如今气候变化问题正引起公众热议。每隔一段时间总会发生极端天气事件，重新将公众视线带回这个问题，不论事件本身对错与否。但这种情况并非历来如此。历史上很长一段时间内，人们并没有深入思考气候变化问题。人们认为气候是稳定的，极端天气等事件只是因为“恶劣天气”的干扰，人们还基于人类中心论赋予了该“恶劣天气”宗教性的解释。18世纪，科学家提出人类活动可能对气候产生影响。19世纪初，科学家又提出化石燃料燃烧导致CO2浓度增加可能会加剧全球变暖。但直到20世纪70年代，这种现象才引起重视。特别是在1988年联合国政府间气候变化专门委员会（Intergovernmental Panel on Climate Change，IPCC)成立之后，全球变暖问题开始受到重视，引起国内外公开讨论。
自然界这种循环的规律是大众知识所要了解的，但却不时被特殊气候事件扰乱。其特殊性质在人类记忆中处于空白地带，但却真实发生了。这些意外事件打破了自然平衡，形成了“恶劣天气”，18世纪出版的《特雷弗词典》（Dictionnaire de Trévoux）给出了其含义：“破坏、糟糕的体质，缺乏公平的性质以及某些事情需要的品质”。恶劣天气会直接影响大气，人们不希望遇到恶劣天气……季节性的恶劣天气会影响大气质量。
气象学的历史与现代科学的诞生密不可分。无论如何，自笛卡尔以来，科学家们从17世纪就开始寻求气象现象的科学解释[4]（参考过去几个世纪的气象观测）。如果解释恶劣天气还不算挑战，那么了解他们正在研究的气候规律便是当务之急。佛罗伦萨的西芒托学院（Academia del Cimento），伦敦的英国皇家学会（Royal Society）和巴黎的法国科学院（Académiedes Sciences）综合了各自的观测结果，制定了有关空气压缩和太阳辐射的第一条物理定律。至于气候方面，这项研究的首要目标是阐明气候的调节机制。他们参与了物理学启蒙运动，以理解上帝创造的自然规律。探寻这些规律需要使用日益精确的仪器、进行大量必要且枯燥的记录，此时我们正试图标准化这些仪器（温度计、气压计、湿度计、雨量计、风速表）和其读数。
但如果认为这些科学家是想了解气候变化，并赋予气候变化以现代意义，我们就大错特错了。对17、18世纪的人们而言，“气候”首先指一个地理区域[5]。1694年里什莱（Richelet）编撰的《法兰西学院词典》（Dictionary of the Académie française）中，“气候”这个词的解释是“两条平行线之间地球的深度”。1762年发行的《学院词典》（Dictionary of the Academy）中，“气候”意味着“大气条件”。在当时医学界日益增长的影响下，“温度”的含义为：“医生们会根据自身感受的温度或热度来判断气候”[6]。观察者关心的与其说是气候规则，不如说是“气候”本身。研究气候实际上就是研究气象现象，并在一个完全空间限定的地理空间中明确其规律。因此，建立观察员网络旨在观测“气候”变化，即在不同地区和国家观察“气候”的特定规律，并试图找到科学解释。拉赫（La Hire）在1710年将他的观测结果与苏黎世人薛特兹（Scheutzer）的观测结果进行比较后指出：“通过比较这些观测结果，我知道瑞士的降雨比巴黎多。而且里昂的降雨比巴黎多的原因在于距离巴黎不远处的瑞士山脉，而这些结果都在后续观测中被证实”。
为确保比较结果可靠，两人都致力于增加年度观测数量，以进一步明确两地的气候规律。1743年杜哈梅尔·蒙索（Duhamel du Monceau）指出：“自然界中一切事物都是运动的，一切事物都在变化，但一切事物也都趋于平衡，其规律并不一致。如果我们在同一国家进行长达几个世纪的天气观测，我们完全有理由相信，该国这个世纪的降雨总量与另一个世纪的降雨量没有显著差异，或者如果存在显著差异，那么该国降雨量的差异趋势将在更长的时间尺度上显示出来。因为我们的地球和大气层并不是一成不变的，其变化一定会影响人类活动，并显示出造成差异和衰退的原因”。他还补充道：“很明显，观测年数越多，得到的平均值就越接近真实平均值”[7]。实际上，巴黎天文台记录的平均降雨量在18世纪上半叶经过多次修改。在这种情况下，出现异常的年份并未视为规律中断或可能发生了变化，而仅仅是一个迹象，表明人们对试图定义的规律仍然存在认知不足。
从伍德沃（Woodward）到布冯（Buffon），关于地球起源的争论引发了激烈冲突，但对气候问题几乎没有影响。1765年，杜哈梅尔·蒙索（Duhamel du Monceau）指出地球“遭受了巨大变化，洪水、火灾和可怕的动荡；整个大陆被吞没并被新的海洋所取代，而在其他地方以及海洋深处，山脉和新的大陆开始上升，在那些地方仍然可以看到海洋的产物”。但这些古老变化的观测并没有改变这一预言：“地球并非一成不变，它的变化迟早会影响人类活动”。
毫无疑问，我们在孟德斯鸠那里发现了这一问题。我们知道，哲学家认为气候的作用是产生差异，这些差异被上升为道德问题。但这也暗中质疑了人类行为在气候变化中的作用。早在1719年，这一观点就出现在“地球的古代和现代历史项目（an ancient and modern history of the Earth）”中，并于同年1月在《新信使》(Le Nouveau Mercure）中正式提出，然后于3月6日的《学者报》（Le Journal des sçavans）中以一个略有不同的版本发表，题为 “致学者们的通告（Avis aux savans）”[8]。这一项目旨在研究地球变化的物理原因，即自然、地理、地质和气候历史方面的原因，除研究地球表面的变化外，还研究人类活动造成的自然平衡变化和改变。强调“人类的双手赋予地球新的面孔”所带来改变的影响，这意味着强调“物理”与“道德”之间（自然与历史之间）的关系。
欧洲人在殖民地的发展为气候变暖提供了显著证据。早在17世纪中期的英属弗吉尼亚或法属加拿大，就出现了经济发展会促进气候变化的观点[11]。在英国皇家学会上，罗伯特·博伊尔（Robert Boyle）早在1671年就提出了这个问题。布冯（Buffon）在18世纪初提出了同样的观点，他认为圭亚那的森林砍伐会导致气温上升，“而在其他被树木覆盖的土地上晚上却很冷，人们不得不生火御寒”。1745年，法国科学院驻魁北克的观测员高迪尔（Gautier）博士也有同样的观点：“我们说过，在加拿大，我们注意到春天开始的时间比以往早，冬天开始得比以往晚，这种气温变化归因于树木的砍伐和土地的开垦。这个国家的长者还向我们讲述，以往金银花到9月15日或16日才会开始收获，而且很少完全成熟”[12]。到17世纪60年代，这种想法趋于普遍。1792年《医学百科全书》（Encyclopedia of Medicine）中 “气候”一文的结论也是如此：“然而，我们可以认为耕作、开荒、森林砍伐以及池塘和沼泽干涸造成了气候变化。想要证明这一事实吗？让我们看看美国，凡是文明没有征服的地方，都是阳光无法穿透的茂密森林和太阳无法晒干的沼泽覆盖着整个地球，这些森林和沼泽会使大气降温，如果想在那里过夜，你得点火取暖”。
