Medieval Warm Period

Medieval castle

What is it?
Our Medieval Warm Period Project is an ongoing effort to document the magnitude and spatial and temporal distributions of a significant period of warmth that occurred approximately one thousand years ago. Its purpose is to ultimately determine if the Medieval Warm Period (1) was or was not global in extent, (2) was less warm than, equally as warm as, or even warmer than the Current Warm Period, and (3) was longer or shorter than the Current Warm Period has been to date.

Why is it?
The project’s reason for being derives from the claim of many scientists — and essentially all of the world’s radical environmentalists — that earth’s near-surface air temperature over the last few decades was higher than it has been during any similar period of the past millennium or more. This claim is of utmost importance to these climate alarmists; for it allows them to further claim there is something unnatural about recent and possibly ongoing warming, which allows them to claim that the warming has its origins in anthropogenic CO2 emissions, which allows them to claim that if humanity will abandon the burning of fossil fuels, we can slow and ultimately stop the warming of the modern era and thereby save the planet’s fragile ecosystems from being destroyed by catastrophic climate changes that they claim will otherwise drive a goodly percentage of earth’s plants and animals to extinction. Since these are serious contentions, we feel that their underlying basis must be rigorously tested with real-world data.

How is the project conducted?
As we discover new peer-reviewed scientific journal articles pertaining to the Medieval Warm Period, we briefly describe their most pertinent findings in the Study Descriptions and Results section of the project. The locations of all such studies are then plotted on a map of the globe, and the intervals of time they associate with the Medieval Warm Period are incorporated into a graph of the frequency distribution of all such time intervals, which is located just beneath the map in the project’s Interactive Map and Time Domain Plot feature. In extremely rare cases where only a single year is specified for the MWP, we assign it a 100-year timespan centered on the year reported by the study’s authors. For studies that allow the determination of an actual temperature difference between the Medieval Warm Period (MWP) and Current Warm Period (CWP), this number is incorporated into the frequency distribution of all such differentials in the project’s MWP-CWP Quantitative Temperature Differentials section. For studies that allow only a qualitative determination of the temperature difference between the MWP and CWP to be made, results are presented in the project’s MWP-CWP Qualitative Temperature Differentials section. Last of all, the names of all scientists and research institutions associated with the MWP Project studies we cite are included in our List of Scientists Whose Work We Cite and List of Research Institutions Associated With the Work We Cite.

When will the project end?
We believe there are enough pertinent studies already published, in the pipeline to be published, currently in progress and yet to be conceived to enable us to continue to add to the project on a weekly basis for an indefinite period of time.

How can you help?
You can help by alerting us to new (and old) research papers documenting the Medieval Warm Period that have not yet been posted on our website. When doing so, please send us a copy of the paper either by email (preferably in pdf format) or by post. Our contact information can be found here.

Study Description and Results
Australia/New Zealand
North America
Northern Hemisphere
South America

MWP-CWP Quantitative Temperature Differentials

MWP-CWP Qualitative Temperature Differentials

Interactive Map and Time Domain Plot
To view this feature, your computer must be configured to run applets that use Java technology.  To download and install free Java software, we recommend Sun Microsystems’ Java Runtime Environment, which is available at  Instructions on how to operate the map’s features are located under the map.  Scroll down after clicking on the link above to view them.

List of Scientists Whose Work We Cite

List of Research Institutions Associated With the Work We Cite

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NIPCC Report


The 2009 report of the Nongovernmental International Panel on Climate Change (NIPCC), Climate Change Reconsidered, was released on Tuesday, June 2, 2009, at a press conference at the Washington Court Hotel in Washington, DC, in conjunction with the Third International Conference on Climate Change. Heartland President Joseph Bast, editor of Climate Change Reconsidered, and authors Craig D. Idso Ph.D. and S. Fred Singer Ph.D. spoke at the press conference.

