EXTREME WEATHER ATTRIBUTION: The Art Of Reading Chicken Entrails
BY IAN WISHART
New Zealand climate agency NIWA is using highly-questionable non peer-reviewed “science” – described by some climatologists as “ambulance chasing” – to try and link major weather events to climate change and scare politicians and the public into action.
For decades the official caution in climate science has been “trust only peer-reviewed science” and “no single event can be attributed to climate change”. Indeed, the latter point is why climate change was measured against 30 year trends and “deniers” were accused of cherrypicking when they pointed out that the planet stopped warming between 1998-2013 – a “pause” now well documented in science journals but extremely difficult for climate supercomputer models to explain (Wei et al, 2021):
“The unexpected global warming slowdown during 1998–2013 challenges the existing scientific understanding of global temperature change mechanisms, and thus the simulation and prediction ability of state-of-the-art climate models since most models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5) cannot simulate it.”[i]
The science, as numerous studies show, remains highly uncertain, but the more uncertain the peer-reviewed studies get, the more the world’s climate lobbyists have ditched sober and considered research in favour of quick and dirty non peer-reviewed reports rushed out mere days or weeks after extreme weather events to capitalise on public fear.
These reports, known as Extreme Weather Event Attribution, or EEA in most commentary, are the equivalent of hasty self-published “pre-print” studies during the covid era. The key point is that EEA reports shoot first and face questions later, generating instant media headlines before any of their peers have a chance to check the calculations and conclusions.
Apart from the blatant hypocrisy of demanding that everyone else has to meet peer-review standards while they themselves don’t, the bigger problem is that for most of the extreme events NIWA and others are trying to measure with EEA the results are so uncertain as to be effectively false if used as evidence of climate change.
Take the Cyclone Gabrielle rapid EEA report rushed out in March 2023 by the World Weather Attribution Group in London.
That study, led by Waikato University’s Luke Harrington and a team of mostly NZ researchers from NIWA and elsewhere, claimed that greenhouse gas emissions made Gabrielle or storms like it four times more likely nowadays, and that it delivered 31% more rainfall for the same reason. Well, that’s how the media reported it, but if you read the study itself you will find a couple of huge caveats:
“The best-estimated return period of the 2023 event averaged over the study region is 11 years (5-45 years), as shown in Fig. 5(b), which we round to an average 1-in-10 years for the attribution analysis. The event is 4 times more likely in the 2023 climate. However, this estimate is not statistically significant with an uncertainty range of [0.4, 3300]. Further, the rainfall is found to be 31% more intense in the current climate, but once again, this estimate is not statistically significant (uncertainty range: -17% to 130%)”.[ii]
Did you catch the “but”? “Not statistically significant”, which in plain scientific terms means the claims are totally unreliable. Unproven. Uncertain. Or as the boffins describe it, there’s no evidence that rises the findings above the threshold of ordinary freak weather, “random chance”.
It must have been devastating. The biggest storm event to hit New Zealand in 35 years, combined with a bunch of climate-crunching supercomputers with brains the size of a planet, a cherrypicked dataset only dating back to 1979 (and thus avoiding including much bigger historical storms in the area with much higher rainfall in the 1800s and 1900s), and despite their best efforts they still couldn’t pin climate change on Gabrielle.
If Harrington and team hadn’t shouted from the rooftops in advance that they were doing the rushed attribution study they might have been tempted to quietly bin the thing when they saw the results. But they couldn’t. They had to release something.
They needn’t have worried. New Zealand’s smartest climate change reporters turned out to be no match for the average bears who churned out the World Weather Attribution study with its “not statistically significant” findings. All the agony and uncertainty was lost or downplayed from the media reports by the time they’d finished spinning it. This from the NZ Herald:
“In Gabrielle’s aftermath, for instance, scientists concluded that extreme deluges had become up to four times more common, unleashing up to 30 per cent more rain, in the hardest-hit East Coast regions.”[iii]
And over at Newshub:
“Scientists have discovered the severity of rainfall during New Zealand’s most significant weather event this century, Cyclone Gabrielle, is likely caused by climate change.
“A new study released on Wednesday has found global warming could cause extreme rainfall events, such as the cyclone, to produce almost one-third more rain than before – and concerningly heavy rainfall is now more common on a warmer planet.
“It found very heavy rain, similar to that of Cyclone Gabrielle, although still rare, has become around four times more common in the region. It also found extreme rainfall events produce around 30 percent more rain than before humans warmed the planet.
“However, these estimates have large mathematical uncertainties due to limited weather station data and the fact that rainfall is highly variable in the region.”[iv]
The Newshub reporting was confused – “heavy rain…although still rare…has become around four times more common”. Really, so we’ve had four Gabrielles in Hawke’s Bay recently?