作为一个特殊观测领域，至于小冰河期的冰川前进，观测者可以不考虑任何气候变化相关的原因。拉蒙德·卡博涅尔（Ramond de Carbonnières）通过对比利牛斯山脉和阿尔卑斯山的变化发现，物理原因（高海拔地区的冰川积累和重力现象）会使低谷地区的冰川前进，他强调：“我不会说冰川前进的增加是全球变冷所致”，并悲观地补充道：“无论这个事实多么令人难过，必须承认冰川会逐渐覆盖整个阿尔卑斯山脉表面，并隔离所包含的温带山谷”[14]。至于同时期的“小冰河期”，冰川前进并不意味着气候变冷，只是证实了自地球形成以来，最冷的山区会不断累积冰川的假说（参考“气候变化的哨兵-冰川”）。这一观点得到广泛认同。一如塞萨尔·鲍迪耶（César Bordier）所说，他们“像软化的蜜蜡”一样滑动。索绪尔（Saussure）并没有再作补充。
然而除了经验观察和预言外，19世纪初，物理学家的工作逐渐证实气候变化的现实，以及气候变化可能是人类活动的结果这一假设。物理学家约瑟夫·傅里叶（Joseph Fourier），曾任伊泽尔省（Isère）县长，在1824年发表的《地球和宇宙温度总论》（General Remarks on Earth and Space Temperatures）中首先将地球的温度问题置于宇宙学背景下，并提出地球对太阳热量的所有影响都因大气的介入和海洋的存在而改变。
20世纪初，阿伦尼乌斯的观点在科学界得到广泛接受。20世纪30年代，英国皇家气象学会的乔治·斯图尔特·卡伦达（George Stewart Callendar）估计，1890年到1938年（基于燃煤的工业革命的52年间），观测发现大气中CO 2增长了10％，这是造成气候变暖趋势的原因之一。20世纪下半叶，“数字系统的进步以及对大气和相关环境状况日益增加的多样化观察……和超级计算机的发展”使人们对气候及其变化的认识有了长足进步，通常以30年为时间尺度定义统计学上的“平均值和变异性”（请参考气候机器&天气预报介绍）。
然而，气候变化问题几乎没有引起媒体注意，而且非常不起眼。如果不是法国科学杂志《科学与生活》（Science et Vie）1959年5月的一篇文章“地球正在变暖”（The Earth is getting warmer）中提到全球变暖的猜想，全球变暖与其他许多原子威胁或滑水轶事相比，将只是一个传闻。20世纪50年代到70年代末，美国或欧洲媒体更担心重新回到极寒冰期。这种担忧部分基于克罗地亚地球物理学家米特林·米兰科维奇（Mitulin Milankovic）提出的气候数学理论，他预测主要冰川期的周期性回归是地球公转轨道（已知）变化和地球自转的函数（多变的轨道离心率和黄赤交角，以及地轴进动）（参考气候的天文学理论（The Astronomical Theory of Climates））。但这主要反映了一些周期性现象：活跃的国际环境（“冷战”，对核冬天的担忧[20]），气温下降（20世纪40年代至70年代末或20世纪70年代的能源危机）。1954年的严冬，皮埃尔（Abbé Pierre）的号召席卷了整个法国。虽然1965年至1979年间发表的绝大多数科学论文都预言，地球会随着CO2含量的增加而变暖——事实也是如此——《时代周刊》多次以“大冰冻”为标题（1973年12月，1977年1月，1979年12月）登上头条。1974年6月，法国的《科学与生活》（Science et Vie）提到了新的冰河时代的可能性，这本法国杂志甚至提议通过融化北极来对抗这一演化。《新闻周刊》在1975年一篇题为“冷却的世界”的文章中也不甘示弱：“在经历了四分之三世纪的极端温暖环境之后，地球的气候似乎正在降温”[21]。
3.2 从政府间气候变化专门委员会到第21届联合国气候变化大会
然而，与此同时，另一场争论开始在科学界显现。研究人员开始警告CO2排放的潜在危险：例如德国的赫曼·弗洛恩（Hermann Flohn）[22]或瑞典的伯特波林（Bert Bolin）。其他人的态度则更加微妙。1973年，法国极地冰的先驱克劳德·洛里乌斯（Claude Lorius）在电视节目屏幕文件夹（Les dossiers de l’ écran）中赞同“CO2导致地球温度发生2℃到3℃变化的可能性”的讨论。许多人认为高估了气温升高的程度。但当谈到200亿吨的CO2被排放到大气中时，他的对手库斯托（Cousteau）指挥官回应道：“哦，这是在胡说八道……人们开始不断讨论CO2事件。还有更危险的灾害值得关注，比如泥石流”[23]。
直到20世纪80年代初，特别是1983年非常炎热的夏天之后，这个问题才引起公众关注。1979年，吉米·卡特（Jimmy Carter）总统收到了美国科学院（American Academy of Sciences）的一份报告，该报告是1979年委托麻省理工学院气象服务主任朱尔·查尼（Jule Charney）指导编写的。报告的结论是，人类活动导致气候变化和CO2浓度不断上升：“如果CO2继续在大气中积累，这将导致气候变化，专家组没有理由质疑，也没有理由忽略不计这些变化……三思而后行意味着结果发生时一切都为时已晚”[24]。尽管罗纳德·里根（Ronald Reagan）的新一届美国政府没有继续采用这份报告，但在皮埃尔·拉菲特(Pierre Lafitte)的倡议下，法国于1984年在国立巴黎高等矿业学院（École des Mines）举行了首届全球气候变化为主题的国际会议。1988年，查尼报告的作者之一伯特·鲍林（Bert Bolin ）主持成立政府间气候变化专门委员会，政治雄心可谓形成，并于1990年发表了第一份报告。1992年的里约热内卢会议上，第二份报告促进了《21世纪议程》的制定（将于21世纪执行2500条建议和两个气候和生物多样性框架公约）。
渐渐地，媒体开始关注这一问题。在法国，《地理》（Géo）杂志于1984年10月发表了《地球变暖》（La Terre se réchauffe）一文，但正文中仍存在疑问：“人类居住的地球正在发热吗？”文章的作者总结道：“最终，没有证据表明如今的地球气候由这些自然波动造成，而这些自然波动可能只是上次冰川消退的遥远余波，正围绕着新的平衡点震荡。如果我们很难理解这种方式，那仅仅是因为从地质时间来看，人类的生命显然太过短暂”。1988年，《新闻周刊》的观点更为乐观：“温室效应。危险。再也看不到炎热的夏天了”。2004年四月，《时代》杂志则以“全球变暖生存指南： 51件力所能及之事” 作为封面标题。
[1] FIERRO A. (1991), Histoire de la météorologie, Paris, Denoël, p. 31-55.
