[Vision2020] April Fools' Day: Solar, Ocean, Cosmic Ray Climate Forcing: "‘Wrong sign paradox’ finally resolved?"

[Ted Moffett]

No doubt the following is an April Fools' Day article on
Realclimate.org, though referencing accurate scientific data that
reveals three of the climate variables sometimes referenced to explain
recent warming Earth temperatures from natural forcings, have in
recent decades trended towards what should be a cooling of Earth's
climate, the opposite of what some so called anthrppogenic climate
change "skeptics" have argued, as 2010 was the warmest year for global
average surface temperature, in the instrumental record since 1880,
accoording to GISS:
http://data.giss.nasa.gov/gistemp/graphs_v3/Fig.A2.gif
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The article below is by Stefan Rahmstorf, who teaches physics of the
oceans as a professor at Potsdam University:
http://www.realclimate.org/index.php/archives/2004/12/stefan-rahmstorf/

http://www.realclimate.org/index.php/archives/2012/04/wrong-sign-paradox-finally-resolved/#more-11329

‘Wrong sign paradox’ finally resolved?
Filed under: Climate Science— stefan @ 1 April 2012

A group of colleagues has all but solved one of the greatest remaining
puzzles in climate science. But the story is not one of scientific
triumph – rather, it is so embarrassing that we had controversial
discussions in our group whether to break this to a wider public at
all.

The puzzle is known amongst climatologists as the “wrong sign paradox”
– our regular readers will probably have heard about it. Put simply,
it is about the fact that a whole number of things in climate science
would fit very nicely together, if only the sign were reversed. If
only plus were minus.

Perhaps the best-known example is how we could explain global warming
with variations in solar activity: the hottest year on record (2010)
happens to coincide with the deepest solar minimum since satellite
measurements of solar luminosity began in the 1970s (Fig. 1). This
can’t just be coincidence. But the sign is wrong: physical theory
stubbornly insists that temperature should be highest when the sun
shines the brightest, not the other way round. The “wrong sign
paradox” here is reinforced by the fact that the overall trend in
solar luminosity is gently downward over the past 30 years – just
those 30 years when we see the well-known strong global warming.

Another prominent example is the Pacific Decadal Oscillation (PDO).
Basic physical considerations would suggest that the global
temperature is warm when the PDO-Index is high, i.e. when sea surface
temperatures in the North Pacific are high. A theory that would
beautifully fit the data – if only the sign were reversed (Fig. 2)!

And just to round this off with a third example (there are more of
course – perhaps our readers can provide some others): cosmic rays. A
very beautiful theory holds that cosmic rays help cloud formation:
lots of cosmic rays means lots of cloud and hence cool global
temperature. Now cosmic rays have been measured since the 1950s, and
they reached their all-time maximum in 2010 (Fig. 3). Bingo: the
warmest year on record! But no: a high cosmic ray count should cause
cold temperatures, not hot ones.

Even a lay person can imagine how powerful these (already popular)
theories would be, if only the data showed exactly the opposite of
what they actually show! If the warmest year on record coincided with
the strongest solar maximum and not the deepest solar minimum, or if
the PDO showed an upward trend over the past 30 years and not a
downward trend. But now a solution seems to be in sight.

Solving the mystery

A group of Dutch and US scientists, led by Harry Van den Budenmeyer
(Utrecht University), has now proposed a surprising explanation. “At
first I did not want to believe it”, Van den Budenmeyer explained to
RealClimate, “but once we started to pursue this, things just fell
into place”.

The story goes back to the late 1980s or early 1990s (the exact date
has not been traced back yet), when a German climate modeller had
persistent problems with results of obviously the wrong sign in his
model. He was unable to track down the error, so instead he introduced
a FORTRAN integer variable called ICHEAT (sorry to get a bit
technical, but you really need to understand this) into his computer
code, assigned it the value -1 and simply multiplied unruly results by
ICHEAT wherever they occurred in his code. Once he’d find the real
problem, he would only need to set ICHEAT to +1 and the code would be
correct again. But he never got round to fix the problem, his model
performed very nicely and over time he forgot about it.

What he did not consider, perhaps understandably at the time: useful
computer code spreads like a virus amongst scientists. The code was
free for download, hundreds of other scientists started to use it and
many only used bits and pieces – nobody ever starts writing scientific
code from scratch if colleagues have already solved aspects of the
task at hand and the code is free.

“At first we were really puzzled when we found a piece of code with
ICHEAT that was used in our lab for climate analysis”, says Van den
Budenmeyer. “But once we discovered what it was we started to search
more systematically and ask colleagues, and by now we’ve found the
ICHEAT bug not just in different European countries but also in
California, New York, Sydney and even a Chinese climate centre. We’ve
only begun to explore the implications, but I am sure that a lot of
the wrong sign paradox that has plagued our science thus far will just
go away.”

We will keep you updated here at RealClimate, of course.

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Vision2020 Post: Ted Moffett