Category Archives: ENSO

July 2017 Gobal Average Temperature –UAH Satellite

The Global Average Temperature (GAT) anomaly rose 0.07°C  in July. The  GAT anomaly now stands at +0.28°C.

The table below shows that the Southern Hemisphere and the Tropics rose from their readings in June.   NOAA says:

“The most recent model forecasts indicate a high probability that the sea surface temperature in the Niño3.4 region will remain at least slightly above average through winter of 2017-18. “

The above is a model prediction, after all.    I note a slight  drop in the ENSO Meter so I suspect that the GAT will continue its downward trend, though maybe not as fast as I had anticipated

2016 01 +0.55 +0.73 +0.38 +0.84
2016 02 +0.86 +1.19 +0.52 +0.99
2016 03 +0.76 +0.99 +0.54 +1.10
2016 04 +0.72 +0.86 +0.58 +0.93
2016 05 +0.53 +0.61 +0.45 +0.71
2016 06 +0.32 +0.47 +0.17 +0.38
2016 07 +0.37 +0.43 +0.30 +0.48
2016 08 +0.43 +0.53 +0.32 +0.50
2016 09 +0.45 +0.50 +0.39 +0.38
2016 10 +0.42 +0.42 +0.41 +0.46
2016 11 +0.46 +0.43 +0.49 +0.36
2016 12 +0.26 +0.26 +0.27 +0.23
2017 01 +0.33 +0.32 +0.33 +0.09
2017 02 +0.39 +0.58 +0.19 +0.07
2017 03 +0.23 +0.37 +0.09 +0.06
2017 04 +0.27 +0.29 +0.26 +0.22
2017 05 +0.44 +0.39 +0.49 +0.41
2017 06 +0.21 +0.32 +0.09 +0.39
2017 07 +0.28 +0.29 +0.27 +0.51

Chart and Tables are from Dr, Roy Spencer’s blog  which you can access by clicking here.



Global Temperature Update– June 2017

The UAH satellite global temperature measurement cooled off to an anomaly of +0.21C in the month of June.  The peak global temperature resulting from the El Nino, is now on its way to normal.  The May global temperature reversed the downward trend by increasing but this was more than offset by the 0.23 C drop in the month of June.  Many postings are arguing that the PAUSE has resumed.   I will leave that alone for several months before commenting.

This anomaly is the lowest since July 2015.

I believe we are in for some global cooling, but it may still be several years away.   I have mixed feelings  about this.  The world will become a harder place for many people if this results in reduced food crops and much higher costs for keeping warm.  Ask those people in Europe that can no longer afford the high cost electricity in the winter  that has resulted from imposing wind and solar energy on them. Cold weather is the real climate killer, not the fantasy of higher temperatures that the warmers spout.  But the good part would be  is it should put a stake in the heart of the catastrophic man-made global warming theory.


2016 01 +0.55 +0.73 +0.38 +0.84
2016 02 +0.86 +1.19 +0.52 +0.99
2016 03 +0.76 +0.99 +0.54 +1.10
2016 04 +0.72 +0.86 +0.58 +0.93
2016 05 +0.53 +0.61 +0.45 +0.71
2016 06 +0.32 +0.47 +0.17 +0.38
2016 07 +0.37 +0.43 +0.30 +0.48
2016 08 +0.43 +0.53 +0.32 +0.50
2016 09 +0.45 +0.50 +0.39 +0.38
2016 10 +0.42 +0.42 +0.41 +0.46
2016 11 +0.46 +0.43 +0.49 +0.36
2016 12 +0.26 +0.26 +0.27 +0.23
2017 01 +0.33 +0.32 +0.33 +0.09
2017 02 +0.39 +0.58 +0.19 +0.07
2017 03 +0.23 +0.37 +0.09 +0.06
2017 04 +0.27 +0.29 +0.26 +0.22
2017 05 +0.44 +0.39 +0.49 +0.41
2017 06 +0.21 +0.32 +0.09 +0.39

Will The Global Temperature Begin To Cool Down In The Near Future?  


