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Lessons from Venus

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by Rasmus Benestad and Ray Pierrehumbert

Venus Express will make unprecedented studies of the largely unkown phenomena taking place in the Venusian atmosphere. Credits: ESA - AOES Medialab A special report in The Observer on Sunday (April 9) titled ‘Venus – The Hot Spot’, provides a well-written account on a mission called the Venus Express. The Venus express is an European Space Agency (ESA) mission to probe the the atmosphere of Venus and address questions regarding the differences between the climates on Venus and Earth. According to the plans, the probe will enter the final orbit around Venus in May 2006, i.e. within about a month.

What relevance does a mission to Venus have for a blog like RealClimate? Primarily, Venus offers scientists the chance to see how the same basic physics used to study Earth’s climate operates under a very different set of circumstances. In one sense, Venus is rather similar to Earth: it has nearly the same mass as Earth, and while its orbit is somewhat closer to the Sun, that effect is more than made up for by the sunlight reflected from Venus’ thick cloud cover. Because of the cloud cover, the surface temperature of Venus would be a chilly -42C if were not for the greenhouse effect of its atmosphere. In reality, the surface of Venus, at 740K (467C) is even hotter than the surface of Mercury, which is a (relatively!) pleasant 440K. Per unit of surface area, the atmosphere of Venus has as much mass as about 100 Earth atmospheres, and it is almost pure CO2. This accounts for its very strong greenhouse effect. In contrast, the CO2 in the Earth’s atmosphere accounts for a mere .00056 of the full mass of one Earth atmosphere.
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Getting the balance right…

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We’ve commented before on the “false objectivity of balance”, i.e. the tendency for many journalists to treat scientific issues–for which differing positions often do not have equal merit– in the same “he said, she said” manner they might treat a story on policy or politics.

This approach can appear balanced, but it leaves it to the reader to figure out on their own which position is most likely correct. However, the reader is rarely as well equipped as the writer to determine the bottom line, and in practice this plays into the hands of those who might seek to confuse the public through clever disinformation campaigns.

Thankfully, some journalists “get it”, and take the time (and effort) to assess where the balance of evidence really lies and report it accordingly. Two recent articles discuss what it takes, the first, an interview with Andy Revkin of the NY Times by Paul Thacker and the second a recent Ideas piece in the Boston Globe by Christopher Shea.

Hopefully this attitude is catching on!

Tropical Cyclones workshop

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One of the nice things about a being a scientist is that you can sometimes go to workshops and meetings and actually hear something new now and again. At the well-timed Tropical Cyclones and Climate Workshop at Columbia a week or so ago, I got a chance to sit in and listen to Emanuel, Landsea, Knutson and Bell talking about their recent work, but I also got to hear some new voices (and issues) in the discussion. It was all pretty enlightening even if it didn’t end up in complete reconciliation of the different views. [Read more…] about Tropical Cyclones workshop

Heat Rising at the Washington Post

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The Washington Post has published a second op-ed in as many days about global warming (“Spinning Global Warming”, By Robert D. Novak, Page A19, April 03, 2006–story is no longer available on the website, but the Chicago Sun Times version is available here). In this one, Novak claims that Hansen in 1988 over-predicted global warming by 400% (a story originated by Pat Michaels and subsequently propagated by Michael Crichton). This story is a fabrication that has already been set right by us in 2004.

Smearing Hansen, a leading climate scientist and member of the National Academy of Sciences, appears to have become sport among contrarian commentators (see our earlier discussions here and here). As ad hominem attacks and “shoot the messenger” strategies are often the last refuge for those losing the substantive debate, this might be viewed by some as a positive sign, indicative of just how intellectually bankrupt the contrarian movement has become.
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Incurious George

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George Will argues now that no one would have noticed the 0.6 deg. C of global average warming to date, if the irresponsible press had not deliberately produced anxiety by pointing it out. He could be right. I expect no one would have personally noticed the ozone hole either. My grandmother smoked like a chimney and lived to be almost 100. If that nasty press had not deliberately stoked my anxieties about cigarettes and lung cancer, I would never have figured out the connection based on my personal experience. George argues that big crusading journalism is the problem. Ignorance is strength, right, George?

And, oh yeah, the global cooling stories, which appeared 30 years ago in the main-stream press (not the scientific literature). Shall we compare this with Will’s deliberate and repeated distortion of a real warning emerging from the scientific enterprise, continuing to the present day?

He looks like such an earnest man. I just don’t get it.

Significant Warming of the Antarctic Winter Troposphere

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The “iconic” Antarctic temperature trends are the large warming seen on the Antarctic Peninsula, which has had various repercussions including the collapse of several ice shelves (some documented in a previous post). Elsewhere, though, the pattern of surface warming is more complex – trends are smaller, and while more are positive than negative they are generally not significant – see this map. Contrary to what you might have heard, this is in general agreement with model predictions.

But meanwhile, there is a record for the upper atmosphere derived from radiosondes, which we have been working on – finding old datasets and digitising them to fill in gaps. What this shows is that around East Antarctica there is a general warming of the troposphere, greatest at around mid-height (at 600 hPa) at 0.7 ºC/decade over the last 30+ years.

In itself, this is an interesting observation. The obvious question is, what does it mean? Is this natural variability; is it a response to global warming, or to changes in ozone; or something else? Ozone is unlikely, because this is winter (which conveniently means that the radiosonde temperature corrections, often a source of potential trouble, are not a problem). Two ways of trying to interpret the record are to see what GCMs run for the same period show; or to look at the re-analyses (essentially, the archived outputs from the weather-prediction models). The latter, of course, incorporate many of the radiosonde observations that we are using, and so don’t count as independant. Despite this, the ECMWF re-analyses show *greater* trends than we see in the observations; and a maximum trend over West Antarctica (which has no radisonde stations to allow us to verify this). A climate model (HadCM3, with an ensemble of four members) shows similar patterns to the observations, but this time too little warming; and a good deal of variation between the ensemble members. So neither of these is helps much with the interpretation.

So we are currently left with an open question; hopefully, this will stimulate us and other researchers to explain it in the future.

[Quick addendum: the paper itself is available via this.]

Bush on “The Fundamental Debate”

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The President of the United States, George W. Bush, recently voiced his opinions on the science of climate change:

We — first of all, there is — the globe is warming. The fundamental debate: Is it manmade or natural. Put that aside.

The first part is the silver lining: despite receiving novelist Michael Crichton in the White House recently, Bush obviously has not bought his theory that the globe is in fact not warming. Crichton is one of the last trend sceptics who deny the warming trend is real.
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Another study on solar influence

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In a recent paper in Geophysical Research Letters, Scafetta & West (S&W) estimate that as much as 25-35% of the global warming in the 1980-2000 period can be attributed changes in the solar output. They used some crude estimates of ‘climate sensitivity’ and estimates of Total Solar Irradiance (TSI) to calculate temperature signal (in form of anomalies). They also argue that their estimate, which is based on statistical models only, has a major advantage over physically based considerations (theoretical models), because the latter would require a perfect knowledge about the underlying physical and chemical mechanisms.

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Pielke père et fils in Nature

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There’s an interesting profile on Roger Pielke Jr. and Sr. in Nature this week. As readers here are probably aware, both of them have blogs (Prometheus for Jr., Climate Science for Sr.) and both have contributed to the discussions on RealClimate. Readers will also be aware that the discussions have at times been heated, though have usually remained collegial. There have been a few times when the discussion may have seemed to be at cross-purposes, but overall the exchanges have been enlightening.
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