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Tuning in to climate models

Filed under: — gavin @ 30 October 2016

There is an interesting news article ($) in Science this week by Paul Voosen on the increasing amount of transparency on climate model tuning. (Full disclosure, I spoke to him a couple of times for this article and I’m working on tuning description paper for the US climate modeling centers). The main points of the article are worth highlighting here, even if a few of the characterizations are slightly off.

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Q & A about the Gulf Stream System slowdown and the Atlantic ‘cold blob’

Last weekend, in Reykjavik the Arctic Circle Assembly was held, the large annual conference on all aspects of the Arctic. A topic of this year was: What’s going on in the North Atlantic? This referred to the conspicuous ‘cold blob’ in the subpolar Atlantic, on which there were lectures and a panel discussion (Reykjavik University had invited me to give one of the talks). Here I want to provide a brief overview of the issues discussed.

What is the ‘cold blob’?

This refers to exceptionally cold water in the subpolar Atlantic south of Greenland. In our paper last year we have shown it like this (see also our RealClimate post about it):

fig1a_new

Fig. 1 Linear temperature trends from 1901 to 2013 according to NASA data. Source: Rahmstorf et al, Nature Climate Change 2015.

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What is new in European climate research?

The EMS 2016 Venue

The EMS 2016 Venue

What did I learn from the 2016 annual European Meteorological Society (EMS) conference that last week was hosted in Trieste (Italy)?

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Scientists getting organized to help readers sort fact from fiction in climate change media coverage

Filed under: — rasmus @ 24 May 2016

Guest post by Emmanuel Vincent

While 2016 is on track to easily surpass 2015 as the warmest year on record, some headlines, in otherwise prestigious news outlets, are still claiming that “2015 Was Not Even Close To Hottest Year On Record” (Forbes, Jan 2016) or that the “Planet is not overheating…” (The Times of London, Feb 2016). Media misrepresentation confuses the public and prevents our policy makers from developing a well-informed perspective, and making evidence-based decisions.

Professor Lord Krebs recently argued in an opinion piece in The Conversation that “accurate reporting of science matters” and that it is part of scientists’ professional duty to “challenge poor media reporting on climate change”. He concluded that “if enough [scientists] do so regularly, [science reporting] will improve – to the benefit of scientists, the public and indeed journalism itself.”

This is precisely what a new project called Climate Feedback is doing: giving hundreds of scientists around the world the opportunity to not only challenge unscientific reporting of climate change, but also to highlight and support accurate science journalism.

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Do regional climate models add value compared to global models?

2016-05-20 10.08.17

Global climate models (GCM) are designed to simulate earth’s climate over the entire planet, but they have a limitation when it comes to describing local details due to heavy computational demands. There is a nice TED talk by Gavin that explains how climate models work.

We need to apply downscaling to compute the local details. Downscaling may be done through empirical-statistical downscaling (ESD) or regional climate models (RCMs) with a much finer grid. Both take the crude (low-resolution) solution provided by the GCMs and include finer topographical details (boundary conditions) to calculate more detailed information. However, does more details translate to a better representation of the world?

The question of “added value” was an important topic at the International Conference on Regional Climate conference hosted by CORDEX of the World Climate Research Programme (WCRP). The take-home message was mixed on whether RCMs provide a better description of local climatic conditions than the coarser GCMs.

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