German geologist and the author of climate science-critical book The Neglected Sun, Dr. Sebastian Lüning has entered his Medieval Warming Period Map in the French government sponsored contest “100 Projects For The Climate“.
Right: Dr. Sebastian Lüning. Photo Die kalte Sonne.
Within the scope of the 100 Projects For The Climate campaign, French Minister of Environment Ségolène Royal created an Internet platform that has the aim of promoting the 100 most innovative citizens’ initiatives for climate. This is all taking place as part of the April 2016 Environment Conference in Paris. Background here.
Lüning’s outstanding Medieval Warming Period (MWP) climate mapping tool allows users to click on any of the numerous flags on the map to call up studies that examine the Medieval Warm Period climate for the that particular area.
(The “Vote” button is at bottom right side, click on “Crush”)
Clearly the studies are showing that the MWP was a global phenomenon, and not one that was isolated in the North Atlantic – as some scientists have tried to have us believe.
I posed some questions to Dr. Lüning about the project, and his fascinating answers follow:
What caused you to start the project?
The climate of the past 1000 years is still surprisingly poorly understood. Especially the Medieval Warm Period (MWP: 1000-1200 AD) lends itself as a key analogue to be compared with the 20th century warming. Which areas have warmed, which cooled during the MWP, and possible reasons. The project aims to come up with maps integrating a great number of studies which have been all too often ignored up to now.”
What surprises if any, did you find?
At least half of all studies focus on changes in hydro-climate. Studies with information and trends on temperature are less frequent than I thought. About 95% of all temperature studies found a warming during the Medieval Warm Period. However there are also some case studies which found cooling. In most cases the cooling is associated with cold meltwater from glaciers that has cooled fjords. In other local cases wind direction changed and coastal upwelling brought colder waters to the surface. It is very important to distinguish regional trends from local developments and their origins.”
In your opinion, have the IPCC and models taken the MWP accurately into account?
Once the data acquisition and mapping is completed, I will take a close look at the AR5 IPCC report to better understand the IPCC database and reporting.”
So far, does your analysis show the MWP was global?
Yes. Especially the wide distribution of MWP warming in Antarctica was surprisingly obvious. It becomes ever clearer that the MWP was not restricted to the Northern Hemisphere. Apart from the temperature curve, the MWP also led to major changes in hydro-climate. This is probably the second key result of the mapping so far. Areas with trends of wetter and drier climate during the MWP can be mapped out, which previously were not always identified systematically.”
Do you think the IPCC needs to revise it’s view of the MWP?
The MWP warming is already recognized by the IPCC. Deep inside the AR5 report the authors admit that the models cannot reproduce the amount of warming identified in the case studies. The new MWP mapping will help to interpret the MWP on a much higher level of detail. It will help to compare apples to apples, and avoid averaging across regions with opposite trends, e.g. in hydro-climate. It will be easier to detect outliers, data errors, interpretation issues and age dating problems.”
What implications could your findings have for the models.
It is fundamental that climate models reproduce the past climate before they are used for future climate modelling. Noteworthy: solar activity during the MWP was equally high as during the late 20th century warming while it declined significantly during the cold Little Ice Age. The global MWP results will help to calibrate the climate models. It is likely that radiative forcing (RF) for solar activity changes has to be drastically increased while the RF of CO2 would have to be reduced accordingly. Climate modellers have to accept this challenge and be open for pragmatic solutions, independent of political constraints and implications.”
Little wonder CO2 climate forcing has been significantly revised downwards over the past decade.
The science is catching up to reality, but the politics will need some more time.”