Hansen's "Pinatubo Explanation" Debunked, a Result of Cherrypicking.

[BethesdaWX]

For another one of skier's fails, he stated "Hansen's explanation makes perfect sense and is basic fact"....

You mean, basic fact based on Assumptions & cherrypicking, yes. Thoroughly debunked, as is.

FYI, Hansen's paper is NON PEER REVIEWED, and SKIER SUPPORTED IT. What does that say about His Bias and Lack of Understanding?

http://wattsupwithth...g-and-all-that/

Small Snippet.

When NASA’s Dr. James Hansen leaves out 25 years worth of data, such things apparently escape his notice. Fortunately for us, Bob Tisdale notices such things and then analyses them. See his note about Figure 13 below in the body of the post. Tisdale also confirms what I suspected, that Hansen’s claim of:

A recent decrease in ocean heat uptake was caused by a delayed rebound effect from Mount Pinatubo aerosols…

Is total bollocks.

On the left, Ocean heat content as Hansen presents it in his recent (non peer reviewed) paper, starting in 1980, or the right, the OHC full dataset, starting in 1955, plotted by Bob Tisdale.

Notes On Hansen et al (2011) – Earth’s Energy Imbalance and Implications

Guest post by Bob Tisdale

UPDATE (April 23, 2011): I’ve added an addition discussion of the delayed rebound effect at the end of the post.

OVERVIEW

Judith Curry’s post Earth’s Energy Imbalance is an introduction to the Hansen et al (2011) paper “Earth’s Energy Imbalance and Implications”. Anthony Watts also prepared a post that discussed the sea level rise suggested by Hansen et al (2011). Refer to the Watts Up With That? post NASA’s Hansen thinks sea level rise will be accelerating – I think not, offering a new paper and updated story on Hansen to show why.

The following are comments about the presentation of NODC Ocean Heat Content (Levitus et al 2009) data in Hansen et al (2011). The signal that causes the decadal variations in the Global Ocean Heat “Uptake” data appears to originate in the Tropical Pacific. The post also discusses their proposed “delayed rebound effect” in Ocean Heat Uptake, their failure to include Sea Level Pressure as a variable that impacts Ocean Heat Content, and their use of outdated Total Solar Irradiance data as a forcing.

INTRODUCTION

Hansen et al used NODC Ocean Content data as one of their primary data sources to illustrate Earth’s energy imbalance. The NODC OHC dataset is based on the Levitus et al (2009) paper “Global ocean heat content (1955-2008) in light of recent instrumentation problems”, Geophysical Research Letters. Refer to Manuscript. It was revised in 2010 as noted in the October 18, 2010 post Update And Changes To NODC Ocean Heat Content Data. As described in the NODC’s explanation of ocean heat content (OHC) data changes, the changes result from “data additions and data quality control,” from a switch in base climatology, and from revised Expendable Bathythermograph (XBT) bias calculations.

In their Figure 13, Hansen et al present what they called Ocean Heat Uptake. Their Figure 13 is Figure 1 in this post. We’ll concentrate on the green curve in the right-hand cell, the one identified as the “Updates of Levitus et al (2009)” dataset.

Figure 1

I’ve reproduced the Ocean Heat Uptake curve in Figure 2, using the NODC OHC data. The KNMI Climate Explorer is the source of the data, so it’s presented in Gigajoules per square meter (GJ/m^2). The curves are the same in Figures 1 and 2, but the units are different. Hansen et al also appear to use half years (1980.5, 1981.5, etc.) in their graph. Basically, what Hansen et al are illustrating with their Ocean Heat Uptake data are 6-year running trends of the Global Ocean Heat Content data. To start the data, the linear trend of the global ocean heat content for the period of 1978 to 1983 is determined and its value plotted at 1980. The 1981 data point would include the linear trend of the OHC data for 1979 to 1984, and so on, until the last point in 2007, which includes the linear trend for the period of 2005 to 2010. The graph shows that global OHC, based on 6-year trends, was dropping from 1980 to 1982/83. It rose from 1982/83 to 1990, increasing fastest in 1988. There was very little rise in Ocean Heat Content for the 6-year period centered on 1990. Then from 1990 to 2005 OHC rose at varying rates, and basically stopped rising for the 6-year period centered on 2005.

Figure 2

Hansen et al selected 1980 as a start year for their Ocean Heat Uptake graph, but the NODC OHC dataset begins in 1955. If we look at the Ocean Heat Uptake data using the full term of the data, Figure 3, we can see that 1980 was well chosen. The six-year period centered on 1980 had greatest drop in OHC since the period centered on 1965. Choosing 1980 for the start year (Figures 1 and 2) makes the increasing changes through the early 2000s seem significant. But with the entire dataset presented, the early period of positive trends from the late 1970s to the late 1980s suppresses the appearance of the recent wiggles. Highlighting “zero” also changes the perspective.

Figure 3

For those interested, Figure 4 is a comparison of annual NODC Global Ocean Heat Content data versus the Ocean Heat Uptake data, from 1955 to 2010. The OHC data has been scaled by a factor of 0.1 to help visual comparisons. Keep in mind the Ocean Heat Uptake (running 6-year trend) data is “centered” on the 3^rdof 6 years, so it skews the dataset slightly.

[skierinvermont]

Tisdale didn't understand what Hansen mean't by a delayed rebound effect and neither do you.

What Hansen is really saying is that OHC was rising unnaturally quickly from 1995-2002 as we recovered from Pinatubo. The 2000-2011 period is more representative of the true underlying trend. The whole point of Hansen's paper is that OHC is not rising as fast as thought during the 90s and early 2000s. It's sort of funny Hansen is actually agreeing with the skeptics in saying that OHC rise has slowed and that the rapid rise during the mid to late 90s was a blip due to the recovery from Pinatubo. He's agreeing with the skeptics but they're too stupid and determined to disagree with anything he says to realize it

All Hansen is saying is that Pinatubo caused OHC to rise faster than normal 1995-2002 and that the current drop is a return to the underlying rate. (Except for the solar minimum). The whole point of Hansen's paper is that OHC isn't rising as fast as previously thought.. previous expectations were skewed by the rebound from Pinatubo during the late 90s.

