I have always been skeptical of the IPCC and Mann temperature data. With well over a 100 studies published in major journals like Nature, Geophysical Letters etc. that pretty conclusively show that the Medieval Warm Period was warmer than today and that the Little Ice Age was much cooler and that they were worldwide. I was taught about both these periods during my college days and there was no controversy about their existence then. The IPCC recognized both these periods until 1995 when the data was mysteriously revised. I am very skeptical of the objectivity of any UN supported organization. The UN oil for food program comes to mind. The Sargasso Sea Data http://www.whoi.edu/page.do?pid=12455&tid=441&cid=8722&ct=61&article=3842 clearly shows that the earth has been warmer on several occasions than it is now during the last 3,000 years. Maybe there is a problem with the ice core data or maybe it is interpreted incorrectly. I have listed only 5 of at least 100 papers showing higher temperatures from all around the world demonstrating the real existence of the Medieval Warming Period and showing it to be warmer than the Current Warm Period. ---------------------------------------------------------------------------- ---- Reference Goni, M.A., Woodworth, M.P., Aceves, H.L., Thunell, R.C., Tappa, E., Black, D., Muller-Karger, F., Astor, Y. and Varela, R. 2004. Generation, transport, and preservation of the alkenone-based U37K' sea surface temperature index in the water column and sediments of the Cariaco Basin (Venezuela). Global Biogeochemical Cycles 18: 10.1029/2003GB002132. What was done Based on the degree of unsaturation of certain long-chain alkenones synthesized by haptophyte algae contained in a sediment core retrieved from the eastern sub-basin of the Cariaco Basin (20°30'N, 64°40'W) on the continental shelf off the Venezuelan central coast, the authors reconstructed a history of sea surface temperatures for that location covering the past 6000 years. What was learned Goni et al. report that the highest alkenone-derived sea surface temperatures "were measured during the Medieval Warm Period (MWP)," which they identified as occurring between AD 800 and 1400. From the graph of their results reconstructed below, it is further evident that peak MWP temperatures were approximately 0.35°C warmer than peak Current Warm Period (CWP) temperatures, and that they were fully 0.95°C warmer than the mean temperature of the last decade of the 20th century. What it means The results of this research are striking in the clarity of their depiction of the MWP, CWP and intervening Little Ice Age (LIA) in a tropical setting. Consequently, they do much to substantiate the global nature of these multi-centennial climatic excursions. They are also significant in that they indicate (1) the LIA was the coldest period of the last six 6000 years, (2) the MWP was the warmest period of the same time interval, and (3) the CWP - especially most recently (in this part of the world at least) - has a long way to go before it can even be said to approach the warmth of the MWP. Reference Newton, A., Thunell, R. and Stott, L. 2006. Climate and hydrographic variability in the Indo-Pacific Warm Pool during the last millennium. Geophysical Research Letters 33: 10.1029/2006GL027234. What was done Working with a sediment core collected at 5°12.07'S, 117°29.20'E in the Indo-Pacific Warm Pool (one of the warmest regions in the modern oceans), Newton et al. analyzed planktonic foraminiferal (Globigerinoides ruber) Mg/Ca and δ18O data to derive high-resolution summer sea surface temperature (SST) and salinity histories extending back in time about a thousand years. What was learned The researchers' work revealed, in their words, that "the warmest temperatures and highest salinities occurred during the Medieval Warm Period," which lasted from about AD 1020 to1260. Over this period, summer SSTs averaged about 29.7°C, as best we can determine from their graph of the data, with a peak of about 30.9°C in the vicinity of AD 1080, which values are to be compared with the region's average modern summer SST of 29.0°C, which is significantly lower than that of the Medieval Warm Period. Likewise, they found that "the coolest temperatures and lowest salinities occurred during the Little Ice Age," the lowest temperatures of which occurred "around AD 1700, during the period of reduced solar intensity known as the Maunder Minimum," when summer SSTs "were 1.0-1.5°C cooler than present," presumably due to the lower solar activity of that period. What it means In contradiction of the climate-alarmist claim that the Medieval Warm Period and Little Ice Age were merely regional phenomena confined to countries surrounding the North Atlantic Ocean, Newton et al. say their data from the Makassar Strait of Indonesia clearly indicate that "climate changes during the Medieval Warm Period and