Project: Mapping the Medieval Warm Period

Projektbeschreibung auf deutsch HIER


Cartography of the Medieval Warm Period: Online atlas of a poorly understood warm phase

About 1000 years ago, large parts of the world experienced a prominent warm phase which in many cases reached a similar temperature level as today or even exceeded present-day warmth. While this Medieval Warm Period (MWP) has been documented in numerous case studies from around the globe, climate models still fail to reproduce this historical warm phase. The problem is openly conceded in the most recent IPCC report from 2013 (AR5, Working Group 1) where in chapter 5.3.5. the IPCC scientists admit (pdf here):

The reconstructed temperature differences between MCA and LIA […] indicate higher medieval temperatures over the NH continents […]. . The reconstructed MCA warming is higher than in the simulations, even for stronger TSI changes and individual simulations […] The enhanced gradients are not reproduced by model simulations … and are not robust when considering the reconstruction uncertainties and the limited proxy records in these tropical ocean regions […]. This precludes an assessment of the role of external forcing and/or internal variability in these reconstructed patterns.

Surprisingly, the media have not picked up on this important issue. Maybe because the information is hidden in small print on page 415 of the voluminous report and omitted in the Summary for Policy Makers? The implications of the mismatch of model vs. reality may be serious: It is common practice in all fields of modeling to test models first on existing data, i.e. a known development, before using them as predictive tools. Models first have to pass the ‚hind cast‘ or ‚history match‘ before they qualify to be used for predictions. According to the IPCC, the climate models seem to have failed this test, appear to be on the road without driving license – so to speak – and are therefore unfit for future climate predictions.

The main questions therefore are: How could it have been so warm one thousand years ago when CO2 concentrations in the atmosphere were on a low pre-industrial level? Which climate drivers could have triggered the MWP warming, that seem to be underrepresented in the current climate models? How would temperature prognoses change when climate models are used that fully account for the MWP warming?

A robust documentation of the MWP forms the basis of this overdue discussion. Unfortunately, there are still voices in the debate that describe the MWP as a local phenomenon, or as a warm phase that globally was much colder than the Modern Warm Period of the 20th and early 21st centuries. There are still press releases written on papers that seem to disprove the MWP concept, even though these studies are outliers or may fit very well into the MWP scheme when considering the full context.

The current MWP mapping project aims to fully evaluate and provide reference access to the existing literature on the global climate history of the past 1500 years. The seed point is provided by the MWP summaries provided by the Medieval Warm Period Project by CO2 Science. Meanwhile, a large amount of additional, new literature has been identified. The data is visualized on a zoomable Google Maps platform which provides userfriendly access. A click on the respective datapoint opens an information panel which summarizes the results of the study using a common, simplifying scheme. Links to the journal abstract and key figure allow quick access to the data. If you like, try it out youself and open the MWP Online Map.

The MWP Mapping Project will help to shed new light on a number of controversial issues: In which regions of the world has MWP warming been documented, in which areas is the MWP warmth missing? Are there regional trends with regards to the onset and termination of the warm phase? What shifts in rainfall did occur? The map is freely accessible on the internet in order to allow maximum distribution among all participants of the climate change debate. The MWP synthesis aims to serve as a neutral facts platform for discussions on the MWP and to provide important paleoclimatological context for modern climate change developments.


Current Status (1 November 2018)

The project has started in late 2015 and since then has made good progress. Initially, the focus was on regions with limited existing data to cover as much area as possible. A synthesis paper on the MWP temperatures in Africa has been published in 2017 in Paleoceanography. A paper on the MWP African hydroclimate came out in Palaeo3 in February 2018. The South America MWP temperature synthesis was published in Octover 2018 in Quaternary International.

During the project startup phase MWP blogposts on Australia/Oceania, Antarctica and a review of the Young et al. 2015 paper on Baffin Island have been published on WUWT. It quickly became clear that in hot regions of the world, the palaeoclimatological reconstructions focus more on precipitation changes (arid vs. humid), rather than on temperature changes. When you click on the MWP online map you see five colours:

red: MWP warming
blue: MWP cooling (very rare)

yellow: MWP more arid
green: MWP more humid

grey: no trend or data ambiguous


Most of western North America and Africa were experiencing drought conditions during the MWP (except some areas in Southwest Africa). In contrast, Australia and the Carribean was more humid. Globally, the majority of all paleoclimatic temperature studies compiled in the map so far show a prominent warming during the MWP. This includes Antarctica and the Arctic.



