by J. Taylor, October 3, 2019 in ClimateChangeDispatch
Climate alarmists Michael Mann and Katharine Hayhoe have been caught using dubious, revisionist temperature data in their attempt, as one Climategate email author put it, to “deal a mortal blow” to the extensively documented Medieval Warm Period.
Before climate change became a political issue, it was scientifically well-established that a significant global warming event occurred between approximately 900 AD and 1200 AD.
For example, the United Nations Intergovernmental Panel on Climate Change (IPCC) First Assessment Report presented a temperature history and visual graph documenting that the Medieval Warm Period existed and that it brought temperatures at least as warm as today (at pg. 7).
Multiple peer-reviewed studies provided additional confirmation of the Medieval Warm Period.
The warming climate of the Medieval Warm Period spurred abundant crop production, fewer extreme droughts and floods, a growing human population, and improving living standards.
The Little Ice Age terminated the Medieval Warm Period and brought devastating weather extremes, widespread crop failures, famines, plagues like the Black Death, and a contracting human population.
For a good summary of the extensive benefits of the Medieval Warm Period and the devastating harms of the Little Ice Age, see the excellent book, “In the Wake of the Plague: The Black Death and the World It Created.”
by K. Richard, September 26, 2019 in NoTricksZone
Greta Thunberg lives in Sweden. According to peer-reviewed science, Sweden was at least 3°C warmer than it is today about 6000 to 9000 years ago, when CO2 concentrations lingered around 265 ppm. At 410 ppm CO2, 21st century Sweden is colder now than almost any time in the last 9000 years.
A Much Warmer Northern Hemisphere
During the Medieval Warm Period, wine vineyards flourished in Scandinavia and Russia at the same latitude (55°N) where polar bears roam today.
by P. Gosselin, Sep. 3, 2019 in ClimateChangeDispatch
More than 1,200 publications show the Medieval Warm Period (MWP) was global – an embarrassment to global warming alarmists who claimed it was regional.
Global-warming-alarmist scientists like claiming that the well-documented Medieval Warm Period (MWP) was mostly a regional, North Atlantic phenomenon, and was not global, and so we should just move along and stop questioning man-made global warming.
For example, the online Britannica entry on the Medieval Warm Period written by John P. Rafferty writes that it occurred “predominantly in the Northern Hemisphere from Greenland eastward through Europe and parts of Asia.”
Britannica does state that the claim of a global extent is highly controversial, though it really isn’t as we are about to see.
More than 1,200 papers evidence it was global
Indeed the claim that it was global is now backed up by a huge body of scientific studies meticulously compiled by Dr. Sebastian Lüning of Die kalte Sonne and presented at Google Maps here.
by P. Homewood, July 29, 2019 in NotaLotofPeopleKnowThat
There have been many attempts to get rid of the Medieval Warming Period and Little Ice Age, and here’s another one:
The science teams reconstructed the climate conditions that existed over the past 2,000 years using 700 proxy records of temperature changes, including tree rings, corals and lake sediments. They determined that none of these climate events occurred on a global scale.
As with the other failed attempts, this latest one claims that the MWP and LIA were only localised phenomena. But nothing could be further from the truth.
These three new studies rely on proxies, but time and again hockey stick studies based on proxies are proven to be fake, based on cherry picked proxies and dodgy statistics.
In fact, we have no need to rely on proxies, because the actual evidence of warm and cold periods is very real and substantial across the world.
We are all familiar with the evidence from Greenland ice cores, which clearly show both the MWP and LIA:
by Larry Hamlin, July 28, 2019 in WUWT
The Los Angeles Times is at it again hyping anti science climate alarmist propaganda trying to conceal the global wide Medieval Warm Period and the Little Ice Age that are supported and justified by hundreds of scientific studies.
This climate alarmist propaganda Times article cites a new “study” that ridiculously attempts to deny these clearly established warm and cool periods in our past.
This alarmist hyped new “study” is addressed in a superb article at the JoNova website demonstrating the complete lack of scientific veracity of this studies claims.