The confusion spreads in this egregious quote in The Conversation from none other than James Renwick, a former NIWA scientist and IPCC author now teaching climate science to impressionable students at Wellington’s Victoria University:[v]
“The obvious question is what role climate change plays in these record-breaking rainfalls.
“Some answers come from the international World Weather Attribution team, which today released a rapid assessment which shows very heavy rain, like that associated with Cyclone Gabrielle, has become about four times more common in the region and extreme downpours now drop 30% more rain.
“The team analysed weather data from several stations, which show the observed increase in heavy rain. It then used computer models to compare the climate as it is today, after about 1.2℃ of global warming since the late 1800s, with the climate of the past.
“The small size of the analysed region meant the team could not quantify the extent to which human-caused warming is responsible for the observed increase in heavy rain in this part of New Zealand, but concluded it was the likely cause.”
Renwick knows full well that “not statistically significant” means the researchers could not prove the link. Mission fail. Did not achieve. Not “likely”. Not “unlikely”. No better than a coin toss. But that’s not how he spun it.
And that bit about the “observed increase in heavy rain”? It’s a crock, which we will come to in a moment.
NIWA principal climate scientist and study co-author Sam Dean was another preaching his version of alternative facts, and 1News lapped it up:
“Emissions of greenhouse gases from human activity caused a 20 to 30% increase in rainfall in the area, and extreme rainfall events like this have become three to four times more likely, while still rare, the study reports.
“We want to try and give them certainty that we have confidence that climate change has contributed to this event,” Dean told 1News.[vi]
Certainty? NIWA definitely didn’t want inconvenient facts getting in the way of a good propaganda story, So Dean doubled down in an article by Imperial College in London:
“I have no doubt whatsoever in my mind with my experience of my life as a climate scientist that climate change has influenced the event.
“Climate change is a serious concern for flooding in New Zealand and you’ve got to understand these are gigantic amounts of rainfall.”[vii]
There’s that reference to the observed rainfall data again. Yes, Gabrielle’s half a metre of rain over its 48 hour duration was big, but by carefully cherrypicking data dates from 1979 to 2023, Harrington et al’s World Weather Attribution study in my view deliberately (or incompetently) left out historical storms that were genuinely “gigantic”.
NIWA’s own Historic Weather Events website Hawke’s Bay records:
14 April 1897: “Hawke’s Bay received 11.5 in (29.21 cm) of rain in 2.5 hours. 21 inches (53.3 cm) of rain in 30 hours was reported in parts of the higher reaches of Tukituki, Ngaruroro and Tutaekuri rivers.”[viii]
Rissington, Hawke’s Bay, 11 March 1924 – “Rissington recorded 512 mm (51.2 cm) of rain in 10 hours to 5pm on the 11th (which has a return period of well over 150 years).”[ix]
23 April 1938: Puketitiri recorded 9.14 in (23.22 cm) of rain in 24 hours on the 23rd. Puketitiri recorded 15.39 in (39.09 cm) of rain in 24 hours on the 24th. Puketitiri recorded 14.87 in (37.77 cm) of rain in 24 hours on the 25th.[x]
“Puketitiri recorded 1001 mm (100.1 cm) of rain in three days (which has a return period of well over 150 years).”
So how does NIWA’s Sam Dean get away with preaching “certainty” to the news media that Gabrielle was much worse than past storms because of climate change? According to NIWA, the highest 24 hour rainfall anywhere in NZ during Gabrielle was 316mm at Tutira in Hawke’s Bay.[xi] But if you drew a trendline between around 480mm in 24 hours in 1897, to 512mm in 1924 and 391mm in 1938 and then 316mm in 2023, the overall trend would slope down \, not up /.
It is just not possible for climate scientists to honestly claim that climate change has made the Gabrielle rainfalls “four times more common” compared with the past, or the rainfall volumes 30% more intense. Any climate scientist making such claims should be laughed out of the room, along with any news media dumb enough to believe them, in my view.
Harrington, Dean and co fell down a rabbit hole of their own making by not scouring the historical records for the area. It’s a massive weakness in NIWA climate research, exposed by the first Climate of Fear report.
