Medieval Warming Period Was Global, Not Regional

By Anthony Watts – Re-Blogged From http://www.WattsUpWithThat.com

From the “we have to get rid of the Medieval Warming Period” department. Even though this paper was published in late 2017, it was recently highlighted in EoS, as shown below. Michael Mann, and others, in their zeal to cover up warming periods of the past, to make it look like his hockey stick is “unprecedented”, won’t like this paper. They also won’t like this map showing over 1000 studies and their results:

Climate reconstructions of the ‘Medieval Warm Period’ 1000-1200 AD. Legend: MWP was warm (red), cold (blue), dry (yellow), wet


From EoS:

Medieval Temperature Trends in Africa and Arabia

A synthesis of paleotemperature reconstructions from published case studies suggests warm onshore temperatures persisted across most of Afro-Arabia between 1000 and 1200 CE.

The Sahara in southeast Libya. The medieval land temperature history is still poorly known in large parts of Africa and Arabia, emphasizing the need for a systematic paleoclimatological research program. Credit: © Karsten Battermann

By 
Reconstructions of Northern Hemisphere temperatures have repeatedly indicated the Afro-Arabian region experienced climate perturbations, including an extended period of anomalously warm conditions, during medieval times. Because this Medieval Climate Anomaly represents the closest analogue to modern warming, it defines a crucial baseline by which modern postindustrial climate trends can be compared.Although the Medieval Climate Anomaly has also been documented in other parts of the world, its occurrence on the Arabian Peninsula and the African continent, which together comprise about one quarter of Earth’s landmass, is less certain.
This is due to the lack of high-quality proxy records, such as ice cores and tree rings, in the region. To help fill this gap, Lüning et al. correlated and synthesized the findings of 44 published paleotemperature case studies from across the region and mapped the resulting trends of the anomaly’s central period, which lasted from about 1000 to 1200 CE.

"WUWT_Hot_Sheet_banner"Neutral advice from the IPCC?

By Richard Ingham (AFP) – 3 hours ago
PARIS — A leaden cloak of responsibility lies on the shoulders of UN scientists as they put the final touches to the first volume of a massive report that will give the world the most detailed picture yet of climate change.

Due to be unveiled in Stockholm on September 27, the document will be scrutinised word by word by green groups, fossil-fuel lobbies and governments to see if it will yank climate change out of prolonged political limbo.

The report will kick off the fifth assessment by the Intergovernmental Panel on Climate Change (IPCC), an expert body set up in 1988 to provide neutral advice on global warming and its impacts.  http://www.google.com/hostednews/afp/article/ALeqM5hHmcL4DZjT-PZWhEHO3VDb5gjsrA?docId=CNG.db54bf0fa84dd93ad7cf71578fe1dcef.681

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Regarding your “Trenberth’s IPCC claim” post, you may like to mention Green & Armstrong (2007) (available here)  in which we addressed Trenberth’s IPCC-don’t-forecast line in some detail. As far as I’m aware, our subsequent paper (Green, Armstrong, & Soon 2009, here) provides the *only* forecast of global mean temperatures over the 21st Century. That is, we state that we are making a forecast (not a scenario or projection), the forecast is stated clearly (annual average temperatures will be within 0.5 C of the 2008 figure), and is unconditional (no matter what happens to CO2 emissions, etc). Unlike Trenberth et al., who try to have it both ways by calling for “action” but aren’t prepared to say they are making forecasts, we stand by our forecast and the clear implication that government climate policies are neither needed nor desirable.

Cheers,  Dr Kesten C Green

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Park Service personnel recently discovered evidence of a buried forest dating back to at least 1170 AD high in the Forelands near the current glacier’s edge…Exit Glacier advanced from the Harding Icefield during the Little Ice Age, burying this existing forest and  advancing to a maximum marked by the terminal moraine dated to 1815…

http://www.nps.gov/kefj/naturescience/upload/The%20Retreat%20of%20Exit%20Glacier.pdf

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It’s baaaaaaack….

Eastern US water supplies threatened by a legacy of acid rain
Noted ecologist Gene Likens, founding director of the Cary Institute of Ecosystem Studies and a co-discoverer of acid rain, was among the study’s authors. The extent of alkalinity change in streams and rivers exceeded his expectations: “This is another example of the widespread impact humans are having on natural systems. Policymakers and the public think that the acid rain problem has gone away, but it has not.”

http://www.eurekalert.org/pub_releases/2013-08/cioe-euw082613.php

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Dr. Roy Spencer continues his greenhouse experiments:

In Part I of this series, I mentioned how Wood’s (1909) “greenhouse box” experiment, which he claimed suggested that a real greenhouse did not operate through “trapping” of infrared radiation, was probably not described well enough to conclude anything of substance. I provided Wood’s original published “Note”, which was only a few paragraphs, and in which he admitted that he covered the issue in only cursory detail.

