By Paul Homewood
I was asked last week about the factchecker smear of Steve Koonin’s book, earlier in the year.
Steve himself posted a detailed reply in May, which I have summarised below.
The original text is in bold, and the factcheckers’ comments in italics. Steve’s response follows, headed SK.
I have also added a few brief comments of my own in red.
It should be pointed out that the factcheck was actually on the Wall Street Journal review of the book. As Steve points out, any such review is far too short to cover all nuances and facts. The factcheck has taken advantage of this to improperly the book itself, which does address their criticisms.
”Greenland’s ice sheet isn’t shrinking any more rapidly today than it was eighty years ago.”
This statement is untrue. In fact, the Greenland Ice Sheet lost more mass during 2003–2010 than during all of 1900–2003 combined.
Response: The “fact check” does not refute the statement quoted, which is about the rate of sea level rise 80 years ago. Quoting the rate over the seven-year period 2003–2010 is not climatologically relevant. And comparison of the rate over the twenty years from 1983 with the average over the 83 years from 1900 obscures the decadal variability during that longer period.
The comparison of recent decadal-scale changes with centennial scale averages is a common artifice to obscure prior decadal-scale variability, whose presence makes recent decades seem less unusual.
The 2019 paper by Frederikse et al. clearly shows that Greenland’s contribution to sea level rise around 1940 was about three times higher than it was in the last decades of the 20th century.
As we know, temperatures across Greenland were as high in the 1930s and 40s, as they have been in the last two decades.
We also know from tide gauges that sea level rise was at a similar level in those years.
Measuring ice sheet changes is still little more than a guess even now. Back in the early 20thC, nobody had the slightest clue. While SK’s statement may be controversial, the factcheckers simply do not have the data to prove otherwise.
”The rate of sea-level rise has not accelerated.”
This statement is inaccurate; all observational sea level rise (SLR) datasets show rapid acceleration in recent years, and most now show sea levels rising faster than at any point since records began in the early 1900s.
Response: The statement [by the WSJ] is a misleading compression, likely due to Mr. Mills’ (or his editor’s) need for brevity. A more complete description would be the acceleration seen over the past few decades is comparable to that seen around 1930, when human influences on the climate were much smaller.
But it is incorrect to attribute the brief statement to me. Chapter 8 of Unsettled is a discussion of sea level data like that shown in the graph, including the acceleration (and deceleration) earlier in the 20th century that complicates attribution of the acceleration in recent decades.
The IPCC has accepted that sea levels were rising at a similar level to now earlier in the 20thC, a fact which is evident from tide gauges.
”The extent of global fires has been trending significantly downward.”
This statement is accurate but misleading. The vast majority of fires globally are purposefully set for agricultural clearing, and these have declined in recent years. Conflating all fires with forest and wildfires is not helpful in understanding changing drivers of fire risk.
Response: The fact checkers do not dispute the statement, which surprises most non-experts, who typically believe that human influences on the climate are the dominant cause of fires. However, I agree that it requires more context than is possible to give in a 900-word book review. I give that context, including many of the points raised, in Unsettled’s Chapter 7.
The factchecks make no comment on the effects of decades of fire suppression and poor forest management which undoubtedly are a major factor now.
Curiously they also ignore the massive decline in US wildfires, including California, since 1900, which has nothing at all to do with “agricultural clearing”.
”Tornado frequency and severity are also not trending up; nor are the number and severity of droughts.”
Koonin sets up a strawman in claiming that tornado frequency and severity are not trending up. The scientific consensus on this is that we simply do not have the data to determine trends in tornadoes, and what little theoretical work has been done on this suggests that severity might go up and frequency might go down, but again there is no real consensus.
Response: The statement is true, and the fact checkers do not dispute it, but rather give reasons why it is true and why it might not be true in the future. The second half of Unsettled’s Chapter 6 covers the points they raise, including the clustering and spatial shifts mentioned by Swain and Prein.
Highlighting that there are no climatologically significant trends in tornadoes, as is true for many other severe weather phenomena, is a tonic to the widespread perception that “we’ve already broken the climate”. Emanuel’s claim of a strawman is then curious. Would he have scientists discuss only those severe weather phenomena that do show a deleterious trend? Doing that would alarmingly misinform non-experts.
The criticism by Kerry Emmanuel is beyond absurd, given he and his colleagues routinely claim trends where no proper data exists.
He is also completely wrong, as NOAA’s won data shows a marked decline the number of strong tornadoes.
” The number and severity of droughts are also not trending up.”