The numbers of scientist predicting a drop in global temperature  are becoming a large group— ready to challenge the mythical 97%.  This blog has posted some of the predictions.  The postings have demonstrated that there is not total unanimity as to reason why the temperature will drop.  Maybe it is a combination of different things. That is refreshing in light of the warmer’s one size fits all theory that CO2 is essentially raising or will raise global temperature all by itself.

First some discussion that suggests that CO2 is not what the warmers claim.

The warmer’s theory says that atmospheric CO2 molecules intercept low-frequency IR waves radiated from Earth on their way back into space.  The exchange warms the atmosphere a little and this causes water to evaporate and move into the atmosphere. Water vapor is a much more significant “greenhouse gas” than CO2. They say that the result is a 3 fold increase in temperature as a result.  This is their so-called “climate sensitivity”.  This is part of the GIGO that is put into the climate models that the warmers use to predict catastrophic in the future.  Let us look and see how well this has turned out for them in the real world versus the computer world.

The chart above was made in June 2013 so it is a little out of date.  Next chart will be the latest update.

The important things to know are the following

  • All those little hair-like lines represent the output from one of the 73 warmer computers. They are all over the place.
  • The heavy black line aggregates all of the 73 outputs into a single line which represents the “official forecast”.
  • The blue squares are the actual recorded global temperatures as measured by satellites.
  • The actual temperature as measured by the weather balloons  are shown as black dots.
  • The balloons and the satellites essentially confirm each other and they are, again, actual measurements.
  • Every 4 or 5 years, the UN’s Intergovernmental Panel on Climate Change (IPCC) gathers and produces an analysis of the state of the climate. They then issue a technical report and a summary that is primarily for the politicians of the world.  One of the features of the IPCC report is how confident they are that their predictions are spot on.
  • The red arrows show their level of confidence, at the time of the report, as to how sure they are that the forecasts are correct.
  • The first report said that they were “confident”. As each new report was issued, they got more confident of their forecasts.  The last one being 95% certain.  This is all happening as the spread between their forecast temperature readings and the actual  temperature readings continued to diverge.

Continue reading

March Global Temperature Anomaly And Solar Cycle 24 Update

This posting combines the March global temperature anomaly and the Solar Cycle 24 stats.   Below are the UAH satellite global temperature anomalies from Dr Roy Spencer’s website. The stats below the graph show the summary since 2016 through March 2017 for the regions.



2016 01 +0.54 +0.69 +0.39 +0.84
2016 02 +0.83 +1.16 +0.50 +0.98
2016 03 +0.73 +0.94 +0.52 +1.08
2016 04 +0.71 +0.85 +0.58 +0.93
2016 05 +0.54 +0.64 +0.44 +0.71
2016 06 +0.33 +0.50 +0.17 +0.37
2016 07 +0.39 +0.48 +0.29 +0.47
2016 08 +0.43 +0.55 +0.31 +0.49
2016 09 +0.44 +0.49 +0.38 +0.37
2016 10 +0.40 +0.42 +0.39 +0.46
2016 11 +0.45 +0.40 +0.50 +0.37
2016 12 +0.24 +0.18 +0.30 +0.21
2017 01 +0.30 +0.26 +0.33 +0.07
2017 02 +0.35 +0.54 +0.15 +0.05
2017 03 +0.19 +0.30 +0.07 +0.03

The anomaly drop of 0.16C was a substantial change.  This has been happening without a La Nina following the El Nino. 


Solar Cycle 24’s to-date April International Sunspot number is 26.6 versus March’s number of 17.7.  So, this month is a little more active but still things are quiet. Cycle 24 began in January 2008.  The mean Cycle length is 11.1 years so it should be over around January of 2019.  