What makes it even more of an own goal is that it appears Luke Harrington, who led the World Weather Attribution Study, didn’t have any institutional memory of the much bigger storms in our colder, low carbon past, as he tweeted that the Gabrielle rainfall appeared to be double the previous record – not a comment he would have phrased that way had he known the 1938 storm was double Gabrielle:
<blockquote class="twitter-tweet"><p lang="en" dir="ltr">I'm calling you out Luke. Looking back at your post Gabrielle tweets it's now clear you knew NOTHING of the historical records in that area. You clearly had no clue that 1m of rain fell in 1938. You fired up a fundamentally flawed rush study and now you and <a href="https://twitter.com/niwa_nz?ref_src=twsrc%5Etfw">@niwa_nz</a> are caught <a href="https://t.co/AXVZTGf4bK">pic.twitter.com/AXVZTGf4bK</a></p>— Ian Wishart (@investigatemag) <a href="https://twitter.com/investigatemag/status/1635946832370208768?ref_src=twsrc%5Etfw">March 15, 2023</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
All of which brings us to the bigger issue. You are going to see a lot more of these rushed Extreme Event Attribution (EEA) studies. Who is behind them and what are their motivations? Perhaps most important of all, how credible is EEA science?
They began in the early 2000s, but have only really taken off in the past decade with improved computing power. Pioneers in the field include Freiderike Otto, who heads World Weather Attribution WWA in London and who co-authored the flawed Harrington report. A large number of NZ climate scientists are involved, especially after Victoria University climate scientist Greg Bodeker set up a private research company and landed NZ taxpayer funding for an Extreme Weather Event research programme called EWERAM.
The EWERAM and WWA systems work on a simple premise: They measure data in the real world where an extreme event has happened, and then run computer simulations of the same location in a fictional virtual world where no human interference with the climate existed.
By comparing the real data with the data from the mythical ‘no humans’ world, they claim they can measure the probability of the event happening, and differences in the intensity of the event.
Of course, smart readers will realise that computer models are only as good as the data you feed into them. The Harrington study was primarily crap because all the really high rainfall data from our low carbon past was not included in the study – data selection bias. But the study was flawed for another reason – the computer models are not strong enough to recreate events in small regions.
Researchers (Jézéquel et al, 2018) looking at the credibility of EEA studies interviewed delegates and climate scientists working in EEA, attending a climate conference in Canada in 2016. They found that even climate scientists using EEA found it unreliable (anonymity was protected by assigning a C-number to the scientists):
“Another technical problem resides in the differences in our capacity to attribute different kinds of events in different regions (e.g. C2, C4 and C9). Some events are easier to attribute than others: it is simpler to get robust results for heat-related events than for precipitations, and attributing storms and hurricanes [on Extreme Weather Events and Attribution, 2016] is a still an unresolved challenge. Additionally, EEA studies in particular and climate sciences in general are more robust when they rely on long observational records.”[xii]
All of which are aspects the Harrington study got tangled in. Rainfall attribution to climate change is notoriously hard; storm attribution is “still an unresolved challenge”.
Basically, the EEA science is only fit for temperature trends. It is not fit for purpose when used for storms, cyclones and heavy rain. There’s a lesson in there for the media.
What about the other proviso? – studies are more robust when they use “long observational records”. Harrington chose to leave out the inconvenient long term records.
Little wonder Harrington’s findings were “not statistically significant”.
Senior UK climate scientist Mike Hulme is one who predicted EEA could lead to junk science headlines about extreme weather (as we are now seeing) because of the high risk of garbage in/garbage out when the models are used for things they can’t handle (like Gabrielle).
Hulme, like the scientists in the study above, raised the same concerns. First, can the computers handle it:[xiii]
“The credibility of this method of weather attribution can be no greater than the overall credibility of the climate model(s) used – and may be less, depending on the ability of the model in question to simulate accurately the precise weather event under consideration at a given scale (e.g. a heatwave in continental Europe, a rain event in northern Thailand).”
“It is likely that attribution of temperature-related extremes using FAR [check] methods will always be more attainable than for other meteorological extremes such as rainfall and wind, which climate models generally find harder to simulate faithfully at the spatial scales involved.”
Hulme was also critical of those who failed to use the best observational data: “For statistical methods to be effective, long homogenous meteorological time series data are required; for some regions of the world these will not be available through instrumental measurements alone nor through combined series of instrumental and proxy measurements.”
Others (Jézéquel et al, 2020) have been more scathing: “On the one hand, a few interviewees raised concerns about the relevance of EEA as a research question. For example, one of the interviewees fears that EEA is “a little bit like ambulance chasing” and “that is what paparazzi do”…Indeed, similar concerns have also been expressed by climate scientists in general, outside of the EEA community. Bray and von Storch’s (2016) survey shows that part of the climate science community is not even convinced it is possible to attribute an event to climate change [see Fig. 77 of Bray and von Storch (2016)] and is not convinced of the robustness of existing EEA results (Fig. 73).[xiv]
The Gabrielle study is not the only World Weather Attribution effort flagged as questionable. In 2016 (King et al) released a rush headline grabbing study claiming the Great Barrier Reef bleaching event that year would have been “impossible” without human-caused warming.[xv] Subsequent peer-reviewed studies (Zhao et al., 2021) suggest cloud cover over the shallow waters has much more impact on coral, because direct sunlight beating down is a far stronger radiative force.
