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Hit the brakes hard

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Translations: (Español) (English)

There is a climate splash in Nature this week, including a cover showing a tera-tonne weight, presumably meant to be made of carbon (could it be graphite?), dangling by a thread over the planet, and containing two new articles (Allen et al and Meinshausen et al), a “News & Views” piece written by two of us, and a couple commentaries urging us to “prepare to adapt to at least 4° C” and to think about what the worst case scenario (at 1000 ppm CO2) might look like.

At the heart of it are the two papers which calculate the odds of exceeding a predefined threshold of 2°C as a function of CO2 emissions. Both find that the most directly relevant quantity is the total amount of CO2 ultimately released, rather than a target atmospheric CO2 concentration or emission rate. This is an extremely useful result, giving us a clear statement of how our policy goals should be framed. We have a total emission quota; if we keep going now, we will have to cut back more quickly later.

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Yet more aerosols: Comment on Shindell and Faluvegi

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Guest post from Drew Shindell, NASA GISS

Our recent paper “Climate response to regional radiative forcing during the twentieth century”, has generated some interesting discussion (some of it very ‘interesting’ indeed). So this post is an attempt to give a better context to the methods and implications of the study.

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Aerosol effects and climate, Part II: the role of nucleation and cosmic rays

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Translations: (Italian) (English)

Guest post by Bart Verheggen, Department of Air Quality and Climate Change , Energy research Institute of the Netherlands (ECN)

In Part I, I discussed how aerosols nucleate and grow. In this post I’ll discuss how changes in nucleation and ionization might impact the net effects.

Cosmic rays

Galactic cosmic rays (GCR) are energetic particles originating from space entering Earth’s atmosphere. They are an important source of ionization in the atmosphere, besides terrestrial radioactivity from e.g. radon (naturally emitted by the Earth’s surface). Over the oceans and above 5 km altitude, GCR are the dominant source. Their intensity varies over the 11 year solar cycle, with a maximum near solar minimum. Carslaw et al. give a nice overview of potential relations between cosmic rays, clouds and climate. Over the first half of the 20th century solar irradiance has slightly increased, and cosmic rays have subsequently decreased. RC has had many previous posts on the purported links between GCR and climate, e.g. here, here and here.

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Aerosol formation and climate, Part I

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Translations: (Italian) (English)

Guest post by Bart Verheggen, Department of Air Quality and Climate Change , Energy research Institute of the Netherlands (ECN)

The impacts of aerosols on climate are significant, but also very uncertain. There are several reasons for this, one of which is the uncertainty in how and how fast they are formed in the atmosphere by nucleation. Here, in part I, I’ll review some of the basic processes that are important in determining the climate effects of aerosols, focusing in particular on their formation. This is also relevant in order to better understand –and hopefully quantify- the hypothetical climate effects of galactic cosmic rays which I’ll discuss in a follow-up post.

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Breaking the silence about Spring

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Did you know that in 1965 the U.S. Department of Agriculture planted a particular variety of lilac in more than seventy locations around the U.S. Northeast, to detect the onset of spring — in turn to be used to determine the appropriate timing of corn planting and the like? The records the USDA have kept show that those same lilacs are blooming as much as two weeks earlier than they did in 1965. April has, in a very real sense, become May. This is one of the interesting facts that you’ll read about in Amy Seidl’s book, Early Spring, a hot-off-the-press essay about the impacts of climate change on the world immediately around us – the forest, the birds, the butterflies in our backyards.
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Wilkins ice shelf collapse

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Since people are wanting to talk about the latest events on the Antarctic Peninsula, this is a post for that discussion.

The imagery from ESA (animation here) tells the recent story quite clearly – the last sliver of ice between the main Wilkins ice shelf and Charcot Island is currently collapsing in a very interesting way (from a materials science point of view). For some of the history of the collapse, see our previous post. This is the tenth major ice shelf to collapse in recent times.

Maybe we can get some updates and discussion of potential implications from the people working on this in the comments….?

Advocacy vs. Science

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The advocate will pick up any piece of apparently useful data and without doing any analysis, decide that their pet theory perfectly explains any anomaly without consideration of any alternative explanations. Their conclusion is always that their original theory is correct.

The scientist will look at all possibilities and revise their thinking based on a thorough assessment of all issues – data quality, model quality and appropriateness of the the comparison. Their conclusion follows from the analysis whatever it points to.

Which one is which?

Farewell to our Readers

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We would like to apologize to our loyal readers who have provided us so much support since we first went online in December 2004. However, after listening to the compelling arguments of the distinguished speakers who participated in the Heartland Institute’s recent global warming contrarian conference, we have decided that the science is settled — in favor of the contrarians. Indeed, even IPCC chair Rajendra Pachauri has now admitted that anthropogenic climate change was a massive hoax after all. Accordingly, RealClimate no longer has a reason for existence. The contrarians have made a convincing case that (a) global warming isn’t happening, (b) even if it is, its entirely natural and within the bounds of natural variability, (c) well, even if its not natural, it is modest in nature and not a threat, (d) even if anthropogenic warming should turn out to be pronounced as projected, it will sure be good for us, leading to abundant crops and a healthy environment, and (e) well, it might actually be really bad, but hey, its unstoppable anyway. (Can we get our check now?)

Michaels’ new graph

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Every so often people who are determined to prove a particular point will come up with a new way to demonstrate it. This new methodology can initially seem compelling, but if the conclusion is at odds with other more standard ways of looking at the same question, further investigation can often reveal some hidden dependencies or non-robustness. And so it is with the new graph being cited purporting to show that the models are an “abject” failure.

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With all due respect…

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Translations: (Italian) (English)

There was a great comedy piece a few years back (whose origin escapes us) that gave examples of how the English would use their language when speaking to a non-native speaker to imply the precise opposite of what was actually being understood. This allowed the English to feel superior without actually damaging international relations. One example was the phrase “with all due respect” which is generally understood to imply that the speaker has a great deal of respect for their counterpart, while the speaker is actually implying that they have no respect in the slightest for their interlocutor. The respect due being precisely zero.

This thought occurred to us when a few of us opened our email this week to see a draft ad being sent around by the Cato Institute (i.e. Pat Michaels) looking for signatories prior to being published in “major US newspapers” sometime soon:

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