Anatomy of a Story: Water Vapour Article in Science

The latest story to start circulating is based on a new paper publised in the journal Science. I paid for a copy of it and have been reading it. I’m interested in following how the story gets translated by various media and blogs, so this post will be for that purpose.

First, the abstract of “Contributions of Stratospheric Water Vapor to Decadal Changes in the Rate of Global Warming“:

Stratospheric water vapor concentrations decreased by about 10% after the year 2000. Here we show that this acted to slow the rate of increase in global surface temperature over 2000-2009 by about 25% compared to that which would have occurred due only to carbon dioxide and other greenhouse gases. More limited data suggest that stratospheric water vapor probably increased between 1980 and 2000, which would have enhanced the decadal rate of surface warming during the 1990s by about 30% compared to estimates neglecting this change. These findings show that stratospheric water vapor represents an important driver of decadal global surface climate change.

The first headline I read was from Climate Depot, which has a link to an article in the National Post:

SHOCK: UN IPCC Co-Chair Susan Soloman Backing Away? Water Vapor ‘research does allude to human emissions having a much smaller role in climate change that previously thought’.  Water vapor caused one-third of global warming in 1990s, study reveals.

The National Post article: Steve Janke: More unsettling science in the global warming camp

Remember how I said that we would be witness to scientists abandoning global warming orthodoxy in an attempt to regain lost credibility?

That the global warming dogma — that the question of global warming was “settled science” and that carbon dioxide emissions from human activity was dramatically warming the planet — would be challenged with new research, research that would not be suppressed?

Turns out I was right.

NASA and NOAA are organizations from which many of true believers in the global warming religion have come, and they’ve played a critical role in providing the scientific-sounding justification for the worst of the alarmist predictions.  But now scientists from NOAA have published research in Science that challenges the core assumptions of the global warming camp:

And further:

This would explain what the global warming alarmists refuse to even mention, and that is that there is evidence that carbon dioxide levels have been much higher in the far past, even during times of global glaciation.

But the best part is the not-so-subtle hint that these scientists are not counting themselves among the warmists any longer:

The research, facilitated by a state-of-the-art NASA satellite codenamed AIRS, suggests that water vapor is responsible for twice the global warming effect of carbon dioxide, both man-made and naturally occurring. While this theory was has been carried by climate change skeptics for some time, global warming advocates dismissed them, saying that water vapor in the atmosphere was only a feedback effect caused by human emissions. NASA scientist Eric Fetzer say that the new study created models much more accurate to past events than those previously used byclimate change advocates, and proves that “water vapor is the big player in the atmosphere as far as climate is concerned.”

I thought the previous models were used by scientists.  But no, according to Eric Fetzer, those models were used by climate change advocates.

It’s us versus them.  This is a new dynamic.  It is a clear indication of the split.

The scientists’ models are better than the warmists’ models.  Our model says correctly that water vapor is the big player, while your model says (incorrectly) that carbon dioxide is the sole driver.

Wow.

The split has come.  The real scientists are no longer counting themselves among the global warming alarmists and are saying so out loud.  And they are challenging the warmists with new research.

The avalanche is coming.

Climate Depot also has a link to The Resilient Earth, which describes itself as:

Having both worked for years on numerous engineering and scientific projects, we resolved to uncover the actual scientific underpinnings of climate science and communicate our findings to a non-scientific audience. During the process of researching and writing The Resilient Earth, we were continually amazed with how little of the real science made it into the public debate. Further surprise came from the lack of knowledge among the general public and scientists, some of whom were involved in climatology. We discovered that global warming is a topic much discussed but little understood.

What you will find posted in our blogs are commentaries on cutting edge research papers from respected scientific journals, like Science,Nature and the Proceedings of the National Academy of Sciences(PNAS). We interpret the “science speak” and dissect the logic of studies and reports on the science of climate change, providing understandable explanations for the non-scientist and alternative interpretations of results that you won’t get from the AGW crowd.

Here’s the headline and quote:

It’s The Water Vapor, Stupid!

A new report in Science underscores what many scientists have been saying for years, it’s water vapor, not CO₂, that has been driving global temperature changes in recent decades. Stratospheric water vapor concentrations decreased by about 10% after the year 2000, slowing the rate of global surface temperature increase over the past 10 years. It also seems likely that water vapor in the stratosphere increased between 1980 and 2000, causing surface temperatures to warm by an extra 30% during the 1990s. These findings show that stratospheric water vapor represents an important driver of decadal global surface climate change, yet the IPCC crowd continues to focus on CO₂.

The new report, “Contributions of Stratospheric Water Vapor to Decadal Changes in the Rate of Global Warming,” by Susan Solomon et al. states that from 2000 to 2009 diminished water vapor levels in the upper atmosphere depressed global warming by about 25% compared to that which would have occurred due only to carbon dioxide and other greenhouse gases. More limited data suggest that stratospheric water vapor probably increased between 1980 and 2000, which would have enhanced the decadal rate of surface warming during the 1990s by about 30% compared to estimates neglecting this change.

The authors conclude their piece:

Once again the limitations of our understanding of the mechanisms that control Earth’s climate are revealed. Here is a plausible explanation as to why the period from 1980 to 1999 was one of noticeable warming, and why since 2000 things have leveled off or even cooled down a bit. Because the mechanisms that link water vapor to temperature regulation are complex and not well understood the climate change clique concentrated on CO₂—and it has become obvious that treating CO₂ as a form of planetary thermostat is simply not a viable explanation. It is no wonder that the IPCC’s carbon dioxide centric climate models didn’t get recent temperature swings right. To steal a phrase from American politics, “It’s the water vapor, stupid!”