“Thermal coral bleaching events (CBEs) over the Pacific, including those over the Great Barrier Reef (GBR), have commonly been linked to the El Niño–Southern Oscillation (ENSO), with bleaching reported to be a direct result of sea surface temperature (SST) anomalies driven by El Niño. However, such a relationship cannot explain CBEs that occurred during La Niña or the neutral phase of the ENSO. Here, we show that the GBR is characterized by a significant negative correlation between total cloud cover anomaly (TCCA) and lagged SST anomaly (SSTA) whose magnitude and spatial extent are greater than the SSTA-ENSO correlation. This significant negative TCCA-SSTA (lagged) correlation prevails over two-thirds of the study domain even after the ENSO signal is removed, which suggests that local-scale reduced cloud cover is a key component of the regional warm shallow water formation over the GBR and the occurrence of thermal CBEs.”[xvi]
In California, the drought and wildfires led to a number of EEA studies, some concluding it was natural and some anthropogenic. A subsequent study of the reaction to the EEA confusion found the media wanted to report certainty (Osaka & Bellamy, 2020):
“One strong theme among journalists was the role of scientific uncertainty in their coverage. Journalists generally felt that the public had difficulty understanding nuance, and that their role as writers was to simplify narratives as much as possible. One interviewee noted, mentioning the issue of California wildfires:
“Communicating uncertainty is sort of antithetical to what we do. Because we try to make things simple and linear for people […] journalists are always quick to put out the disclaimer that we can’t blame x, y, z, fire on climate change […] But it’s a balancing act, because the more you cloud up a story with uncertainty, the more the readers’ eyes glaze over.” (J2).
“Another said, “How do I simplify without falsifying? That is always the core issue” (J4).
“At the same time, most of the journalists felt that the science around the attribution of the California drought had been particularly controversial (J4, J5, J7). Some identified a form of scientific consensus – that climate change had made the drought worse, but not necessarily more likely – but others were uncertain. J5 said:
“You see studies offering different conclusions and obviously they’re all prurient, but if they’re saying different things they can’t all be right. Even within the [attribution science] community there was disagreement.”
“In the face of this type of controversy, reporters emphasized that they were especially cautious about making strong statements connecting weather events and climate change.
“Meanwhile, two journalists (J1, J2) reporting for regional papers expressed doubt about the legitimacy of EEA. J2 said:
“Part of the problem is, you can never really point to specific events. The scientists always […] say – we can’t say this fire happened because of climate change, or these hurricanes happened because of climate change. All we know is that climate is sort of brewing up a soup that makes all of this more likely to happen.”
The study found, like others before it, that extreme weather attribution studies don’t work for storms, rainfall or droughts: “…there is more understanding on the role of climate change in extreme heat and cold events than there is for extreme rainfall, droughts, or tropical cyclones (National Academies of Sciences, Engineering, and Medicine, 2016).[xvii]
The comment that climate change is brewing up a probability soup needs further scrutiny. It’s what the Al Gore programmers push in their messaging, but is it true?
As you’ve seen from some of the studies quoted earlier, the answer might be no. Close to home, NIWA has found only four low pressure systems (big storms) since 1960 with barometric readings of 982 millibars or lower. Four, in a period of 63 years when global warming has apparently been rampaging out of control. Yet between 1868-1890, just a 22 year portion of NZ’s pre-industrial climate, 24 storms of that size or deeper slammed the country. One per year.
That revelation was embarrassing for NIWA because a) they’d never done the research work themselves, and b) they refused to answer media questions on the point.
Why is it important? Because disinformation hives like NIWA and the Climate Reality Project have been pushing the message for decades that a warmer climate will usher in more extreme weather. So when they are confronted with evidence that NZ’s cold pre-industrial climate was 20x worse than the modern warm era, the fact they can’t explain why is damning.
For Gore’s climate disinformation project, it’s all about ignoring the inconvenient truth in favour of false simple messaging:
“Put simply, here’s what we know for sure:
– We know that carbon dioxide (and other greenhouse gases) trap heat in the Earth’s atmosphere.
– And we know that humans are burning fossil fuels, releasing huge amounts of carbon pollution and trapping more and more heat in the atmosphere.
– There’s only one conclusion: humans are the primary reason the planet is warming and we see our climate changing today.”
