W. and Balling, N. 1998. Past temperatures directly from the Greenland Ice Sheet. Science 282: 268-271.


Wagner, B. and Melles, M. 2001. A Holocene seabird record from Raffles So sediments, East Greenland, in response to climatic and oceanic changes. Boreas 30: 228-239.

Jiang, H., Seidenkrantz, M-S., Knudsen, K.L. and Eiriksson, J. 2002. Late-Holocene summer sea-surface temperatures based on a diatom record from the north Icelandic shelf. The Holocene 12: 137-147.

Seppa, H. and Birks, H.J.B. 2002. Holocene climate reconstructions from the Fennoscandian tree-line area based on pollen data from Toskaljavri. Quaternary Research 57: 191-199.

Moore, J.J., Hughen, K.A., Miller, G.H. and Overpeck, J.T. 2001. Little Ice Age recorded in summer temperature reconstruction from varved sediments of Donard Lake, Baffin Island, Canada. Journal of Paleolimnology 25: 503-517.

Grudd, H., Briffa, K.R., Karlen, W., Bartholin, T.S., Jones, P.D. and Kromer, B. 2002. A 7400-year tree-ring chronology in northern Swedish Lapland: natural climatic variability expressed on annual to millennial timescales. The Holocene 12: 657-665


Knudsen, K.L., Eiriksson, J., Jansen, E., Jiang, H., Rytter, F. and Gudmundsdottir, E.R. 2004. Palaeoceanographic changes off North Iceland through the last 1200 years: foraminifera, stable isotopes, diatoms and ice rafted debris. Quaternary Science Reviews 23: 2231-2246.


Grinsted, A., Moore, J.C., Pohjola, V., Martma, T. and Isaksson, E. 2006. Svalbard summer melting, continentality, and sea ice extent from the Lomonosovfonna ice core. Journal of Geophysical Research 111: 10.1029/2005JD006494.


Besonen, M.R., Patridge, W., Bradley, R.S., Francus, P., Stoner, J.S. and Abbott, M.B. 2008. A record of climate over the last millennium based on varved lake sediments from the Canadian High Arctic. The Holocene 18: 169-180.

So now, how do you suppose the permafrost didn't melt during those periods of higher temperatures? What physical law has changed that preserved the permafrost then when the temprerature was higher but will melt it now at lower temperatures?

 

[Old Rocks]

Now that is Greenland, which has a considerable differant climate than Siberia and the Arctic of North America

Past Temperatures Directly from the Greenland Ice Sheet

A Monte Carlo inverse method has been used on the temperature profiles measured down through the Greenland Ice Core Project (GRIP) borehole, at the summit of the Greenland Ice Sheet, and the Dye 3 borehole 865 kilometers farther south. The result is a 50,000-year-long temperature history at GRIP and a 7000-year history at Dye 3. The Last Glacial Maximum, the Climatic Optimum, the Medieval Warmth, the Little Ice Age, and a warm period at 1930 A.D. are resolved from the GRIP reconstruction with the amplitudes –23 kelvin, +2.5 kelvin, +1 kelvin, –1 kelvin, and +0.5 kelvin, respectively. The Dye 3 temperature is similar to the GRIP history but has an amplitude 1.5 times larger, indicating higher climatic variability there. The calculated terrestrial heat flow density from the GRIP inversion is 51.3 milliwatts per square meter.

 

[SSDD]

The paper that this is based on was published in Nature. Do you have a peer reviewed study that states that their data and conclusions are not correct?

I don't see anything there to substantiate their claim that the ice is less now than during the medieval warm period even though the bulk of research clearly shows that it was warmer in the arctic during that time than it is now.

THE HOCKEY SCHTICK: Paper: Arctic Temperatures 2-3C higher only 1000 years ago

A 5,000 year alkenone-based temperature record from Lower Murray Lake reveals a

A paper presented at the American Geophysical Union meeting this week finds that Ellesmere Island in the Canadian High Arctic experienced a "dramatic" Medieval Warming Period from 800-1200 AD with temperatures 2 to 3 degrees C higher than the mean temperature of the past 100 years. Ellesmere Island was also in the news this week due to a discovery of a mummified forest where "no trees now grow" due to its "current frigid state."

2 to 3 degrees warmer and you don't think more ice melted?

So now, about the time stamps in those videos where you believe some proof of something is presented?