Be safe, enjoy the interglacial and stay skeptical.

Over at the Daily Mail, there’s an article titled: Water vapour a ‘major cause of global warming and cooling’:

Climate scientists have overlooked a major cause of global warming and cooling, a new study reveals today.

American researchers have discovered that the amount of water high in the atmosphere is far more influential on world temperatures than previously thought.

Although the findings do not challenge the theory of man-made global warming, they help explain why temperatures can rise and fall so dramatically from decade to decade.

The study, published in the journal Science, says a 10 per cent drop in humidity 10 miles above the Earth’s surface explains why global temperatures have been stable since the start of the century, despite the rise in carbon dioxide in the atmosphere.

And a rise in water vapour in the 1980s and 90s may also explain why temperatures shot up so quickly in the previous two decades, they say.

The stratosphere is a region of the atmosphere from about eight to 30 miles above the Earth’s surface. Water vapour enters the stratosphere mainly as air rises in the tropics.

Dave Britton from the Met Office said the study highlighted the complexity of climate science. ‘But it does not challenge the basic science that carbon dioxide and other greenhouse gases released from human activity are warming the planet,’ he said.

Dr Vicky Pope, head of climate science at the Met Office, said: ‘Whatever’s causing this change from decade to decade is having an influence at the surface. But it is a small variation on top of the long term increase in manmade greenhouse gases.’

Here’s the New York Times:  Less Water Vapor Slows Earth’s Warming:

A decrease in water vapor concentrations in parts of the middle atmosphere has contributed to a slowing of Earth’s warming, researchers are reporting. The finding, they said, offers part of the explanation for a string of years with relatively stable global surface temperatures.

Despite the decrease in water vapor, the study’s authors said, the overall trend is still toward a warming climate, primarily caused by a buildup in emissions of carbon dioxide and other heat-trapping gases from human sources.

“This doesn’t alter the fundamental conclusion that the world has warmed and that most of that warming has to do with greenhouse gas emissions caused by man,” said Susan Solomon, a climate scientist at the National Oceanic and Atmospheric Administration and the lead author of the report, which appears in the Jan. 29 issue of the journal Science.

Here’s Andrew Revkin’s Dot Earth post: On Water Vapor and Warming:

A new study led by Susan Solomon, a federal climate scientist and co-leader of the 2007 science review by the Intergovernmental Panel on Climate Change, is fascinating not only for the revelations, but the underlying lessons, too.

The study, described in an article today in The Times, finds that poorly understood variations in water vapor concentrations in the stratosphere were probably responsible for a substantial wedge of the powerful warming trend in the 1990s and a substantial portion of “the flattening of global average temperatures since 2000″ (to anyone who  hates talk of plateaus and the like, those are the authors’ words, not mine). The stratosphere is the blue layer in the image above, taken by the crew of Space Shuttle Endeavor in 1992. [UPDATE, 9:45 p.m.: Realclimate.org has  posted some thoughts on the paper.]

Here’s the take-home line from the paper:

[S]tratospheric water vapor very likely made substantial contributions to the flattening of the global warming trend since about 2000. Although earlier data are less complete, the observations also suggest that stratospheric water contributed to enhancing the warming observed during 1980–2000.

Here’s Real Climate: The Wisdom of Solomon:

First of all, this is a paper about internal variability of the climate system in the last decade, not on additional factors that drive climate. Second, this is a discussion about stratospheric water vapour (10 to 15 km above the surface), not water vapour in general. Stratospheric water vapour comes from two sources – the uplift of tropospheric water through the very cold tropical tropopause (both as vapour and as condensate), and the oxidation of methane in the upper stratosphere (CH4+2O2 –> CO2 + 2H2O NB: this is just a schematic, the actual chemical pathways are more complicated). There isn’t very much of it (between 3 and 6 ppmv), and so small changes (~0.5 ppmv) are noticeable.

The decreases seen in this study are in the lower stratosphere and are likely dominated by a change in the flux of water through the tropopause. A change in stratospheric water vapour because of the increase in methane over the industrial period would be a forcing of the climate (and is one of the indirect effects of methane we discussed last year), but a change in the tropopause flux is a response to other factors in the climate system. These might include El Nino/La Nina events, increases in Asian aerosols, or solar impacts on near-tropopause ozone – but this is not addressed in the paper and will take a little more work to figure out.

The study includes an estimate of the effect of the observed stratospheric water decadal decrease by calculating the radiation flux with and without the change, and comparing this to the increase in CO2 forcing over the same period. This implicitly assumes that the change can be regarded as a forcing. However, whether that is an appropriate calculation or not needs some careful consideration. Finally, no-one has yet looked at whether climate models (which have plenty of decadal variability too) have phenomena that resemble these observations that might provide some insight into the causes.

What I find interesting in the Real Climate post is a series of comments from Ray Ladbury and Anand:

Ray Ladbury:

The Nature article provides only a very weak constraint on carbon-cycle feedback (very large error bars). The favored value is at the low end of expectations, but 1)it’s one study, 2)I don’t have access to Nature here at home 3)it doesn’t preclude higher values with any sensitivity, and 4)it doesn’t change the overall estimates of climate sensitivity, which are strongly constrained to be around 3 degrees per doubling.