Kiwi climate scientist Kevin Trenberth is a bit more careful with his words. In a 2023 piece announcing the arrival of a very strong El Niño he admits that although human-caused global warming is real, “so far, there is little evidence that climate change has altered ENSO events themselves.”[xviii]
The admission is crucial, and concurs with the studies cited earlier. ENSO is a massive natural driver of the climate globally, and frequently generates hottest years. Trenberth expects 2023/24 to be the hottest years yet: “Time will tell, but El Niño has been looming for some time. Evidence of its imminent arrival could be seen last year in subsurface ocean temperatures, with a buildup of warm water in the Coral Sea and western tropical Pacific.”
Again, another important clue. The Coral Sea is where Cyclone Gabrielle began in February this year. While climate grifters have been falling over themselves to link it to climate change, the evidence suggests natural factors played the dominant role.
And what of all those other weather extremes being attributed to climate change?
“Of course, major events related to El Niño have serious social and economic impacts, too. Droughts, floods, heatwaves and other changes can severely disrupt agriculture, fisheries, health, energy demand and air quality (mainly from wildfires).
“Research shows El Niño “persistently reduces country-level economic growth”, with damage now estimated in the trillions of US dollars.
“Globally, El Niño is the largest cause of droughts; they are more intense, set in quicker and increase the risk of wildfires, especially in Australia, Indonesia and Brazil. In the weak 2019-20 El Niño, smoke from fires in eastern Australia affected the southern hemisphere to the extent that it blocked the sun and may have exacerbated the subsequent La Niña conditions.
“Meanwhile, torrential rains are heavier, with greater risk of flooding, especially in Peru and Ecuador. Very wet conditions can also (though not always) occur in California and the southeast US.”
But always remember, ENSO is natural: “so far, there is little evidence that climate change has altered ENSO events themselves.”
Unfortunately, the poisonous climate disinformation that permeates the news media is affecting the judgement of IPCC political delegates, according to another study (Jézéquel et al, 2018):
“The general understanding of how extreme weather events are affected and will be affected by climate change also differs from one delegate to the other. Most of them declare that climate change affects the severity and the frequency of extreme events, without discriminating between regions of the world and types of events.”[xix]
In other words, the messaging has become so sloganized and simplistic that it’s not true, and even IPCC scientists are banging their heads on the wall in frustration: “The Intergovernmental Panel on Climate Change (IPCC) establishes this variability in the influence of anthropogenic climate change on different types of events and in different regions in its last assessment report [Bindoff et al., 2013] and specifically in its special report on extreme events [Seneviratne et al., 2012]. This shows that those research findings have not been assimilated by all the negotiators.
“Delegates also generally consider the knowledge on extreme weather events to be greater than that on slow onset events. Slow onset events include “sea level rise, increasing temperatures, ocean acidification, glacial retreat and related impacts, salinization, land and forest degradation, loss of biodiversity and desertification.” [CP.16, 2010] However, the scientific understanding of how climate change affects some extreme events is yet lower than for slow onset events [James et al., 2014].”
Plain English translation? Politicians and COP conference delegates have been brainwashed into assuming the science on extreme weather events is settled, when it’s the least settled of all. Blame the media. Blame Al Gore. Blame Greta. All major sources of dangerous climate disinformation.
And they show no sign of returning to climate reporting sanity any time soon, judging by this dissertation from Haley Koch, a US journalism graduate who has clearly drunk the Kool-Aid:
“Climate scientists now have the capacity to say observable effects of anthropogenic climate change exist that are the source of exacerbation for many categories of extreme weather events. As climate change, in general, is a subject lacking depth of public understanding and saliency, it becomes essential to the progress of climate solutions that anthropogenic climate change and its effects be robustly communicated through media whenever possible; Events of extreme weather are a devastating truth of our climate today, but provide an incredibly tangible representation of what the effects of climate change can look like, which is why media outlets should be making the connection clearly apparent.[xx]
This urge by young green evangelicals to preach their gospel from the bully pulpit is also identified as one of the motivations for hyping up extreme weather through rushed EEA studies – journalists are desperate to present proof that they’re not a bunch of Chicken Littles (Hulme, 2014):
“A final reason for scientists to be investing in this area of climate science – a reason stated explicitly less often…and yet one which underlies much of the public interest in the ‘extreme-weather blame’ question – is frustration with, and argument about, the invisibility of climate change.[xxi]
“If this is believed to be true – that only scientists can make climate change visible and real – then there is extra onus on scientists to answer the ‘extreme-weather blame’ question as part of an effort to convince citizens of the reality of human-caused climate change. One danger of this motivation is that it may skew research.”
