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Arctic sea ice watch

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A few people have already remarked on some pretty surprising numbers in Arctic sea ice extent this year (the New York Times has also noticed). The minimum extent is usually in early to mid September, but this year, conditions by Aug 9 had already beaten all previous record minima. Given that there is at least a few more weeks of melting to go, it looks like the record set in 2005 will be unequivocally surpassed. It could be interesting to follow especially in light of model predictions discussed previously.

There are a number of places to go to get Arctic sea ice information. Cryosphere Today has good anomaly plots. The Naval Sea ice center has a few different algorithms (different ways of processing the data) that give some sense of the observational uncertainty, and the National Snow and Ice Data Center give monthly updates. All of them show pretty much the same thing.

Just to give a sense of how dramatic the changes have been over the last 28 years, the figures below show the minimum ice extent in September 1979, and the situation today (Aug 9, 2007).

Sep 05 1979Aug 09 2007

The reduction is around 1.2 million square km of ice, a little bit larger than the size of California and Texas combined.

Update: As noted by Andy Revkin below, some of the discussion is about ice extent and some is about ice area. The Cryosphere Today numbers are for area. The difference is whether you count ‘leads’ (the small amounts of water between ice floes) as being ice or water – for the area calculation they are not included with the ice, for the extent calculation they are.

Update: From the comments: NSIDC will now be tracking this on a weekly basis.

Friday roundup

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An eclectic round-up of the week’s climate science happenings (and an effort to keep specific threads clear of clutter).

It’s the sun! (not)

As regular readers here will know, the big problem for blaming the sun for the recent global warming is that there hasn’t been a trend in any index of solar activity since about 1960, and that includes direct measurements of solar output by satellites since 1979. Well, another paper, has come out saying exactly the same thing. This is notable because the lead author Mike Lockwood has worked extensively on solar physics and effects on climate and certainly can’t be credibly accused of wanting to minimise the role of solar forcing for nefarious pro-CO2 reasons!

Stefan was quoted in Nature as saying this is the ‘last nail in the coffin’ for solar enthusiasts, but a better rejoinder is a statement from Ray P: “That’s a coffin with so many nails in it already that the hard part is finding a place to hammer in a new one.”

TGGWS Redux

The still-excruciating ‘Great Global Warming Swindle’ got another outing in Australia this week. The heavily edited ‘new’ version dumped some of the obviously fake stuff that was used the first time around, and edited out the misleading segment with Carl Wunsch. There is some amusing feedback in the post-show discussion panel and interview (via DeSmogBlog).

RC Wiki

As an aside, this is as good a time as any to point people to a new resource we are putting together: RC Wiki, which is an index to the various debunkings of the contrarian articles, TV programs, and internet pseudo-science that is out there. The idea is to have a one-stop shop so that anyone who comes across a piece and wants to know what the real story just has to start there. For instance, the page on TGGWS has a listing of many of the substantive criticisms from the time of the first showing.

Editing the wiki is by invitation only, but let us know if you want to help out, or if you have any suggestions or comments.

The sweet spot for climate predictability

Between the difficulty of long-term weather forecasts and the impossibility of accurate predictions for economic conditions a century hence, there is a sweet spot for climate forecasts. This spot, maybe between 20 and 50 years out, is where the emissions scenarios don’t matter too much (given the inertia of the system) and where the trends start to be discernible over the noise of year to year weather. Cox and Stephenson have a good discussion of the point in this week’s Science and a great conceptual graphic of the issues.

One could quibble with the details (we’d put the sweet spot a little earlier) but the underlying idea is sound, and in judging climate forecasts, it will be projections in that range that should be judged (i.e. the early Hansen projections).

A Saturated Gassy Argument

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Translations: (Português)

A guest post by Spencer Weart, in collaboration with Raymond T. Pierrehumbert

The simple physics explanations for the greenhouse effect that you find on the internet are often quite wrong. These well-meaning errors can promote confusion about whether humanity is truly causing global warming by adding carbon dioxide to the atmosphere. Some people have been arguing that simple physics shows there is already so much CO2 in the air that its effect on infrared radiation is "saturated"— meaning that adding more gas can make scarcely any difference in how much radiation gets through the atmosphere, since all the radiation is already blocked. And besides, isn’t water vapor already blocking all the infrared rays that CO2 ever would?

[Read more…] about A Saturated Gassy Argument

Part II: What Ångström didn’t know

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By raypierre , with the gratefully acknowledged assistance of Spencer Weart

In Part I the long struggle to get beyond the fallacious saturation argument was recounted in historical terms. In Part II, I will provide a more detailed analysis for the reader interested in the technical nitty-gritty of how the absorption of infrared really depends on CO2 concentration. At the end, I will discuss Herr Koch’s experiment in the light of modern observations.
[Read more…] about Part II: What Ångström didn’t know

Glacier Mass Balance: equilibrium or disequilibrium response?