There is nothing I can add to show how politically contrived and inane the claims are from this new “study” beyond the excellent presentation in the JoNova article.
Provided below are excerpts from this excellent article which demonstrate the lack of scientific credibility of the new “study” as well as the politically driven anti science climate alarmism bias of the Times.
by K. Richard, July 25, 2019 in NoTricksZone
About 45 years ago, the “consensus” in climate science (as summarized by Williamson, 1975) was quite different than today’s version.
1. The Medieval Warm Period was about 1°C warmer than present overall while the “largely ice-free” Arctic was 4°C warmer, allowing the Vikings to navigate through open waters because there was “no or very little ice” at that time.
2. The island of Spitsbergen, 1237 km from the North Pole and home to over 2000 people, “benefited” because it warmed by 8°C between 1900 and 1940, resulting in 7 months of sea-ice free regional waters. This was up from just 3 months in the 1800s.
3. Central England temperatures dropped -0.5°C between the 1930s to the 1950s.
4. Pack-ice off northern and eastern iceland returned to its 1880s extent between 1958 and 1975.
5. In the 1960s, polar bears were able to walk across the sea (ice) from Greenland to Iceland for the first time since the early 1900s. (They had somehow survived the 7 months per year of sea-ice-free waters during the 1920s-1940s).
by Lüning et al., July 6, 2019 in NoTricksZone
For a long time it has been said that the Medieval Warm Period was a purely North Atlantic phenomenon. This has proved to be wrong.
On 29 June 2019, a paper by Lüning et al. 2019 on the Medieval Warm Period in Antarctica appeared in the trade journal Palaeogeography, Palaeoclimatology, Palaeoecology. Here is the abstract:
With the publication of this paper, the Medieval Climate Anomaly (MCA) has now been confirmed on all four continents of the southern hemisphere.
While the largest part of the southern hemisphere apparently experienced a warm phase during the MCA, there were also isolated areas that cooled down. To the latter regions belong, for example, coasts, where cold water from the depth rose increasingly. In other areas so-called climate seesaws or dipoles were active, as we know them from today’s climate. One end of the “seesaw” heats up, the other end cools down.
Another result of the studies is that the medieval climate history of huge areas in the southern hemisphere is simply unknown. A task force urgently needs to be set up to fill in this climatic “empty space” with information on pre-industrial temperature development. This information is urgently needed to calibrate the climate models on the basis of which far-reaching socio-political planning is currently taking place.
What follows are publications on the Medieval Period climate of the southern hemisphere as an overview:
Lüning, S., M. Gałka, F. Vahrenholt (2019): The Medieval Climate Anomaly in Antarctica. Palaeogeogr., Palaeoclimatol., Palaeoecol., doi: 10.1016/j.palaeo.2019.109251
by P. Gosselin, June 19, 2019 in NoTricksZone
Dry summers were not rare 1000 years ago. Researchers from the University of Greifswald’s research group ‘Landscape Ecology and Ecosystem Dynamics’ have been able to reconstruct 1000 years of the dry summer period in northern Germany.
Beech forest – photo: Dr. Tobias Scharnweber
The article ‘Removing the no-analogue bias in modern accelerated tree growth leads to stronger medieval drought’ was published in 2019’s February edition of the journal Scientific Reports.
As part of the current collaborative research project BaltRap (The Baltic Sea and its Southern Lowlands: Proxy-Environment interactions in times of rapid changes), the researchers investigated growth rings in nearly 2000 living beech trees – including some from the university’s own Elisenhain forest – and archaeological wood used for construction from around 1000 A.D. The growth rings found in this wood are a unique archive of previous environmental conditions. If the climatic conditions are good, growth rings are wide; in unfavourable years, like in dry 2018, there is little growth. Dendroclimatology uses this correlation to reconstruct past environmental conditions.
by Marcia Wendorf, May 15, 2019 in InterestingEngineering
Between 1300 and 1850, the Earth experienced a Little Ice Age whose cause to this day is not known.
