Ocean Cooling: A Science Lesson for Denialists/Delayers

By Johnny Rook, editor of Climaticide Chronicles

PART ONE: Of Denialists and Mixed-Up Russian Data

 

The great majority of rank-and-file Climaticide denialists/delayers know nothing about how science works, nor, generally, are they interested. Since their opposition to the reality of global warming is founded principally in ideology, they care little for the scientific process or facts except when they can cherry-pick the latter to bolster their position. This cherry-picking of facts is even typical of climate denialists/delayers who do have a science background, but who deny global warming either because of their commitment to their right-wing anti-government ideology, or simply their need to be contrarian is greater than their commitment to scientific truth.

Although I don't expect the denialists/delayers to pay any attention, there is much to be learned about how science works in the stories below.

Recently, the climate scientists at NASA's GISS published data on warming worldwide for the month of October. Due to an error somewhere along the way September data was used instead of October data for some 90 measuring stations in Russia. This was pointed out by one of the more scientific denialist web sites and GISS promptly made corrections.

GISS Surface Temperature Anomaly

Corrected Version of October Surface Temperature Anomaly (From NASA GISS)

Gavin Schmidt, who works at GISS and writes for Real Climate, the Internet's number one climate blog, RealClimate, in a post recognizing that an error had been made added the following commentary:

It's clearly true that the more eyes there are looking, the faster errors get noticed and fixed. The cottage industry that has sprung up to examine the daily sea ice numbers or the monthly analyses of surface and satellite temperatures, has certainly increased the number of eyes and that is generally for the good. Whether it's a discovery of an odd shift in the annual cycle in the UAH MSU-LT data, or this flub in the GHCN data, or the USHCN/GHCN merge issue last year, the extra attention has led to improvements in many products. Nothing of any consequence has changed in terms of our understanding of climate change, but a few more i's have been dotted and t's crossed.

But unlike in other fields of citizen-science (astronomy or phenology spring to mind), the motivation for the temperature observers is heavily weighted towards wanting to find something wrong. As we discussed last year, there is a strong yearning among some to want to wake up tomorrow and find that the globe hasn't been warming, that the sea ice hasn't melted, that the glaciers have not receded and that indeed, CO2 is not a greenhouse gas.[emphasis-JR] Thus when mistakes occur (and with science being a human endeavour, they always will) the exuberance of the response can be breathtaking - and quite telling.

A few examples from the comments at Watt's blog will suffice to give you a flavour of the conspiratorial thinking: "I believe they had two sets of data: One would be released if Republicans won, and another if Democrats won.", "could this be a sneaky way to set up the BO presidency with an urgent need to regulate CO2?", "There are a great many of us who will under no circumstance allow the oppression of government rule to pervade over our freedom--PERIOD!!!!!!" (exclamation marks reduced enormously), "these people are blinded by their own bias", "this sort of scientific fraud", "Climate science on the warmer side has degenerated to competitive lying", etc... (To be fair, there were people who made sensible comments as well).

The Russian temperature data is a fairly straightforward example of a mistake, made, caught, and corrected. It received as much blogosphere attention as it did because the error was caught by one of the denialist/delayers and so could be perceived as part of a conspiracy to use Climaticide as an excuse to strip us of our freedoms and establish a totalitarian one-world government. (Check out my links at the beginning of this post if you find such thinking incredible.)

PART TWO: Josh Willis, Ocean Cooling and the 3 H's

Now, lets turn to a case where an a more complicated error in the data led to false conclusions, but where the application of scientific principles without political prejudice led the scientist who had made the error to find it and correct it. This is the Science Lesson of this post's title and although the title says it is for denialists/delayers the fact is that such folk will learn nothing from what I write here. However, I thought it might be useful for the rest of us as an example of how real science works and a reminded of what the Climaticide denialists/delayers fail to do in their own writings.

Sir John Houghton towards the end of his classic, Global Warming: The Complete Briefing, (p.328) emphasizes that a proper attitude towards research requires what he calls the 3 H's: honesty, humility and holism. The case of Josh Willis and ocean cooling provides a perfect example of the application of Houghton's 3 principles.