As noted in previous postings the solar polar field strength following a maximum is currently a popular way to predict the following Cycle strength.  The Black line in the chart below is the line to watch. That line is the combined North and South solar polar field strength. So far it is slightly smaller than the size of Solar Cycle 23—thus using this theory, it    Cycle 25 should be about the same size as 24 or maybe just a bit smaller.  Amended for clarity on 4/20  cbdakota






Four Key Charts for a Climate Change Skeptic

Rebloging from WattsUpWithThat “4 Key Charts for the Climate Change Skeptic”.
I could have used these charts to illustrate my reply to a commenter who said that I must not believe in climate change.
From my blog:
I don’t know any skeptic that does not believe in climate change. Every 100,000 years or so, the Earth experiences roughly 80,000 years of a very cold climate and about 20,000 years of warm climate called the interglacial period. As you can tell the geological scientists mean that the warm period is squeezed in between glacial periods. This cycle has been going on for about a million years. The question is not, does the climate change, but rather what causes it to do so. Surely you don’t think that this natural cycle has been caused by man burning fossil fuels.
Most skeptics believe the primary cause of the change is natural and most think that man’s activities may play a minor role in the recent climate change. What we believe in is actual measurable data. What we don’t believe in is climate models that have proved time and time again to fail to be even close to actual measurements. For eighteen years or so, there was no statistically significant rise in global temperatures. You may think that the recent temperature spike due to a natural event, El Nino, has caused the “pause” to be broken. I ask you to look at the predicted temperatures versus the current temperature and you will still see that it is way below what is predicted by the computer models. And here is a kicker, the atmospheric CO2 levels used in these selected mean computer temperature predictions are typically lower than the actual measured CO2 level. Wow. That should make the spread between actual and computer predicted temperatures even bigger.
No, I don’t want dirty water or air. You propose so many strawmen that you could populate a remake of the Wizard of Oz. I support the Clean Water and Clean Air Acts. Have done so as an engineer and manager of design and installation of environmental facilities throughout my industrial career. But how is it that one could support regulations that are predicated on SECRET SCIENCE? The EPA is out of control. Congress makes the laws. The EPA cannot be allowed to do that.
cbdakota (two minor grammatical corrections from the original reply.)

The WUWT is below:

Watts Up With That?

Skeptics often get asked to show why they thinks climate change isn’t a crisis, and why we should not be alarmed about it. These four graphs from Michael David White are handy to use for such a purpose.

By Michael David White

10,000 Years of Climate Change.jpgClimate Models Fail to Predict Warming Trends.jpg140 Years of Climate Change on Two Scales.jpgThe Banality of Climate Change.jpg

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Study Says CO2 Not Statistically Significant In Global Temperature Change

This might be the most important report written in 2016 and perhaps in this century. In my simple understanding of things global warming, it seems that any honest scientist that reads this must be able to show this report to be wrong or, if not already, join us as a skeptic. By zeroing out natural causes, this report shows why man-made CO2 does not have a statistically significant impact on global warming. It validates other studies, especially ice cores,that show that CO2 is a lagging variable, not a leading variable.

A new report “ On the Existence of a “Tropical Hot Spot “& The Validity of EPA’s CO2 Endangerment Finding” demonstrates that CO2 has only minimal effect on the global warming. The authors of the report challenge critics of these finding by saying :

“Moreover, on an all-other-things-equal basis, there is no statistically valid proof that past increases in Atmospheric CO2 concentrations have caused the reported rising, even claimed record setting temperatures. To validate their claim will require mathematically credible, publically available, simultaneous equation parameter estimation work. Where is it?”

Some background. The damage to the US economy caused by the EPA claiming that CO2 emissions will eventually lead to catastrophic increases in Global temperatures was first permitted as a result of the US Supreme Court telling the EPA to determine if CO2 was hazardous. So if the EPA could make an endangerment  determination, then the Court would allow CO2 (and several other minor greenhouse gases) be added to the Clean Air Act (CAA). CO2 was considered in detail by Congress when they passed the CAA and Congress rejected its inclusion. Once again the Supreme Court, fully aware of Congress’ rejection, decided to legislate –not their prerogative– by including CO2 if the EPA said it was hazardous.