During the period 950 CE to 1250 CE, the earth experienced an unusually warm period, which became known as the Medieval Warm Period (MWP) or the Medieval Climatic Anomaly. At their height, temperatures during that period were similar to those experienced during earth’s mid-20th-century warming period.
Following the Medieval Warm Period came a period of intense cold, which has become known as the Little Ice Age (LIA). The term “Little Ice Age” was coined by Dutch-born American geologist F.E. Matthes in 1939. The LIA began around 1300 CE and lasted until about 1850 CE.
Within that stretch, NASA’s Earth Observatory has described three particularly cold periods: one around 1650, a second around 1770, and the third around 1850.
by Don J. Easterbrook, 2011 in ScienceDirect
The Medieval Warm Period (MWP) was a time of warm climate from about 900 A.D. to 1300 A.D. when global temperatures were apparently somewhat warmer than at present. Its effects were evident in Europe where grain crops flourished, alpine tree lines rose, many new cities arose, and the population more than doubled. The Vikings took advantage of the climatic amelioration to colonize Greenland, and wine grapes were grown as far north as England where growing grapes is now not feasible and about 500 km north of present vineyards in France and Germany. Grapes are presently grown in Germany up to elevations of about 560 m, but from about 1100 A.D. to 1300 A.D., vineyards extended up to 780 m, implying temperatures warmer by about 1.0–1.4 °C (Oliver, 1973).
by I.B. Bauhi & S. Akçer-Ön, August 30, 2018 in QuaternaryInternational
by Lüning et al., 2018 in NoTricksZone
Global warming alarmist scientists like claiming that the well documented Medieval Warm Period (MWP) was merely a regional phenomenon, and not global. However a new publication by Lüning et al adds yet another study that shows the warm period from 1000 years ago was indeed global.
by Kirye, October 23, 2048 in NoTricksZone
Dr. Fukai also points out that global vegetation coverage increased by 11% in 29 years, from 1982 to 2010, as increasing CO2 has helped the greening of the Sahel and Sahara Desert. He contradicts the often heard media claims that drought is spreading globally, writing: “The media spread the word that desertification is progressing globally, but practically the desert is greening through CO2.” […] “Everyone should be aware that increasing CO2 concentrations in atmosphere is not in itself harmful, but it’s a good thing.”
Dr. Fukai also shows that the earth’s temperature change is not simple and does not correlate at all with CO2. He shows graphs from D. M. Etheridge et al., Mauna Loa Observatory and the temperature data from Moberg et al. (2005).
The retired Japanese professor writes that at around 1000 A.D. — the Medieval Warm Period — there were no signs showing CO2 concentration was higher. A temperature graph using data from Moberg et al. (2005) shows the Medieval Warm Period appears clearly and that CO2 was in fact around 280 ppm at that time.
by S. Lüning, January 9, 2018 in WUWT
The climate of the pre-industrial past is of greatest importance to the ongoing climate discussion. Current climate can only be understood when interpreting it in the paleoclimatological context of the past few thousand years. Until not too long ago it was thought that the pre-industrial climate was monotonous and constant. This idea was e.g. promoted by Mann et al. whose famous hockey stick curve featured prominently in the IPCC report of 2001. Over the last 15 years, however, a large number of studies changed this view by providing robust evidence for the existence of significant natural climate variability. Of particular interest are the past 1000 years which commenced with the generally warm ‘Medieval Climate Anomaly’ (MCA, aka ‘Medieval Warm Period’, MWP), that eventually passed into the ‘Little Ice Age’ (LIA), before returning to the warm climate of the current ‘Modern Warm Period’ of the 20th and early 21st centuries.
There have been controversial debates about the existence of the MWP, …
by K. Richard, April 2, 2018
Canada’s stable-to-increasing polar bear population extends its range slightly further south of the 55th parallel (York et al., 2016).
According to published geological evidence from the 1950s, remnants of wine grape vineyards have been unearthed in regions as far north as the polar-bear-inhabiting 55th parallel during the Medieval Warm Period (~800s to 1300s AD).