The IPCC’s latest AR6 report 2023, when you read the actual scientific data in it rather than the PR-spin Summary for Policymakers, says this:
On Extreme Tropical Cyclone Frequency “For a 2°C global warming, the median proportion of Category 4–5 TCs increases by 13%, while the median global TC frequency decreases by 14%, which implies that the median of the global Category 4–5 TC frequency is slightly reduced by 1% or almost unchanged (Knutson et al., 2020). Murakami et al. (2020) projected a decrease in TC frequency over the coming century in the North Atlantic due to greenhouse warming, as consistent with Dunstone et al. (2013), and a reduction in TC frequency almost everywhere in the tropics in response to +1% CO2 forcing.”
On Maximum Cyclone Windspeeds “The increase in global TC maximum surface wind speeds is about 5% for a 2°C global warming across a number of high-resolution multi-decadal studies (Knutson et al., 2020). This indicates the deepening in global TC minimum surface pressure under the global warming conditions.”
On Cyclone Intensity “TCs are also measured by quantities such as ACE [accumulated cyclone energy] and the power dissipation index (PDI), which conflate TC intensity, frequency, and duration (Murakami et al., 2014). Several TC modelling studies (Yamada et al., 2010; H.S. Kim et al., 2014; Knutson et al., 2015) project little change or decreases in the globally accumulated value of PDI or ACE, which is due to the decrease in the total number of TCs.”
On Cyclone Rainfall “A projected increase in global average TC rain rates of about 12% for a 2°C global warming is consistent with the Clausius–Clapeyron scaling of saturation-specific humidity (Knutson et al., 2020).”
On Cyclone Size “The spatial extent, or ‘size’, of the TC wind field is an important determinant of storm surge and damage. No detectable anthropogenic influences on TC size have been identified to date, because TCs in observations vary in size substantially (Chan and Chan, 2015) and there is no definite theory on what controls TC size, although this is an area of active research (Chavas and Emanuel, 2014; Chan and Chan, 2018). However, projections by high-resolution models indicate future broadening of TC wind fields when compared to TCs of the same categories (Yamada et al., 2017), while Knutson et al. (2015) simulate a reasonable interbasin distribution of TC size climatology, but project no statistically significant change in global average TC size. A plausible mechanism is that, as the tropopause height becomes higher with global warming, the eye wall areas become wider because the eye walls are inclined outward with height to the tropopause. This effect is only reproduced in high-resolution convection-permitting models capturing eye walls, and such modelling studies are not common. Moreover, the projected TC size changes are generally on the order of 10% or less, and these size changes are still highly variable between basins and studies. Thus, the projected change in both magnitude and sign of TC size is uncertain.”
On Warmer Oceans Mean Fewer Cyclones “Changes in SST (sea surface temp.) and atmospheric temperature and moisture play a role in tropical cyclogenesis (Walsh et al., 2015). Reductions in vertical convective mass flux due to increased tropical stability have been associated with a reduction in cyclogenesis (Held and Zhao, 2011; Sugi et al., 2012). Satoh et al. (2015) further posit that the robust simulated increase in the number of intense TCs, and hence increased vertical mass flux associated with intense TCs, must lead to a decrease in overall TC frequency because of this association.”
Human Influence On Extratropical Cyclones “The human influence on individual extreme ETC events has been considered only a few times and there is overall low confidence in the attribution of these changes (NASEM, 2016; Vautard et al., 2019).”
On ETC Frequency In The Southern Hemisphere “Over the Southern Hemisphere, future changes (RCP8.5 scenario; 1980–1999 to 2081–2100) in extreme ETCs were studied by Chang (2017) using 26 CMIP5 models, and a variety of intensity metrics (850-hPa vorticity, 850-hPa wind speed, mean sea level pressure and near-surface wind speed). They found that the number of extreme cyclones is projected to increase by at least 20% and as much as 50%, depending on the specific metric used to define extreme ETCs. Increases in the number of strong cyclones appear to be robust across models and for most seasons, although they show strong regional variations, with increases occurring mostly over the southern flank of the storm track, consistent with a shift and intensification of the storm track.” Caveat: Chang (2017)[xxii] reports that these increased storms will mostly occur “between 45° and 60°S, extending from the South Atlantic across the south Indian Ocean into the Pacific”, which places them south of NZ firmly in the Southern Ocean (most are expected to occur between Australia and India). The computer models expect the storms to track towards Antarctica rather than towards the tropics. The RCP8.5 scenario used to achieve this prediction is based on an assumption that no effort is made to reduce emissions and that temperatures increase by 4.3C by 2100. Interestingly, the southern Indian Ocean was also bearing the brunt of Antarctic storms a century ago, “Antarctica, however, exercises its greatest influence in the South Indian Ocean, the mean surface temperature of that body of water being considerably lower than the South Pacific in a corresponding latitude. As a consequence, regions in the Indian Ocean in the latitude of the Bluff not infrequently experience, snowsqualls in the height of summer.”[xxiii]
On Extreme Weather Attribution “Attributable increases in probability and magnitude have been identified consistently for many hot extremes. Attributable increases have also been found for some extreme precipitation events, including hurricane rainfall events, but these results can vary among events. In some cases, large natural variations in the climate system prevent attributing changes in the probability or magnitude of a specific extreme to human influence. Additionally, attribution of certain classes of extreme weather (e.g., tornadoes) is beyond current modelling and theoretical capabilities.”