[2] FAVIER R. (2006), « Les hommes et la catastrophe dans la France du XVIIe siècle », in MONTEMAYOR J. (dir.), Les sociétés anglaises, espagnoles et françaises au XVIIe siècle, Paris, Ellipses, p. 263-274 ; « Sociétés urbaines et culture du risque. Les inondations dans la France d’Ancien Régime », in WALTER F, FANTINI B. et DELVAUX P. (dir.), Les cultures du risque (XVIe-XXIe siècle), Presse d’histoire suisse, Genève, 2006, p. 49-86.
[3] LACHIVER M. (1991), Les années de misère. La famine au temps du Grand Roi, Paris, Fayard, p. 516 et 510.
[4] FAVIER R. (2008), « Penser le changement climatique au siècle des Lumières », in LAMARRE D., Climat et risques. Changement d’approches, Paris, Lavoisier, p. 9-23.
[5] To relate these ancient notions to contemporary discourse, see KRINNER Gerhard (2019), The Climate Machine, Encyclopedia of the Environment, [online ISSN 2555-0950] url : https://www.encyclopedie-environnement.org/en/climate/the-climate-machine/
[6]Encyclopédie méthodique, médecine, par une société de médecins, Paris, Panckoucke, 1792, p. 878.
[8] MONTESQUIEU (1719), Projet d’une histoire de la Terre ancienne et moderne, texte établi, présenté et annoté par Lorenzo Bianchi, in œuvres complètes de Montesquieu, volume 8, œuvres et écrits divers, tome I, Voltaire Foundation, 2003.
[10] BUFFON G.-L. (1778), Époques de la nature, dans : Supplément à l’Histoire naturelle, vol. V, p. 243-244.
[11] GROVE R. H. (1997), Ecology, climate and Empire : colonialism and global environmental history, 1400-1940, Cambridge, White Horse Press ; FRESSOZ J.-B. et LOCHER F. (2015), L’agir humain sur le climat et la naissance de la climatologie historique, XVe-XVIIIe siècles, Revue d’histoire moderne et contemporaine, n° 62, p. 48-78.
[13] FRESSOZ J.-B. et LOCHER F. (2015), L’agir humain sur le climat et la naissance de la climatologie historique, XVe-XVIIIe siècles, op. cit.
[14] RAMOND de CARBONNIERES L. (1781), Lettres de M. William Coxe à M. W. Melmoth sur l’état politique, civil et naturel de la Suisse, traduit de l’Anglois, à Paris, chez Belin.
[15] FRESSOZ J.-B. et LOCHER F. (2015), L’agir humain sur le climat et la naissance de la climatologie historique, XVe-XVIIIe siècles, op. cit.
[16] BOURGUET N.-M. (1993), « L’image des terres incultes : la lande, la friche, le marais », in CORVOL A., La nature en Révolution, 1750-1800, Paris, L’Harmattan ; GRANET-ABISSET A.-M. (2005), « La bataille des bois. Enjeux sociaux et politiques de la forêt pour les sociétés rurales en France au XIXe siècle », in TANGUY J.-F. (dir.), Les campagnes dans les évolutions sociales et politiques en Europe des années 1830 à la fin des années 20, Paris, Ellipses.
[17] RAUCH F.-M. (1802), Harmonie hydrovégétale et météorologique, Paris, Levrault, 2 vol., 375 et 299 p. ; LARRERE R. (1985), L’utopie forestière de François-Antoine Rauch, Paris, INRA.
[18] Dr FUSTER (1845), Des changements dans le climat de la France. Histoire de ses révolutions météorologiques, Paris, Capelle, Libraire – Éditeur, 503 p.
[19] ARRHENIUS S. (1910), L’évolution des mondes, Paris, C. Béranger, V-246 p.