Little Ice Age were not confined to the high latitudes," nor, we would add, to countries bordering the North Atlantic Ocean. Reference Liu, Y., An, Z., Ma, H., Cai, Q., Liu, Z., Kutzbach, J.K., Shi, J., Song, H., Sun, J., Yi, L., Li, Q., Yang, Y. and Wang, L. 2006. Precipitation variation in the northeastern Tibetan Plateau recorded by the tree rings since 850 AD and its relevance to the Northern Hemisphere temperature. Science in China: Series D Earth Sciences 49: 408-420. What was done The authors used three well-dated Sabina Przewalskii ring-width chronologies derived from a total of 77 trees growing in three locations near Dulan, China, on the northeastern Tibetan Plateau (36.0-36.3°N, 98.2-98.6°E), to reconstruct annual precipitation variations in that region over the period AD 850-2002, after which they compared the results with instrumental temperature data for the same region over the period of temporal overlap. What was learned Working with 10-year moving averages, the thirteen scientists found that precipitation and temperature were "significantly correlated with r = 0.85 (p<0.0001), after the precipitation lagged temperature for 2 years." Hence, they went on to produce a 40-year moving average curve that was "significantly correlated with seven temperature curves of the Northern Hemisphere," which led them to conclude that their 40-year smoothed reconstruction "could be regarded as the millenary temperature curve for the northeastern Tibetan Plateau." What it means In viewing Liu et al.'s final "millenary temperature curve," it can readily be seen that the 40-year-averaged temperature proxies in the vicinity of AD 915 are definitely greater than those at the end of the 20th century, which comprise the next highest peak of the record. Hence, this study represents another specific instance where peak temperatures of the Medieval Warm Period likely were greater than the peak temperatures of the 20th century. And as we continue to accumulate ever more examples of such circumstances in the Medieval Warm Period Record of the Week section of our website, it is becoming ever more clear there is no compelling reason to believe that 20th-century global warming was in any way dependent upon the 20th-century increase in atmospheric CO2 concentration, which was far, far less a thousand or more years ago, when it was even warmer than it is today. What was done The authors synthesize the findings of a variety of paleoclimate studies based on analyses of the sediment records of several crater lakes and lakes formed by lava dams that are scattered across the Trans Mexican Volcanic Belt of central Mexico and that have an absolute chronology provided by radiocarbon dates extending back to 1500 14C yr BP. What was learned Noting that the degree of coherence among the records "is remarkable," Metcalf and Davis report - in what is perhaps the key finding of their analysis - that "dry conditions, probably the driest of the Holocene [our italics], are recorded over the period 1400 to 800 14C yr BP (ca. AD 700-1200)," the significance of which finding is augmented by their observation that "the present day climate of central Mexico is typical of most of the country." Giving the result even broader significance is the fact that it is, in the words of the two researchers, "consistent with results from the Yucatan Peninsula (Hodell et al., 1995, 2005) .. and from the Cariaco basin (Haug et al., 2003) and the Isthmus of Panama (Lachniet et al., 2004)." What is more, Mayewski et al. (2004) have identified the central portion of this period (AD 800 to 1000) as a time of truly global anomalous climate. What it means This study provides convincing evidence that one of the strongest manifestations of the Medieval Warm Period throughout most of Mexico, and even extending beyond its borders, was a major lack of moisture, which in this particular part of the world better delineates the temporal realm of the Medieval Warm Period than even the epoch's primary defining characteristic of elevated temperature. And this is why we sometimes rely on moisture characteristics to help identify the Medieval Warm Period in this and other parts of the world in our growing-by-the-week Medieval Warm Period Project. Reference Andreev, A.A., Pierau, R., Kalugin, I.A., Daryin, A.V., Smolyaninova, L.G. and Diekmann, B. 2007. Environmental changes in the northern Altai during the last millennium documented in Lake Teletskoye pollen record. Quaternary Research 67: 394-399. What was done Working with a sediment core extracted from the central and deepest part of Lake Teletskoye in the northeastern part of the Altai Mountains in southern Siberia (51°43'N, 87°39'E), the authors analyzed pollen and charcoal stratigraphy to develop "the first detailed climate and vegetation reconstruction for the last millennium in the northern Altai Mountains." What was learned Quoting the