Willis is a scientist at NASA's Jet Propulsion Laboratory specializing in measuring how much heat is stored in the oceans from year to year. In 2004 Willis published a time series running from 1993-2003 which showed that the heat being stored in the upper layer of the ocean was increasing. In 2006, he and John Lyman at Pacific Marine Environmental Laboratory in Seattle published an update to the time series covering the years 2003-2005. Contrary to the earlier study, the latest data indicated that the oceans were now cooling and at a rate 5 times faster than that at which they had been warming in the earlier study.

Not surprisingly, says Willis wryly, that paper got a lot of attention, not all of it the kind a scientist would appreciate. In speaking to reporters and the public, Willis described the results as a "speed bump" on the way to global warming, evidence that even as the climate warmed due to greenhouse gases, it would still have variation. The message didn't get through to everyone, though. On blogs and radio talk shows, global warming deniers cited the results as proof that global warming wasn't real and that climate scientists didn't know what they were doing.

Willis continued to monitor and update the data. Then in February 2007 while preparing for a presentation on Ocean Cooling at the National Center for Atmospheric Research in Boulder, Colorado, he took a look at the charts and graphs that he had just made using the most recent data and realized that something was wrong. The latest data showed that the entire Atlantic Ocean had gone cold, really cold. It was at that moment that he realized that ocean cooling was probably not real.

In order to solve the mystery, Willis entered into collaboration with Takmeng Wong and his colleagues at NASA's Langley Research Center in Virginia. Wong and his Langley colleagues were engaged in research that attempted to show, using satellite data, what was "the net flux of energy at the top of the Earth's atmosphere-how much solar energy is coming in minus how much the Earth reflects and radiates as heat."

Scientists are always looking for ways to check the accuracy of these pieced-together climate records. Since the ocean is the planet's single biggest reservoir for surplus energy, the energy imbalance Wong and his colleagues detected in net flux observations ought to be detectable in ocean heat content, too. The connection between these two related, but independently measured vital signs of Earth's climate brought Wong and Willis into collaboration in 2006.

Willis's data from the 1993-2003 study, which came from various sounding devices in the ocean corroborated Wong's findings and the two published a paper together. Not surprisingly then, Wong was among those concerned when Willis published his follow-up paper on the 2003-2005 period because the now sounding data did not match the satellite data.

At first Willis thought that perhaps meltwater from Greenland and Antarctica might explain the ocean cooling, but satellite data, as Wong pointed out to him, although it did show a contribution to sea-level rise from Greenland and Antarctic melting, did not support the idea that such melting was sufficient to account for the cooling.

XBT

An XBT may look like a rocket, but it's more like a fishing weight: a heavy zinc nose houses a thermistor (to measure temperature) attached to a spool of copper wire. The XBT is launched from a ship, then falls through the water at a constant rate. Temperature measurements are sent back to the ship through the wire until the entire length of wire is unspooled (up to 1,500 meters), at which point the connection breaks and the XBT falls to the ocean floor. (Render by Robert Simmon, NASA Goddard Space Flight Center.)

It was not until February 2007 then, when Willis saw the Atlantic Ocean data graphed and charted that he began to doubt his own data. It consisted of three sorts: satellite altimeter data which uses radar to measure ocean expansion and contraction (a warming ocean expands and and a cooling one contracts) and data from two "ocean-based data sets, including temperature profiles from the Argo robot fleet as well as from expendable bathythermographs, called "XBTs" for short."

Argo robots are free-floating devices that sink into the ocean to a depth of up to 2000 meters, float along with the currents, then rise to the surface where they transmit to a satellite the ocean-temperature data they have accumulated as they rose. XBT's are temperature sensors that are dragged along behind a ship on a line. As the the XBT's sink they take measurements of ocean temperatures at different depths. Eventually, around 1500 meters, the sensor disconnects from the line and drops to the ocean bottom.

Argo float

Argo floats are aquatic robots that measure ocean temperature, pressure, and salinity at depths of up to 2,000 meters. The floats augment satellite, ship, and buoy measurements of the ocean. (Photograph © 2004 Sabrina Speich, Argo Information Centre.)