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Guest Commentary from Mauri S. Pelto

I get asked at least once a day about the future prognosis for alpine glaciers and whether they have a future. I will focus here on North American glaciers whose mass balance measurements in the West from 1984-2005 indicate a declining trend. The trend suggests that all of the glaciers are out of balance and that some will disappear. The question is determining which glaciers are merely out of equilibrium and can retreat to a position of equilibrium, and which are in complete disequilibrium and will melt away? Let me explain.
[Read more…] about Glacier Mass Balance: equilibrium or disequilibrium response?

Start here

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[Note this is page is updated regularly. Please notify us of any dead links. Last update: 10 May 2022.]

We’re often asked to provide a one stop link for resources that people can use to get up to speed on the issue of climate change, and so here is a selection. Unlike our other postings, we’ll amend this as we discover or are pointed to new resources. Different people have different needs and so we will group resources according to the level people start at.

For complete beginners:

NCAR: Weather and climate basics
Center for Climate and Energy Solutions: Climate basics
Wikipedia: Global Warming
NASA: Global Warming
National Academy of Science: America’s Climate Choices (2011)
Encyclopedia of Earth: Climate Change
Global Warming: Man or Myth? (Scott Mandia, SUNY Suffolk)
Open Learn: The Basics of Climate Prediction

There is a booklet on Climate Literacy from multiple agencies (NOAA, NSF, AAAS) available here (pdf).

The UK Govt. had a good site on The Science of Climate Change (archived).

The portal for climate and climate change of the ZAMG (Zentralaanstalt für Meteorologie und Geodynamik, Vienna, Austria). (In German) (added Jan 2011).

Those with some knowledge:

The IPCC Frequently Asked Questions are an excellent start (AR4 version here , updates were provided in the 5th Assessment report (pdf) and again for AR6).

The UK Royal Society and US National Academies of Science produced a joint Q&A on climate change in 2014, and an update in 2017.

RealClimate: Start with our index.

Informed, but in need of more detail:

Science: You can’t do better than the IPCC reports themselves (AR6 2021, AR5 2013, AR4 2007, TAR 2001). Also the Climate Science Special Report for the US National Climate Assessment.

History: Spencer Weart’s “Discovery of Global Warming” (AIP)

Informed, but seeking serious discussion of common contrarian talking points:

All of the below links have indexed debunks of most of the common points of confusion:

Please feel free to suggest other suitable resources, particularly in different languages, and we’ll try to keep this list up to date.

A Slovak translation is available here

Tłumaczenie na polski dostępne jest tutaj
A Bulgarian translation is available here (via Ivan Boreev).

Beck to the future

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Guest commentary from Georg Hoffmann

Our understanding of the natural carbon cycle has greatly improved since the times of Svante Arrhenius (1859-1927) and Guy Stewart Callendar (1898-1964). We know what the atmospheric background value of CO2 currently is (it passed 380ppm last year, about 100ppm over the pre-industrial level), we know the seasonal/diurnal cycle in different environments, we have been able to put reasonable constraints on terrestrial and marine sources and sinks, and finally we know the impact of fuel combustion both globally and locally in heavily polluted areas.
[Read more…] about Beck to the future

Full IPCC AR4 report now available

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The complete WG1 IPCC 4th Assessment report (AR4) is now available online. It’s missing the index and some supplemental data, but all should be available by May 7.

Over the next few weeks we’ll try and go through the report chapter by chapter, but since this is likely to the key reference for a number of years, we can take a little time to do it properly. Happy reading!

Hurricane Spin

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Michael Mann and Gavin Schmidt

A recent paper by Vecchi and Soden (preprint) published in the journal Geophysical Research Letters has been widely touted in the news (and some egregiously bad editorials), and the blogosphere as suggesting that increased vertical wind shear associated with tropical circulation changes may offset any tendencies for increased hurricane activity in the tropical Atlantic due to warming oceans. Some have even gone so far as to state that this study proves that recent trends in hurricane activity are part of a natural cycle. Most of this is just ‘spin’ (pun intended), but as usual, the real story is a little more nuanced.
[Read more…] about Hurricane Spin

Lindzen in Newsweek

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Gavin Schmidt and Michael Mann

As part of a much larger discussion on Learning to live with Global Warming in Newsweek recently, the editors gave some space for Richard Lindzen to give his standard ‘it’s no big deal’ opinion. While we disagree, we have no beef with serious discussions of the costs and benefits of various courses of action and on the need for adaption to the climate change that is already locked in.

However, Lindzen’s piece is not a serious discussion.
[Read more…] about Lindzen in Newsweek