Global temperature update: no warming for 18 years 4 months
By Christopher Monckton of Brenchley
Since December 1996 there has been no global warming at all (Fig. 1).
This month’s RSS temperature – so far unaffected by the most persistent
el Niño conditions of the present rather attenuated cycle – shows a new
record length for the ever-Greater Pause: 18 years 4 months – and
This result rather surprises me. I’d expected even a weak el Niño to
have more effect that this, but it is always possible that the
temperature increase that usually accompanies an el Niño will come
through after a lag of four or five months. On the other hand, Roy
Spencer, at his always-to-the-point blog (drroyspencer.com), says: “We
are probably past the point of reaching a new peak temperature anomaly
from the current El Niño, suggesting it was rather weak.” I shall defer
to the expert, with pleasure. For if la Niña conditions begin to cool
the oceans in time, there could be quite some lengthening of the Pause
just in time for the Paris world-government summit in December.
Figure 1. The least-squares linear-regression trend on the RSS
satellite monthly global mean surface temperature anomaly dataset shows
no global warming for 18 years 4 months since December 1996.
The hiatus period of 18 years 4 months, or 220 months, is the
farthest back one can go in the RSS satellite temperature record and
still show a sub-zero trend.
Given that the Paris summit is approaching and most “world leaders”
are not being told the truth about the Pause, it would be a great help
if readers were to do their best to let their national negotiators and
politicians know that unexciting reality continues to diverge ever more
spectacularly from the bizarre “settled-science” predictions on which
Thermageddon was built.
The divergence between the models’ predictions in 1990 (Fig. 2) and
2005 (Fig. 3), on the one hand, and the observed outturn, on the other,
also continues to widen, and is now becoming a real embarrassment to the
profiteers of doom – or would be, if the mainstream news media were
actually to report the data rather than merely repeating the failed
predictions of catastrophe.
Figure 2. Near-term projections of warming at a rate equivalent to
2.8 [1.9, 4.2] K/century, made with “substantial confidence” in IPCC
(1990), for the 303 months January 1990 to March 2015 (orange region and
red trend line), vs. observed anomalies (dark blue) and trend (bright
blue) at less than 1.4 K/century equivalent, taken as the mean of the
RSS and UAH satellite monthly mean lower-troposphere temperature
3. Predicted temperature change, January 2005 to March 2015, at a rate
equivalent to 1.7 [1.0, 2.3] Cº/century (orange zone with thick red
best-estimate trend line), compared with the near-zero observed
anomalies (dark blue) and real-world trend (bright blue), taken as the
mean of the RSS and UAH satellite lower-troposphere temperature
The Technical Note has now been much expanded to take account of the
fact that the oceans, according to the ARGO bathythermograph data, are
Key facts about global temperature
Ø The RSS satellite dataset shows no global warming at all for 220
months from December 1996 to March 2014 – more than half the 435-month
Ø The global warming trend since 1900 is equivalent to 0.8 Cº per
century. This is well within natural variability and may not have much
to do with us.
Ø Since 1950, when a human influence on global temperature first
became theoretically possible, the global warming trend has been
equivalent to below 1.2 Cº per century.
Ø The fastest warming rate lasting ten years or more since 1950
occurred over the 33 years from 1974 to 2006. It was equivalent to 2.0
Cº per century.
Ø In 1990, the IPCC’s mid-range prediction of near-term warming was
equivalent to 2.8 Cº per century, higher by two-thirds than its current
prediction of 1.7 Cº/century.
Ø The global warming trend since 1990, when the IPCC wrote its first
report, is equivalent to below 1.4 Cº per century – half of what the
IPCC had then predicted.
Ø Though the IPCC has cut its near-term warming prediction, it has
not cut its high-end business as usual centennial warming prediction of
4.8 Cº warming to 2100.
Ø The IPCC’s predicted 4.8 Cº warming by 2100 is well over twice the
greatest rate of warming lasting more than ten years that has been
measured since 1950.
Ø The IPCC’s 4.8 Cº-by-2100 prediction is almost four times the
observed real-world warming trend since we might in theory have begun
influencing it in 1950.
Ø The oceans, according to the 3600+ ARGO bathythermograph buoys, are
warming at a rate equivalent to just 0.02 Cº per decade, or 0.2 Cº per
Ø Recent extreme weather cannot be blamed on global
warming, because there has not been any global warming to speak of. It
is as simple as that.
Our latest topical graph shows the least-squares linear-regression
trend on the RSS satellite monthly global mean lower-troposphere dataset
for as far back as it is possible to go and still find a zero trend.
The start-date is not “cherry-picked” so as to coincide with the
temperature spike caused by the 1998 el Niño. Instead, it is calculated
so as to find the longest period with a zero trend.
