Crovitz falsely claimed Jones “said there was more warming in the medieval period”

From Crovitz' February 22 Wall Street Journal column:

Phil Jones, the University of East Anglia scientist at the center of the emails, last week acknowledged to the BBC that there hasn't been statistically significant warming since 1995. He said there was more warming in the medieval period, before today's allegedly man-made effects. He also said “the vast majority of climate scientists” do not believe the debate over climate change is settled. Mr. Jones continues to believe in global warming but acknowledges there's no consensus.

In fact, Jones said available data does not establish that globe was warmer during Medieval Warm Period

Jones: Insufficient data available to determine “whether the Medieval Warm Period was global in extent.” During his Q&A with BBC, Jones stated that "[t]here is much debate over whether the Medieval Warm Period [MWP] was global in extent or not" and that "[f]or 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." Jones further said: “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.” From the Q&A:

[BBC:] G - 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?

[JONES:] 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.

IPCC report similarly notes that Medieval Warm Period data is insufficient. Contrary to the suggestion that Jones' remarks about the Medieval Warm Period are a new admission by climate scientists, Jones' statement is “fully consistent with the conclusions of the most recent IPCC report,” as RealClimate.org noted. Indeed, Working Group I of the IPCC stated in its 2007 report that "[i]n order to reduce the uncertainty" about the Medieval Warm Period, “further work is necessary to update existing records ... and to produce many more, especially early, palaeoclimate series with much wider geographic coverage.” From the IPCC report: [emphasis added]:

In order to reduce the uncertainty, further work is necessary to update existing records, many of which were assembled up to 20 years ago, and to produce many more, especially early, palaeoclimate series with much wider geographic coverage. There are far from sufficient data to make any meaningful estimates of global medieval warmth (Figure 6.11). There are very few long records with high temporal resolution data from the oceans, the tropics or the SH [Southern Hemisphere].

The evidence currently available indicates that NH mean temperatures during medieval times (950-1100) were indeed warm in a 2-kyr context and even warmer in relation to the less sparse but still limited evidence of widespread average cool conditions in the 17th century (Osborn and Briffa, 2006). However, the evidence is not sufficient to support a conclusion that hemispheric mean temperatures were as warm, or the extent of warm regions as expansive, as those in the 20th century as a whole, during any period in medieval times (Jones et al., 2001; Bradley et al., 2003a,b; Osborn and Briffa, 2006).

Jones: “I'm 100% confident that the climate has warmed” and “most of the warming since the 1950s is due to human activity.” Jones also stated during the BBC Q&A, “I'm 100% confident that the climate has warmed. As to the second question, I would go along with IPCC Chapter 9 - there's evidence that most of the warming since the 1950s is due to human activity.” Jones also said that "[t]he fact that we can't explain the warming from the 1950s by solar and volcanic forcing" supports the conclusion that recent warming has been largely man-made while previous periods of warming were caused by natural forces.

Crovitz falsely claimed IPCC “has backed away from” statement that 40 percent of Amazon rainforest is sensitive to rainfall changes

From Crovitz' February 22 Wall Street Journal column:

Some journalistic digging into the 2007 U.N. climate change report revealed that its most quoted predictions were based on dubious sources. The IPCC now admits that its prediction that the Himalayan glaciers might disappear by 2035 was a mistake, based on an inaccurate citation to the World Wildlife Foundation. This advocacy group was also the basis for a claim the IPCC has backed away from -- that up to 40% of the Amazon is endangered.

In fact, IPCC has defended Amazon finding, which forest expert said “was correct” despite incomplete citation

IPCC said it “has valid reasons for publishing the text as it stands in the report.” From a February IPCC 19 press release:

Recent media interest has drawn attention to two so-called errors in the Fourth Assessment Report (AR4) of the IPCC, the first dealing with losses from disasters and the second on the subject of Amazon forests. The leadership of the IPCC has looked into both these instances and concluded that the challenges are without foundations. In neither case, did we find any basis for making changes in the wording of the report. We are convinced that there has been no error on those issues on the part of the IPCC. We released a statement about the disaster issue. As far as the second subject dealing with the Amazon is concerned, again, the IPCC has valid reasons for publishing the text as it stands in the report.

Author of studies supporting Amazon finding said “the IPCC statement on the Amazon was correct.” Daniel Nepstad, senior scientist at Woods Hole Research Center and the author of the study cited by the World Wildlife Foundation report, which was in turn cited by IPCC, stated that “the IPCC statement on the Amazon was correct,” but "[t]he report that is cited in support of the IPCC statement (Rowell and Moore 2000) omitted some citations in support of the 40% value statement."

FactCheck.org: “The claim actually has support in peer-reviewed data.” FactCheck.org wrote on February 18 that “a claim that 'up to 40 percent of the Amazonian forests could react drastically to even a slight reduction in precipitation' was backed up with a citation of another WWF report. The claim actually has support in peer-reviewed data, but IPCC's citation to an environmental advocacy group has given skeptics grounds to attack its objectivity and credibility."

UCS: IPCC “got its citations wrong” on threat to Amazon, but “got the science right.” The Union of Concerned Scientists (UCS) stated on February 10 that “IPCC got the science right about drought and fire threats to Amazon, but got its citations wrong.” UCS further said: “While the IPCC should have cited the original peer-reviewed literature, not a summary of that literature by WWF and IUCN, the basic science was sound. And regardless of how the IPCC cited the references, tropical forests are increasingly vulnerable to drought and fire because of climate change as well as from forest degradation from destructive logging practices.”