Climate Science: Roger Pielke Sr. Research Group News

In responses to the April 1 2008 Climate Science weblog, I e-mailed to Josh Willis to both alert him to the weblog and follow up on his comments about upper ocean heat trends. With his permission I am posting our e-mail exchanges below. These adds to our knowledge of this critically important climate metric of global warming and cooling.

E-mail Inquiry

Hi Josh,

I have read your op-ed on the weblog http://network.nationalpost.com/np/blogs/fullcomment/archive/2008/03/31/josh-willis-on-climate-change-global-warming-is-real.aspxand will be weblogging myself on it in the next week or so.

It seems you have developed a difference of interpretation of your data from what you had e-mailed previously. The Argo data indicates that if global warming occurred over the last 4 years, it was in the deeper ocean and is thus not available in the short term to the atmosphere (in fact, if it is there, it likely more diffused and therefore could only enter the atmosphere slowly if at all), or it has exited into space. The other heat stores in the climate system are too small (and the atmosphere has clearly not warmed over the last few years). Global sea ice cover is actually above average at present (the Antarctic sea ice is at a near record level). The continued sea level rise indicates to me that the heat is in the deeper ocean (which is not predicted by the models).

There is also no unrealized heat in the system. This is a fallacy of using temperature trends as the surrogate for heat trends as I have reported on my weblog. The GCM models also do not report on 4 year time periods without any warming for the current decades.

I will comment further in my weblog but I am perplexed by your dismissal of the actual significance of your results. It appears you have jumped on the advocacy bandwagon with your last paragraph.

Best Regards

Roger

First E-mail Reply

Hi Roger,

Thanks for the email.  Attached is a plot showing the upper 750 m ocean heat content from the GFDL CM2.1 coupled climate model.  The blue line is the 12-month running mean heat content from one run and the green line shows the monthly-mean heat content for the same run, but with the control run subtracted.  Subtracting the control run essentially takes out the seasonal cycle.  Even apart from the period after the eruption of Mt. Pinatubo in the early 1990s there are several multi-year periods when OHCA is flat.

Also, I believe that after all the dust settles on the XBT bias corrections, the 50 year observational record of OHCA will have still have several multi-year periods with little or no warming.

I do agree with you that heat content is a much better measure of forcing than surface temperature.  I also agree that the cause for this most recent flat period is not understood and figuring it out is important for understanding climate change.  Furthermore, if it is some type of natural variability (which seems reasonable to me), it is important for the IPCC models to simulate it correctly, especially if there is an effort to move toward decadal projections instead of just the centennial projections that they now produce.

That said, it does seem very likely to me that the 50-year trend in ocean heat content is part of the climate’s ongoing response to greenhouse forcing.  If that is the case, I think it is pretty easy to argue that the oceans and surface temperature will be warmer 50 years from now than they are today, and this is the reason for my comment in the National Post.

As for the sea level rise discrepancy, I do not think that it is possible for enough heat to have been absorbed by the deep oceans to fully explain the difference between the altimeter and the upper ocean thermal expansion we reported in the JGR paper.  There have been many repeat hydrographic sections that show warming in the deep ocean, but inventories of these suggest that a few tenths of a mm/yr is the most that could be accounted for by this.  This points to some kind of systematic error in one of the three observing systems, which is not entirely unlikely.

Cheers,
Josh

My Reply

Hi Josh, Thanks for the further feedback. Can you send the figure with just the forced run on it? It would be clearer to just have that plot.

On the reasons for sea level rise, I asked the question about rises in the ocean sea bed when I was at the University of Texas at Austin last year, and they told me it was too small of an effect. This is certainly not my expertise, but I would be interested in further discussion on the uncertainties of this measurement for decadal and yearly time scales.

On model performance on ENSOs, PDO and the NAO, they certainly do a poor job on seasonal time scales (as exemplified for this past winter), and I would be interested in any papers that have examined these specific circulation indices on longer time periods. I know that some of the models produce ENSO events but do not know how realistic in frequency or magnitude they are.

There was a talk on this by De-Zheng Sun of CIRES in my class last year;

http://cires.colorado.edu/science/groups/pielke/classes/atoc7500/sun.pdf

where he found the models, when run in a coupled atmosphere-ocean mode, over predicted ocean surface warming.

Roger

P.S. On posting your comments, can I also cut text out of your latest e-mail to add? I will send the final draft to you first before posting to make sure it accurately conveys your viewpoint.

