Latest Decadal Forecast From The Met Office
By Paul Homewood
The Met Office has published its latest decadal forecast of global temperatures, commenting:
During the five-year period 2016-2020, global average temperature (see blue shading in Figure 3 below) is expected to remain between 0.28°C and 0.77°C (90% confidence range) above the long-term 1981-2010 mean (0.88°C to 1.37°C relative to pre-industrial conditions represented by the period 1850 to 1900). The warmest individual year in the 160-year Met Office Hadley Centre global temperature record is 2015 with a temperature of 0.44 ± 0.1 °C above the 1981-2010 mean. Averaged over the whole five-year period 2016-2020, global average temperature is expected to be between 0.42°C and 0.67°C above the 1981-2010 mean (1.02°C to 1.27°C relative to pre-industrial conditions).
The forecast is for continued global warming largely driven by continued high levels of greenhouse gases. However, other changes in the climate system, including the largest El Niño since 1997 and longer term shifts in both the Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO), are also contributing. Near record temperatures are predicted for the coming five years, consistent with the Met Office annual global temperature forecast. However, the recent run of consecutive record years is likely to end in 2017 as El Niño declines. The forecast remains towards the mid to upper end of the range simulated by CMIP5 models that have not been initialised with observations (green shading in Figure 3). Barring a large volcanic eruption or a very sudden return to La Niña or negative AMO conditions which could temporarily cool climate, ten year global average warming rates are likely to return to late 20th century levels within the next two years. Nevertheless, the recent slowdown in surface warming is still an active research topic and trends over a longer (15 year) period will take longer to respond. For further discussion on the surface warming slowdown see the Met Office reports on the recent pause in warming and on big changes underway in the climate system
Eyeballing suggests a rise of nearly 0.3C by 2020 from the 0.44C recorded in 2015. This really does look to be pie in the sky, but they have painted themselves in a corner where they have got to keep on forecasting big rises in temperature to fit in with their earlier predictions and models.
We must not forget that their decadal forecasts a few years ago were predicting temperatures would be 0.3C higher by now than in 2004. Even with the current El Nino, which has probably added 0.2C to global temperatures, that forecast has only just been achieved by moving the goal posts, and adding 0.06C to current temperatures, when they switched from HADCRUT3 to HADCRUT4.
In all likelihood, global temperatures in 2020 will still be lower than last year, although they may slightly pick up this year, depending on how long El Nino conditions last.
Perhaps more relevant is the 5-year average, which they expect to be 0.55C (between 0.42 and 0.67C). If we get a major La Nina event in the next year or so, I suspect we’ll be looking at an average no higher than the last five years, which is 0.24C. This would be a mammoth fail for the Met Office.
They have, of course, given themselves get out clauses, referring to barring a large volcanic eruption or a very sudden return to La Niña or negative AMO conditions which could temporarily cool climate.
The reality is that they know they are on extremely shaky ground.
A look at the pattern of PDO and AMO cycles shows that the warm 1930’s and 40’s occurred when both ocean cycles were in warm phase. Similarly the cold 1960’s and 70’s coincided with the cycles at rock bottom.
The AMO is still in warm mode, but probably for not much longer. Meanwhile, the PDO has temporarily turned sharply positive. There is no evidence that the cold phase has ended prematurely, and there have been similar, if less pronounced, episodes in the past. For instance, in 1957/8, strong El Nino conditions saw an interruption to the cold phase of the PDO, which quickly returned to normal for another two decades.
The prognosis for long term warming is not good, as I think the Met Office realise. But they cannot afford to admit this.