Looking back at what was reported in the late 90s and the early years of this century everyone was expecting the rise in global temperature seen in the 90s to continue at an IPCC sanctioned rate of 0.3 deg C per decade. Only years later in the face of no temperature rise was it mentioned that what might have been meant was an average rate of 0.3 deg C per decade, sometimes it could be less, sometimes more. Hold onto your hats it was implied, today’s slower rate would soon be replaced by a much larger one, as part of regression to the mean.
In other words we had been extraordinary lucky that the global surface temperature has not risen in about 17 years. A few years ago the Met Office said that a ten-year hiatus occurred about every eight decades in climate simulations, and a fifteen-year one never. Since then others have suggested a 15-year one could be every ten decades or so. It would be a fair observation that as the global temperature standstill continues, the estimates of its importance seems to diminish in some quarters. If you try hard enough some model can always be found to suggest it’s just a fluctuation.
But think how lucky we have been. Since global surface temperatures started rising in about 1980 we have had a 15-year period of ‘average’ warming followed by an unusual 15-year period of no warming. The second 15-year period has, say, a chance of occurring of about, being generous, one in fifteen. So any sample of 30-year climate simulations shows us that reality has been a low probability outcome. What if the standstill continues for 20 years? Two, one in eight probability decades back-to-back!
The science journal Nature said only last week that the global temperature standstill “is one of the biggest mysteries in climate science.”
So many climate modelers have been waiting, with apparently increasing frustration, for the upward trend to recur. It’s in their models you see. The very ones they find very hard to tweek to reproduce a 15-year hiatus. The exercise is an important one, for it demonstrates, or undermines, faith in climate models. Can they reproduce the standstill, and predict its end?
Well no, not yet. Since 2007, the Met Office Hadley Centre has produced a decadal forecast every year, out for the next 5 to 10 years, as part of its advice to the UK Government. In 2007 (at which time the current global temperature standstill had already been noticed) Smith et al predicted that 2014 would be 0.3 deg C warmer than 2004, and that half the years after 2009 would be hotter than the Super El Nino year 1998.
It obviously wasn’t, there has been no change in global temperature. The best way to regard such near-term predictions of global temperature is that they are a work in progress, experimental, and not to rely on the results they have produced so far. I hope the UK government took the advice in that manner.
Since then decadal forecasting has not come of age. They generally set out predicting little change over the next few years (because the global temperature moves slowly) and then an increase. They initially appear good, but then fail spectacularly.
Meanwhile the expectation that things will change continues. Each year for 13 years the Met Office forecast a warmer next year than actually happened 12 out of 13 times.
The most recent Met Office decadal forecast was issued in December 2012. According to them it showed, “that the Earth is expected to maintain the record warmth that has been observed over the last decade, and furthermore a substantial proportion of the forecasts show that new record global temperatures may be reached in the next 5 years.” It’s the same scenario. It starts the same, and after a few years gets warmer.
Note that a record ‘may’ be reached in the next few years. When journalists said this meant probably 5 more years of no global temperature change – a perfectly reasonable interpretation – the Met Office objected saying that the media had got it wrong!
Here’s my forecast. This year, 2013, will not be a record breaker. There might be a new record after 2014 but it will be due to an El Nino and not underlying global warming. If it does start to warm, taking into account El Nino effects, It will take about five years at least to establish that it is significant, even with record breakers.
What if the standstill continues? Phil Jones famously said that models were in trouble after 15 years hiatus. Some scientists have said that if the global temperature doesn’t rise in the next five years they will admit everything they know about climate science was wrong! Some have said that there could be another 30 years of no warming and it will make no difference. In five years time the UK will be starting the run-up to a new General Election. If the temperature still hasn’t gone up by then the politicians’ situation will be an interesting one to watch.
Just like Monty Python’s Spanish Inquisition nobody expected the current standstill in global surface temperature.