Skip to content

Climate variability in Northern Europe

November 19, 2012

A report from the World Bank is making rounds in media today. While portraying catastrophic scenarios, it contains no new actual research and is simply extrapolating statistical possibilities. Unfortunately the media headlines aren’t really reflecting the content – not unusual regardless of the topic.

However, it does give me an opportunity to post about some actual research that has taken place since the last IPCC report, while we wait for the new one to come out next year. The focus is on Scandinavia, both since I live here as well as it being one of the places where extensive climate proxies exist.

(Most Swedes know that in our recent history the climate has been both a lot colder as well as nice and balmy. We have no reason to believe our climate should stabilize)

“The level of warmth during the peak of the MWP (Medieval Warm Period) in the second half of the 10th century, equaling or slightly exceeding the mid-20th century warming, is in agreement with the results from other more recent large-scale multi-proxy temperature reconstructions.”


– B. Christiansen and F. C. LjungqvistThe extra-tropical Northern Hemisphere temperature in the last two millennia: reconstructions of low-frequency variabilityClimate of the Past


“The record provides evidence for substantial warmth during Roman and Medieval times, larger in extent and longer in duration than 20th century warmth.”


–  Esper et. al, Variability and extremes of northern Scandinavian summer temperatures over the past two millenniaGlobal and Planetary Change

And maybe one of the more interesting ones. This is an updated reconstruction by Briffa, famous for having authored one of the hockey sticks used by the IPCC. Apparently the stick has now disappeared.

Some previous work found that MXD and TRW chronologies from Torneträsk were inconsistent over the most recent 200 years, even though they both reflect predominantly summer temperature influences on tree growth. We show that this was partly a result of systematic bias in MXD data measurements and partly a result of inhomogeneous sample selection from living trees (modern sample bias). We use refinements of the simple Regional Curve Standardisation (RCS) method of chronology construction to identify and mitigate these biases. The new MXD and TRW chronologies now present a largely consistent picture of long-timescale changes in past summer temperature in this region over their full length, indicating similar levels of summer warmth in the medieval period (MWP, c. CE 900–1100) and the latter half of the 20th century.


– T. M. Melvin, H. Grudd and K. R. BriffaPotential bias in ‘updating’ tree-ring chronologies using regional curve standardisation: Re-processing 1500 years of Torneträsk density and ring-width data, The Holocene


I’m quite Popperian when it comes to science. Feel free to voice hypotheses, but if they’re falsified they need to be scrapped and new ones looked into. There are many competing explanations as to how and why the climate on Earth changes and we’re not doing society a favor by only talking about one of them.

Especially when the actual science does not support the hyperbole.

No comments yet

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: