Halfway to 2°C – halfway to hell on Earth or just a number?
Guest essay by Christopher Monckton of Brenchley
The Met Office is at it again. Just in time for Paris, in a stunt co-ordinated with the unspeakable BBC, it issued a characteristically mendacious press release saying that global mean surface temperature was about to exceed 1 C° above the mean for the reference period 1850-1900 for the first time.
And this, said the excitable David Shukman, the BBC’s pseudoscience editor on the ten o’clock news, was the halfway milestone to 2 C°, which, he said, was generally accepted to be the threshold of dangerous global warming.
Here, in pictures, is the answer to the Met Office’s hysterical press release.
First, the near-zero HadCRUT4 trend for the reference period [1850-1900]:
Next, the warming since 1850:
The Met Office has used the questionable statistical device of subtracting the –0.3 C° baseline anomaly from the single +0.8 C° monthly anomaly arising from the current el Niño, when the correct approach is to determine the least-squares linear trend on the entire dataset since 1850 – whose trend, however, is only 0.81 C°, not 1.00 C°.
How quickly will the trend reach 1 C° above 1850-1900? One indicator is the warming rate since Man might first have had a noticeable influence on global temperature in 1950. The trend since then is equivalent to 0.113 C° per decade. If that warming rate were to continue, it would be the best part of two decades before global temperature reached 1 C° above the 1850-1900 reference period.
How likely is that post-1950 rate to continue? Not very. For the warming rate has slowed to a standstill. For the past 18 years 9 months there has been none at all:
The incurious Shukman did not mention this particular inconvenient truth. Nor, of course, did he mention that the first monthly anomaly to reach 1 C° above 1850-1900 was as far back as 1998. It is this fact, above all, that shows the Met Office’s press release to have been a pure stunt intended to contribute to the pre-Paris mood music.
The BBC has been continuously silent about just how far below prediction the warming rate is. Since the IPCC first made its predictions in 1990, all five of the longest-standing global temperature datasets – three terrestrial and two satellite – have shown warming rates well below even the lower bound of the IPCC’s very wide interval of predicted global warming.
On the graph, the orange zone shows the IPCC’s roughly straight-line predictions from 1990 to 2100. The IPCC’s central estimate is that from 1990 to the present there should have been about 0.72 C° of global warming. However, the observed trend even on the radically tampered-with GISS dataset is only 0.44 C°.
Remarkably, the IPCC’s predicted rate of warming is three times the UAH observed trend of just 0.24 C° since 1990.
How much warming would mainstream climate science lead us to expect between now and 2100? On IPCC’s RCP 6.0 “business-almost-as-usual” scenario, the central estimate is 2.2 C° warming from 2015-2100. However, extrapolating the much-overstated GISS warming rate to 2100 would lead us to expect only 1.45 C° of warming; at the lower bound, UAH would show still less, at just 0.95 C°.
However, one cannot safely use past trends as an indication of future warming, as the Pause demonstrates all too clearly. The IPCC admits that 111 of 114 models over-predicted future warming, not least because they contained a large element of extrapolation from past warming.
Let us apply mainstream climate-science considerations to predict the warming from now till 2100. Climate sensitivity to the 3.71 W m–2 radiative forcing from a doubled CO2 concentration is 3.3 K (AR4, Box 10.2, p. 798).
However, the feedback sum was cut from the CMIP3/AR4 value 1.93 W m–2 K–1 to the CMIP5/AR5 value 1.47 W m–2 K–1, reducing the central estimate of climate sensitivity by a third to 2.1 K.
The anthropogenic forcing from 2015-2100 on IPCC’s “business-almost-as-usual” RCP 6.0 scenario is 2.75 W m–2, about three-quarters of the forcing at CO2 doubling, so that the equilibrium warming from a 2.75 W m–2 pulse of forcing is 1.6 K.
However, only two-thirds of equilibrium response to a pulse of forcing occurs within 85 years, so that the transient response in 2100 to a 2.75 W m–2 pulse of forcing that arose today would be 1.0 K.
However, the 2.75 W m–2 forcing arises not in a single pulse today but in small, near-linear annual increments, halving the in-century warming to 0.5 K.
As the table confirms, the 21st-century warming likely to occur on the basis of the most realistic of IPCC’s four CO2 concentration growth scenarios is two-thirds of three-quarters of two-thirds of one-half of the 3.3 K equilibrium sensitivity to CO2 doubling in IPCC’s 2007 Fourth Assessment Report: i.e., 0.5 K.
IPCC, of course, says the warming over the rest of this century will be 2.2 [1.4, 3.1] K on the RCP 6.0 scenario. IPCC’s central estimate of warming to 2100 is thus, inexplicably, four and a half times greater than its own mainstream methods, data and results would lead it to expect. So grossly overstated is its central estimate of 21st-century warming that it is actually greater than what it would expect equilibrium warming to be in response to a CO2 doubling.
IPCC’s flagrant and manifestly deliberate overstatement of 21st-century predicted warming has gravely misled the governments that have been foolish enough to believe its predictions. As the step-by-step calculation in the table shows, there is no need whatsoever for any action this century to make global warming go away.
For the 2 C°-above-1850 target that the Met Office and the BBC say we must avoid (though there is no rational scientific justification for what is purely a political target) is not going to be reached this century, even if little or no mitigation of global warming is attempted.
Now, when will the BBC or the Met Office ever admit that the mainstream science outlined above shows just how very little anthropogenic warming we should expect this century?
And when will the nations of the Earth realize they have been fooled by a small clique of well-placed, extravagantly-funded, powerfully-protected fraudsters surrounded by a host of useful idiots?
Pigs might fly.