Omertà

An article in the Guardian caught my eye today. It represented another in a long series of Guardian articles looking at a part of the world, and blaming its problems largely on climate change. This article carried the startling claim that “Rainfall is down 40% since 2003 and experts predict a third of Sicily will be desert by 2030”.

I was unable to find a link in support of this claim, though there was a link to an article in Catania Today, dated 16th February 2024, so not bang up to date, but good enough for current purposes. Thanks to the wonders of Google Translate, I was able to read it, and you can too if you are interested. There is no doubt at all that Sicily is currently suffering a severe drought, and that rainfall levels since autumn 2023 have been low. However, I could find nothing in the article (perhaps I just missed it) to justify the claims that rainfall is down by 40% with the prospect of one-third of Sicily being desert in just six years’ time.

More than that, the Catania Today article contains a rainfall graph representing the historical series of average rainfall in the period July-December since 1921. This surprised me greatly, for although it very low levels of rainfall in 2023, it wasn’t significantly less (so far as one can tell by eye-balling the graph) than in 1978, with other low (though admittedly not quite so low) rainfall seasons in 1922, the early 1950s, early 1970s and the early years of this century. That didn’t seem to indicate any soer of trend to me, nor does the graph as a whole, which so far as I can see shows 2021 as being the second-wettest July to December period during the century covered by the graph. Also of interest is the fact that significant rainfall occurred in April, May and June 2023 (though not enough to prevent 2023 overall showing a significant negative anomaly). The article suggests that an unusual (and unusually prolonged) area of high pressure was responsible for the low rainfall in the second half of 2023.

So far, so good. But what of the alarming long-term trend strongly suggested by the Guardian, towards ongoing reductions in rainfall? Well, I can’t see any evidence for it in the Catania Today article, but curiously enough the Guardian article also mentions a specific reason why the reduced rainfall has had such a drastic effect in late 2023/early 2024. The 2030 desertification claim is attributed to Christian Mulder, a professor of ecology and climate emergency at the University of Catania on the island, but Professor Mulder also said this:

The ancient Arabs who once inhabited the island had successfully devised ways to manage water. However, these old aqueducts have not been maintained or updated. Sicily is now facing the concrete consequences of decades of mismanagement of water resources.

The Guardian skips past that to claim that aquifers and large storage tanks constructed after the second world war are being adversely affected by “increasingly scarce winter rainfall”. Yet as I say, I saw no evidence in the Catania Today graph of increasingly scarce winter rainfall, save for late 2023 (and presumably continuing into 2024).

The Guardian acknowledges that “[f]or three decades, essential maintenance to the irrigation network has been neglected, diminishing the capacity of the island’s reservoirs”, and then goes on to blame summer droughts and soaring heat for the problem, thereby letting off the hook those who have failed to maintain the infrastructure.

But are the claims of declining rainfall actually correct? So far as I can see, other than with regard to the last twelve months (far too short a period to draw conclusions regarding climate change) the answer is a resounding “no”. I looked to two studies looking at rainfall statistics in Sicily to come to my conclusion that differs completely from the Guardian’s scare-mongering. A 2013 paper by E. Arnone, D. Pumo, F. Viola, L. V. Noto, and G. La Loggia offered some support for the Guardian’s position:

A high percentage of the Sicilian rain gauge stations have shown a significant negative trend in the total annual precipitation, mainly due to a reduction in the seasonal rainfall during the wet period (fall and winter). A similar percentage of stations have shown how all the rainfall events (during both the wet and dry season) tend to be less intense, while very few stations are characterized by significant changes in the frequency of rainfall events.

However, another paper was released in February 2024 by V. Pecorino, T. Di Matteo, M. Milazzo, L. Pasotti, A. Pluchino, and A. Rapisarda, and it came to rather different (and more up-to-date) conclusions:

We identified as evidence of climate change the yearly reduction of rainfall volumes and events in winter as well as a summer upward trend. At the same time, the characterization of precipitation variables across all seasons and considering precipitation intensity classes improved our knowledge about pluviometric regimes, allowing the detection of climate anomalies. Before 2013, the best contribution to multi-annual volumes was brought by winter whilst, during the last eleven years, autumn became the most rainy season. The growing number of extreme events and the extremization of precipitation volumes can be considered also anomalies. Even the fact that all extreme events have duration around 2-3 hours across all seasons is an important anomalous tendency, in contrast to the years 2002-2012, when the number of events was homogeneously distributed with respect to duration. In other words seasons seems to behave more and more similarly. From our study we see that, after the heavy summer drought during 2009-2012, all seasons recorded a sudden volume variation: increasing during autumn-summer and decreasing in winter-spring. This coupled behavior emerges as a characteristic feature of the period 2013-2023: the similarity between summer-autumn and winter-spring highlights the passage from a 4 to a 2 season-like cycle. This means that the differentiation of pluviometric regimes in 4 seasons, typical of the 20th century till 2012, is not characteristic for the time period 2013-2023. With its temperate climate, Sicily has always been characterized by rainy winter and autumn and heavy dry summer. Extreme events usually occurred from august to march: we had 3 dry months and 9 wet months. During this last eleven years, the occurrence of extreme events became common during all seasons, the contribution of summer precipitation were increasing noticeably and most of rainfall was concentrated during autumn months: this means that from December to August we could observe 9 dry months followed by 3 rainy months.

