The signal to noise ratio around here seems to be pretty low, as often happens with these global warming posts.
I just want to point out some of the actual content of the Nature Climate Change article (not the ridiculous Register article).
What was actually recorded/measured? The proxy record in question is an estimate of summer temperature within a part of Scandinavia for the past ~2000 years. This is no small feat. But, it is important to recognize this (1) not a global temperature record, and not even a 'hemispheric' land record [which would involve aggregating far more data]. (2) it is also not an annual mean temperature record.
So right off the bat you know that saying ANYTHING AT ALL about changes in global mean, annual mean temperature (which lies at the heart of climate science) is going to involve a lot of conjecture and hand-waving. So go ahead and skip over 90% of the posts in response to this article and probably most of the internet, since they do not have much to do with this article.
Do these data provide a challenge to either prior data or model results? With respect to data, please see the prior point. One regional, seasonal temperature series, however good, and however important, is not enough to overturn itself a suite of other data. It simply adds an interesting nuance and fills in some data gaps.
With respect to implications for modeling the future, note that the article explicitly states that this Scandinavian summer warmth is predicted by models. These are the same models we use to the predict the future. Thus this study is a vindication of coupled (ocean+atmosphere) models to accurately reproduce the regional pattern of climate change to well established (orbital variations) forcings.
One note on the magnitude of the 'forcing'. There is a bit of misleading language in the article and I see it echoed in posts here with regards to the magnitude of orbital forcing. There is NO ANNUAL MEAN/GLOBAL MEAN radiative forcing at the top of the atmosphere introduced by obliquity and precession (the orbital bands changing here). The forcing is entirely regional (i.e. at that latitude) and seasonal (more radiation in summer exactly cancelled by less in winter). It bears little resemblance to the forcing due to CO2 which does have a strong presence even in global and annual mean. The orbital forcing important for this problem is akin to holding a blowtorch to the mid-to-high latitude regions preferentially in summer. There is no surprise that it warms things. It tells us little about global temperatures or the global relationship between radiative forcing and temperature response.
Slashdot Mirror
-O3.
$$pls.
The signal to noise ratio around here seems to be pretty low, as often happens with these global warming posts.
I just want to point out some of the actual content of the Nature Climate Change article (not the ridiculous Register article).
What was actually recorded/measured?
The proxy record in question is an estimate of summer temperature within a part of Scandinavia for the past ~2000 years. This is no small feat. But, it is important to recognize this (1) not a global temperature record, and not even a 'hemispheric' land record [which would involve aggregating far more data]. (2) it is also not an annual mean temperature record.
So right off the bat you know that saying ANYTHING AT ALL about changes in global mean, annual mean temperature (which lies at the heart of climate science) is going to involve a lot of conjecture and hand-waving. So go ahead and skip over 90% of the posts in response to this article and probably most of the internet, since they do not have much to do with this article.
Do these data provide a challenge to either prior data or model results?
With respect to data, please see the prior point. One regional, seasonal temperature series, however good, and however important, is not enough to overturn itself a suite of other data. It simply adds an interesting nuance and fills in some data gaps.
With respect to implications for modeling the future, note that the article explicitly states that this Scandinavian summer warmth is predicted by models. These are the same models we use to the predict the future. Thus this study is a vindication of coupled (ocean+atmosphere) models to accurately reproduce the regional pattern of climate change to well established (orbital variations) forcings.
One note on the magnitude of the 'forcing'. There is a bit of misleading language in the article and I see it echoed in posts here with regards to the magnitude of orbital forcing. There is NO ANNUAL MEAN/GLOBAL MEAN radiative forcing at the top of the atmosphere introduced by obliquity and precession (the orbital bands changing here). The forcing is entirely regional (i.e. at that latitude) and seasonal (more radiation in summer exactly cancelled by less in winter). It bears little resemblance to the forcing due to CO2 which does have a strong presence even in global and annual mean. The orbital forcing important for this problem is akin to holding a blowtorch to the mid-to-high latitude regions preferentially in summer. There is no surprise that it warms things. It tells us little about global temperatures or the global relationship between radiative forcing and temperature response.