When he looked at the data from the Argo robots and the XBT's Willis made some interesting discoveries. It turned out that some of the new Argo floats had relayed bad data indicating ocean cooling when other data sources had not. When Willis removed the data from the bad floats most, but not all, of the cooling went away. Next he looked at the XBT data. It turned out that when one compared XBT data from several earlier decades with more dependable measuring devices, such as bottled water samples gathered from ships on research expeditions, that the XBT data was too warm. In other words the XBT data had made the oceans look warmer than they were in the earlier periods while the Argo data had made them look cooler in the later period. Once Willis made the corrections, the discrepancies disappeared. The ocean was indeed warming.

Ocean temperature change

Willis' map of ocean temperature change from 2004 to 2006 originally showed drops of over 1.5° Celsius in the Atlantic Ocean. The apparent large drop in temperature was due to bad data from the Argo floats and XBTs, and it disappeared when errors in these data sets were corrected. (The remaining large swings in temperature visible in these maps are due to shifting positions of ocean currents.) (Maps by Robert Simmon, based on data from Josh Willis and John Lyman.)

Other scientists' research benefited from Willis tracking down the errors in his own data. The corrected data smoothed out bumps in the historical record over a much longer period of time when the heat absorbed by the ocean seemed to jump or drop dramatically for no particular reason. It also helped to balance the inputs and outputs of sea-level rise. Sea level rise is attributable to melting glaciers, ice sheets etc. and thermal expansion (water expands as it absorbs heat and warms). Until Willis made his corrections scientists had not been able to reconcile all the contributing factors to sea-level rise with total sea-level rise.

There is a lot more detail to this fascinating story on NASA's Earth Observatory web site. The narrative and excerpts that I have provided here are meant to illustrate the 3 H's referred to above. When Willis's own data became so contradictory that it no longer made sense he was both humble and honest enough to question his results, despite the fact that he had already staked out a position and published his earlier results. (By the way, the fact that he had published his cooling results, which flew in the face of what the models projected and what everyone expected, in a peer-reviewed journal, gives the lie to the denialist/delayer assertion that the peer-reviewed literature is simply a propaganda arm for Climaticide alarmists that rejects contrary opinions.) He used a holistic approach in checking and comparing his own data sources both with each other and with other outside data such as Wongs. And, finally, he was humble and honest enough to admit his previous mistake and publish his revised conclusions.

As the Earth Observatory article concludes:

If there is a moral to this story, it's that when it comes to understanding the climate system, it's hard to imagine too much redundancy. Every scientist involved in these studies says the same thing: to understand and predict our climate and how it is going to change, we need it all.

We need multiple, independent, overlapping sets of observations of climate processes from space and from the Earth's surface so that we can create long-term climate records-and have confidence that they are accurate. We need theories about how the parts of the Earth system are related to each other so that we can make sense of observations. And we need models to help us see into the future.

"Models are not perfect," says Syd Levitus. "Data are not perfect. Theory isn't perfect. We shouldn't expect them to be. It's the combination of models, data, and theory that lead to improvements in our science, in our understanding of phenomena."

This is how science works. It's not about ideology, or conspiracy theories, or conclusions deduced from a priori premises unblemished by concern for the facts. Nor is it about disagreeing for the sake of disagreement.

No, it's the three H's: honesty, humility and a holistic approach to research. The denialists and delayers may not always know or remember that, but the rest of us should.

2 comments

If you see any unhelpful comments, please let us know immediately.

James Becket (anonymous)

A very good article, thank you, and thank the internet as when I read a denier saying the oceans were getting cooler along with the usual vituperative prose I was able to find this. Science is never 100% certain, only political ideologues are.

Written in February 2010

Bruce (anonymous)

Wow, I'm glad "Scientists" can always find a way to adjust data to fit their models. They seem to do that a lot don't they? "What, the raw data shows it's cooling? It must be wrong. Oh, the adjusted data shows warming? It must be right. We never make mistakes with data showing it's warming."

Written in May 2010

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  • Posted on Nov. 22, 2008. Listed in:

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