So that’s how the IPCC sees it – a far cry from the ridiculous disinformation surfacing in the media.
One last point before we leave extreme weather – storminess. It has been accepted wisdom that warmer temperatures create more storminess. The computer models used by NIWA and the IPCC are programmed with the ‘warm means storm’ assumption. But what if it’s not true?
The implicit threat of Gabrielle-sized storms hammering NZ every six months is the very reason Al Gore is using extreme storms as a motivational scarecrow. Fear sells.
However the revelation in the first Climate of Fear report[xxiv] that our cold pre-industrial climate was 20 times more extreme than today’s warm climate is a game-changer. That study used historical news reports to track the progress of 24 massive storms that hit New Zealand in the 22 years from 1868 to 1890. It is believed to be the first study to do that in New Zealand.
The technique has also been used in Italy, where historical documents dating back 12 centuries were searched for references to big storms. That study (Diodata et al, 2020), like the New Zealand one, found much higher storminess and rainfall during cold climates like the Little Ice Age, and the opposite in warm, casting doubt on modern assumptions about what a warm climate will lead to.
“…recurrences of storminess become less statistically predictable outside the LIA. This may demonstrate that dynamic atmospheric processes are present in generating cyclone-related precipitation extremes throughout the LIA (Raible et al 2018), departing from the Clausius–Clapeyron thermodynamic expectations of an increase in precipitation intensity associated with atmospheric warming (Pall et al 2007, Trenberth 2011, Trenberth et al 2014, Kirby 2016, Prein and Pendergrass 2019). Our study thus shows the same tendency as revealed by Ljungqvist et al (2019) for a negative low-frequency temperature–hydroclimatic coupling (i.e., warm and dry) in southern Europe.”[xxv]
Another study: “These authors found that flood occurrences in central Europe during the entire year are enhanced in the rather cold periods of the LIA compared to warm periods. They suggested a negative correlation between temperature and floods…This proxy evidence is ostensibly in contrast to the thermodynamic theory which states that a warmer atmosphere can hold more moisture based on the Clausius–Clapeyron equation.”[xxvi]
And from New Zealand and Europe to the Caribbean, the same story: colder climates have more extreme weather (Winkler et al, 2022):
“Despite variations in individual records, a 1500-year compilation of these records documents significantly higher storminess in the subtropical North Atlantic during the Little Ice Age (LIA, 1300-1850 CE)”.[xxvii]
If a warmer climate is not actually going to lead to worse weather, then what are we all scaring ourselves silly for? It’s not a rhetorical question, it’s the elephant in the room and neither the media nor NIWA want to talk about it.
[i] Wei, M., Shu, Q., Song, Z. et al. Could CMIP6 climate models reproduce the early-2000s global warming slowdown?. Sci. China Earth Sci. 64, 853–865 (2021). https://doi.org/10.1007/s11430-020-9740-3
[ii] Harrington, LJ; Dean, SM; Awatere, S; Rosier, S; Queen, L; Gibson, PB; Barnes, C; Zachariah, M; Philip, S; Kew, S; Koren, G; Pinto, I; Grieco, M; Vahlberg, M; Snigh, R; Heinrich, D; Thalheimer, L; Li, S; Stone, D; Yang, W; Vecchi, GA; Frame, DJ; Otto, FEL (2023). The role of climate change in extreme rainfall associated with Cyclone Gabrielle over Aotearoa New Zealand’s East Coast. World Weather Attribution Initiative Scientific Report.
