Monday, Dec 08, 2008
When is a short term trend not a short term trend? When it’s an upward anomaly.
James Randerson in the Guardian tells us that,
This year is set to be the coolest since 2000, according to a preliminary estimate of global average temperature that is due to be released next week by the Met Office. The global average for 2008 should come in close to 14.3C, which is 0.14C below the average temperature for 2001-07.
But just when you thought it was safe to rush out to buy a guilt-free 4×4… <scary music>
The relatively chilly temperatures compared with recent years are not evidence that global warming is slowing however, say climate scientists at the Met Office. “Absolutely not,” said Dr Peter Stott, the manager of understanding and attributing climate change at the Met Office’s Hadley Centre. “If we are going to understand climate change we need to look at long-term trends.”
Here’s a curious thing… Whether or not global warming ever existed, if ‘relatively chilly temperatures are not ‘evidence that global warming is slowing’, then what is?
That’s not to say that cooler temperatures ‘prove’ that there’s no global warming, but that cooler temperatures must be evidence that ‘global warming is slowing’. The difference is between ‘evidence’ on the one hand, and ‘proof’ on the other. Evidence can support contradictory hypotheses.
If this was mere journalistic oversight, that’s one thing – even though Randerson, one of the Guardian’s science correspondents, with a PhD in evolutionary genetics, really really ought to know the difference between evidence and proof, and what they stand for. But if the argument belongs to Peter Stott, then it surely raises questions about his partiality. ‘Absolutely not‘? Cooling temperatures absolutely are evidence for the hypothesis that there is no global warming underway, necessarily.
Prof Myles Allen at Oxford University who runs the climateprediction.net website, said he feared climate sceptics would overinterpret the figure. “You can bet your life there will be a lot of fuss about what a cold year it is. Actually no, its not been that cold a year, but the human memory is not very long, we are used to warm years,” he said, “Even in the 80s [this year] would have felt like a warm year.”
Allen is right to say that people have short memories, but he is wrong to think that it’s only sceptics who have them, and make a fuss about exceptional years. For example, Anderson continues,
The Met Office predicted at the beginning of the year that 2008 would be cooler than recent years because of a La Niña event – characterised by unusually cold ocean temperatures in the equatorial Pacific Ocean. It is the mirror image of the El Niño climate cycle. The Met Office had forecast an annual global average of 14.37C.
Anderson has a short memory. So does Allen. Scientists at the Met office are so keen to make a big deal out of unexpected temperatures that they ‘overinterpret the figures’ before they have even happened.
(ARTICLE CONTINUES BELOW)
At the begining of 2007, a BBC article informed the world that
“The world is likely to experience the warmest year on record in 2007, the UK’s Met Office says.”
The global surface temperature is projected to be 0.54C (0.97F) above the long-term average of 14C (57F), beating the current record of 0.52C (0.94F), which was set in 1998.
The annual projection was compiled by the UK Met Office’s Hadley Centre, in conjunction with the University of East Anglia.
Such ‘a fuss about what a hot year it is’… (even though it hadn’t happened yet).
We have actually run this forecast three times, updating it every month… and it is completely stable.”
But didn’t the Hadley Centre’s own Peter Stott just tell us that we ought to be looking at long-term trends? And yet, a forecast of a short term trend is considered newsworthy. Double standards are rife in climate science activism.
The Hadley Centre has been issuing the annual forecast for the past seven years and says it has just a 0.06C margin of error.
Eight months later, and the Met Office’s confident prediction was shown to be utter bunk. Temperatures were falling. They revised their predictions, saying that they had created a new, more powerful computer model for predicting the future.
Powerful computer simulations used to create the world’s first global warming forecast suggests temperature rises will stall in the next two years, before rising sharply at the end of the decade.
But as we suggested earlier in the year, the incautious statements issued by Met Office scientists looked less like the work of scientific enquiry, and more like post-hoc speculation about which way the weather would turn.