[20] See the cartoon SOS Météores by Edgard P. Jacobs, published in 1958-1959, Editions du Lombard, Belgium
Thinking about climate change (16th-21st centuries)
The issue of climate change is now feeding into public debate. Every week, there is not an event that is not, rightly or wrongly, brought back to this question. However, this has not always been the case. For a long time, people did not “think” about climate change. This was postulated to be stable, only disturbed by “bad weather” to which men gave anthropocentric interpretations of a religious nature. It was not until the 18th century that the idea that human action could have an impact on the climate emerged. During the 19th century, the idea emerged that the increase in CO2 resulting from the combustion of fossil fuels favoured global warming. But the phenomenon was not perceived as a real threat until the 1970s. Since then, particularly after the creation of the IPCC in 1988, the issue of global warming has continued to gain prominence in national and international public debates.
1. The birth of modern science and the search for climate rules (17th-18th centuries)
1.1. People and climate
People have always been concerned about the climate. In societies where most of the resources and wealth come from the land, such attention should not be surprising. This statement applies to all civilizations, from ancient China to the Inca world. Questions everywhere give rise to scholarly astronomical observations or the development of empirical knowledge. In Transoxiana*, Ulugh Beg built the world’s largest observatory at the beginning of the 15th century. In the Inca world, the solar and lunar calendar is used to manage agricultural cycles. In the West, countless observations provide an empirical knowledge of atmospheric phenomena, often concentrated in the form of sayings, sentences and proverbs, in an attempt to predict the weather and organize ploughing, sowing and harvesting in the most effective way possible [1].
This cycle of nature, whose rhythms popular knowledge intends to understand, is however periodically disrupted by accidents whose exceptional character, unknown “in human memory”, is affirmed by witnesses. But these accidents upset the ordinary balance and constitute “bad weather“, in the sense given by the Dictionnaire de Trévoux in the 18th century: “Disruption, bad constitution, lack of a fair temperament, qualities required in certain things. We say it first of all about the air. The bad weather of the air, of this climate, makes it deserted… The bad weather of the seasons had left a malignant impression in the air.
Popular knowledge struggles to explain these “bad weather” – disturbances, torrential rains, extreme cold, droughts, storms – which are often interpreted in anthropocentric perspectives. God intervenes in the course of things to punish or warn people. Heaven “has sent against us, to punish our ingratitude, disease, mortality, extreme famine, an astonishing bad weather…. “says Bossuet [2]. In the second half of the 17th century, preachers placed less emphasis on the negative significance of the plagues, and more on their saving value. If God remains at their origin, his mercy prevails over his vengeance. In the winter of 1709, it was mainly the miraculous spring barley harvest that was greeted by contemporaries: “God granted it to us [his Mercy] by giving us a favourable time for the barley and oats that were collected in abundance,” notes the priest of Asquins. “This abundance is a blessing visible from heaven and a prodigious multiplication of divine Providence” adds Velaines’ [3].
However, in addition to these miraculous interpretations, scientists began, as early as the 17th century, to give more rational explanations to climatic events.
1.2. The birth of modern science
The history of meteorology is inseparable from the birth of the modern scientific movement. However, since Descartes, scientists began in the 17th century to seek purely scientific explanations for meteorological phenomena [4] (see Meteorological observations over the past centuries). But if the bad weather does not fail to challenge them, it is first of all to understand the rules of the climate that they are working on. At the Academia del Cimento in Florence, the Royal Society in London, the Académie des Sciences in Paris, they multiplied their observations and developed the first physical laws on air compression and solar radiation. With regard to climate in particular, this research aims first and foremost to shed light on regulatory mechanisms. They participate in the work carried out by the physics of the Enlightenment to understand the rules of nature, as God had created it. The search for these rules requires the use of increasingly precise instrumentation that we are trying to standardize (thermometer, barometer, hygrometer, rain gauge, anemometer), and a multitude of readings whose character is as necessary as it is tedious.
Figure 1. Miller’s Nautical Atlas of the World, work by Lopo Homen, Portuguese cartographer (1519), Manuscript on Velin. [Source: gallica.bnf.fr, Bibliothèque nationale de France].But if these scientists are wondering about climate variations, we would be seriously mistaken if we thought they gave this expression a contemporary meaning. For 17th and 18th century men, “climate” refers first and foremost to a geographical area [5]. For the Dictionary of the Académie française of 1694, as for Richelet, the word “climate” is first of all “an estenduë of the globe of the Earth between two parallels”. It was only belatedly, in its 1762 edition, that the Dictionary of the Academy, which is associated with this meaning, that of “atmospheric conditions”, before taking, under the growing influence of medical circles, the meaning of “temperature”: “Doctors consider climates particularly by their own temperature or degree of heat” [6]. It is not so much the rules of climate as “climates” that observers are concerned with. Studying a climate means examining meteorological phenomena and specifying their rules in a perfectly spatially delimited geographical space. The establishment of observer networks thus responds to the desire to observe the variations of “climates”, i.e. the regimes specific to different regions and countries, and to try to find scientific explanations for them. Comparing his observations with those of the Zurich native Scheutzer, La Hire noted in 1710: “By comparing these observations, we know that it rains much more in Switzerland than in Paris. I had already noticed by the observations of the rain made in Lyon that it rains much more than in Paris, and I attributed the cause to the mountains of Switzerland, which are not very far from it; and this is what is confirmed by these last observations.
To ensure that comparisons are solid, both are working on increasing the number of annual observations to better specify the rules of each climate. “Everything is movement and everything changes in Nature, but everything also tends to balance and the very inconsistency of its laws,” said Duhamel du Monceau in 1743, “If we had weather observations of several centuries in the same country, there is every reason to believe that the total sum of rains that have fallen in this country for a century is not significantly different from that of another century, or that if there are marked differences, an even greater number of centuries will reveal their progress and compensation. Because finally, the parts of the machine of our globe and its atmosphere are not infinite, their revolutions must give us back about the same effects, or indicate to us the cause of the variation and decline that disturbs the returns. “It is clear,” he added, “that the greater the number of years, the closer the adopted average will be to the true one [7]. In fact, the rainfall averages recorded at Paris Observatory were modified several times in the first third of the 18th century. In this context, the exceptional years were not interpreted as a sign of a disruption or an announcement of a possible change, but only as a sign of insufficient knowledge of the laws being sought to define.
