water Article Rethinking Climate, Climate Change, and Their Relationship with Water Demetris Koutsoyiannis Department of Water Resources and Environmental Engineering, School of Civil Engineering, National Technical University of Athens, 15780 Athens, Greece; [email protected] Abstract: We revisit the notion of climate, along with its historical evolution, tracing the origin of the modern concerns about climate. The notion (and the scientific term) of climate was established during the Greek antiquity in a geographical context and it acquired its statistical content (average weather) in modern times after meteorological measurements had become common. Yet the modern definitions of climate are seriously affected by the wrong perception of the previous two centuries that climate should regularly be constant, unless an external agent acts upon it. Therefore, we attempt to give a more rigorous definition of climate, consistent with the modern body of stochastics. We illustrate the definition by real-world data, which also exemplify the large climatic variability. Given this variability, the term “climate change” turns out to be scientifically unjustified. Specifically, it is a pleonasm as climate, like weather, has been ever-changing. Indeed, a historical investigation reveals that the aim in using that term is not scientific but political. Within the political aims, water issues have been greatly promoted by projecting future catastrophes while reversing true roles and Citation: Koutsoyiannis, D. causality directions. For this reason, we provide arguments that water is the main element that drives Rethinking Climate, Climate Change, climate, and not the opposite. and Their Relationship with Water. Water 2021, 13, 849. https://doi.org/ Keywords: climate; climate change; water; hydrology; climatology 10.3390/w13060849 Academic Editors: There’s no such thing as bad climate, only bad clothes Alexander Shiklomanov, Vasileios Tzanakakis, Paraphrasis of a Scandinavian proverb Stavros Alexandris, Each definition is a piece of secret ripped from Nature by the human spirit. Maria Psychogiou and Andreas Nikolai Luzin (from [1]) N. Angelakis 1. Introduction Received: 6 February 2021 As concerns about climate become all the more widespread in society, it is useful to Accepted: 18 March 2021 Published: 19 March 2021 revisit the notion of climate in scientific terms, along with its historical evolution and the very origin of the concerns per se. Water issues have been central among climate concerns, Publisher’s Note: MDPI stays neutral and thus it is useful to clarify the relationship between climate and water. As will be with regard to jurisdictional claims in detailed in Section2, the notion (and the scientific term) of climate was established in published maps and institutional affil- ancient Greece in a geographical context, while it acquired a statistical content (average iations. weather) in modern times after meteorological measurements had become common. Yet the modern definitions of climate, which are discussed in Section3, are deficient as they are affected by a wrong perception of the 19th and 20th centuries that the climate at a certain place should regularly be constant, unless an external agent acts upon it. For this reason, in Section4 we attempt to propose a more rigorous and consistent definition of climate, Copyright: © 2021 by the author. Licensee MDPI, Basel, Switzerland. based on stochastics. We illustrate the definition by real-world data, which also exemplify This article is an open access article the large variability of climate. Given this variability, the term “climate change” turns out distributed under the terms and to be scientifically unjustified. Specifically, it is a pleonasm, as the climate, like the weather, conditions of the Creative Commons has been ever-changing. Indeed, the analysis in Section6 reveals that the objective of using Attribution (CC BY) license (https:// the term is not scientific but political. creativecommons.org/licenses/by/ Concerning, in particular, the relationship of climate and water, the analysis of 4.0/). Section5 shows that water is the main element that drives climate, rather than just being Water 2021, 13, 849. https://doi.org/10.3390/w13060849 https://www.mdpi.com/journal/water Water 2021, 13, 849 2 of 38 weather, has been ever-changing. Indeed, the analysis in Section 6 reveals that the objec- Water 2021, 13, 849 tive of using the term is not scientific but political. 