The authors definitely conclude that there is climate change in evidence, though it is not entirely in accord with the claims made by the Guardian. Rainfall in summer and autumn is generally increasing, while reducing in winter and spring, with the difference in rainfall volumes across the seasons becoming less extreme. The authors also acknowledge the problem Sicily has with poor rainfall management:

Historically, the allocation of water resources has not been very efficient in Sicily, therefore this lack of precipitation can seriously damage agricultural and farming activities as well as citizens welfare. Even a flash flood can represents a disaster for urban infrastructures, economical activities and citizen life. Moreover, prolonged dry periods followed by prolonged wet periods acts deeply in the ground settlement and water reservoirs, influencing viability and affecting vegetation biodiversity. In Sicily the primary sector gives a great contribution to the regional economy and the results of our study indicate that a deep change is ongoing: authorities and citizen should realize that these clear anomalies in the water cycle are important warning signals. Therefore new strategies for managing resources and damages are urgently needed in order to reduce human and economic losses.

Is this all really something new, or simply a recurring cycle? I don’t know. Unfortunately I haven’t succeeded in downloading a copy of a paper titled “Evidence of Drought in Western Sicily during the Period 1565–1915 from Liturgical Offices”, but the brief synopsis is suggestive of Sicilian droughts being a centuries-long problem:

In the present work, the drought events that occurred in western Sicily during the period 1565–1915 have been analysed, using historical information.Inside the cathedral of Erice, a small and ancient town in western Sicily,there is a marble plate reporting the dates of the processions held during that period.This information, together with other documents and manuscripts found in the city library,has allowed us to reconstruct the drought chronology. The comparison between these series and the quantitative data on precipitation indicates some agreement.The application of the operator ARP (Automatic Research for Periodicities) shows significant periods of 11, 17, 22, 32, 73, 90 years. Finally, the comparison between ENSO and drought chronology shows that in periods of many drought events a reduction of ENSO events occurred and vice versa.

What none of these studies appear to talk about is the effect of deforestation in Sicily, which really is too important to allow Omertà to airbrush it from the discussion. Here is the short version from Wikipedia:

Sicily is an often-quoted example of man-made deforestation, which has occurred since Roman times when the island was turned into an agricultural region.This gradually dried the climate, leading to a decline in rainfall and the drying of rivers.

The long version can be found here: “Three Millennia of Vegetation, Land-Use, and Climate Change in SE Sicily”. The study is well worth a read, offering a fascinating insight into the effect of human activities in Sicily over thousands of years, but also for a frank discussion of climate change over the millennia. There are too many intriguing snippets in the study to quote from it at length, but this is worth noting, as confirming the terrible droughts of the past, as mentioned above:

A huge body of archival documentation, collected by the Italian historian Trasselli, reports evidence of enhanced drought between the end of the 15th century and the first quarter of the 16th century in Sicily, falling within the Spörer Solar Minimum. In his pioneering work, the author carefully gathered a large number of dry historical episodes (1494, 1497, 1505, 1507, 1510, 1511, 1512, 1515, 1519, 1521 AD), emphasizing the effects of prolonged aridity in determining crop failure, livestock death, economic instability, and political disorders throughout the island.

Historical records from the city of Erice, in W Sicily, report the occurrence of rogation ceremonies associated with severe droughts, revealing the occurrence of 50 processions from 1568 to 1913. These ad aqua petendam (asking for rain) rituals constitute a piece of evidence of recurrent dry spells on the island, which occurred with a frequency of 2–3 years from 1568 and 1668, right in the middle of the LIA. Historically, in Sicily, the LIA coincided with a period of continuous political turmoil and miserable events such as the famines of 1591, 1634, 1636, 1647, 1671, and 1793, the plague of 1624, and the earthquake of 1693.The conclusion references the Late Antique Little Ice Age, the Medieval Climatic Anomaly and the Little Ice Age, all talking points for climate sceptics, usually downplayed by climate alarmists.

What to make of it all? Undoubtedly Sicily is experiencing unusual heat and drought of late. Equally clearly, such extremes are nothing new, and are being exacerbated by failures in management of water resources and by deforestation. Also, although rainfall patterns have shifted over the last decade, and rainfall levels have declined, the shift has not been uniform over the last twenty years or so, with variations in the first and second decades of this century. Also, contrary to the impression created by the Guardian, summer rainfall levels are actually increasing, and rainfall extremes by season appear to be reducing.

A climate Omertà should not prevent a full debate regarding all the factors at play and the significance of short-term trends compared to the dramatic long-term fluctuations the island of Sicily has endured. If one-third of Sicily is a desrt by 2030, and if this is due to climate change rather than mismanagement, I will eat my words. Please feel free to make a diary note and to remind me in due course.

via Climate Scepticism

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July 1, 2024 at 03:11PM

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