2. From anthropogenic origins to climate change?
If for scientists, climate is thus a regulated physics whose mechanisms should be decoded, if for mountain observers, the advance of glaciers does not in any way testify to major changes, it cannot be said that 18th century men, despite their postulate of climate stationarity, completely ignore the very idea of change, and in particular the possibility of anthropic action.
2.1. Observation of past changes
The debate on the origins of the Earth, which from Woodward to Buffon gives rise to heated clashes, hardly affects climate issues. In 1765, Duhamel du Monceau pointed out that the Earth had “suffered considerable changes, floods, fires and terrible upheavals; that entire continents had been swallowed up and replaced by new seas, while elsewhere and from the bottom of the sea, mountains and new continents had risen, where marine productions were still visible. “But the observation of these old changes does not change the prospects: “The parts of the earth machine are not infinite, and their revolutions must sooner or later give us about the same effects”.
Figure 2. Le Mercure de France, January 1719.
It is undoubtedly at Montesquieu that we find the first questions on this subject. We know the role that philosopher attributed to the climate as a producer of differences that were transposed into morals. But it also implicitly questions the role of human action in climate change. As early as 1719, the idea appeared in a Project of an ancient and modern history of the Earth, which was first announced in Le Nouveau Mercure in January (under the heading “Book”), then in a slightly different version in Le Journal des sçavans on March 6 under the title “Avis aux savans” [8]. The objective was to investigate the physical causes of Earth’s change, i.e. a natural, geographical, geological and climatic history, to study, in addition to changes at the Earth’s surface, the variations and alterations in the natural balance produced by human activity. Emphasizing the effect of the changes made “by man’s hand that have given a new face to the Earth”, means for him to emphasize the problems of the relationship between “physical” and “moral” (between nature and history).
In the 18th century, several philosophers or scientists began to question whether human action could have consequences on the climate. In his memoirs to the Académie des Sciences, Duhamel states: “There is every reason to believe that there is little climate that does not change significantly from one century to the next, either by the landings that accumulate there, or by the floods that remove part of the land; and if it is cultivated, by the drying up of ponds and marshes, by the cutting or planting of wood, and by a hundred other causes of this species” [9].
Taking up the old hypothesis of the Greek philosopher Theophrastus that forest degradation could favour the multiplication of bad weather, John Woodward concludes that there is a possibility of local impacts on the climate. But it was undoubtedly Buffon who first formulated the most precise answers to Montesquieu’s questions in Les Époques de la Nature. For him, the development of human settlements, the drying up of marshes and the clearing of forests were the conditions for global warming. “A single more or less forest in a country is enough to change its temperature” [10]. This would explain the warming of the climate in Western Europe since Roman times.
2.2. The colonial world and climate change
The installation of Europeans in the colonies would provide observable evidence of this. The idea that economic development would promote climate change began to emerge as early as the mid-17th century in English Virginia or French Canada [11]. At the Royal Society, Robert Boyle raised the issue as early as 1671. Taking the same ideas, Buffon argues at the beginning of the 18th century that the clearing of Guyana would result in a warming of the temperature, “while in all other wood-covered lands it is cold enough at night to be forced to light the fire”. In 1745, the observations of Dr. Gautier, the Academy’s correspondent in Quebec, were in the same vein: “We said that in Canada we notice that spring begins earlier, and winter later than before, and that this change in air temperature is attributed to the amount of wood that has been cut down and the amount of land that is now being cultivated. The elders of the country also assure us that in the past the harvest of the bleds only began on the 15th or 16th of September, and that they rarely reach perfect maturity” [12]. In the 1760s, the idea tended to become more widespread. The conclusion of the “climate” article in the Encyclopedia of Medicine in 1792 goes in the same direction: “However, we can calculate a change that is due to cultivation, clearing, forest abbots, and the drying up of ponds and marshes. Do we want demonstrative proof of this truth? Let us look at America, wherever culture has not won, thick forests that light never penetrates, swamps that the heat of the sun cannot dry up, cover the whole Earth and cool the atmosphere so much that when you have to spend the night there, you have to light a fire.
2.3. The birth of historical climatology
In the last third of the 18th century, attempts to reconstruct the climate for distant periods emerged, not on the basis of old measurements, but on indicators revealing the historicity of the climate: the state of rivers, vegetation, glaciers, extreme meteorological events, the “climate proxies”, which today have become “the pillars of historical climatology” [13].
Figure 3. “View of the glacier and the Argentière needle in the Chamounis valley”, Colourful engraving by Samuel Grundmann from the early 19th century [Source: Paul Payot Conservatory of Art and History Collection, Annecy].A privileged field of observation, the considerable advance of glaciers during the Little Ice Age does not encourage observers to consider any climate change either. A particularly attentive observer of the upheavals that occurred in the Pyrenees and then in the Alps, Ramond de Carbonnières concludes that there is a physical cause (the accumulation of ice in high altitude areas and a gravitational phenomenon) to explain the advance of glaciers in the lower valleys: “I will not say that their increase is due to the cooling of the globe,” he emphasizes, adding pessimistically:”It must be admitted, however sad this truth may be, that ice tends to cover the entire surface of the high Alps, and to isolate the more temperate valleys they contain [14]. “For contemporaries of the “Little Ice Age”, the advance of glaciers bears no evidence of climatic cooling, but only confirms the hypothesis of a constant accumulation of ice in the coldest parts of the mountains since the beginning of the Earth’s formation (see Mountain glaciers, sentinels of climate change). The idea is widely shared. For César Bordier, they slide “like softened beeswax”. Saussure doesn’t really say anything else.
