Are Ocean Temperatures Gradually Increasing?
The Cato Institute’s Patrick Michaels had some interesting commentary on a recent much-publicized study that found the temperature of the Earth’s oceans had increased by 0.11 degress Celsius from 1955-1996.
First, Michaels notes that the author of the study, Sydney Levitus, was unable to find any warming trend in the top 1,000 feet of ocean water. Instead, Levitus focuses on temperatures in the top 10,000 feet of water.
But Levitus does something interesting to produce his trends — rather than just compare temperatures from 1955 to 1996, he creates five year averages of the temperatures. Done this way, his data produces the 0.11 degree Celsius warming increase. Does using five year averages make it look like there is a warming trend that isn’t there?
Michaels decided to take another look at the 1,000 feet data, for which the straight data rather than 5 year averages were used, and apply the 5 year methodology to them. The result:
For fun, we decided to treat the shallow ocean (1,000 foot) data, which weren’t manipulated to begin with, to the same averaging. Sure enough, the 1976-77 shift disappears and the resultant figures look just like the deep ocean (10,000 foot) data, which resembles the climate models. Proof again that if you torture the data, it will confess to whatever you want.
What’s going on here is an odd one-time event called the great Pacific climate shift. From 1955 to 1976 the temperature of the Pacific Ocean didn’t warm, and from 1977-1996 it didn’t warm, but in 1976-77 the average temperature of the Pacific Ocean suddenly increased. No one is quite sure why, but it appears to be part of a 40-50 year cooling and warming cycle in the Pacific Ocean.
By using running five year averages rather than the raw yearly temperature data, Levitus’ study in effect smoothes out the abrupt 1976-77 temperature shift to give the appearance that the increase in temperature occurred gradually over a longer period of time rather than abruptly occurring in just one year.
And, of course, no climate model to my knowledge predicts a one year jump in Pacific Ocean temperatures followed by 23 years of no warming. As Michaels puts it,
As noted above, there is no statistically significant warming trend on either side of it. How can a climate model explain this? The sun didn’t suddenly get brighter in 1976. And the three big volcanoes that dominate this study period occurred in 1963 (Mt. Agung), 1982 (El Chichon), and 1991 (Mt. Pinatubo) surely don’t presage a step-change in the temperature in one year. The match between the ocean history and the climate models results from human influence on the data rather than human influence on the atmosphere.
Source:
Tortured Data Confesses!. Patrick J. Michaels, Cato Institute, April 23, 2001.
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