Observed spatial trends in global hydroclimate over the past century have been consistent with those expected from human influence in the climate system. In many mid-latitude and subtropical regions, this has indeed included an increase in the frequency/intensity of drought[36,37]–but in other regions (such as the Northern Hemisphere high latitudes), this includes an increase in moisture availability and decrease in drought (as expected from climate model simulations). Therefore, it doesn’t really make sense to make blanket statements regarding overall global drought trends, since only some places are expected to get drier (and others wetter) in a warming climate.
Response: Perhaps, as Swain says, “it doesn’t really make sense to make blanket statements” like this, but that’s precisely what the IPCC did. Unsettled (pg 98) quotes the following from IPCC AR5 WGI Section 184.108.40.206
. . . low confidence in a global-scale observed trend in drought or dryness (lack of rainfall) since the middle of the 20th century . . .
And the report’s page 215 elaborates:
In summary, the current assessment concludes that there is not enough evidence at present to suggest more than low confidence in a global-scale observed trend in drought or dryness (lack of rainfall) since the middle of the 20th century, owing to lack of direct observations, geographical inconsistencies in the trends, and dependencies of inferred trends on the index choice. Based on updated studies, AR4 conclusions regarding global increasing trends in drought since the 1970s were probably overstated. However, it is likely that the frequency and intensity of drought has increased in the Mediterranean and West Africa and decreased in central North America and north-west Australia since 1950.
As my book’s Chapter 7 says (beginning on page 138), it is also difficult to see any long-term trend in drought across the contiguous US, but there are clear regional trends, particularly in the US Southwest.
“Humans have had no detectable impact on hurricanes over the past century”
This statement is flat out wrong. In the first place, the theoretically predicted trends would not have been detectable in the sparse and noisy hurricane record until recently, and in fact they HAVE recently been detected. The most up-to-date research published in the Proceedings of the National Academy of Sciences demonstrates an increase in the proportion of hurricanes that become major hurricanes (Category 3–5) globally, supporting theoretical predictions that date back to 1987.
Furthermore, the phrase “in the past century” is telling nothing since no one familiar with the global record of tropical cyclones would look at data prior to 1980; it is just way too poor to be able to detect trends.
Response: Emanuel seems to have forgotten that he was a co-author on a 2019 paper that displayed and assessed hurricane trends extending back more than a century. I paraphrase that paper’s conclusion on Unsettled’s page 119:
Those authors found that the strongest case for any detectable change in tropical cyclone activity was a very slow northward shift of the average track of storms in the northwest Pacific (0.19° ± 0.125° latitude per decade over the past seventy years, a 1.5 σ result). Moreover, even for that slow, small change (21 km or 13 miles per decade), eight of the eleven authors had only low to medium confidence. Most significantly, the majority of the authors had only low confidence that any other observed tropical cyclone changes were beyond what could be attributed to natural variability.
As I discuss in Unsettled’s Chapter 6, that conclusion is consonant with those of 2014 US National Climate Assessment and of the subsequent 2017 CSSR (its Section 9.2).
Emmanuel tries to establish century long trends by using data since 1980. However, as he ought to know, the short period since 1980 is influenced by the switch from cold to warm phase of the AMO. Real hurricane experts, which he is not, say that hurricanes tend to become more intense during the warm phase, which we have been in since the mid 1990s.
Real hurricane experts also confirm that SK’s statement is essentially correct.
”Global crop yields are rising, not falling.”
While global crop yields are rising, this does not constitute evidence that climate change is not adversely affecting agriculture. IPCC estimates are that increased heat and drought resulting from anthropogenic warming will slow the rate of yield growth, not reverse it
Response: The fact checkers agree with the statement, which is another tonic to the notion that the world is suffering from climate devastation. Their additional points concern proving counterfactuals about a different measure of agricultural productivity — what would agriculture have been if the climate had not been subject to human influences? There are fundamental problems in validating such claims, as I discuss in Unsettled’s Chapter 9.
This criticism by the factcheckers is beyond absurd. They are basing it on theoretical modelling, in stark contrast to Kerry Emmanuel’s earlier complaint that we should not draw conclusions where we do not have the full data!
Nobody has a clue in reality what yields would have been in a colder world.
The criticism also ignores the fact that society now has the infrastructure, skills and knowledge to adapt crops to changing climate and extreme weather.
These factcheckers have no interest in facts. Their only concern is that views are not expressed which run counter to their extremist outlook, which is not based on fact and hard data, but on models and prejudice.