To no one’s surprise, the EPA did conclude it was hazardous and began sending out regulations of all kinds based upon their catastrophic global warming theory. The EPA in their CO2 Endangerment Finding said they had found 3 lines of evidence that demonstrates their Finding: They are:

“The assumption of the existence of a “Tropical Hot Spot (THS)” is critical to all Three Lines of Evidence in EPA’s GHG/CO2 Endangerment Finding. Stated simply, first, the THS is claimed to be a fingerprint or signature of atmospheric and Global Average Surface Temperatures (GAST) warming caused by increasing GHG/CO2 concentrations1. (The new report scientist are challenging this by saying that the proper test for the existence of the THS in the real world is very simple. Are the slopes of the three temperature trend lines [upper & lower troposphere and surface] all statistically significant and do they have the proper top down rank order?)

Second, higher atmospheric CO2 and other GHGs concentrations are claimed to have been the primary cause of the claimed record setting GAST over the past 50 plus years.

Third, the THS assumption is imbedded in all of the climate models that EPA still relies upon in its policy analysis supporting, for example, its Clean Power Plan–recently put on hold by a Supreme Court Stay. These climate models are also critical to EPA’s Social Cost of Carbon estimates used to justify a multitude of regulations across many U.S. Government agencies.

The scientists that issued the report: On the Existence of a “Tropical Hot Spot “& The Validity of EPA’s CO2 Endangerment Finding” have set out in detail their methodology and data used to arrive at their conclusions. These can be examined by clicking on the link above.

In summary, the scientists looked at natural causes for increases and decreases in global temperature as well as man-made causes. CO2 produced by burning of fossil fuels is a man-made source. There were three natural factors—an increase or decrease in Solar radiation, volcanic activity, and ENSO (El NINO Southern Oscillation) . Natural factors can not be the result of human actions.

ENSO is a three part phenomenon.. ElNino, LaNina and Neutral


El Ninos and La Ninas are irregular in their size and frequency. While this chart goes back to the fifties when ENSO was first recognized, Scripps Institute of Oceanography says:

There have been many El Niños observed in the past. Theres every reason to think that they have been happening for many thousands of years”

Obviously, fossil fuel produced CO2 is not a issue here.

These scientists removed from 13 temperature records the effect of natural causes of temperature changes leaving only the man-made causes. The temperature records were from balloons, satellite, ground and ocean temperature readings.

From the scientists report, here is what they did and found:

“These analysis results would appear to leave very, very little doubt that EPA’s claim of a Tropical Hot Spot, caused by rising atmospheric CO2 levels, simply does not exist in the real world. Also critically important, even on an all-other things-equal basis, this analysis failed to find that the steadily rising Atmospheric CO2 Concentrations have had a statistically significant impact on any of the 13 temperature time series analyzed.

Thus, the analysis results invalidate each of the Three Lines of Evidence in the EPA’s CO2 Endangerment Finding. Once EPA’s THS assumption is invalidated, it is obvious why the climate models they claim can be relied upon, are also invalid. And, these results clearly demonstrate–13 times in fact–that once just the ENSO impacts on temperature data are accounted for, there is no “record setting” warming to be concerned about. In fact, there is no ENSO-Adjusted Warming at all. These natural ENSO impacts involve both changes in solar activity and the 1977 Pacific Shift.

Moreover, on an all-other-things-equal basis, there is no statistically valid proof that past increases in Atmospheric CO2 Concentrations have caused the officially reported rising, even claimed record setting temperatures. To validate their (critic’s) claim will require mathematically credible, publically available, simultaneous equation parameter estimation work. Where is it?

I reviewed a website that had discussed these findings that there is no significant statistical evidence of CO2 causing global warming. Not a single challenge using data and facts. All of critics were saying that “97%” could not be wrong or using ad hominem attacks on the author.