However, in response to the competition launched by the Berne Economic Society, the son of a pastor from the Grindelwald Valley, Bernhard Kuhn is becoming more observant. Based on the examination of the moraines, he shows that the glaciers would have reached their maximum size by the end of the 16th century, and after a decline in the early 18th century, would have resumed their advance, thus contradicting the thesis of a gradual cooling [15].
Figure 4. Changes in the climate of France, Paris, 1845.
More than any other, however, it is the forest that tends, at the end of the 18th century, to become the main marker of climate change. However, the conclusions that observers draw from them are not all the same. In contrast to those who see in the clearing of colonial forests the assurance of a favourable transformation of the climate, and the guarantees of a much more profitable exploitation, the engineers of the Water and Forests for their part express the fear that deforestation, especially in mountainous countries, will negatively affect the climate, with changes in wind direction and rainfall patterns, and will constitute an aggravating, if not triggering, factor in the flooding that could occur in the forelands. It is undoubtedly the agronomist Rougier-Labergerie, prefect of Yonne, who in the year IX (1801) best expresses this new concern: “We already believe we are observing transformations in wind direction, temperatures and precipitation. The felled forests… have changed the climate, opened a passage to the winds that destroy the flowers of trees and vines, turned rains into floods, mountains into rocks, plains into burning fields” [16]. At the same time, the prophetic engineer François-Antoine Rauch sounded the alarm: “As soon as man carried his sacrilegious axe, or war torch in the forests, he began by altering the heat and fecundity of the Earth, by reducing the domain of animals… by destroying plants, in which the fire of life was constantly flowing [17].”Hurricanes and storms, the growing threat of glaciers are the result of the devastation of forests.
Overall, however, there were still many questions at the beginning of the 19th century, and the idea of a global change was discussed. In 1845, after a first highly contested brief addressed to the Academy of Sciences, Dr Fuster in turn intended to establish the proof of man’s action on climate [18]. “I’m not writing a meteorology book,” he wrote in the preface. “My only goal is to shed light on an obscure strong point in the history of our climate. Has the climate in France changed and is it changing? A question so many times agitated and never resolved was well worth being captivated. “For him, the history of climate is the combined result of meteorological phenomena and human action on nature, in particular “forest clearing, crop development, land extension and water reduction”, usually linked to government quality: “Weather phenomena and industrial efforts conspire in various ways to change our climate. Weather phenomena apply directly and by themselves; industrial work contributes only indirectly and through these phenomena. Moreover, the two actions unite, mix and complicate each other. Their irresistible power gradually wears out, deteriorates and destroys the old climatological elements; in the long run, it must even completely rebuild the climate. »
3. From empirical observation to scientific discourse
However, alongside empirical observations and prophetic discourses, the work of physicists gradually began to confirm the reality of climate change, and the hypothesis that it could be the consequence of human action, at the beginning of the 19th century. It is the physicist Joseph Fourier, former Prefect of Isère, who, in his General Remarks on Earth and Space Temperatures published in 1824, first placed the problem of Earth’s temperatures in a cosmological context, and developed the idea that all the earth’s effects of the sun’s heat were modified by the interposition of the atmosphere and the presence of the ocean.
3.1. From climate history to global warming
Although Fourier’s data did not allow him to quantify this “greenhouse effect”, the work of geologists and physicists gradually confirmed the reality of the historicity of the climate in the 19th century. In the early 1830s, Charles Lyell’s work on geological layers confirmed the hypotheses about the Earth’s very long history. In the 1850s, Lord Kelvin developed his research on cooling based on the work of Joseph Fourier. However, he concludes that the Earth’s history is 10 to 20 million years old, incompatible with the geological data developed by Lyell. It was not until the 20th century that nuclear physics made it possible to report geological observations and establish its age in billions of years. On another level, in 1873, the Irish John Tyndall made a decisive contribution to the issue of glacier flow.
Figure 5. Portrait of Svante Arrhenius. (Public domain, via Wikimedia Commons)
After having been the first to situate the greenhouse effect in the carbon cycle, it was Svante Arrhenius who in 1903 was responsible for linking the issue of global warming to that of the use of fossil fuels. But for him, as for Quebec doctor Gautier a century and a half earlier, the warming generated by this combustion becomes the guarantee of future safety. It gave the Earth the assurance of repelling a hypothetical new ice age and its inhabitants the promise of a bright future:
“As a result of the increase in carbonic acid in the air, we can expect periods that will provide more equal temperatures and milder climatic conditions for mankind. This will probably happen in the coldest regions of our Earth. These periods will allow the soil to produce significantly higher harvests than today, for the benefit of a population that appears to be growing faster than ever [19]. »
At the beginning of the 20th century, Arrhenius’ ideas were widely shared in the scientific sphere. In the 1930s, George Stewart Callendar of the Royal Metorological Society of England estimated that the 10% increase in CO2 observed in the atmosphere from 1890 to 1938 (in 52 years of the industrial revolution based on coal combustion) was one of the causes of the warming trend observed during the same period. In the second half of the 20th century, “the progress of digital systems and the increasingly numerous and varied observations of the state of the atmosphere and related environments…, the development of supercomputers” allowed considerable advances in the knowledge of climate and its variations, defined statistically “in terms of means and variability” over periods usually 30 years (see The climate machine & Introduction to weather forecasting).
