Viscount Matthew Ridley, school mate of David Cameron, inheritor of his father’s surname, first name, title, estate and, unbelievably, job as chairman of Northern Rock (how’s modern meritocracy working out for them, I wonder), has written an article called ‘Roll up: cherry pick your results here’.
Cherry-picking is where one selects a few data points which support one’s position, whilst ignoring the majority which don’t. For example, making a fuss about a cold snap in your local area whilst ignoring global temperatures rising decade on decade for fifty years. Or insisting that the most important period for climate science is from 1998 onwards. Why 1998? Because 1998 was a statistical outlier, an unusually hot year caused by the El Nino oscillation, and so using that as your starting date minimises the temperature rise.
It’s a bit like measuring the changes in average height over the last fifty years and taking the 1964 Olympic basketball team as your baseline. Can I give you an example of a denier doing just this? Why yes, yes I can. In this piece from a year ago Ridley cherry picks data to claim “there’s been no net global warming now for 16 years”.
A slightly more subtle version is to relentlessly cite climate science models and papers which indicate that climate sensitivity (the amount of warming expected from a doubling of atmospheric CO2) is towards the lower end of the IPCC’s range of 1.5 to 5 degrees, whilst ignoring all the models and papers which indicate central or high-end values. Can I give you an example of a denier doing just this? Why yes, yes I can. In this piece Ridley says “The most likely estimate is 1.3C.”
However, with a baffling lack of self awareness, in ‘Roll up: cherry pick your results here’, Ridley isn’t advertising his services as a high-profile and successful cherry-picker, he’s claiming that climate science itself is based on cherry picking. Is this plausible? Well, whilst both the North and South poles are losing ice, you never hear climate scientists mention the East and West poles, do you? And though all of the Earth’s oceans are warming, why does no-one ever talk about the relentlessly stable temperature of the sea of tranquillity? And why do climate scientists bang on relentlessly about all the warming in the 20th century, and never the distinct cooling trend in the 15th?
Believe it or not, this last point is actually the one Ridley is trying to make.
And so to the ‘hockey stick’, Viscount Ridley’s cherry of choice in this week’s Times piece.
‘Hockey stick’ graphs are reconstructions of how the climate behaved before instrumental record began, produced using proxy data to put the rapid rise of global temperatures over the last century into context. These reconstructions show a long, wobbly, gentle downward drift in temperatures over the last few thousand years, with a very steep uptick in the twentieth century. They're pretty alarming to look at, and so climate deniers have put a lot of effort into trying to discredit them.
If you wanted to avoid cherry picking and present a rounded view of the issue, then you could do worse than this graph, which shows a dozen different reconstructions. All show a long, wobbly, gentle downward drift followed by a very steep uptick this century. Like a hockey stick.
Alternatively, you could use this graph:
This is just one reconstruction, but it’s very recent (2013) and covers nearly twelve thousand years.
And yet Ridley ignores 99% of this data and tries to convince us that the hockey stick should be discarded because in two early versions, one from a 1998 study and another from 2001, some of the source data is (according to Ridley, but not according to climate scientists) inadequate. And as the hockey stick is so iconic in the climate debate, he thinks, these alleged weaknesses mean all of climate science, and all the policies and attempts to deal with the problem, are based on cherry picked data, and therefore unreliable.
What was it Alanis Morrissette said in that song?
Cherry picking isn’t hard. I could have written a blog about the new research, published last week in Nature, showing that climate sensitivity is likely to be between three and five degrees, whilst studiously ignoring any earlier papers indicating that it might be lower.
But people who support the scientific consensus don’t have to cherry-pick, because the entire body of climate science research, taken as a whole with all the relevant datasets and both low-end and high-end forecasts included, supports the consensus position.
Because that’s what the consensus position is.
