They took their best shot, an all court press trying to convince the people of the world that climate catastrophe was imminent, that humanity had irreversibly fouled its own nest with billowing clouds of greenhouse gasses. Yet the world remains. There has been climate change aplenty, just not the climate change predicted by the IPCC. More and more scientists have begun to face the fact that their climate model estimates are not correct, forced by nature itself to conclude that there is something fundamentally wrong with how climate science is done.
In a recent edition of a major scientific journal, a gaggle of climate scientists have issued a statement that just a few years ago would have been considered heresy: “The rate of global mean warming has been lower over the past decade than previously.” This leads them to conclude that a lower range of temperature increase at the point of doubling of the atmospheric CO2concentration is indicated.
Appearing in Nature Geoscience, the innocuously titled article “Energy budget constraints on climate response,” is not a full recanting of climate science’s false prophesies, but it is a beginning. A first crack in the wall of falsehood. The first modest step down from the strident claims of world wide catastrophe promulgated by the climate change cabal. An international collection of scientists, lead by Alexander Otto, from Oxford’s Environmental Change Institute, had issued a short correspondence explaining that the rate of warming just might be a bit over estimated. How big a change? Not much, only three tenths of a degree in overall transient climate response (TCR). Here is how they stated their findings in the article:
The rate of global mean warming has been lower over the past decade than previously. It has been argued that this observation might require a downwards revision of estimates of equilibrium climate sensitivity, that is, the long-term (equilibrium) temperature response to a doubling of atmospheric CO2 concentrations. Using up-to-date data on radiative forcing, global mean surface temperature and total heat uptake in the Earth system, we find that the global energy budget implies a range of values for the equilibrium climate sensitivity that is in agreement with earlier estimates, within the limits of uncertainty. The energy budget of the most recent decade does, however, indicate a lower range of values for the more policy-relevant transient climate response(the temperature increase at the point of doubling of the atmospheric CO2 concentration following a linear ramp of increasing greenhouse gas forcing) than the range obtained by either analysing the energy budget of earlier decades or current climate model simulations.
Do not confuse this retrenchment for an overall admission of error—the climate crowd still stubbornly insists that they will be proven right in the long run. Of course, none of them will be around to be either damned or vindicated, so far in the future lies the validation or invalidation of their predictions. Still, parsing the carefully crafted scientific double speak in the paragraph above we find a number of points applicable to the hear and now.
To start with, they are admitting that the climate’s response to rising greenhouse gas levels is not what it was predicted to be. Climate scientists love to talk about climate sensitivity, how much temperature will rise if the amount of CO2 in the atmosphere is doubled. This gives them a nice single figure to quote during news interviews, and even politicians can usually remember a single number. But here they are changing the ground rules slightly: instead of quoting equilibrium climate sensitivity (ECS) they report their findings in terms of transient climate response (TCR). Both quantities are related to the global mean temperature change ΔT, the radiative forcing change ΔF, and the change in the rate of the total increase in heat content of the Earth system, ΔQ. This is what they mean by the global energy budget. For those who prefer the more concise definitions as contained in actual equations see below:
Here F2x is the forcing due to doubling atmospheric CO2 concentrations. The authors used a value of F2x of 3.44 W m−2 claiming that using a higher estimate of 3.7 W m−2would shift the estimated ranges for ECS and TCR by only by about 0.1 K. Both equations (1) and (2) assume constant linear feedbacks and (2) further assumes that the ratio of ΔQ to ΔT for the observed period is the same as that at year 70 of a simulation in which atmospheric CO2 levels increase at 1% per year, “which is approximately the case over the past few decades if we exclude periods strongly affected by volcanic eruptions,” according to the authors.
Note that the underlying forcing is an estimate, taken from earlier papers by other climate scientists. An estimate that is as apt to be erroneous as any other figure quoted by such research. That is not all—the estimations just keep on coming:
For ΔT, we use the HadCRUT4 ensemble data set of surface temperatures averaged globally and by decade. For ΔQ, we derive annual estimates of the change in total heat content of the Earth system for the period 1970 to 2009, by combining data-based estimates for all the main components of the Earth system (ocean, continent, ice and atmosphere); the ocean component dominates the heat uptake (see Supplementary Section S1). For ΔF, we use the multi-model average of the CMIP5 ensemble of climate simulations with emissions that follow a medium-to-low representative concentration pathway (RCP4.5). We include the historic record from 1850–2005 and the RCP4.5 scenario values from 2006–2010, scaled to match an ensemble of possible forcing estimates for 2010 (see Supplementary Section S1) to adjust for fast feedbacks and capture uncertainties.
In short, the witches brew of model outputs and “adjustments” for this new estimate is much the same as the for the old ones. Naturally there is a pretty picture to look at, this one showing the newly rejiggered estimates for ECS and TCR. “Uncertainties include observational errors and internal variability estimated from control simulations with general circulation models,” the authors candidly admit.
Shown are observations of the global mean temperature change plotted against change in forcing minus heat uptake (ΔF–ΔQ) for the equilibrium climate sensitivity (ECS) (a) and against ΔF for the transient climate response (TCR) (b), for each of the four decades 1970s, 1980s, 1990s and 2000s and for the 40-year period 1970–2009. After all of the simulating and hand waving the bottom line is that the shorter term response, TCR, has taken a bit of a dip, while the long-term forecast, ECS, remains as before. But the actual numbers reported are not the important point here.