2 of 38 Concerning, in particular, the relationship of climate and water, the analysis of Sec- tion 5 shows that water is the main element that drives climate, rather than just being affectedaffected by by climate climate as as commonly commonly thought. thought. This This demands demands a a more more active active role role of of hydrologistshydrologists inin climate climate research, research, replacing replacing their their current current passive passive role role in in studying studying climate climate impacts. impacts. ToTo faithfully faithfully follow follow the the development development of of ideas ideas about about climate climate from from antiquity antiquity to to modern modern science,science, wewe examineexamine andand quotequote severalseveral historicalhistorical andandmodern modern texts. texts. WhileWhile thethe subject subject of of thisthis paper paper looks looks general, general, and and its its content content perhaps perhaps trivial, trivial, the the investigations investigations performed, performed, the the informationinformation given given and and the the synthesis synthesis thereof, thereof, are are mostly mostly new. new. 2.2. HistoryHistory ofof thethe NotionNotion ofof ClimateClimate AlthoughAlthough thethe historianhistorian HerodotusHerodotus ((<HἩρόδοτοςróδoτoV;; c.c. 484–c. 484–c. 425 425 BC)BC) isis perhapsperhaps thethe first first whowho describeddescribed differentdifferent climatesclimates ofof somesome areasareas onon EarthEarth inin a a geographical geographicalcontext context (see(see AppendixAppendixA A),), it it was was Aristotle Aristotle (Figure (Figure1) 1) who, who, a centurya century later, later, put put the the notion notion of of climate climate in in aa scientificscientific context.context. In his famous famous book book MeteorologicaMeteorologica hehe describes describes the the climates climates on on Earth Earth in inconnection connection with with latitude, latitude, but but he he uses uses a a different different term, term, crasis (krκρᾶσιςᾶsiV),), literallyliterally meaningmeaning mixing,mixing, blendingblending ofof thingsthings which which form form a a compound, compound, or or temperament. temperament. TheThe termterm climateclimate ((klκλίμαÐma,, plural pluralkl κλίματαÐmata)) was was coined coined as as a a geographical geographical term term by by the the astronomerastronomer Hipparchus Hipparchus (Figure (Figure1 )1) in in his his Commentary Commentary on on Aratus Aratus ( <I(Ἱππάρχουppάrcou t τῶνῶn >A Ἀράτουrάtou kaκαὶÈ E ΕὐδόξουÎdóxou jain φαινομένωνomènwn ἐ xhgἐξηγήσεωςήs#wV [2 [2]).]). Hipparchus Hipparchus is is also also known known in in climatology climatology for for his his discoverydiscovery and and calculation calculation of ofprecession precession of of the the equinoxes equinoxes(m#t (μετάπτωσιςάptwsiV Êshm#ri ἰσημεριών¸n) by) studyingby study- measurementsing measurements on several on several stars. stars. In the In 20ththe 20th century, century, this this precession precession would would be found be found to be to relatedbe related to the to the climate climate of theof the Earth Eart andh and constitutes constitutes one one of of the the so-called so-calledMilankovitch Milankovitch cycles cycles (see(see Section Section5 ).5). The The term termclimate climateoriginates originates fromfrom thethe verbverbkl κλίνεινÐn#in,, meaning meaning ‘to ‘to incline’ incline’ and and originallyoriginally denoted denoted the the angle angle of of inclination inclination of theof the celestial celestial sphere sphere and and the terrestrialthe terrestrial latitude lati- characterizedtude characterized by this by angle this angle [2]. [2]. Figure 1. (left) Aristotle (Ἀριστοτέλης; 384–322 BC), Greek philosopher of the Classical period, Figure 1. (left) Aristotle (>ArιστoτèληV; 384–322 BC), Greek philosopher of the Classical period, founder of the Lyceum and the Peripatetic school of philosophy. (right) Hipparchus of Nicaea founder of the Lyceum and the Peripatetic school of philosophy. (right) Hipparchus of Nicaea (Ἵππαρχος ὁ Νικαεύς; c. 190–c. 120 BC), Greek astronomer, geographer and mathematician VIππα χ ὁ ικαεύ (founderr oofV trigonometryN V; c. 190–c.and discov 120 BC),erer Greek of the astronomer,precession of geographer the equinoxes, and mathematiciandepicted in the founder back offacet trigonometry of a coin of and the discoverer Roman period. of the (Image precession sources: of the [3]). equinoxes, depicted in the back facet of a coin of the Roman period. (Image sources: [3]). Hipparchus’s Table of Climates was described by Strabo the Geographer (Στράβων; Hipparchus’s Table of Climates was described by Strabo the Geographer (Sτrάβων; 64 or 63 BC–c. 24 AD), from whom it became clear that the Climata of that Table are just 64 or 63 BC–c. 24 AD), from whom it became clear that the Climata of that Table are latitudes of several cities, from 16° to 58°N (for a reconstruction of the Table see Shcheglov just latitudes of several cities, from 16◦ to 58◦ N (for a reconstruction of the Table see [2]). However, Strabo himself used the term climate with a