 

[Old Rocks]

So the 1800's was the coldest century recorded there. But by the 1990's, we are back to the MWP temperatures. However, the MWP temperatures were primarily a North Atlantic event, the rest of the globe warmed only slightly. At present, almost the whole of the planet is experiancing the warming.

http://www.polarresearch.net/index.php/polar/article/download/7379/pdf_208

Two isotopic ice core records from western Svalbard are calibrated to
reconstruct more than 1000 years of past winter surface air temperature
variations in Longyearbyen, Svalbard, and Vardø, northern Norway. Analysis
of the derived reconstructions suggests that the climate evolution of the last
millennium in these study areas comprises three major sub-periods. The
cooling stage in Svalbard (ca. 800
1800) is characterized by a progressive
winter cooling of approximately 0.9 8C century1 (0.3 8C century1 for
Vardø) and a lack of distinct signs of abrupt climate transitions. This makes it
difficult to associate the onset of the Little Ice Age in Svalbard with any
particular time period. During the 1800s, which according to our results was
the coldest century in Svalbard, the winter cooling associated with the Little
Ice Age was on the order of 4 8C (1.3 8C for Vardø) compared to the 1900s. The
rapid warming that commenced at the beginning of the 20th century was
accompanied by a parallel decline in sea-ice extent in the study area. However,
both the reconstructed winter temperatures as well as indirect indicators of
summer temperatures suggest the Medieval period before the 1200s was at
least as warm as at the end of the 1990s in Svalbard.

 

[Old Rocks]

THE HOCKEY SCHTICK: Paper: Arctic Temperatures 2-3C higher only 1000 years ago

blog

A 5,000 year alkenone-based temperature record from Lower Murray Lake reveals a

Abstract
Lake-based paleotemperature reconstructions are of particular importance in the Arctic, where other useful archives (e.g., tree rings, speleothems) for developing dense networks of quantitative climate records are absent or limited. Lacustrine alkenone paleothermometry offers a new avenue for investigating the evolution and variability of Arctic temperatures during the Holocene. We have generated a ~5,000 year long, decadally-resolved record of summer water temperature from the annually-laminated sediments of Lower Murray Lake on Ellesmere Island in the Canadian High Arctic. The varved sediments of Lower Murray Lake allowed high-resolution sampling and excellent chronologic control of the sedimentary record. We calibrated the alkenone paleothermometer for Lower Murray Lake using previously published data as well as new data from lakes in Norway and Svalbard, providing a quantitative record of temperature variability for the past 5,000 years. The previously published mass accumulation rate from Lower Murray Lake has been interpreted as a paleotemperature record and provides complimentary information to the new alkenone record. Melt percentage measurements from the nearby Agassiz Ice Cap provide another independent summer temperature reconstruction for comparison. Most strikingly, the alkenone record reveals warm lake water temperatures beginning ~800 AD and persisting until ~1200 AD, with temperatures up to 2-3 deg C warmer than the mean temperature for the past 100 years. This dramatic medieval warm period on Ellesmere Island interrupted a distinct (neoglacial) cooling trend that had begun approximately 2000 years earlier. Furthermore, the three warmest intervals seen in the alkenone record during the past 5,000 years correspond to the periods during which the area was occupied by Paleo-Eskimo groups, providing evidence that local climate conditions played a significant role in determining migration patterns of people of the Arctic Small Tools tradition.

Very good. Now I accept that as good evidence that the temperature in Ellesmere was that warm at that time. The scientists in Alaska are doing the same kind of research,using the same tools, however, you will not accept their evidence.

And the MWP was primarily a North Atlantic event, with a total increase in global warmth, as indicated by sediment cores from various tropical areas, of only 0.2 C. We are at an increase of 0.7 C right now, and rising.

 

[SSDD]

And the MWP was primarily a North Atlantic event, with a total increase in global warmth, as indicated by sediment cores from various tropical areas, of only 0.2 C. We are at an increase of 0.7 C right now, and rising.[/B]

That simply is not true. There are more than 200 papers covering the entire globe stating that the medieval warm period was both warmer than the present and global in nature. If you like, I can provide published papers from Africa, Asia, Antartica, New Zealand, Australia, Eurpoe, all of the oceans, and South America.

It is first class denial to claim that a world wide event was just a north atlantic event. Think about it a second and use your brain....some of the strongest MWP signals were found in the Vostok ice cores not so far away from the south pole.

 

[Old Rocks]

A NEW RECONSTRUCTION OF TEMPERATURE VARIABILITY IN THE EXTRA-TROPICAL NORTHERN HEMISPHERE DURING THE LAST TWO MILLENNIA - LJUNGQVIST - 2010 - Geografiska Annaler: Series A, Physical Geography - Wiley Online Library


ABSTRACT.


A new temperature reconstruction with decadal resolution, covering the last two millennia, is presented for the extratropical Northern Hemisphere (90–30°N), utilizing many palaeo-temperature proxy records never previously included in any large-scale temperature reconstruction. 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. Our temperature reconstruction agrees well with the reconstructions by Moberg et al. (2005) and Mann et al. (2008) with regard to the amplitude of the variability as well as the timing of warm and cold periods, except for the period c. ad 300–800, despite significant differences in both data coverage and methodology.