But it’s easy to understand why many have gotten excited about the interview that global warming high priest Phil Jones gave to the BBC. Jones was the director of the Climate Research Unit at the University of East Anglia, whose emails, leaked by a whistle-blower, sparked a major scientific scandal. In some respects, Jones seemed candid in the BBC interview, if not remorseful. For example, he agreed that currently, the climate is not warming:
Do you agree that from 1995 to the present there has been no statistically-significant global warming?
Yes, but only just. I also calculated the trend for the period 1995 to 2009. This trend (0.12C per decade) is positive, but not significant at the 95% significance level. The positive trend is quite close to the significance level. Achieving statistical significance in scientific terms is much more likely for longer periods, and much less likely for shorter periods.
Further, he acknowledged that, far from being unprecedented, the rate of warming in the modern era is nearly identical to prior warming periods. In other words, goodbye, hockey stick:
Do you agree that according to the global temperature record used by the IPCC, the rates of global warming from 1860-1880, 1910-1940 and 1975-1998 were identical?
… Temperature data for the period 1860-1880 are more uncertain, because of sparser coverage, than for later periods in the 20th Century. The 1860-1880 period is also only 21 years in length. As for the two periods 1910-40 and 1975-1998 the warming rates are not statistically significantly different (see numbers below).
I have also included the trend over the period 1975 to 2009, which has a very similar trend to the period 1975-1998.
So, in answer to the question, the warming rates for all 4 periods are similar and not statistically significantly different from each other. Here are the trends and significances for each period:
1860-1880: 21 0.163 Yes
1910-1940: 31 0.15 Yes
1975-1998: 24 0.166 Yes
1975-2009: 35 0.161 Yes
Those are indeed welcome admissions; the last concession is completely at odds with the UN’s 2007 IPCC report. In other instances, however, Jones continued to manifest the errors in logic that typify climate alarmists. Thus, he was asked about the Medieval Warm Period:
There is a debate over whether the Medieval Warm Period (MWP) was global or not. If it were to be conclusively shown that it was a global phenomenon, would you accept that this would undermine the premise that mean surface atmospheric temperatures during the latter part of the 20th Century were unprecedented?
There is much debate over whether the Medieval Warm Period was global in extent or not. The MWP is most clearly expressed in parts of North America, the North Atlantic and Europe and parts of Asia. For it to be global in extent the MWP would need to be seen clearly in more records from the tropical regions and the Southern Hemisphere. There are very few palaeoclimatic records for these latter two regions.
Of course, if the MWP was shown to be global in extent and as warm or warmer than today (based on an equivalent coverage over the NH and SH) then obviously the late-20th century warmth would not be unprecedented. On the other hand, if the MWP was global, but was less warm that today, then current warmth would be unprecedented.
We know from the instrumental temperature record that the two hemispheres do not always follow one another. We cannot, therefore, make the assumption that temperatures in the global average will be similar to those in the northern hemisphere.
Understand what Jones is saying here: Where we have records–Europe, North America, and parts of Asia–they show that the Medieval Warm Period existed and was, in fact, warmer than current conditions. In the tropical regions and the Southern Hemisphere, however, “There are very few palaeoclimatic records.” That’s true. Why? Because the Southern Hemisphere and the tropical regions are mostly water. The Earth’s land mass is concentrated in the Northern Hemisphere. Currently we can track ocean temperatures, but for obvious reasons there is no way to reconstruct marine temperatures from 1,000 years ago. Jones concludes that we can’t “make the assumption” that global temperatures were equally as elevated in the areas for which we have no records. A more honest assessment would be that we may never know for sure, but all indications are that the MWP was indeed warmer than our current climate.
Of course, Jones and his fellow alarmists do indeed “make assumptions” every time they produce a chart that purports to show what global temperatures were 1,000 years ago. In those charts, they consistently rely on computer models to minimize the MWP in a manner that contradicts what we know about actual land temperatures at the time.
Jones also was unpersuasive when he tried to defend his own email comments about using “tricks” to “hide the decline” in current temperatures:
Let’s talk about the e-mails now: In the e-mails you refer to a “trick” which your critics say suggests you conspired to trick the public? You also mentioned “hiding the decline” (in temperatures). Why did you say these things?
This remark has nothing to do with any “decline” in observed instrumental temperatures. The remark referred to a well-known observation, in a particular set of tree-ring data, that I had used in a figure to represent large-scale summer temperature changes over the last 600 years.
The phrase ‘hide the decline’ was shorthand for providing a composite representation of long-term temperature changes made up of recent instrumental data and earlier tree-ring based evidence, where it was absolutely necessary to remove the incorrect impression given by the tree rings that temperatures between about 1960 and 1999 (when the email was written) were not rising, as our instrumental data clearly showed they were.
This “divergence” is well known in the tree-ring literature and “trick” did not refer to any intention to deceive – but rather “a convenient way of achieving something”, in this case joining the earlier valid part of the tree-ring record with the recent, more reliable instrumental record.
I was justified in curtailing the tree-ring reconstruction in the mid-20th Century because these particular data were not valid after that time – an issue which was later directly discussed in the 2007 IPCC AR4 Report.
So Jones admits that he and other climate alarmists have used tree ring data where they were helpful to the global warming theory and discarded them where they were not. Never answered is the obvious question: if tree ring data are unreliable after the mid-20th Century, why were they reliable before then? Nor does Jones address the second criticism of tree ring data, which was discussed in the leaked East Anglia emails: the authors of the principal tree ring studies apparently cherry-picked the trees that gave them the rings they were looking for, while ignoring larger numbers of trees that did not.
When the interviewer gets to the ultimate question, the hollowness of the anthropogenic global warming theory stands exposed:
If you agree that there were similar periods of warming since 1850 to the current period, and that the MWP is under debate, what factors convince you that recent warming has been largely man-made?
The fact that we can’t explain the warming from the 1950s by solar and volcanic forcing – see my answer to your question D.
This was question D and Jones’s answer:
Do you agree that natural influences could have contributed significantly to the global warming observed from 1975-1998, and, if so, please could you specify each natural influence and express its radiative forcing over the period in Watts per square metre.
This area is slightly outside my area of expertise. When considering changes over this period we need to consider all possible factors (so human and natural influences as well as natural internal variability of the climate system). Natural influences (from volcanoes and the Sun) over this period could have contributed to the change over this period. Volcanic influences from the two large eruptions (El Chichon in 1982 and Pinatubo in 1991) would exert a negative influence. Solar influence was about flat over this period. Combining only these two natural influences, therefore, we might have expected some cooling over this period.
In fact, solar activity has not been “about flat” over the period in question, rather it was at a higher level early in the warming period and more recently has been declining as manifested by an unusual scarcity of sunspots. Jones attributes little impact to the variations in solar output because he discounts the current theory, now being hotly debated, that cosmic rays associated with greater solar activity magnify the effect of increased solar energy by affecting cloud cover and by increasing water vapor in the atmosphere. This theory may ultimately be proved or disproved, but it is a fact, not easily dismissed by the alarmists, that for the time period or which we have records there is a close correlation between sunspot activity (a good proxy for variations in solar intensity) and temperatures on earth.
In any event, it is simply not scientific to assume that if two other factors–solar intensity and volcanoes–do not fully explain changes in temperatures, then whatever remains must be due to anthropogenic global warming. The Earth’s climate system is complex and not well understood. There is no scientific basis for assuming that AGW accounts for “everything else,” just as, in the 1970s, there was no scientific basis for assuming that human activity must be responsible for the cooling that was then occurring.