Second E-Mail Reply

Hi Roger,

New plot attached.  As a rule, you are welcome to quote my emails whenever you want on the blog.  I’ll let you know if there’s something I don’t want you to share.  :)

The issue of the sea bed moving is one that has been given some thought by the geodesists, and in our paper we make an adjustment 0.3 mm/yr to the altimeter for this.  All of the people I’ve talked to have told me that this should be fairly linear over time scales of a few hundred years, but I don’t know that anyone has looked into short time scale variability specifically.
Cheers, Josh

 Third E-Mail Reply

Hi Roger, Yes, you are more than welcome to post the comments and plot.  Never mind the forced-control line.  That’s leftover from my habit of looking at the deep ocean, which has a significant drift.I haven’t looked at the radiative imbalance in this model, but there is a pretty large amount of heat entering the deep ocean.  I’m not sure how realistic this is (that’s one of the things I’m looking into), but getting that right is important for getting the overall radiative imbalance and I suspect that lots of the IPCC models do a bad job in the deep ocean. You are right that this model only has very short periods (4 years at most) and I suspect that they have something to do with El Nino in this particular model.  That’s also something I’m looking into. But of course in the real ocean there are other quasi-global scale ocean phenomena, like the PDO, and I don’t have any idea if any climate models get that right.

Cheers, Josh

_______________________________________________________ 

Climate Science Conclusion

• The ocean heat content remains the most appropriate climate metric to monitor global warming (or cooling).
• The models (of which the figure presented above is a representative example)show a more-or-less monotonic increase in upper ocean heat content in coming years.
• Any leveling off of this increase is short lived in the models and, at most 4 years in the example presented above.
• The recent (last 4 years) upper ocean observations show no warming.
• If heat is entering the deep ocean, it is, therefore, not contributing to an increase in sea surface temperature. This necessarily reduces the amount of water vapor evaporated into the atmosphere from what would occur if the heat were in the upper ocean.
• The assessment of upper ocean heat content provides an ideal quantitative comparision tool with the models, using the approach presented on Prometheus.

Andy Revkin has started a dialog on the policy statements of professional organizations with respect to the role of humans within the climate system on his weblo Dot Earth.

 Please enter this discussion if you are a credentialed climate scientist. My comment that I have submitted is

 ”Andy - Thank you for bring this issue up. There is actually considerable diversity of views on the role of humans within the climate system. The AGU (and AMS) policy statements are actually written by just a few individuals.  While this captures their views, it is incorrect and inaccurate to present these policy statements as a consensus of these professional organizations. These policy statements certainly do not represent my views on this issue.

Readers of your weblog should also visit my Climate Science weblog [http://climatesci.org/], where other viewpoints are presented, including that of a 2005 National Research Council report entitled

Radiative forcing of climate change: Expanding the concept and addressing uncertainties [http://www.nap.edu/openbook/0309095069/html/].”

I also urge you, for completeness, to post the policy statement of the AGU Natural Hazards Committee.

We have moved our weblog to a new private host and we are back up and running. Thanks for your patience and understanding.
Our new link is http://climatesci.org

Roger Pielke Sr. and Dallas Staley

Today is the last day of our weblog. You can still find it on the same url, we have not moved that, but comments will no longer be accepted. So please, go ahead and browse the archives, but realize, no new posts will be forthcoming, and no comments will be accepted.

Thanks for everyone’s participation!

Dallas Staley

I want to thank everyone who has contributed to the diverse subjects on Climate Science! The site has been active since July 2005. However, the maintenance and preparation for the weblog requires quite a bit of time, and I have decided to move onto other activities. I have also extensively presented my perspective on climate science. The weblog will remain available as an archive on our research website.

After the remaining weblogs have posted (on September 2), the last weblog will identify where the archive can be found. Comments, of course, will not be accepted after that time, but the entire history of the weblog will be available for those who are interested.

Our site has been down for several days as many of you have noticed and emailed us to inquire about. We had a power outage last Friday and problems following that, but we are back up this morning and back on track.

thanks! dallas

We continue to receive comments with insults and name calling. I have reluctantly posted some despite some of this, because there was substance in part of the comments. From now on, however, there will be a no tolerance policy, and regardless of the merit of a comment, it will not be posted if there is any of this objectionable personal attack material in them. They detract very significantly from any scientific substance that is present.

After two days, Climate Science is back on line. Thank you for all of the e-mails asking why it was offline. We have had a long term chronic problem with our connection in the original location of the server for the website. We have now been able to move the computer to a different location, and after two days, the set up was complete. We expect uninterrupted service for the foreseeable future!