Wood’s experiment was not described well enough to replicate. We have no idea how much sunlight was passed through his plate of rock salt-covered box versus the glass-covered box. We also don’t know exactly how he placed another glass window over the rock salt window, which if it was very close at all, invalidated the whole experiment.

http://www.drroyspencer.com/2013/08/revisiting-woods-1909-greenhouse-box-experiment-part-ii-first-results/

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New witch hunt: “Environmental Campaign Suggests Naming Vicious Storms After Climate-Change Deniers”

Environmental Campaign Suggests Naming Vicious Storms After Climate-Change Deniers

New York agency Barton F. Graf has turned its roguish attention to the issue of climate change, and is helping 350 Action, a climate change activist group, with the amusing video below. According to the YouTube description: “Since 1954, the World Meteorological Organization has been naming extreme storms after people. But we propose a new naming system. One that names extreme storms caused by climate change, after the policy makers who deny climate change and obstruct climate policy. If you agree, sign the petition at climatenamechange.org.” The snarky tone preaches to the choir, but it’s hard to resist lines like, “If you value your life, please seek shelter from Michele Bachmann.”

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Satellite temps flat for 200 months now
by Werner Brozek
If the global warming era started in June 1988 with Jim Hansen’s drama-queen congressional testimony, then atmospheric temps have been flat 67% of the time since.

Read more at WUWT.

” data-medium-file=”” data-large-file=”” class=”wp-image-92425 size-full” src=”https://eos.org/wp-content/uploads/2018/02/bujumbura-lake-tanganyika.jpg?x35494″ alt=”A comprehensive review of paleotemperature reconstructions paints a picture of warm onshore temperatures across Afro-Arabia between 1000 and 1200 AD.” scale=”0″ width=”500″ height=”376″>

To better characterize temperature fluctuations in Africa and Arabia during medieval times, researchers synthesized paleotemperature records from across the region, including the Tanzanian portion of Lake Tanganyika (pictured here). A core from this lake represents one of the few medieval paleotemperature reconstructions that are available from the East Africa Rift. Credit: Andreas31, CC BY-SA 3.0

The results indicate that the majority of onshore Afro-Arabian sites experienced warming during the Medieval Climate Anomaly. The one exception was the southern Levant, which endured a cold phase during the same interval. From offshore records, the team also documented cooling in locations that currently experience cold-water upwellings but generally warmer conditions away from these upwelling zones during the same period.


AT AMAZON, save on Flashlights. You can never have too many. A lantern or two is nice to have as well, for power outages.


In some records, the researchers noted the presence of obvious cold spikes during intervals corresponding to decreased solar activity or declining ocean cycles. This, they argue, suggests that solar forcing and changing ocean circulation are the most likely causes of medieval era climate change.

This study represents a step toward globally characterizing the Medieval Climate Anomaly, an improved understanding of which will help scientists refine global climate models and improve hindcasting. To date, however, very few paleotemperature data exist from Afro-Arabia; the authors note that all of West Africa is currently represented by a single data point. Systematic research will be necessary to adequately reconstruct medieval paleotemperature patterns and their causes across this vast region. (Paleoceanography and Paleoclimatologyhttps://doi.org/10.1002/2017PA003237, 2017)


Warming and Cooling: The Medieval Climate Anomaly in Africa and Arabia

Sebastian Lüning, Mariusz Gałka, Fritz Vahrenholt

Abstract

The Medieval Climate Anomaly (MCA) is a well-recognized climate perturbation in many parts of the world, with a core period of 1000–1200 Common Era. Here we present a palaeotemperature synthesis for the MCA in Africa and Arabia, based on 44 published localities. The data sets have been thoroughly correlated and the MCA trends palaeoclimatologically mapped. The vast majority of available Afro-Arabian onshore sites suggest a warm MCA, with the exception of the southern Levant where the MCA appears to have been cold. MCA cooling has also been documented in many segments of the circum-Africa-Arabian upwelling systems, as a result of changes in the wind systems which were leading to an intensification of cold water upwelling. Offshore cores from outside upwelling systems mostly show warm MCA conditions. The most likely key drivers of the observed medieval climate change are solar forcing and ocean cycles. Conspicuous cold spikes during the earliest and latest MCA may help to discriminate between solar (Oort Minimum) and ocean cycle (Atlantic Multidecadal Oscillation, AMO) influence. Compared to its large share of nearly one quarter of the world’s landmass, data from Africa and Arabia are significantly underrepresented in global temperature reconstructions of the past 2,000 years. Onshore data are still absent for most regions in Africa and Arabia, except for regional data clusters in Morocco, South Africa, the East African Rift, and the Levant coast. In order to reconstruct land palaeotemperatures more robustly over Africa and Arabia, a systematic research program is needed.

CONTINUE READING –>

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