DOI: https://doi.org/10.25561/102624
[iii] https://www.nzherald.co.nz/nz/nzs-forests-soak-up-far-more-extreme-rainfall-than-we-realise/PR6I7KPVIJGBRF44B4O5TGAPVU/
[iv] https://www.newshub.co.nz/home/new-zealand/2023/03/scientists-say-climate-change-likely-behind-the-intensity-of-rainfall-from-cyclone-gabrielle.html
[v] https://theconversation.com/floods-cyclones-thunderstorms-is-climate-change-to-blame-for-new-zealands-summer-of-extreme-weather-201161
[vi] https://www.1news.co.nz/2023/03/15/study-finds-cyclone-gabrielle-rainfall-affected-by-climate-change/
[vii] https://www.imperial.ac.uk/news/243771/climate-change-likely-increased-extreme-rain/
[viii] https://hwe.niwa.co.nz/event/April_1897_North_Island_Flooding
[ix] https://hwe.niwa.co.nz/event/March_1924_Hawkes_Bay_Flooding
[x] https://hwe.niwa.co.nz/event/April_1938_Gisborne_and_Hawkes_Bay_Flooding
[xi] https://niwa.co.nz/news/in-numbers-new-zealands-wild-summer-weather
[xii] Jézéquel, Aglaé, Pascal Yiou, and Jean-Paul Vanderlinden. “Challenging the use of extreme event attribution for loss and damage.” (2018). https://hal.science/hal-01896553/
[xiii] Hulme, M. (2014). Attributing weather extremes to ‘climate change’: A review. Progress in Physical Geography: Earth and Environment, 38(4), 499–511. https://doi.org/10.1177/0309133314538644
[xiv] Jézéquel, A., V. Dépoues, H. Guillemot, A. Rajaud, M. Trolliet, M. Vrac, J. Vanderlinden, and P. Yiou, 2020: Singular Extreme Events and Their Attribution to Climate Change: A Climate Service–Centered Analysis. Wea. Climate Soc., 12, 89–101, https://doi.org/10.1175/WCAS-D-19-0048.1.
[xv] King, A. D., D. J. Karoly, M. T. Black, O. Hoegh-Guldberg, and S. E. Perkins-Kirkpatrick, 2016: Great Barrier Reef bleaching would be almost impossible without climate change. The Conversation, accessed 10 June 2016. [Available online at https://theconversation.com/great-barrier-reef-bleaching-would-be-almost-impossible-without-climate-change-58408.]
[xvi] Zhao, W., Huang, Y., Siems, S., & Manton, M. (2021). The role of clouds in coral bleaching events over the Great Barrier Reef. Geophysical Research Letters, 48, e2021GL093936. https://doi.org/10.1029/2021GL093936
[xvii] Shannon Osaka, Rob Bellamy,
Natural variability or climate change? Stakeholder and citizen perceptions of extreme event attribution,
Global Environmental Change,
Volume 62,
2020,
102070,
ISSN 0959-3780,
(https://www.sciencedirect.com/science/article/pii/S0959378019307939)
[xviii] https://www.nzherald.co.nz/nz/el-nino-combined-with-global-warming-means-big-changes-for-new-zealands-weather/WHZXHXXWSFAX7HFIO7ZLS36OXM/
[xix] Jézéquel, Aglaé, Pascal Yiou, and Jean-Paul Vanderlinden. “Challenging the use of extreme event attribution for loss and damage.” (2018). https://hal.science/hal-01896553/
[xx] https://scholarsbank.uoregon.edu/xmlui/bitstream/handle/1794/25034/Final_Thesis-Koch.pdf?sequence=1
[xxi] Hulme, M. (2014). Attributing weather extremes to ‘climate change’: A review. Progress in Physical Geography: Earth and Environment, 38(4), 499–511. https://doi.org/10.1177/0309133314538644
[xxii] Chang, E. K. M., 2017: Projected Significant Increase in the Number of Extreme Extratropical Cyclones in the Southern Hemisphere. J. Climate, 30, 4915–4935, https://doi.org/10.1175/JCLI-D-16-0553.1.
[xxiii] Nelson Mail, 24 January 1929, https://paperspast.natlib.govt.nz/newspapers/NEM19290124.2.97
[xxiv] https://ianwishart.com/2023/03/climate-of-fear/
[xxv] Nazzareno Diodato et al 2020 Environ. Res. Commun. 2 031004 https://doi.org/10.1088/2515-7620/ab7ee9
[xxvi] Raible, Christoph C., Joaquim G. Pinto, Patrick Ludwig, and Martina Messmer. “A review of past changes in extratropical cyclones in the northern hemisphere and what can be learned for the future.” Wiley Interdisciplinary Reviews: Climate Change 12, no. 1 (2021): e680. https://doi.org/10.1002/wcc.680
[xxvii] Winkler, Tyler Scott, Jeffrey P. Donnelly, Peter J. van Hengstum, Elizabeth Jane Wallace, Vittorio Maselli, Nancy A. Albury, Laura Barnett et al. “Disentangling the spatial drivers of late-Holocene tropical cyclone frequency variability across the North Atlantic using high-resolution sedimentary archives.” In AGU Fall Meeting Abstracts, vol. 2022, pp. PP12B-05. 2022. https://ui.adsabs.harvard.edu/abs/2022AGUFMPP12B..05W/abstract
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