We Need Your Support

The project requires time-consuming data acquisition, processing, research and map compilation which requires manpower processing support. Additional costs arise from IT, literature, and possible publication fees. The total project budget has been calculated at €25.000 (=US $27,180) which works out at less than US$ 4000 per continent. Currently, about 60% of the total project sum has been secured, donated through crowd funding. We hope for your active support to find the remaining funds to allow completion of the project.

Please support the Medieval Warm Period Project, e.g. via Paypal:


Please let us also know in the subject line, if your full name can appear in the official list of project sponsors (“list-Yes”, “list-No”). If you do not add „list-Yes“ we will assume that you prefer to stay anonymous.


A big Thank You to our Sponsors!

We want to thank all sponsors who have already contributed to the MWP mapping project. Your help is much appreciated. Find below the fundraising thermometer and list of sponsors:



Received via Paypal:

€ 200 Donation by M.P.
€ 20 Donation by T.S.
€ 25 Donation by A.S.
€ 20 Donation by Hans Euler
€100 Donation by Klaus Öllerer
€100 Donation by H.F.
US$30 Donation by T.H.
€80 Donation by K.R.
€30 Donation by G.O.
€8 Donation by G.T.
€50 Donation by D.K.
€100 Donation by T.V.
€25 Donation by U.J.
€50 Donation by G.M.
€200 Donation by E.W.
€10 Donation by W.L.
US$75 Donation by R.H.
€25 Donation by A.R.
€25 Donation by A.S.
€50 Donation by K.R.
€15 Donation by H.S.
€10 Donation by O.W.
€20 Donation by C.V.
€10 Donation by G.G.
€100 Donation by F.S.
€25 Donation by J.P.
€100 Donation by H.K.
€150 Donation by G.R.
€10 Donation by T.P.
€50 Donation by Edgar Alt
€100 Donation by M.R.
€20 Donation by J.H.
€25 Donation by A.R.
€15 Donation by Berthold Robert
€200 Donation by J.R.
€50 Donation by J.B.
€100 Donation by H.S.
€200 Donation by R.D.
€25 Donation by Jens Bornmüller
€50 Donation by F.S.
€100 Donation by Dr. Ulrich Steiner
€300 Donation by H.S.
US$250 Donation by W.R.
US$40 Donation by C.K.
US$15 Donation by T.T.
US$20 Donation by B.P.
€150   Donation by P.W.
US$40 Donation by S.W.
US$25 Donation by R.M.
US$10 Donation by L.B.
US$10 Donation by D.H.
US$20 Donation by H.G.
US$10 Donation by J.R.
US$25 Donation by G.J.
US$50 Donation by A.G.
US$25 Donation by G.E.
US$50 Donation by W.B.
US$50 Donation by A.S.
US$15 Donation by J.H.
€100   Donation by Hans Fischer
US$50 Donation by R.L.


Received via bank transfer:

€25 Donation by Christiane Grunenberg
€25 Donation by Michael Grunenberg
€100 Donation by W.S.
€250 Donation by H.S.
€30 Donation by K.W.
€5000 Donation by J.K.
€50 Donation by N.F.
€10 Donation by K.S.
€50 Donation by Oliver Slota
€50 Donation by V.B.
€50 Donation by Uli Weber
€25 Donation by G.R.
€200 Donation by S.D.
€100 Donation by W.D.
€50 Donation by Arnd Externbrink
€50 Donation by Hans-Joachim Dammschneider
€100 Donation by T.F.
€25 Donation by C.K.
€25 Donation by K.M.
€300 Donation by H.B.
€100 Donation by J.Z.
€150 Donation by V.B.
€100 Donation by S.S.
€500 Donation by W.B.
€500 Donation by Prof. Rainer Frank Elsaesser
€59 Donation by G.G.
€100 Donation by R.B.
€50 Donation by N.S.
€200 Donation by J.S.
€50 Donation by W.R.
€100 Donation by H.B.
€300 Donation by I.K.
€50 Donation by E.E.
€28 Donation by M.B.
€50 Donation by Uli Weber
€2000 Donation by C.U.
€100 Donation by Jochen Zimmermann
€50 Donation by D.K.
US$25 Donation by MA
US$30 Donation by J.P.
€100 Donation by S.K.