So as the authors of the report say about having a factual disagreement, “Where is it?


Denying The Climate Catastrophe: 5A Argument For Attributing Past Warming To Man (Warren Meyers Essay)

This posting is a continuation of  the Warren Meyers Essay debunking the Climate Catastrophe theory.   Here he takes the reader though the warmerist’s reasoning of why CO2 emitted from fossil fuels will result in a climate catastrophe.


Having established that the Earth has warmed over the past century or so (though with some dispute over how much), we turn to the more interesting — and certainly more difficult — question of finding causes for past warming.  Specifically, for the global warming debate, we would like to know how much of the warming was due to natural variations and how much was man-made.   Obviously this is hard to do, because no one has two thermometers that show the temperature with and without man’s influence.

I like to begin each chapter with the IPCC’s official position, but this is a bit hard in this case because they use a lot of soft words rather than exact numbers.  They don’t say 0.5 of the 0.8C is due to man, or anything so specific.   They use phrases like “much of the warming” to describe man’s affect.  However, it is safe to say that most advocates of catastrophic man-made global warming theory will claim that most or all of the last century’s warming is due to man, and that is how we have put it in our framework below:


click to enlarge


By the way, the “and more” is not a typo — there are a number of folks who will argue that the world would have actually cooled without manmade CO2 and thus manmade CO2 has contributed more than the total measured warming.  This actually turns out to be an important argument, since the totality of past warming is not enough to be consistent with high sensitivity, high feedback warming forecasts.  But we will return to this in part C of this chapter

Past, Mostly Abandoned Arguments for Attribution to Man

There have been and still are many different approaches to the attributions problem.  In a moment, we will discuss the current preferred approach.  However, it is worth reviewing two other approaches that have mostly been abandoned but which had a lot of currency in the media for some time, in part because both were in Al Gore’s film An Inconvenient Truth.

Before we get into them, I want to take a step back and briefly discuss what is called paleo-climatology, which is essentially the study of past climate before the time when we had measurement instruments and systematic record-keeping for weather.   Because we don’t have direct measurements, say, of the temperature in the year 1352, scientists must look for some alternate measure, called a “proxy,”  that might be correlated with a certain climate variable and thus useful in estimating past climate metrics.   For example, one might look at the width of tree rings, and hypothesize that varying widths in different years might correlate to temperature or precipitation in those years.  Most proxies take advantage of such annual layering, as we have in tree rings.

One such methodology uses ice cores.  Ice in certain places like Antarctica and Greenland is laid down in annual layers.  By taking a core sample, characteristics of the ice can be measured at different layers and matched to approximate years.  CO2 concentrations can actually be measured in air bubbles in the ice, and atmospheric temperatures at the time the ice was laid down can be estimated from certain oxygen isotope ratios in the ice.  The result is that one can plot a chart going back hundreds of thousands of years that estimates atmospheric CO2 and temperature.  Al Gore showed this chart in his movie, in a really cool presentation where the chart wrapped around three screens:

click to enlarge



As Gore points out, this looks to be a smoking gun for attribution of temperature changes to CO2.  From this chart, temperature and CO2 concentrations appear to be moving in lockstep.  From this, CO2 doesn’t seem to be a driver of temperatures, it seems to be THE driver, which is why Gore often called it the global thermostat.

But there turned out to be a problem, which is why this analysis no longer is treated as a smoking gun, at least for the attribution issue.  Over time, scientists got better at taking finer and finer cuts of the ice cores, and what they found is that when they looked on a tighter scale, the temperature was rising (in the black spikes of the chart) on average 800 years before the CO2 levels (in red) rose.

This obviously throws a monkey wrench in the causality argument.  Rising CO2 can hardly be the cause of rising temperatures if the CO2 levels are rising after temperatures.