The RSS dataset is arguably less unreliable than other datasets in
that it shows the 1998 Great El Niño more clearly than all other
datasets (though UAH runs it close). The Great el Niño, like its two
predecessors in the past 300 years, caused widespread global coral
bleaching, providing an independent verification that RSS is better able
to capture such fluctuations without artificially filtering them out
than other datasets. Besides, there is in practice little statistical
difference between the RSS and other datasets over the 18-year period of
the Great Pause.
Terrestrial temperatures are measured by thermometers. Thermometers
correctly sited in rural areas away from manmade heat sources show
warming rates below those that are published. The satellite datasets are
based on reference measurements made by the most accurate thermometers
available – platinum resistance thermometers, which provide an
independent verification of the temperature measurements by checking via
spaceward mirrors the known temperature of the cosmic background
radiation, which is 1% of the freezing point of water, or just 2.73
degrees above absolute zero. It was by measuring minuscule variations in
the cosmic background radiation that the NASA anisotropy probe
determined the age of the Universe: 13.82 billion years.
The RSS graph (Fig. 1) is accurate. The data are lifted monthly
straight from the RSS website. A computer algorithm reads them down from
the text file, takes their mean and plots them automatically using an
advanced routine that automatically adjusts the aspect ratio of the data
window at both axes so as to show the data at maximum scale, for
The latest monthly data point is visually inspected to ensure that it
has been correctly positioned. The light blue trend line plotted across
the dark blue spline-curve that shows the actual data is determined by
the method of least-squares linear regression, which calculates the y-intercept and slope of the line.
The IPCC and most other agencies use linear regression to determine
global temperature trends. Professor Phil Jones of the University of
East Anglia recommends it in one of the Climategate emails. The method
is appropriate because global temperature records exhibit little
Dr Stephen Farish, Professor of Epidemiological Statistics at the
University of Melbourne, kindly verified the reliability of the
algorithm that determines the trend on the graph and the correlation
coefficient, which is very low because, though the data are highly
variable, the trend is flat.
RSS itself is now taking a serious interest in the length of the
Great Pause. Dr Carl Mears, the senior research scientist at RSS,
discusses it at remss.com/blog/recent-slowing-rise-global-temperatures.
Dr Mears’ results are summarized in Fig. T1:
Figure T1. Output of 33 IPCC models (turquoise) compared with
measured RSS global temperature change (black), 1979-2014. The transient
coolings caused by the volcanic eruptions of Chichón (1983) and
Pinatubo (1991) are shown, as is the spike in warming caused by the
great el Niño of 1998.
Dr Mears writes:
“The denialists like to assume that the cause for the
model/observation discrepancy is some kind of problem with the
fundamental model physics, and they pooh-pooh any other sort of
explanation. This leads them to conclude, very likely erroneously, that
the long-term sensitivity of the climate is much less than is currently
Dr Mears concedes the growing discrepancy between the RSS data and
the models, but he alleges “cherry-picking” of the start-date for the
“Recently, a number of articles in the mainstream press have pointed
out that there appears to have been little or no change in globally
averaged temperature over the last two decades. Because of this, we are
getting a lot of questions along the lines of ‘I saw this plot on a
denialist web site. Is this really your data?’ While some of these
reports have ‘cherry-picked’ their end points to make their evidence
seem even stronger, there is not much doubt that the rate of warming
since the late 1990s is less than that predicted by most of the IPCC AR5
simulations of historical climate. … The denialists really like to fit
trends starting in 1997, so that the huge 1997-98 ENSO event is at the
start of their time series, resulting in a linear fit with the smallest
In fact, the spike in temperatures caused by the Great el Niño of
1998 is largely offset in the linear-trend calculation by two factors:
the not dissimilar spike of the 2010 el Niño, and the sheer length of
the Great Pause itself.
Curiously, Dr Mears prefers the much-altered terrestrial datasets to
the satellite datasets. However, over the entire length of the RSS and
UAH series since 1979, the trends on the mean of the terrestrial
datasets and on the mean of the satellite datasets are near-identical.
Indeed, the UK Met Office uses the satellite record to calibrate its own
The length of the Great Pause in global warming, significant though
it now is, is of less importance than the ever-growing discrepancy
between the temperature trends predicted by models and the far less
exciting real-world temperature change that has been observed. It
remains possible that el Nino-like conditions may prevail this year,
reducing the length of the Great Pause. However, the discrepancy between
prediction and observation continues to widen.
