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Speculative polar cartography

Filed under: — group @ 5 October 2011

Guest commentary from Kevin Brown

The curious mismapping of Greenland’s ice sheet cover by the venerable Times Atlas recently has excited a lot of outraged commentary. But few people noted that this follows an old tradition of speculative cartography of the polar regions. ‘Modern’ mapmakers as early as the 16th century combined real facts and scientific knowledge with fundamental misinterpretations of that knowledge to create speculative mappings of the world’s unknown shores – and nowhere was this more prevalent than at the poles.

Early cartographers had a particularly difficult time mapping the Polar Regions. Factually, they based their maps on reports from mariners who dared sail the dangerous waters. This was supplemented by information from earlier maps, speculations based upon their personal theories of geography, religious beliefs, and the fiscal and political ambitions of their patrons.
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Global warming and ocean heat content

Filed under: — gavin @ 3 October 2011

The connection between global warming and the changes in ocean heat content has long been a subject of discussion in climate science. This was explicitly discussed in Hansen et al, 1997 where they predicted that over the last few decades of the 20th Century, there should have been a significant increase in ocean heat content (OHC). Note that at the time, there had not been any observational estimate of that change (the first was in 2000 [Levitus et al, 2000]), giving yet another example of a successful climate model prediction. At RC, we have tracked the issue multiple times e.g. 2005, 2008 and 2010. Over the last few months, though, there have been a number of new papers on this connection that provide some interesting perspective on the issue which will certainly continue as the CMIP5 models start to get analysed.
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References

  1. S. Levitus, "Warming of the World Ocean", Science, vol. 287, pp. 2225-2229. DOI.

Unforced variations: Oct 2011

Filed under: — gavin @ 1 October 2011

Open thread for October…

Cosmic rays and clouds: Potential mechanisms

Filed under: — group @ 26 September 2011

Guest Commentary by Jeffrey Pierce (Dalhousie U.)

I’ve written this post to help readers understand potential physical mechanisms behind cosmic-ray/cloud connections. But first I briefly want to explain my motivation.

Prior to the publication of the aerosol nucleation results from the CLOUD experiment at CERN in Nature several weeks ago [Kirkby et al, 2011], I was asked by Nature Geoscience to write a “News and Views” on the CLOUD results for a general science audience. As an aerosol scientist, I found the results showing the detailed measurements of the influences of ammonia, organics and ions from galactic cosmic rays on aerosol formation exciting. While none of the results were entirely unexpected, the paper still represents a major step forward in our understanding of particle formation. This excitement is what I tried to convey to the general scientific audience in the News and Views piece. However, I only used a small portion of the editorial to discuss the implications to cosmic rays and clouds because (1) I felt that these implications represented only a small portion of the CLOUD findings, and (2) the CLOUD results address only one of several necessary conditions for cosmic rays to affect clouds, and have not yet tested the others.

Many of the news articles and blog posts covering the CLOUD article understandably focused much more on the cosmic-ray/cloud connection as it is easy to tie this connection into the climate debate. While many of the articles did a good job at reporting the CLOUD results within the big picture of cosmic-ray/cloud connections, some articles erroneously claimed that the CLOUD results proved the physics behind a strong cosmic-ray/cloud/climate connection, and others still just got it very muddled. A person hoping to learn more about cosmic rays and clouds likely ended up confused after reading the range of articles published. This potential confusion (along with many great questions and comments in Gavin’s CLOUD post) motivated me to write a general overview of the potential physical mechanisms for cosmic rays affecting clouds. In this post, I will focus on what we know and don’t know regarding the two major proposed physical mechanisms connecting cosmic rays to clouds and climate.
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References

  1. J. Kirkby, J. Curtius, J. Almeida, E. Dunne, J. Duplissy, S. Ehrhart, A. Franchin, S. Gagné, L. Ickes, A. Kürten, A. Kupc, A. Metzger, F. Riccobono, L. Rondo, S. Schobesberger, G. Tsagkogeorgas, D. Wimmer, A. Amorim, F. Bianchi, M. Breitenlechner, A. David, J. Dommen, A. Downard, M. Ehn, R.C. Flagan, S. Haider, A. Hansel, D. Hauser, W. Jud, H. Junninen, F. Kreissl, A. Kvashin, A. Laaksonen, K. Lehtipalo, J. Lima, E.R. Lovejoy, V. Makhmutov, S. Mathot, J. Mikkilä, P. Minginette, S. Mogo, T. Nieminen, A. Onnela, P. Pereira, T. Petäjä, R. Schnitzhofer, J.H. Seinfeld, M. Sipilä, Y. Stozhkov, F. Stratmann, A. Tomé, J. Vanhanen, Y. Viisanen, A. Vrtala, P.E. Wagner, H. Walther, E. Weingartner, H. Wex, P.M. Winkler, K.S. Carslaw, D.R. Worsnop, U. Baltensperger, and M. Kulmala, "Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric aerosol nucleation", Nature, vol. 476, 2011, pp. 429-433. DOI.

Greenland meltdown

Filed under: — gavin @ 21 September 2011

After a record-breaking 2010 in terms of surface melt area in Greenland [Tedesco et al, 2011], numbers from 2011 have been eagerly awaited. Marco Tedseco and his group have now just reported their results. This is unrelated to other Greenland meltdown this week that occurred at the launch of the new Times Atlas.
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References

  1. M. Tedesco, X. Fettweis, M.R. van den Broeke, R.S.W. van de Wal, C.J.P.P. Smeets, W.J. van de Berg, M.C. Serreze, and J.E. Box, "The role of albedo and accumulation in the 2010 melting record in Greenland", Environmental Research Letters, vol. 6, 2011, pp. 014005-. DOI.
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