However, the issue of climate change is hardly entering the media sphere. And never unambiguously. If the French science magazine Science et Vie mentions in May 1959 the hypothesis of global warming in an article (“The Earth is getting warmer”), it is only anecdotally in comparison with the many others on the atomic threat, or water skiing. From the 1950s to the end of the 1970s, it was more the fear of a return of the great cold that the American or European media echoed. The concern is partly based on the mathematical theories of climate developed by the Croatian geophysicist Mitulin Milankovic, who predicts the cyclical return of major glaciation periods as a function of (known) variations in the orbit and Earth’s rotation (variable eccentricity of the orbit, variable obliquity of the ecliptic, and precession of the Earth’s axis) (see The Astronomical Theory of Climates).But it mainly reflects cyclical phenomena: a buoyant international context (the “Cold War”, fear of the nuclear winter [20]), a drop in temperatures (between 1940 and the end of the 1970s or the energy crisis in the 1970s. During the great winter of 1954, Abbé Pierre’s call moved all of France. While the vast majority of scientific articles published between 1965 and 1979 predicted that the Earth would warm up as carbon dioxide levels increased – as it did – Time made several headlines (December 1973, January 1977, December 1979) on “The Big Freeze”. In June 1974, the same magazine, as in France Science et Vie, mentioned the possibility of a new Ice Age, the French magazine even proposing to fight against this evolution… by melting the Arctic! Newsweek is not to be outdone in a 1975 article entitled “The cooling world”: “After three quarters of a century of extremely mild conditions, the Earth’s climate seems to be cooling down” [21].
3.2. From the IPCC to COP 21
At the same time, however, another debate was beginning to take shape in the scientific world. Researchers are beginning to warn of the potential dangers of CO2 emissions: for example, Germany’s Hermann Flohn [22] or Sweden’s Bert Bolin. Others remain even more nuanced. In 1973, in the television program Les dossiers de l’écran, Claude Lorius, a French pioneer in polar ice, agreed to discuss the “possibility of a change of 2 to 3° centigrade due to CO2. There are many people who think it is overrated. But when he talks about the 20 billion tonnes of CO2 released into the atmosphere, his opponent, Commander Cousteau, reacts: “Oh, this is bullshit… People are starting to break my ears with this CO2 thing. There are much more serious risks that are slag rains” [23].
Figure 6. Cover of the “Time” of April 9, 2007, “The Global Warming survival guide”.
However, the concerns of scientists were reflected in the 1972 Meadows Report, commissioned by the Club of Rome two years earlier, in particular the depletion of non-renewable natural resources and environmental degradation, in relation to the acceleration of industrialization and the strong growth of the world population. But in 1979, the first World Climate Conference, held in Geneva, received little attention in the political or media sphere.
It was not until the early 1980s, particularly after the very hot summer of 1983, that the issue emerged in the public arena. In 1979, President Jimmy Carter received a report commissioned in 1979 from the American Academy of Sciences and produced under the direction of Jule Charney, Director of the Meteorological Service of MIT. The report concludes that there is a reality of human-induced climate change and rising CO2: “If carbon dioxide continues to accumulate in the atmosphere, the expert group sees no reason to doubt that climate changes will result, nor any reason to believe that they will be negligible… Waiting to see before acting means waiting until it is too late” [24]. Although Ronald Reagan’s new American administration did not follow up on this report, in France a first international meeting on global climate change was held in 1984 at the École des Mines, at the initiative of Pierre Lafitte. Political ambitions took shape in 1988 with the creation of the IPCC (Intergovernmental Panel on Climate Change), chaired by Bert Bolin, one of the authors of the Charney report, who issued his first report in 1990. At the 1992 Rio Conference, its second report led to the elaboration of Agenda 21 (2500 recommendations to be implemented in the 21st century, and two framework conventions on climate and biological diversity).
Gradually, the media took over the issue. In France, the magazine Géo published in October 1984 “La Terre se réchauffe”, but the main article still has a question mark: “Does the planet of men burn? “Ultimately,” concludes the author of the article,”there is no evidence that the planet’s climate today is due to these natural fluctuations, which may only be the distant aftermath of the last deglaciation, oscillations around a new equilibrium point. If we have any difficulty in perceiving it in this way, it is simply because, in view of geological time, human life is decidedly too short. In 1988, Newsweek was more positive: “Greenhouse effect. Danger. No more hot summers in sight. “The Global Warming. Survival Guide: 51 Things you can do make a Difference” title for its part Time in April 2009.
Figure 7. Laurent Fabius, President of COP 21, 7 December 2015.[ Source Photo COP PARIS, via Flickr, public domain].From then on, the climate became a political issue. In 1997, the Kyoto Protocol committed states to reduce the production of greenhouse gases. While many States, including some important ones, refuse to sign the protocol, twenty years later, COP 21 in December 2015 is the occasion for a first universal agreement, unanimously approved by 196 delegations, which reflects a growing consensus in the scientific world on the anthropogenic origins of current global warming.
In 2007, the IPCC’s 4th report states that the probability that global warming is due to human activities is more than 90%. In its 5th report, it insists, alongside CO2, on the role of methane (produced by ruminants, rice paddies, natural gas leaks and thawing permafrost). For the same amount, methane produces a more powerful warming than CO2, but methane emissions are much lower, and therefore CO2 emissions induced by human activities have a much greater influence on global warming.
The political success of the COP 21 agreement, however, does not mean unanimous support for the objectives. While China has deliberately engaged in the implementation of the agreement, US President Donald Trump, elected at the end of 2016, ignores ecological and economic arguments. In June 2017, he announced his intention to withdraw from the Paris Agreement. In addition to strategic and political issues, these oppositions are driven by the development of so-called “climatosceptic”discourses, and cover two realities. The first is the very questioning of global warming by certain commercial interests (“Climate change is a Chinese invention to harm the American economy”), certain churches (American Evangelists) or certain scientists, particularly in France, with Claude Allègre [25] and Vincent Courtillot. It is a global cooling that awaits us, and not a warming, also continues to say some Russian scientists [26]. But this discourse is having less and less resonance among the world’s citizens. The second reality is the ability of societies to accept the role of man in this evolution and, against the selfish defence of economic interests or individual comforts, the changes in behaviour essential to face the climate challenge.