Watch the press conference by [watching the videos here], or read the text of the report by selecting the Chapters below. The report may also be purchased from



2009 Report Contents

Full Report PDF (7.8 MB)

Front Matter PDF (0.4 MB)

Chapter 1
Global Climate Models   PDF (0.3 MB)

Chapter 2
Feedback Factors and Radiative Forcing   PDF (0.6 MB)

Chapter 3
Observations: Temperature Records   PDF (2.4 MB)

Chapter 4
Observations: Glaciers, Sea Ice, Precipitation, and Sea Level   PDF (0.8 MB)

Chapter 5
Solar Variability and Climate Cycles   PDF (1.1 MB)

Chapter 6
Observations: Extreme Weather   PDF (0.7 MB)

Chapter 7
Biological Effects of Carbon Dioxide Enrichment   PDF (1.6 MB)

Chapter 8
Species Extinction   PDF (0.7 MB)

Chapter 9
Human Health Effects   PDF (0.5 MB)

Appendix 1: Acronyms   PDF (0.1 MB)

Appendix 2: Table 7.1.1 – Plant Dry Weight (Biomass) Responses to Atmospheric CO2 Enrichment   PDF (0.2 MB)

Appendix 3: Table 7.1.2 – Plant Photosynthesis Responses to Atmospheric CO2 Enrichment   PDF (0.2 MB)

Appendix 4: The Petition Project   PDF (1.8 MB)

Reviews HTML

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Polar Bears Thrive, Contrary to WWF Claims


You’ve probably seen the commercials; TV actor Noah Wyle (ER, The Librarian) somberly informs us of an impending grave catastrophe: “A tragedy is unfolding in the world today. Climate change is threatening one of the most magnificent wild animals on the planet. Polar bears. They’re struggling to survive.”

Heart-tugging violins accompany video footage of a mother polar bear and her cuddly cub on a small ice flow.

The ice is melting all around them and food is becoming harder to find as they lose their hunting grounds. Climate change. It’s happening right now and its leaving mothers weaker and unable to provide for their young and cubs dying without enough to eat. As the struggle and the search for food continues polar bears are hanging on for survival. Polar bears are on their way to extinction. If we don’t act now, most will die in our children’s lifetime. But you can change that. Call now and join the Wildlife Rescue Team. For just $16 a month you’ll be part of the most ambitious effort to save wildlife and wild places the world has ever seen…. If we don’t act now, it could be too late for the polar bear.

It is a fundraising appeal for the World Wildlife Fund (WWF), one of the wealthiest environmentalist groups on the planet. The implied message is that the mother bear and cub in the film have been caught by the camera crew in their last desperate gasps, victims of man-made global warming. We are supposed to believe from the images we see, based upon Wyle’s narration, that they are weak and starving and soon will be joining the other members of their rapidly dying species.

However, there are several big problems with this picture and message. First of all, there is no evidence provided in the commercial or by WWF in its literature or on its website that this particular polar bear and her cub are weak, starving, or in any distress whatsoever. For all we can tell they are healthy and happy, floating on their iceberg as polar bears do and have done since they’ve been around on this planet. It is only the narration and the music that suggest otherwise. But, more importantly, the main message of the commercial is a … big lie. No sense in mincing words. Completely contrary to the WWF’s maudlin claims that the cuddly predators are on “their way to extinction,” polar bear populations have been exploding. The number of polar bears in the world is four to five times greater than it was 50 years ago, increasing from around 5,000 to an estimated 25,000. 

Canadian biologist Dr. Mitchell Taylor, one of the foremost authorities on polar bears, says: “We’re seeing an increase in bears that’s really unprecedented, and in places where we’re seeing a decrease in the population it’s from hunting, not from climate change.” Dr. Taylor is a real scientist who actually goes out into the field and tracks, observes, tags, and counts polar bears and other arctic mammals. He has been doing this for over two decades, unlike the computer modelers who are making their dire predictions based on their own theoretical climate scenarios.


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The Dark Side of Solar Energy


Ed. note: With all the talk lately of solar panels being Earth’s salvation, especially at the G20 summit and China in particular, it seemed only appropriate to re-post the following article. Below is an excerpt from Sunburned: Solar’s Dirty Little Secrets from the May 2009 issue of Mac|Life.