It is now mostly thought that what this chart represents is the liberation of dissolved CO2 from oceans as temperatures rise.  Oceans have a lot of dissolved CO2, and as the oceans get hotter, they will give up some of this CO2 to the atmosphere.

The second outdated attribution analysis we will discuss is perhaps the most famous:  The Hockey Stick.  Based on a research paper by Michael Mann when he was still a grad student, it was made famous in Al Gore’s movie as well as numerous other press articles.  It became the poster child, for a few years, of the global warming movement.

So what is it?  Like the ice core chart, it is a proxy analysis attempting to reconstruct temperature history, in this case over the last 1000 years or so.  Mann originally used tree rings, though in later versions he has added other proxies, such as from organic matter laid down in sediment layers.

Before the Mann hockey stick, scientists (and the IPCC) believed the temperature history of the last 1000 years looked something like this


click to enlarge

Generally accepted history had a warm period from about 1100-1300 called the Medieval Warm Period which was warmer than it is today, with a cold period in the 17th and 18th centuries called the “Little Ice Age”.  Temperature increases since the little ice age could in part be thought of as a recovery from this colder period.  Strong anecdotal evidence existed from European sources supporting the existence of both the Medieval Warm Period and the Little Ice Age.  For example, I have taken several history courses on the high Middle Ages and every single professor has described the warm period from 1100-1300 as creating a demographic boom which defined the era (yes, warmth was a good thing back then).  In fact, many will point to the famines in the early 14th century that resulted from the end of this warm period as having weakened the population and set the stage for the Black Death.

However, this sort of natural variation before the age where man burned substantial amounts of fossil fuels created something of a problem for catastrophic man-made global warming theory.  How does one convince the population of catastrophe if current warming is within the limits of natural variation?  Doesn’t this push the default attribution of warming towards natural factors and away from man?

The answer came from Michael Mann (now Dr. Mann but actually produced originally before he finished grad school).  It has been dubbed the hockey stick for its shape:

click to enlarge

The reconstructed temperatures are shown in blue, and gone are the Medieval Warm Period and the Little Ice Age, which Mann argued were local to Europe and not global phenomena.  The story that emerged from this chart is that before industrialization, global temperatures were virtually flat, oscillating within a very narrow band of a few tenths of a degree.  However, since 1900, something entirely new seems to be happening, breaking the historical pattern.  From this chart, it looks like modern man has perhaps changed the climate.  This shape, with the long flat historical trend and the sharp uptick at the end, is why it gets the name “hockey stick.”

Oceans of ink and electrons have been spilled over the last 10+ years around the hockey stick, including a myriad of published books.  In general, except for a few hard core paleoclimatologists and perhaps Dr. Mann himself, most folks have moved on from the hockey stick as a useful argument in the attribution debate.  After all, even if the chart is correct, it provides only indirect evidence of the effect of man-made CO2.

Here are a few of the critiques:

  • Note that the real visual impact of the hockey stick comes from the orange data on the far right — the blue data alone doesn’t form much of a hockey stick.  But the orange data is from an entirely different source, in fact an entirely different measurement technology — the blue data is from tree rings, and the orange is form thermometers.  Dr. Mann bristles at the accusation that he “grafted” one data set onto the other, but by drawing the chart this way, that is exactly what he did, at least visually.  Why does this matter?  Well, we have to be very careful with inflections in data that occur exactly at the point that where we change measurement technologies — we are left with the suspicion that the change in slope is due to differences in the measurement technology, rather than in the underlying phenomenon being measured.
  • In fact, well after this chart was published, we discovered that Mann and other like Keith Briffa actually truncated the tree ring temperature reconstructions (the blue line) early.  Note that the blue data ends around 1950.  Why?  Well, it turns out that many tree ring reconstructions showed temperatures declining after 1950.  Does this mean that thermometers were wrong?  No, but it does provide good evidence that the trees are not accurately following current temperature increases, and so probably did not accurately portray temperatures in the past.
  • If one looks at the graphs of all of Mann’s individual proxy series that are averaged into this chart, astonishingly few actually look like hockey sticks.  So how do they average into one?  McIntyre and McKitrick in 2005 showed that Mann used some highly unusual and unprecedented-to-all-but-himself statistical methods that could create hockey sticks out of thin air.  The duo fed random data into Mann’s algorithm and got hockey sticks.
  • At the end of the day, most of the hockey stick (again due to Mann’s averaging methods) was due to samples from just a handful of bristle-cone pine trees in one spot in California, trees whose growth is likely driven by a number of non-temperature factors like precipitation levels and atmospheric CO2 fertilization.   Without these few trees, most of the hockey stick disappears.  In later years he added in non-tree-ring series, but the results still often relied on just a few series, including the Tiljander sediments where Mann essentially flipped the data upside down to get the results he wanted.  Taking out the bristlecone pines and the abused Tiljander series made the hockey stick go away again.There have been plenty of other efforts at proxy series that continue to show the Medieval Warm Period and Little Ice Age as we know them from the historical record:





click to enlarge

As an aside, Mann’s hockey stick was always problematic for supporters of catastrophic man-made global warming theory for another reason.  The hockey stick implies that the world’s temperatures are, in absence of man, almost dead-flat stable.   But this is hardly consistent with the basic hypothesis, discussed earlier, that the climate is dominated by strong positive feedbacks that take small temperature variations and multiply them many times.   If Mann’s hockey stick is correct, it could also be taken as evidence against high climate sensitivities that are demanded by the catastrophe theory.


The Current Lead Argument for Attribution of Past Warming to Man

So we are still left wondering, how do climate scientists attribute past warming to man?  Well, to begin, in doing so they tend to focus on the period after 1940, when large-scale fossil fuel combustion really began in earnest.   Temperatures have risen since 1940, but in fact nearly all of this rise occurred in the 20 year period from 1978 to 1998:

click to enlarge

To be fair, and better understand the thinking at the time, let’s put ourselves in the shoes of scientists around the turn of the century and throw out what we know happened after that date.  Scientists then would have been looking at this picture:

click to enlarge

Sitting in the year 2000, the recent warming rate might have looked dire .. nearly 2C per century…

click to enlarge

Or possibly worse if we were on an accelerating course…

click to enlarge


Scientists began to develop a hypothesis that this temperature rise was occurring too rapidly to be natural, that it had to be at least partially man-made.  I have always thought this a slightly odd conclusion, since the slope from this 20-year period looks almost identical to the slope centered around the 1930’s, which was very unlikely to have much human influence.

click to enlarge

But never-the-less, the hypothesis that the 1978-1998 temperature rise was too fast to be natural gained great currency.  But how does one prove it?

What scientists did was to build computer models to simulate the climate.  They then ran the computer models twice.  The first time they ran them with only natural factors, or at least only the natural factors they knew about or were able to model (they left a lot out, but we will get to that in time).  These models were not able to produce the 1978-1998 warming rates.  Then, they re-ran the models with manmade CO2, and particularly with a high climate sensitivity to CO2 based on the high feedback assumptions we discussed in an earlier chapter.   With these models, they were able to recreate the 1978-1998 temperature rise.   As Dr. Richard Lindzen of MIT described the process:

What was done, was to take a large number of models that could not reasonably simulate known patterns of natural behavior (such as ENSO, the Pacific Decadal Oscillation, the Atlantic Multidecadal Oscillation), claim that such models nonetheless accurately depicted natural internal climate variability, and use the fact that these models could not replicate the warming episode from the mid seventies through the mid nineties, to argue that forcing was necessary and that the forcing must have been due to man.

Another way to put this argument is “we can’t think of anything natural that could be causing this warming, so by default it must be man-made.  With various increases in sophistication, this remains the lead argument in favor of attribution of past warming to man.

In part B of this chapter, we will discuss what natural factors were left out of these models, and I will take my own shot at a simple attribution analysis.