Sources of the IPCC projections in Figs. 2 and 3
IPCC’s First Assessment Report predicted that global
temperature would rise by 1.0 [0.7, 1.5] Cº to 2025, equivalent to 2.8
[1.9, 4.2] Cº per century. The executive summary asked, “How much
confidence do we have in our predictions?” IPCC pointed out some
uncertainties (clouds, oceans, etc.), but concluded:
“Nevertheless, … we have substantial confidence that models can
predict at least the broad-scale features of climate change. … There are
similarities between results from the coupled models using simple
representations of the ocean and those using more sophisticated
descriptions, and our understanding of such differences as do occur
gives us some confidence in the results.”
That “substantial confidence” was substantial over-confidence. For
the rate of global warming since 1990 – the most important of the
“broad-scale features of climate change” that the models were supposed
to predict – is now below half what the IPCC had then predicted.
In 1990, the IPCC said this:
“Based on current models we predict:
“under the IPCC Business-as-Usual (Scenario A) emissions of
greenhouse gases, a rate of increase of global mean temperature during
the next century of about 0.3 Cº per decade (with an uncertainty range
of 0.2 Cº to 0.5 Cº per decade), this is greater than that seen over the
past 10,000 years. This will result in a likely increase in global mean
temperature of about 1 Cº above the present value by 2025 and 3 Cº
before the end of the next century. The rise will not be steady because
of the influence of other factors” (p. xii).
Later, the IPCC said:
“The numbers given below are based on high-resolution models, scaled
to be consistent with our best estimate of global mean warming of 1.8 Cº
by 2030. For values consistent with other estimates of global
temperature rise, the numbers below should be reduced by 30% for the low
estimate or increased by 50% for the high estimate” (p. xxiv).
The orange region in Fig. 2 represents the IPCC’s less extreme
medium-term Scenario-A estimate of near-term warming, i.e. 1.0 [0.7,
1.5] K by 2025, rather than its more extreme Scenario-A estimate, i.e.
1.8 [1.3, 3.7] K by 2030.
Some try to say the IPCC did not predict the straight-line global
warming rate that is shown in Figs. 2-3. In fact, however, the IPCC’s
predicted global warming over so short a term as the 25 years from 1990
to the present are little different from a straight line (Fig. T2).
Figure T2. Historical warming from 1850-1990, and predicted warming
from 1990-2100 on the IPCC’s “business-as-usual” Scenario A (IPCC, 1990,
Because this difference between a straight line and the slight uptick
in the warming rate the IPCC predicted over the period 1990-2025 is so
small, one can look at it another way. To reach the 1 K central estimate
of warming since 1990 by 2025, there would have to be twice as much
warming in the next ten years as there was in the last 25 years. That is
Likewise, to reach 1.8 K by 2030, there would have to be four or five
times as much warming in the next 15 years as there was in the last 25
years. That is still less likely.
But is the Pause perhaps caused by the fact that CO2 emissions have
not been rising anything like as fast as the IPCC’s “business-as-usual”
Scenario A prediction in 1990? No: CO2 emissions have risen rather above
the Scenario-A prediction (Fig. T3).
Figure T3. CO2 emissions from fossil fuels, etc., in 2012, from Le Quéré et al. (2014),
plotted against the chart of “man-made carbon dioxide emissions”, in
billions of tonnes of carbon per year, from IPCC (1990).
Plainly, therefore, CO2 emissions since 1990 have proven to be closer
to Scenario A than to any other case, because for all the talk about
CO2 emissions reduction the fact is that the rate of expansion of
fossil-fuel burning in China, India, Indonesia, Brazil, etc., far
outstrips the paltry reductions we have achieved in the West to date.
True, methane concentration has not risen as predicted in 1990 (Fig.
T4), for methane emissions, though largely uncontrolled, are simply not
rising as the models had predicted, and the predictions were
The overall picture is clear. Scenario A is the emissions scenario
from 1990 that is closest to the observed emissions outturn, and yet
there has only been a third of a degree of global warming since 1990 –
about half of what the IPCC had then predicted with what it called
Figure T4. Methane concentration as predicted in four IPCC Assessment Reports, together
with (in black) the observed outturn, which is running along the bottom
of the least prediction. This graph appeared in the pre-final draft of
IPCC (2013), but had mysteriously been deleted from the final, published
version, inferentially because the IPCC did not want to display such a
plain comparison between absurdly exaggerated predictions and unexciting
To be precise, a quarter-century after 1990, the global-warming
outturn to date – expressed as the least-squares linear-regression trend
on the mean of the RSS and UAH monthly global mean surface temperature
anomalies – is 0.35 Cº, equivalent to just 1.4 Cº/century, or a little
below half of the central estimate of 0.70 Cº, equivalent to 2.8
Cº/century, that was predicted for Scenario A in IPCC (1990). The
outturn is visibly well below even the least estimate.