Solar-powered gadgets have become de rigueur in our attempts at shrinking our carbon footprint. And utilizing the power of the sun is the one bright shining beacon of the alternative-energy movement. But there is a dark side to solar energy.

Materials used in solar panels are toxic.
Because solar is the hip, happening alt-energy trend du jour, the number of photovoltaic cells produced globally has increased dramatically in the past few years. But unfortunately, many of the solar panels manufactured today are made with cadmium, a highly toxic carcinogen that can cumulate in plant, animal, and human tissues. The Silicon Valley Toxics Coalition has recently published a 45-page report, “Toward a Just and Sustainable Solar Energy Industry,” claiming that many of the environmental risks associated with the production and disposal of solar panels are not currently being addressed by the industry.

And because solar panels have a shelf life of 20 to 30 years, the Coalition claims that the panels have the potential of creating the next wave of hazardous e-waste when they “die.” What to do? Clearly, as the solar industry grows, environmentalists and consumers must demand that manufacturers develop systems to ensure that solar panels are recycled and their hazardous toxins kept out of our ecosystem.

China is dumping hazardous waste from solar factories in fields.
According to the Washington Post, in the race to cash in on the world’s demand for solar products, China been leading the charge in producing polysilicon, a key component in sunlight-capturing wafers. Unfortunately, China is not enforcing environmental regulations, and many of the new factories are dumping toxic silicon tetrachloride (a byproduct of polysilicon production) directly into nearby farmlands. (Just for perspective, 4 tons of this toxic byproduct is produced for every ton of polysilicon.) Because it is expensive and time-consuming to set up systems to recycle the hazardous materials, companies are instead dumping indiscriminately, and people close to these sites are complaining of illness, crop failures, acrid air, and dead fields. How to proceed? Alt-energy companies around the globe need to make sure the factories from which they acquire their solar components are practicing environmentally responsible manufacturing.

We use fossil fuels to make green energy.
Yes, solar power produces clean energy, but it requires utilizing our current resources to produce it. For the green movement to be truly sustainable, we need to make sure we are not trading one environmental problem for another. Yes, the world needs renewable energy as our fossil fuels dwindle, but we need to make sure we are not polluting and depleting to acquire and perfect the new technology.

Read rest…

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Climate Change Dispatch

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Why the IPCC models are wrong

Dr. Roy Spencer explains the IPCC models under estimate natural feedbacks plus have sensitivities far more than the natural system has & therefore they greatly exaggerate what effect CO2 has on global temperatures.

Part 1:

Part 2:

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The Amazing Story Behind the Global Warming Scam

Roger Revelle

Roger Revelle, who later apologized for sending the UN IPCC and Al Gore on this wild goose chase called global warming

The following article is reprinted with permission. Visit Coleman’s Corner for more articles, posts, and information.

The key players are now all in place in Washington and in state governments across America to officially label carbon dioxide as a pollutant and enact laws that tax us citizens for our carbon footprints. Only two details stand in the way: the faltering economic times and a dramatic turn toward a colder climate. The last two bitter winters have led to a rise in public awareness that there is no runaway global warming. A majority of American citizens are now becoming skeptical of the claim that our carbon footprints, resulting from our use of fossil fuels, are going to lead to climatic calamities. But governments are not yet listening to the citizens.

How did we ever get to this point where bad science is driving big government to punish the citizens for living the good life that fossil fuels provide for us?

The story begins with an Oceanographer named Roger Revelle. He served with the Navy in World War II. After the war he became the Director of the Scripps Oceanographic Institute in La Jolla in San Diego, California. Revelle obtained major funding from the Navy to do measurements and research on the ocean around the Pacific Atolls where the US military was conducting post war atomic bomb tests. He greatly expanded the Institute’s areas of interest and among others hired Hans Suess, a noted Chemist from the University of Chicago. Suess was very interested in the traces of carbon in the environment from the burning of fossil fuels. Revelle co-authored a scientific paper with Suess in 1957—a paper that raised the possibility that the atmospheric carbon dioxide might be creating a greenhouse effect and causing atmospheric warming. The thrust of the paper was a plea for funding for more studies. Funding, frankly, is where Revelle’s mind was most of the time.

