Saturday, August 9, 2014

New paper finds another non-hockey-stick in Norway

A new paper published in Quaternary Science Reviews reconstructs land and sea surface temperatures in Norway since the last ice age and shows land surface temperatures during the early Holocene ~7,000 years ago were approximately the same as at the end of the record in ~2010. The data also shows sea surface temperatures near Norway were warmer during the Medieval Warm Period 1000 years ago and Roman Warm Period ~2000 years ago in comparison to the end of that record in ~2004. 

The paper joins more than 1000 other non-hockey-sticks published in the literature demonstrating global temperatures were naturally as warm or warmer than the present over the past 10,000 years. 

Reconstructed temperature in left graph starting from ~25,000 years ago during the last ice age. Horizontal axis on left graph is thousands of years before the present. Red line is land temperatures, blue line is sea surface temperatures, and black line is Atlantic inflow [which is stable and in middle of the range over the Holocene]. Note the final land temperature datapoint in ~2010 was one of the lowest since 1950. 

A brief history of climate – the northern seas from the Last Glacial Maximum to global warming

Northern maritime climate is presented from the LGM through to the 21st century.
The most complete temperature reconstruction for Norway and the Norwegian Sea to date.
The strength of the Norwegian Atlantic Current is quantified from the reconstruction.
One unified record of reconstructions, observations, and model projection.


The understanding of climate and climate change is fundamentally concerned with two things: a well-defined and sufficiently complete climate record to be explained, for example of observed temperature, and a relevant mechanistic framework for making closed and consistent inferences concerning cause-and-effect. This is the case for understanding observed climate, as it is the case for historical climate as reconstructed from proxy data and future climate as projected by models. The present study offers a holistic description of northern maritime climate – from the Last Glacial Maximum through to the projected global warming of the 21st century – in this context. It includes the compilation of the most complete temperature record for Norway and the Norwegian Sea to date based on the synthesis of available terrestrial and marine paleoclimate reconstructions into continuous times series, and their continuation into modern and future climate with the instrumental record and a model projection. The scientific literature on a variable northern climate is reviewed against this background, and with a particular emphasis on the role of the Norwegian Atlantic Current – the Gulf Stream's extension towards the Arctic. This includes the introduction of an explicit and relatively simple diagnostic relation to quantify the change in ocean circulation consistent with reconstructed ocean temperatures. It is found that maritime climate and the strength of the Norwegian Atlantic Current are closely related throughout the record. The nature of the relation is however qualitatively different as one progresses from the past, through the present, and into the future.

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