In 1990, the IPCC’s central prediction of the near-term warming rate
was higher by two-thirds than its prediction is today. Then it was 2.8
C/century equivalent. Now it is just 1.7 Cº equivalent – and, as Fig. T5
shows, even that is proving to be a substantial exaggeration.
Is the ocean warming?
One frequently-discussed explanation for the Great Pause is that the
coupled ocean-atmosphere system has continued to accumulate heat at
approximately the rate predicted by the models, but that in recent
decades the heat has been removed from the atmosphere by the ocean and,
since globally the near-surface strata show far less warming than the
models had predicted, it is hypothesized that what is called the
“missing heat” has traveled to the little-measured abyssal strata below
2000 m, whence it may emerge at some future date.
Actually, it is not known whether the ocean is warming: each of the
3600 automated ARGO bathythermograph buoys somehow has to cover 200,000
cubic kilometres of ocean – a 100,000-square-mile box more than 316 km
square and 2 km deep. Plainly, the results on the basis of a resolution
that sparse (which, as Willis Eschenbach puts it, is approximately the
equivalent of trying to take a single temperature and salinity profile
taken at a single point in Lake Superior less than once a year) are not
going to be a lot better than guesswork.
Fortunately, a long-standing bug in the ARGO data delivery system has
now been fixed, so I am able to get the monthly global mean ocean
temperature data – though ARGO seems not to have updated the dataset
since December 2014. However, that gives us 11 full years of data.
Results are plotted in Fig. T5. The ocean warming, if ARGO is right, is
equivalent to just 0.02 Cº decade–1, or 0.2 Cº century–1 equivalent.
Figure T5. The entire near-global ARGO 2 km ocean temperature dataset
from January 2004 to December 2014 (black spline-curve), with the
least-squares linear-regression trend calculated from the data by the
author (green arrow).
Finally, though the ARGO buoys measure ocean temperature change
directly, before publication NOAA craftily converts the temperature
change into zettajoules of ocean heat content change, which make the
change seem a whole lot larger.
The terrifying-sounding heat content change of 260 ZJ from 1970 to
2014 (Fig. T6) is equivalent to just 0.2 K/century of global warming.
All those “Hiroshima bombs of heat” are a barely discernible pinprick.
The ocean and its heat capacity are a lot bigger than some may realize.
Figure T6. Ocean heat content change, 1957-2013, in Zettajoules from NOAA’s NODC Ocean Climate Lab: http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT,
with the heat content values converted back to the ocean temperature
changes in fractions of a Kelvin that were originally measured. NOAA’s
conversion of the minuscule temperature change data to Zettajoules,
combined with the exaggerated vertical aspect of the graph, has the
effect of making a very small change in ocean temperature seem
considerably more significant than it is.
Converting the ocean heat content change back to temperature change
reveals an interesting discrepancy between NOAA’s data and that of the
ARGO system. Over the period of ARGO data, from 2004-2014, the NOAA data
imply that the oceans are warming at 0.05 Cº decade–1, equivalent to 0.5 Cº century–1, or rather more than double the rate shown by ARGO.
ARGO has the better-resolved dataset, but since the resolutions of
all ocean datasets are very low one should treat all these results with
caution. What one can say is that, on such evidence as these datasets
are capable of providing, the difference between underlying warming rate
of the ocean and that of the atmosphere is not statistically
significant, suggesting that if the “missing heat” is hiding in the
oceans it has magically found its way into the abyssal strata without
managing to warm the upper strata on the way. On these data, too, there
is no evidence of rapid or catastrophic ocean warming.
Furthermore, to date no empirical, theoretical or numerical method,
complex or simple, has yet successfully specified mechanistically either
how the heat generated by anthropogenic greenhouse-gas enrichment of
the atmosphere has reached the deep ocean without much altering the heat
content of the intervening near-surface strata or how the heat from the
bottom of the ocean may eventually re-emerge to perturb the
near-surface climate conditions that are relevant to land-based life on
Most ocean models used in performing coupled general-circulation
model sensitivity runs simply cannot resolve most of the physical
processes relevant for capturing heat uptake by the deep ocean.
Ultimately, the second law of thermodynamics requires that any heat
which may have accumulated in the deep ocean will dissipate via various
diffusive processes. It is not plausible that any heat taken up by the
deep ocean will suddenly warm the upper ocean and, via the upper ocean,
If the “deep heat” explanation for the hiatus in global warming were
correct (and it is merely one among dozens that have been offered), then
the complex models have failed to account for it correctly: otherwise,
the growing discrepancy between the predicted and observed atmospheric
warming rates would not have become as significant as it has.