Next Revelle hired a Geochemist named David Keeling to devise a way to measure the atmospheric content of Carbon dioxide. In 1958 Keeling published his first paper showing the increase in carbon dioxide in the atmosphere and linking the increase to the burning of fossil fuels. These two research papers became the bedrock of the science of global warming, even though they offered no proof that carbon dioxide was in fact a greenhouse gas. In addition they failed to explain how this trace gas, only a tiny fraction of the atmosphere, could have any significant impact on temperatures.

Back in the1950s, when this was going on, our cities were entrapped in a pall of pollution left by the crude internal combustion engines and poorly refined gasoline that powered cars and trucks back then, and from the uncontrolled emissions from power plants and factories. There was a valid and serious concern about the health consequences of this pollution. As a result a strong environmental movement was developing to demand action.

Government heard that outcry and set new environmental standards. Scientists and engineers came to the rescue. New reformulated fuels were developed, as were new high tech, computer controlled, fuel injection engines and catalytic converters. By the mid seventies cars were no longer significant polluters, emitting only some carbon dioxide and water vapor from their tail pipes. New fuel processing and smoke stack scrubbers were added to industrial and power plants and their emissions were greatly reduced as well.

But an environmental movement had been established and its funding and very existence depended on having a continuing crisis issue. Roger Revelle’s research at the Scripps Institute had tricked a wave of scientific inquiry. So the concept of uncontrollable atmospheric warming from the increase in atmospheric carbon dioxide from the burning of fossil fuels became the cornerstone issue of the environmental movement. Automobiles and power planets became the prime targets.

Revelle and Keeling used this new alarmism to keep their funding growing. Other researchers with environmental motivations and a hunger for funding saw this developing and climbed aboard as well. The research grants flowed and alarming hypotheses began to show up everywhere.

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35 Inconvenient Truths

The errors in Al Gore’s movie

A spokesman for Al Gore has issued a questionable response to the news that in October 2007 the High Court in London had identified nine “errors” in his movie An Inconvenient Truth. The judge had stated that, if the UK Government had not agreed to send to every secondary school in England a corrected guidance note making clear the mainstream scientific position on these nine “errors”, he would have made a finding that the Government’s distribution of the film and the first draft of the guidance note earlier in 2007 to all English secondary schools had been an unlawful contravention of an Act of Parliament prohibiting the political indoctrination of children.

ImageAl Gore’s spokesman and “environment advisor,” Ms. Kalee Kreider, begins by saying that the film presented “thousands and thousands of facts.” It did not: just 2,000 “facts” in 93 minutes would have been one fact every three seconds. The film contained only a few dozen points, most of which will be seen to have been substantially inaccurate. The judge concentrated only on nine points which even the UK Government, to which Gore is a climate-change advisor, had to admit did not represent mainstream scientific opinion.

Ms. Kreider then states, incorrectly, that the judge himself had never used the term “errors.” In fact, the judge used the term “errors,” in inverted commas, throughout his judgment.

Next, Ms. Kreider makes some unjustifiable ad hominem attacks on Mr. Stewart Dimmock, the lorry driver, school governor and father of two school-age children who was the plaintiff in the case. This memorandum, however, will eschew any ad hominem response, and will concentrate exclusively on the 35 scientific inaccuracies and exaggerations in Gore’s movie.

Ms. Kreider then says, “The process of creating a 90-minute documentary from the original peer-reviewed science for an audience of moviegoers in the U.S. and around the world is complex.” However, the single web-page entitled “The Science” on the movie’s official website contains only two references to articles in the peer-reviewed scientific journals. There is also a reference to a document of the IPCC, but its documents are not independently peer-reviewed in the usual understanding of the term.