A new article has appeared

Christy J. R., W. B. Norris, R. W. Spencer, J. J. Hnilo (2007), Tropospheric temperature change since 1979 from tropical radiosonde and satellite measurements, J. Geophys. Res., 112, D06102, doi:10.1029/2005JD006881

which updates the assessment of tropical tropospheric temperature trends. The abstract of the paper is

“Temperature change of the lower troposphere (LT) in the tropics (20°S–20°N) during the period 1979–2004 is examined using 58 radiosonde (sonde) stations and the microwave-based satellite data sets of the University of Alabama in Huntsville (UAH v5.2) and Remote Sensing Systems (RSS v2.1). At the 29 stations that make both day and night observations, the average nighttime trend (+0.12 K decade−1) is 0.05 K decade−1 more positive than that for the daytime (+0.07 K decade−1) in the unadjusted observations, an unlikely physical possibility indicating adjustments are needed. At the 58 sites the UAH data indicate a trend of +0.08 K decade−1, the RSS data, +0.15. When the largest discontinuities in the sondes are detected and removed through comparison with UAH data, the trend of day and night releases combined becomes +0.09, and using RSS data, +0.12. Relative to several data sets, the RSS data show a warming shift, broadly occurring in 1992, of between +0.07 K and +0.13 K. Because the shift occurs at the time NOAA-12 readings began to be merged into the satellite data stream and large NOAA-11 adjustments were applied, the discrepancy appears to be due to bias adjustment procedures. Several comparisons are consistent with a 26-year trend and error estimate for the UAH LT product for the full tropics of +0.05 ± 0.07, which is very likely less than the tropical surface trend of +0.13 K decade−1.”

Excerpts from the paper read

“We have and will continue to examine various families of radiosondes to document inhomogeneities which create problems for time series analysis. To date, using a number of tools, we have discovered both positive and negative biases in many types of radiosondes [Christy and Norris, 2004, 2006]. As noted here, many shifts appear to be spuriously negative, but there are also many, including some of the largest in magnitude, which appear to be spuriously positive. Thus in total these would seem to have a relatively small impact on lower-tropospheric trends of large-scale averages. Given the results of the current versions of the data sets and experiments presented here, we see that all (except RSS and one RSS-adjusted sonde experiment) indicate trends for the tropical lower troposphere that are less than that of the surface (+0.125 K decade−1). This yields trend ratios of troposphere versus surface of less than 1.0, which is smaller than the ratio of 1.3 generated from climate model simulations for this time period.”

and

” A key difference between the UAH and RSS data sets occurred around January 1992 when a significant positive shift occurred in the RSS data relative to UAH. This date coincides with the inclusion of data from the newly launched NOAA-12 satellite and the latter part of NOAA-11’s time series when large corrections needed to be applied. Further comparisons with sonde and other data sets between the periods before and after January 1992 show consistency with the UAH data but a relative positive shift in the RSS data of 0.07–0.13 K. The upward shift in the RSS data relative to UAH and the other data sets cannot be explained by potential discontinuities in those data sets at this time. We speculate that the upward shift in RSS data likely relates to warming due to corrections applied to NOAA-11. Overall, the results presented here indicate consistency with the estimated UAH LT trend of +0.052 ± 0.07 K decade−1 for the entire tropics. With a corresponding surface trend of +0.125 K decade−1, the ratios of the present versions of UAH, sonde and reanalyzes tropospheric warming trends versus the surface trend are less than 1.0 while for RSS the ratio is 1.2.”

This study documents the value of the University of Alabama microwave satellite analysis in assessing long term trends in tropospheric temperatures. Current information on their analysis of long term trends and anomalies can be found at http://vortex.nsstc.uah.edu/data/msu/t2lt/uahncdc.lt.

The correction to the paper

Lyman, J. M., J. K. Willis, and G. C. Johnson (2006), Recent cooling of the upper ocean,
Geophys. Res. Lett., 33, L18604, doi:10.1029/2006GL027033

will be available soon. The cooling will be shown to have been removed; however, the warming of the 1990s and up to 2002 will be shown not to have persisted. This will still be a challenge for the global climate modelers to explain, since the IPCC perspective of global warming requires a more-or-less monotonic increase in Joules within the climate system, in the absence of a major volcanic eruption (i.e. see A Litmus Test For Global Warming - A Much Overdue Requirement).

The possibility of the availability of the Argo data in near real time and displayed in the same format as the sea surface temperature anomalies (see) will be a very major contribution to climate science. This will include the comparison of the global climate models with this critically important metric to monitor global average warming and cooling, and its spatial variations. An important question is whether the lack of continued global warming in recent years will be temporary, or is this further evidence that the climate system is more complex than concluded in such assessments as provided by the IPCC.