six researchers, "dense Siberian pine forest dominated the area around the lake at least since ca. AD 1020," when they say "climate conditions were similar to modern [our italics]." Then, "between AD 1100 and 1200, a short dry period with increased fire activity occurred," and "around AD 1200, climate became more humid with the temperatures probably higher than today [our italics]." This period of rather stable climate, "possibly reflecting [the] Medieval Warm Epoch, lasted until AD 1410," after which "slightly drier climate conditions occurred between AD 1410 and 1560." Thereafter, they say "a subsequent period with colder and more arid climate conditions between AD 1560 and 1820 is well correlated with the Little Ice Age," after which they found evidence for a climate warming they "inferred from the uppermost pollen spectra, accumulated after AD 1840," which was "consistent with the instrumental data" of the modern period. What it means It is clear from Andreev et al.'s findings that the Altai Mountain region of southern Siberia displays the characteristic millennial-scale cycling of climate from Medieval Warm Period to Little Ice Age to Current Warm Period conditions that is characteristic of most of the rest of the world (see Climate Oscillations (Millennial Variability) in our Subject Index). In addition, it is of interest to note that from approximately AD 1200 to 1410, they conclude that temperatures in the region of their study were "probably higher than today," providing yet another example of times and places when low-CO2 Medieval Warm Period temperatures were likely higher than high-CO2 Current Warm Period temperatures. For more on this eye-opening subject, see our Medieval Warm Period Project. -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Kevin Poe Sent: Sunday, March 08, 2009 7:21 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Runaway Greenhouse Dave, I too have always been facinated by the willingness of some to accept 30 years of fragmented data on a different planet with only a couple of insturments, but endlessly refute 600,000 years of ice core data from three different corners of Earth studied by independent teams all arriving at the same conclusions that CO2 and temp are related and never higher in last 600,000 years then they are now. It all goes back to believing what you want to believe. On Sun, Mar 8, 2009 at 9:29 AM, <erikhansen@thebluezone.net> wrote:
David,
I do not recall anyone saying that it would be the to the same extent as what has occurred on Venus. Life will not end but will need to adapt.
I think anyone that has observed Mars has noted changes in the Albedo during dust storms, which is what the article said. The article stating that it occurs inthe absence of man was kind of silly.
Erik
A word on nomenclature. Runaway greenhouse could not occur for Earth
as it has on Venus. Earth is not close enough to Sun, nor is it likely to be during the time humans inhabit this planet. No climatologist worth his salt has ever predicted runaway greenhouse for Earth.
Also, concerning insolation (INcoming SOLar radiaTION) on Mars. First, data citing only regional observations of Martian polar ice phenomena can not be extrapolated to a "global" temperature scenario for Mars. Second, global mean temperature on Mars is very sensitive to the strength and duration of hemispheric dust storms. Mean temperatures between Martian years (687 days) can vary by many degrees. For example, Viking measurements in the 1970's show significant planet- wide cooling relative to current temperatures recorded by Mars Global Surveyor. This is due, primarily, to increased large-scale dust storms on Mars in the 1970's compared to global atmospheric dynamics at present. Insolation forcing during this period was not a significant factor for global climate temperature differences observed by Viking, nor is it significant now.
Recently, changes in south polar ice cover are, most likely, a consequence of topographic forcing of regional atmospheric dynamics. The changes are not due to a "global warming" trend on Mars. Take the time to read Nature, vol. 435, 12 May 2005, pg. 184-188.
Isn't it ironic that regional polar changes on Mars, instantly, signals "global warming" to some people while, at the same time, much more persuasive evidence in favor of man's contribution to Earth's global warming is, repeatedly, denied?
Dave Gary
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-- By the 3rd millennium, the reckless use of light nearly vanquished the night. A formidable few rushed to defend the last sanctuaries of natural darkness.
From the national parks, armed with science, mythology and a love for all things nocturnal came warrior poets who pushed back against the light. They were called Dark Rangers, and no one knew their names. . .
Kevin Poe 435-590-9498 (c) _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com