What Hansen is describing can be seen in the right hand panel of this graph:

Tisdale's comments in red are wrong... OHC does show a pronounced Pinatubo effect. It stops rising during the early to mid 90s.. then rises rapidly from 1995-2002 in the recovery from Pinatubo.

[BethesdaWX]

Skier Fail 3rd of the night and counting.

You have no clue what you're saying, and I'll explain it to you yet again!

There is no evidence Pinatubo Caused ANY delayed rebound effect, because when you extend back the full Dataset, we see flucuations before Pinatubo in the 1960's matching exactly that of the 1990's... since there is a known 2 year resiliance!

You missed the point, there is no evidence of Pinatubo Causing any Rebound effect

Hansen Also Uses

-Outdated TSI data

-Non Peer reviewed data

Tisdale then EXPLAINS what was Causing the flat-lining in Sea Uptake! It is a decrease in Uptake over the Atlantic!

LOOK

Figure 14 shows the Solar Forcing data and impacts presented by Hansen et al (2011). The Total Solar Irradiance (TSI) data in the left-hand cell appears to be based on an early reconstruction by Judith Lean, including background effects, with current TSI data spliced onto the end. The Lean TSI dataset is outdated. Note the early rise in solar minimums from the 1880s to the 1940s.The current understanding of TSI variability is that the minimum TSI in 1880 should be in the vicinity of the recent solar minimums. In other words, that rise from the 1880s to the 1940s does not exist. The use of outdated TSI was discussed in the post IPCC 20th Century Simulations Get a Boost from Outdated Solar Forcings, which was also cross posted at WattsUpWithThat: IPCC 20th Century Simulations Get a Boost from Outdated Solar Forcings. Refer to the comments there by Leif Svalgaard, Solar Physicist from Stanford University. The red curve in the middle cell of Figure 14 shows the impact of the variations in TSI on Global Surface Temperatures. For the last three solar cycles, the temperature variations from solar minimum to maximum should be on the order of 0.07 to 0.1 deg C. Hansen et al (2011) are showing considerably less impact from solar variability.

Hansen et al (2011) write in the abstract, “A recent decrease in ocean heat uptake was caused by a delayed rebound effect from Mount Pinatubo aerosols and a deep prolonged solar minimum.”

First, it’s difficult to find the impact of Mount Pinatubo on the Ocean Heat Content data for many of the ocean basins. Refer once again to the post ENSO Dominates NODC Ocean Heat Content (0-700 Meters) Data. I included GISS Aerosol Optical Thickness Data (a proxy for the timing and magnitude of explosive volcanic eruptions) in many of the graphs. Only two of the ocean basins, the South Atlantic and South Indian Oceans , show clear signs of the effects from Mount Pinatubo in 1991, but they rebounded quickly, as one would expect. Refer to Figures 9 and 11 in that post. Since the Ocean Heat Content data for the basins show few signs of being impacted by Mount Pinatubo, the claim of a delayed rebound is surprising.

Second, as shown in the recent post ARGO-Era NODC Ocean Heat Content Data (0-700 Meters) Through December 2010, the recent flattening of Global OHC data is caused primarily by the significant drops in the OHC of the North Atlantic and South Pacific, Figure 8. But these are countered by the significant rises in the Indian and South Atlantic Oceans. Are Hansen et al suggesting that the “delayed rebound effect” is only impacting the North Atlantic and South Pacific basins? If Hansen et al are proposing a mechanism for the “delayed rebound effect”, I did not find it. I would have to believe it would be Meridional Overturning Circulation (MOC), and would be based on the assumptions that the cooler waters created by the Mount Pinatubo eruption would be circulated to depths below the 700 meter reach of the NODC OHC dataset and then reemerge 20-plus years later. If so, then the MOC circulation time would have be the similar in the North Atlantic and South Pacific, but not the other ocean basins. And if they are proposing MOC now in their Energy Balance Models, they should also consider that warm and cool waters distributed by ENSO would also be subducted to depths below 700 meters and then reemerge “x” decades later, with more warm water than cool being redistributed during epochs when El Niño events dominate, and vice versa when La Niña events dominate.

This is the Cause of the Drop in the ARGO era, THE ATLANTIC ALONE

[skierinvermont]

Tisdale doesn't even understand what it is Hansen is saying. Hansen is saying that OHC rose quickly during the mid-late 90s (which it did) as a rebound from Pinatubo.. we've slowed since then because we have returned to the normal underlying rate.

Tisdale seems to think Hansen is saying our current trend is unnaturally slow and that Pinatubo is still causing cooling... for example he proposes that hypothetically cold water created by Pinatubo was stored below 700m and is now resurfacing 20 years later.

This reveals that Tisdale doesn't even know what Hansen is saying. Tisdale seems to think that Hansen is saying Pinatubo is still causing cooling. Hansen is NOT saying that. What he's saying is that the rebound from Pinatubo in the mid to late 90s caused exaggerated OHC warming, and we have now returned to the underlying rate. (-minus the solar min of course).

It's completely irrelevant where the warming or cooling occurs. Pinatubo doesn't dictate the spatial pattern.. it is simply a net effect everywhere. The fact that one area cooled and one area warmed doesn't mean it's not Pinatubo. It just means that without Pinatubo the area that cooled would have cooled less and the area that warmed would have warmed more. Isolating the spatial pattern doesn't prove anything.