Ms. Kreider then says, “The judge stated clearly that he was not attempting to perform an analysis of the scientific questions in his ruling.” He did not need to. Each of the nine “errors” which he identified had been admitted by the UK Government to be inconsistent with the mainstream of scientific opinion.

Ms. Kreider says the IPCC’s results are sometimes “conservative,” and continues: “Vice President Gore tried to convey in good faith those threats that he views as the most serious.” Readers of the long list of errors described in this memorandum will decide for themselves whether Mr. Gore was acting in good faith. However, in this connection it is significant that each of the 35 errors listed below misstates the conclusions of the scientific literature or states that there is a threat where there is none or exaggerates the threat where there may be one. All of the errors point in one direction ‚Äì towards undue alarmism. Not one of the errors falls in the direction of underestimating the degree of concern in the scientific community. The likelihood that all 35 of the errors listed below could have fallen in one direction purely by inadvertence is less than 1 in 34 billion. Read the rest…

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Does CO2 from coal-fired power plants damage forests?

Carbon dioxide (CO2) is the principal gas that trees and other plants need to survive, just like oxygen (O2) is the principal gas that humans and other animals require. Trees absorb CO2 and release O2– animals inhale O2 and exhale CO2. See how nice this all works!

Earth’s first, primitive forests made their prolific debut 300 million years ago during the Carboniferous Period . Before then, the atmosphere held far more CO2 but concentrations declined throughout the Carboniferous Period as plants flourished.

During the Carboniferous Period the atmosphere became greatly depleted of CO2 (declining from about 2500 ppm to 350 ppm) so that by the end of the Carboniferous the CO2-impoverished atmosphere was less favorable to plant life and plant growth slowed dramatically. Today, CO2 concentrations are barely at 380 ppm (0.038% of our atmosphere) and most of that comes from entirely natural sources.

Carbon dioxide (CO2) is not to be confused with its poisonous evil cousin carbon monoxide (CO), which can kill humans and animals in just a few minutes. Life as we know it could not exist without carbon dioxide in our atmosphere.

Recent studies


Did you know …

Carbon dioxide is invisible. The puffs of clouds you see from coal-fired power plants are just that– clouds. Powerplants use steam to drive the turbines which generate electricity. Steam must be cooled and condensed to water to reuse it to make more steam.

The fat, curvy towers that look like they are belching white smoke are really only emitting pure water vapor. They are in effect making clouds.

The actual exhaust emissions come from the smokestack, which is the tall skinny tower. Because modern technology makes it possible to remove much of the fly ash and sulfur before releasing smokestack gases to the air, smokestack emissons today are often almost invisible.

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What is the main cause of Global Warming?

The Greenhouse Effect is not the major factor controlling Global Warming. The news media and certain politicians often speak of “global warming” and “greenhouse effect” interchangeably, like they were one and the same. This is misleading, because global warming occurs in cycles caused mainly by changes in the sun’s energy output and the sun’s position relative to the earth.

Major Causes of Global Temperature Shifts:

(1) Astronomical Causes

  • 11 year and 206 year cycles: Cycles of solar variability ( sunspot activity )
  • 21,000 year cycle: Earth’s combined tilt and elliptical orbit around the Sun ( precession of the equinoxes )
  • 41,000 year cycle: Cycle of the +/- 1.5¬∞ wobble in Earth’s orbit ( tilt )
  • 100,000 year cycle: Variations in the shape of Earth’s elliptical orbit ( cycle of eccentricity )

(2) Atmospheric Causes

  • Heat retention: Due to atmospheric gases, mostly gaseous water vapor (not droplets), also carbon dioxide, methane, and a few other miscellaneous gases– the “greenhouse effect”
  • Solar reflectivity: Due to white clouds, volcanic dust, polar ice caps

(3) Tectonic Causes

  • Landmass distribution: Shifting continents (continental drift) causing changes in circulatory patterns of ocean currents. It seems that whenever there is a large land mass at one of the Earth’s poles, either the north pole or south pole, there are ice ages.
  • Undersea ridge activity: “Sea floor spreading” (associated with continental drift) causing variations in ocean displacement.

For more details see:

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