This month’s open thread. We’re going to guess that most of what people want to talk about is related to the IPCC WG1 AR5 report… Have at it!
Unforced variations: Sept. 2013
This month’s open thread… Expect pre-IPCC report discussion (SPM due on Sep 27, full report (pre-copy-editing) Sep 30th), analysis of this years Arctic ice cover minimum, and a host of the usual distractions.
Unforced variations: August 2013
This month’s open thread.
Since there are two main topics (Advocacy and Methane bombs) buzzing around the blogo-twitter-sphere this week, perhaps those are our starters for ten… (Feel free to populate the comments with links to various commentaries – we will chime in as we find time).
Unforced Variations: July 2013
This month’s open thread…
We have just updated the blog software, and are taking a little time to assess how up-to-date some the content is (including the theme, mobile theme, blogroll, about pages and the RC wiki etc.). So this might be a good time to chime in with your suggestions as well as discussing the latest climate science issues.
Yamal and Polar Urals: a research update
Guest commentary from Tim Osborn, Tom Melvin and Keith Briffa, Climatic Research Unit, UEA
Records of tree-ring characteristics such as their width (TRW) and density (usually the maximum density of the wood formed towards the end of the growing season – the “maximum latewood density” – MXD) are widely used to infer past variations in climate over recent centuries and even millennia. Chronologies developed from sites near to the elevational or latitudinal tree lines often show sensitivity to summer temperature and, because of their annual resolution, absolute dating and relatively widespread nature, they have contributed to many local, continental and hemispheric temperature reconstructions. However, tree growth is a complex biological process that is subject to a range of changing environmental influences, not just summer temperature, and so replication, coherence and consistency across records and other proxies are an important check on the results.
Tree-ring records have greater replication (both within a site and between nearby sites) than other types of climate proxy. Good replication helps to minimise the influence of random localised factors when extracting the common signal, and it also allows the comparison of information obtained from different independent sets or sub-sets of data. If independent sets of data – perhaps trees with different mean growth rates or from different sites – show similar variations, then we can have greater confidence that those variations are linked to real variations in climate.
In a new QSR paper (Briffa et al., 2013), (BEA13) we have used these approaches to re-assess the combined tree-ring evidence from the Yamal and Polar Urals region (Yamalia) of northern Siberia, considering the common signal in tree-growth changes at different sites and in subsets of data defined in other ways. Together with our Russian colleagues and co-authors, we have incorporated many new tree-ring data, to increase the replication and to update the chronology to 2005 and have reassessed the inferences about summer temperature change that can be drawn from these data. The paper is published as an open-access paper (no paywall) and supplementary information including the raw tree-ring and instrumental temperature data are available from our website.
[Read more…] about Yamal and Polar Urals: a research update
References
- K.R. Briffa, T.M. Melvin, T.J. Osborn, R.M. Hantemirov, A.V. Kirdyanov, V.S. Mazepa, S.G. Shiyatov, and J. Esper, "Reassessing the evidence for tree-growth and inferred temperature change during the Common Era in Yamalia, northwest Siberia", Quaternary Science Reviews, vol. 72, pp. 83-107, 2013. http://dx.doi.org/10.1016/j.quascirev.2013.04.008
Unforced Variations: June 2013
Introducing PubPeer.com
Guest post from PubPeer.com
The process of reviewing published science is constantly occurring and is now commonly being called post-publication peer review. It occurs in many places including on blogs such as this one, review articles, at conferences around the world, and has even been encouraged on the websites of some journals. However, the process of recording and searching these comments is, unfortunately, inefficient and underused by the larger scientific community for several reasons: To successfully impact the publication process, this database of knowledge has to accomplish two important tasks. First it requires participation by a large part of a given scientific community so that it reflects an average impression instead of an outlier’s impression. Second, it requires that the collective knowledge is centralized and easy to search in order find out what the community collectively thinks about an individual paper or a body of work. A recent initiative, the San Francisco Declaration on Research Assessment (DORA), echoes many of these same concerns.
In an attempt to assemble such a database, a team of scientists, have put together a website called PubPeer.com that is searchable and encourages participation by the larger scientific community. With a critical mass of usage an organized system of post-publication review could improve both the process of scientific publication as well as the research that underlies those publications.
Unforced Variations: May 2013
The PAGES-2k synthesis
Guest commentary by Darrell Kaufman (N. Arizona U.)
In a major step forward in proxy data synthesis, the PAst Global Changes (PAGES) 2k Consortium has just published a suite of continental scale reconstructions of temperature for the past two millennia in Nature Geoscience. More information about the study and its implications are available at the FAQ on the PAGES website and the datasets themselves are available at NOAA Paleoclimate.
The main conclusion of the study is that the most coherent feature in nearly all of the regional temperature reconstructions is a long-term cooling trend, which ended late in the 19th century, and which was followed by a warming trend in the 20th C. The 20th century in the reconstructions ranks as the warmest or nearly the warmest century in all regions except Antarctica. During the last 30-year period in the reconstructions (1971-2000 CE), the average reconstructed temperature among all of the regions was likely higher than anytime in at least ~1400 years. Interestingly, temperatures did not fluctuate uniformly among all regions at multi-decadal to centennial scales. For example, there were no globally synchronous multi-decadal warm or cold intervals that define a worldwide Medieval Warm Period or Little Ice Age. Cool 30-year periods between the years 830 and 1910 CE were particularly pronounced during times of weak solar activity and strong tropical volcanic eruptions and especially if both phenomena often occurred simultaneously.
[Read more…] about The PAGES-2k synthesis
References
- . , "Continental-scale temperature variability during the past two millennia", Nature Geoscience, vol. 6, pp. 339-346, 2013. http://dx.doi.org/10.1038/ngeo1797