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Guest post from BruinKid.

They’re at it again.  Over at ICECAP, a site that claims to not be made up of global warming deniers, but turns out to host some of the biggest names in the global warming denial field that get serious $$$ from the oil companies, Joseph D’Aleo (a meteorologist, not climate scientist) put up their latest lie.  This graph is the brunt of their argument.

See??  There’s no correlation between temperatures and CO2 output!

Debunking after the fold.

First, in climate science, 10 years does not make a trend.  You need at least 30 years to establish what the baseline should be.  So looking at a graph of only 10 years does little to tell us anything.  What was it like before?  Well gee, notice this graph starts at a temperature high point of 1998, which was in part due to El Niño that year.  How convenient of them to start at the outlier.

So, why not look at the Hadley measurements going back further than 1998?  Maybe because when you see a fuller record, it paints a very different picture these deniers don’t want us to see.

Hey, whaddaya know?  There seems to be a pretty significant increase in the surface temperature readings since the 1970s!

John Mitchell of the Hadley Centre has more about this myth that global warming stopped in 1998 that deniers like to spout.

1998 saw an exceptional El Niño event which contributed strongly to that record-breaking year. Research shows that an exceptional El Niño can warm global temperatures by about 0.2°C in a single year, affecting both the ocean surface and the land air temperatures. It is therefore not surprising that 1998 appears as a warm outlier. Had any recent years experienced such an El Niño, it is very likely that this record would have been broken. More recently, 2005 was also an unusually warm year, the second highest in the global record, but was not boosted by the El Niño conditions that augmented the warmth of 1998.

The fact remains that the rise in underlying surface temperature has averaged in excess of 0.15°C per decade since the mid 1970s. A simple mathematical calculation of the temperature change over the latest decade (1998-2007) alone shows a continued warming of 0.1°C per decade. The warming trend can be seen in the graph (above) of observed global temperatures. The red bars show the global annual surface temperature, which exhibit year-to-year variability. The blue line clearly shows the upward trend, far greater than the uncertainties which are shown as thin black bars. Recent slight slowing of the warming is due to a shift towards more-frequent La Niña conditions in the Pacific since 1998. These bring cool water up from the depths of the Pacific Ocean, cooling global temperatures.

Another way of looking at the warming trend is that 1999 was a similar year to 2007 as far the cooling effects of La Niña are concerned. The 1999 global temperature was 0.26°C above the 1961-90 average, whereas 2007 is expected to be 0.41°C above this average, 0.15°C warmer than 1999.

So if you encounter the 1998 myth from someone you know, tell them about El Niño, and then ask them to explain 2005.  See, here’s the thing.  When you rank the hottest years going back to 1850, the 17 warmest years all happened in the last 20 years.

And what about La Niña?

There are a number of natural factors contributing to so-called interannual variability, the single most important being the El Niño Southern Oscillation or ENSO.  The global climate is currently being influenced by the cold phase of this oscillation, known as La Niña (see Met Office: Expert speaks on La Niña).

The current La Niña began to develop in early 2007, having a significant cooling effect on the global average temperature. Despite this, 2007 was one of the ten warmest years since global records began in 1850 with a temperature some 0.4 °C above average.

The La Niña has strengthened further during early 2008 and is now the strongest since 1988/89, significantly contributing to a lower January temperature in 2008 compared to recent years. In addition, global average temperature has been influenced by very cold land temperatures in parts of the northern hemisphere and extensive snow cover.

However, once La Niña declines, it is very likely that renewed warming will occur as was the case when the Earth emerged from the strong La Niña events of 1989 and 1999.

So given all this, the graph at the top of this diary D’Aleo talked about is simply completely misleading, as it does NOT take La Niña into account!  Presenting a graph of temperatures in 2007 not rising when compared with CO2 output without the caveat about La Niña is pretty intellectually dishonest.  (And obviously, La Niña has nothing to do with CO2 output, but certainly has an effect on average global temperatures.)  But that’s the graph the global warming denial crowd will seize upon.  I’ve already seen it pop up on other message boards, posted triumphantly by ignornant right-wingers who refuse to understand the science behind the data.

In statistics, we call the presence of La Niña a confounding factor.  In order to draw any meaningful conclusions, you must account for confounding factors first, otherwise your results are… well… HORSE SHIT.  Look at the correlation AFTER adjusting for it.  But D’Aleo and the people at ICECAP do not.  Even though D’Aleo MENTIONS El Niño and La Niña in his post!

See in the attached pdf though how the temperatures do correspond far better with the ENSO cycles and longer term with PDO which controls the relative frequency of El Nino and La Nina. With an apparent shift on the regime of the PDO to cool and the prospects of solar cycles 24 and 25 being quiet, global cooling is more likely than global warming in the decades ahead.

Now while he is correct to say that the temperatures correspond far better with ENSO (the El Niño Southern Oscillation, for those that missed the term explained above), it is misleading, because he’s comparing it to a correlation that did NOT take into account ENSO in the first place!  Why not compare the correlation here, with the correlation of temperature and CO2 after adjusting for ENSO?  Perhaps because if the latter has a higher correlation, that would destroy his argument?

And global cooling??  No.  Sorry, wrong conclusion.  Thanks for playing, though.  Even with La Niña cooling things down, 2007 was still one of the 10 hottest years since 1850.  What does he think will happen once La Niña goes away?  That unlike in 1989, the temperature won’t go back up??  OK, if so, then why?  He cannot just state that without something to back up his laughable claim.  Sorry Mr. D’Aleo, the trend lines are going up no matter how you spin it.

Folks, we need to be aggressive in countering these lies and deceptions coming from the deniers.  The environment should be everyone’s #1 issue, and many people don’t see how closely tied the war in Iraq is with the state of our environment.  CO2 emissions?  Gee, if we weren’t so dependent on oil that we invaded a Middle Eastern country……………  Do people not understand this connection?  And do people not see how throwing billions and billions of dollars down the drain in Iraq over the last couple years has seriously impacted our economy?  Do people think these issues are unrelated?
As for the “experts” at ICECAP, notice how names appear in a 2006 diary I wrote showing how “Friends of Science” was really a Big Oil mouthpiece, with those scientists bought and paid for by the oil industry.  The big names that appear again are Sallie Baliunas, Bob Carter, Vincent Gray, the Idso family, Pat Michaels (who has since been fired by the University of Virginia for lying about what he did there), Gary Sharp, Fred Singer, Roy Spencer, and George Taylor.  New names (but not new in the GW denier category) include Robert Balling, Reid Bryson (who was responsible for the global cooling stuff in the 1970s that right-wingers mocked scientists for; now he’s on “their” side, so they’re cool with him), Chris De Freitas, William Gray, Tad Murty, and James O’Brien.  I’m sure there are other connections to Big Oil with the other people on that list too.

(h/t to Climate Progress for exposing the truth behind the lies)

And, another valuable place for a drop in, RealClimate’s Uncertainty, noise and the art of model-data comparison.