In January 2007, the Met Office backed the wrong horse – El Niño. When La Niña emerged as the favourite, they changed their bets. This wasn’t sophisticated computer modelling. This was gambling by gamblers posing in lab coats. It was a safe bet that La Niña’s effects would last until 2009.
In order to wrong-foot sceptics, activist climate scientists (for that is what they must be if they are not agnostic about global warming) have had to reinterpret the evidence. Any downward tendency is waved away as short-term ‘natural variation’, caused by La Niña. This creates a casuality for the alarmists – it means that the significance of the record temperature in 1998 is diminished – clearly it was caused by El Niño. But on the other hand, ruling out the ‘98 El Niño as ‘natural variation’ allows the claim that temperatures have increased since 1998 to be made.
Such chopping-and-changing appears to be the stock-in-trade of climate scientists and Guardian hacks. But this is because so much political capital is invested in the direction of lines on graphs representing weather statistics. And this is particularly clear in the pages of the Guardian, who have, over the last 12 or so months been especially keen to remind us that cooling trends are ‘not evidence that global warming is slowing’. There’s Randerson’s article, for example. Then there’s an article by Ian Sample, also a science correspondent, who last year reported that
The forecast of a brief slump in global warming has already been seized upon by climate change sceptics as evidence that the world is not heating. Climate scientists say the new high-precision forecast predicts temperatures will stall because of natural climate effects that have seen the Southern Ocean and tropical Pacific cool over the past couple of years.
A Germany study published earlier this month predicts the world will cool over the coming decade. British climate modellers at the Met Office don’t go so far. They think nature’s cooling will be more than counterbalanced by the warming effect of man-made carbon dioxide in the atmosphere.
But nobody is sure. In any case, we can expect the deniers to make the most of this opportunity to pour cold water on the whole climate change narrative. No year has yet been hotter than 1998, they will say. True: it was a huge El Niño year. Now we are on the way back down, they will say. Nonsense. The underlying trend remains upwards; and as every decade passes, natural cycles can do less and less to counter the growing human influence on temperature.
As we pointed out about the dramatisation of the movement of Arctic ice extent recently, the progression of curves representing climate statistics are the dynamic driving political discourse. The unfolding, present-tense narrative of lines on charts fuels the commentary about the conflict between the bad-minded ‘deniers’, and the honest scientists, seeking to destroy or save the world respectively.
The twists and turns of little blue lines excite the audience, and provide superficially important news fodder. It fuels debates, but with wild speculation and utterly meaningless and inconsequential factoids that will be forgotten by the time the next climate record is set. Repeat ad nauseam. These artificial dramas are elevated to ludicrous heights by claims that our entire futures depend on them. Consequently, life imitates this art. The drama extends into our real lives. It becomes politics, ethics, laws. The more we look to little blue lines, the less we realise that whatever little blue lines do only determines what our existences will consist of if we believe that the direction of the little blue line is instructive. It isn’t.
As the comments supplied by scientists at the National Snow and Ice Data Center (NSIDC) about sea ice extent and the Met Office’s scientists careless posturing demonstrate, they are complicit in the politicisation of the climate debate. That is to say they are not impartial. They are not agnostic about climate change. And they are not disinterested observers of nature. Climate science is not a value-free investigation of the material universe.
Climate scientists and science correspondents imbue statistics with undue political significance. Therefore, they have to resort to use combative rhetoric when the trends offer conflicting evidence they cannot yet explain. Rather than contradicting themselves about the significance of short term trends, and moving the goal posts constituting long terms trends, climate scientists ought to be distancing themselves from the political significance of their work. Because to do otherwise is to legitimise the very ‘deniers’ they seek to diminish. If ‘climate science’ is where politics happens, then it is not only reasonable to ask if changes in the direction of change do represent a weakness in the prevailing view, it is essential.
Of course, a trend of 0.14 below average does not represent a static climate, but neither does an anomaly of 0.54C represent the dawn of a new, hostile geological epoch. Fools rush in to make statements about what such small numbers mean about how many angels can dance on the head of a pin.
This article was posted: Monday, December 8, 2008 at 4:57 am