As a result, collective action remains very uneven across countries. While China seems to be persevering with the commitment made in Paris in December 2015, US President Donald Trump has chosen to withdraw from the climate agreement. The new Brazilian President Jair Bolsonaro announced in the fall of 2018 that he wanted to do the same. Even in countries where people are most sensitive to the climate threat, governments often struggle to get the necessary measures and the efforts they impose accepted. “The house is burning and we are looking elsewhere,” President Jacques Chirac told the Earth Summit in Johannesburg on 2 September 2002. His call is still relevant.
4. Messages to remember
Until the 18th century, the idea that climate could change permanently over time remained outside the representation of individuals. Only the “bad weather”, violent disturbances, challenged men who gave them anthropocentric interpretations of a religious nature
With the birth of meteorology, scientists sought to understand the “rules” of climate, just as Newton had found those of attraction
From the mid-18th century onwards, observations suggested that human action could influence the climate. For some, particularly in the colonial world, deforestation favoured global warming and was favourable to agricultural development; others, on the contrary, denounced the destructive nature of this human intervention from the beginning of the 19th century onwards.
In the 19th century, physicists began to link climate change to human action in more certain ways, particularly the increase in CO2 resulting from fossil fuel combustion and industrial development. Nobel Prize winner in 1902, Svante Arrhenius sees this warming as the promise of a bright future.
While in the first two thirds of the 20th century, the development of scientific observations led to considerable advances in knowledge of the climate and its statistically defined variations, the fear of a return of extreme cold remains largely present in the collective imagination
From the 1970s, researchers (including Bert Bollin) began to warn of the potential dangers of CO2 emissions. The creation of the IPCC in 1988, of which Bert Bollin became the first president, embodies the international recognition of this threat. In 2015, at COP 21, a first universal agreement was unanimously approved by 196 delegations, reflecting a growing consensus on the anthropogenic origins of current warming.
However, this awareness has come up against economic, religious or political interests, as evidenced by the difficulties faced by States in implementing the COP 21 mechanisms and, even more so, the election of President Donald Trump in the USA.
Notes and references
Cover image. Colbert presents to Louis XIV the members of the Royal Academy of Sciences created in 1667, oil on canvas by Henri Testelin (1616 – 1695), Château de Versailles (Public domain).
[1] FIERRO A. (1991), Histoire de la météorologie, Paris, Denoël, p. 31-55.
[2] FAVIER R. (2006), « Les hommes et la catastrophe dans la France du XVIIe siècle », in MONTEMAYOR J. (dir.), Les sociétés anglaises, espagnoles et françaises au XVIIe siècle, Paris, Ellipses, p. 263-274 ; « Sociétés urbaines et culture du risque. Les inondations dans la France d’Ancien Régime », in WALTER F, FANTINI B. et DELVAUX P. (dir.), Les cultures du risque (XVIe-XXIe siècle), Presse d’histoire suisse, Genève, 2006, p. 49-86.
[3] LACHIVER M. (1991), Les années de misère. La famine au temps du Grand Roi, Paris, Fayard, p. 516 et 510.
[4] FAVIER R. (2008), « Penser le changement climatique au siècle des Lumières », in LAMARRE D., Climat et risques. Changement d’approches, Paris, Lavoisier, p. 9-23.
[5] To relate these ancient notions to contemporary discourse, see KRINNER Gerhard (2019), The Climate Machine, Encyclopedia of the Environment, [online ISSN 2555-0950] url : https://www.encyclopedie-environnement.org/en/climate/the-climate-machine/
[6]Encyclopédie méthodique, médecine, par une société de médecins, Paris, Panckoucke, 1792, p. 878.
[8] MONTESQUIEU (1719), Projet d’une histoire de la Terre ancienne et moderne, texte établi, présenté et annoté par Lorenzo Bianchi, in œuvres complètes de Montesquieu, volume 8, œuvres et écrits divers, tome I, Voltaire Foundation, 2003.
[10] BUFFON G.-L. (1778), Époques de la nature, dans : Supplément à l’Histoire naturelle, vol. V, p. 243-244.
[11] GROVE R. H. (1997), Ecology, climate and Empire : colonialism and global environmental history, 1400-1940, Cambridge, White Horse Press ; FRESSOZ J.-B. et LOCHER F. (2015), L’agir humain sur le climat et la naissance de la climatologie historique, XVe-XVIIIe siècles, Revue d’histoire moderne et contemporaine, n° 62, p. 48-78.
[13] FRESSOZ J.-B. et LOCHER F. (2015), L’agir humain sur le climat et la naissance de la climatologie historique, XVe-XVIIIe siècles, op. cit.
[14] RAMOND de CARBONNIERES L. (1781), Lettres de M. William Coxe à M. W. Melmoth sur l’état politique, civil et naturel de la Suisse, traduit de l’Anglois, à Paris, chez Belin.
[15] FRESSOZ J.-B. et LOCHER F. (2015), L’agir humain sur le climat et la naissance de la climatologie historique, XVe-XVIIIe siècles, op. cit.
[16] BOURGUET N.-M. (1993), « L’image des terres incultes : la lande, la friche, le marais », in CORVOL A., La nature en Révolution, 1750-1800, Paris, L’Harmattan ; GRANET-ABISSET A.-M. (2005), « La bataille des bois. Enjeux sociaux et politiques de la forêt pour les sociétés rurales en France au XIXe siècle », in TANGUY J.-F. (dir.), Les campagnes dans les évolutions sociales et politiques en Europe des années 1830 à la fin des années 20, Paris, Ellipses.
[17] RAUCH F.-M. (1802), Harmonie hydrovégétale et météorologique, Paris, Levrault, 2 vol., 375 et 299 p. ; LARRERE R. (1985), L’utopie forestière de François-Antoine Rauch, Paris, INRA.
[18] Dr FUSTER (1845), Des changements dans le climat de la France. Histoire de ses révolutions météorologiques, Paris, Capelle, Libraire – Éditeur, 503 p.
[19] ARRHENIUS S. (1910), L’évolution des mondes, Paris, C. Béranger, V-246 p.
[20] See the cartoon SOS Météores by Edgard P. Jacobs, published in 1958-1959, Editions du Lombard, Belgium
