Archives par mot-clé : History

Impact of Volcanic Eruptions on Decadal to Centennial Fluctuations of Arctic Sea Ice Extent during the Last Millennium and on Initiation of the Little Ice Age

by J Slawinska and A Robock, November 29, 2017 in AmerMeteorSoc

We evaluate different hypotheses of the origin of the Little Ice Age, focusing on the long-term response of Arctic sea ice and oceanic circulation to solar and volcanic perturbations. We analyze the Last Millennium Ensemble of climate model simulations carried out with the Community Earth System Model at the National Center for Atmospheric Research. We examine the duration and strength of volcanic perturbations, as well as initial and boundary conditions such as the phase of the Atlantic Multidecadal Oscillation, and their impact on decadal to multi-centennial perturbations of the cryospheric, oceanic, and atmospheric components of the climate system.


by Dr David Whitehouse, December 24, 2017 in GWPF

The data for November 2017 HadCRUT4 (click on image to enlarge) has just been released by the UK Met Office. It is 0.547, better expressed as 14.55 +/- 0.10 °C. Given the substantial monthly variability evident in this database one has to be careful in drawing many conclusions about it. Given that, it is interesting to note that November 2017 is statistically the same as most Novembers of the so-called pause years, i.e. 1997, 2001, 2004, 2005, 2006, 2008, 2009, 2010, 2010, 2012, 2014 and even 2016.

Oceans driving warming this century, same as in 1930s

by Ron Clutz, November 8, 2017, in ClimateChangeDispatch

The graph [after the jump] is noisy, but the density is needed to see the seasonal patterns in the oceanic fluctuations. Previous posts focused on the rise and fall of the last El Nino starting in 2015.

This post takes a longer view, encompassing the significant 1998 El Nino and since. The color schemes are retained for Global, Tropics, NH and SH anomalies. 

Despite the long time frame, I have kept the monthly data (rather than yearly averages) because of interesting shifts between January and July.


Surprise: Defying Models, Antarctic Sea Ice Extent 100 Years Ago Similar To Today

by P. Gosselin, October 17, 2017 in NoTricksZone

from Dr. L. Lüning and Prof. F. Vahrenbolt

Satellite measurements of Antarctic sea ice do not go back even 40 years. That’s not very much, especially when we consider that many natural climate cycles have periods of 60 years and more.

Luckily we have the field of climate reconstruction. Using historical documents and sediment cores, the development of ice cover can be estimated. In November, 2016, Tom Edinburg and Jonathan Day examined shipping log books from the time of Antarctic explorers and published on ice extent in The Cryosphere (…)

Nature Unbound V – The elusive 1500-year Holocene cycle

by Javier,  September 15, 2017, in Judith Curry Climate Etc.

The existence of a 1500-year climatic cycle during the Holocene, related to the glacial Dansgaard-Oeschger cycle, is a matter of intense debate. However, by introducing precise timing requirements it can be shown that the 1500-year cycle displayed in Northern Hemisphere glacial records is also observed in Holocene records from all over the world.

The cycle is most prominently displayed in oceanic subsurface water temperatures, Arctic atmospheric circulation, wind deposits, Arctic drift ice, and storminess records.

Histoire longue des cyclones aux Antilles

by Benoît Rittaud, 13 septembre 2017

Le cyclone Irma qui a dévasté Saint-Martin et Saint-Barthélémy dans les Antilles françaises a servi de prétexte à de nombreux commentateurs et journalistes pour en remettre une couche sur les “dérèglements climatiques d’origine humaine”. Comme d’habitude, les vagues éléments de prudence rappelant qu’on ne peut tirer de conclusions d’un élément isolé ont vite été noyés par les “appels à l’action” et l’invocation de l’Accord de Paris de 2015.

Or s’agissant du climat aux Antilles l’année 2015 a été importante pour une toute autre raison que la signature de l’Accord de Paris : c’est l’année de publication d’un article de recherche tout à fait passionnant sur les ouragans dans cette région du monde.

Evidence for Little Ice Age in Antarctica

by UC Santa Cruz Newscenter, August 31, 2017 in WUWT

Changes in the sources of nitrogen and the composition of the phytoplankton community are more likely to account for the differences seen in the isotope data, Huckstadt said. “It looks more like a shift at the base of the food web, probably related to the transition from the Little Ice Age to current conditions, causing changes in the phytoplankton community,” he said.

See also: “Here we present new data from the Ross Sea, Antarctica, that indicates surface temperatures were ~ 2 °C colder during the LIA, with colder sea surface temperatures in the Southern Ocean and/or increased sea-ice extent, stronger katabatic winds, and decreased snow accumulation.”