Wednesday, July 29, 2009

Barbecue Summer Meets The Funnel Of Doubt

How come nobody mentioned the funnel?

Just for fun, let's see if we can work out the relationship between the following four statements:

1. "The coming summer is 'odds on for a barbecue summer', according to long-range forecasts. Summer temperatures across the UK are likely to be warmer than average and rainfall near or below average for the three months of summer." (Met Office press notice 30 April 2009)

2. "You will need a brolly on holiday in the UK in August - the Met Office is issuing a revised forecast for more unsettled weather well into the month. It is a far cry from the "barbecue summer" it predicted back in April. The news will raise questions about the Met Office's ability to make reliable seasonal forecasts." (Roger Harrabin, BBC environment analyst, 29 July 2009)

3. "The BBC has held a high-level seminar with some of the best scientific experts, and has come to the view that the weight of evidence no longer justifies equal space being given to the opponents of the consensus." ("Safeguarding impartiality in the 21st century", BBC Trust Report 2007, justifying the BBC's overtly partial coverage of global warming; and see here).

4. "What of the... corridor of uncertainty? It must be related in some way to the ‘expanding funnel of doubt’ of which we hear so much in our line of work. Perhaps... ‘corridor of uncertainty’ is a generic term, used to describe a ‘funnel of doubt’ whose expansion/contraction properties are less well defined?" (The Actuary, 1 April 2005)

You see, the thing is, if the £180m pa Met Office's three months weather forecast is no better than than the flip of a coin, HTF can they possibly reckon to forecast our climate 50-100 years ahead? And given the rain lashing down on the barbecue, how can anyone possibly believe they are capable of that?

Admittedly, Tyler is no scientist (although I dare say he knows more about number krunching than the BBC's Environment analyst, who has an English degree). But in all the many forecasting exercises in which Tyler has been involved over the years, there is always this thing called the Funnel of Doubt.

The Funnel starts out nice and narrow - anchored to what we understand as today's reality.

But as you extend your forecast further into the future, the funnel expands rapidly. Known unknowns bombard the forecast from all sides, so that by the time you've got out a couple of years - at most - the funnel is so wide you're pretty well back to coin flipping.

A typical example is this chart showing 20 year projections of US government bond yields, ranging from roughly zero right up to 14%:

And that's without even considering the unknown unknowns, which have a nasty habit of cropping up... well... unknowably. You can't even model them.

The bottom line is that once you crank your forecasts out beyond the hand in front of your face, they are pretty well fiction. To be taken with a huge pinch of salt.

So what of that sodden barbecue?

According to Mr Harrabin:

"Some now ask if the Met Office risks its reputation by attempting to popularise its work this way. Certainly, at the time of the forecast there was pressure on the Met Office from tourism chiefs in the UK to be positive about holidays at home. Did Met Office staff feel an obligation to put on a sunny face?"

Actually, Roger, some of us are now asking a lot more than that.
Some of us are now asking why we taxpayers are stumping up £180m pa for a quango that has become the world's biggest producer of eco-doom fiction?
And yet more of us are asking why we are paying another £3.5bn pa quango to report such fiction as reality?
It's time we were treated like grown-ups. We don't believe any "experts" know what's going to happen to our climate a century from now. Still less do we believe they can justify the massive eco-costs they are now imposing on us.
Where there is doubt, let us see that funnel reported openly and clearly.

1 comment:

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