Geoengineering refers to a real set of techniques, studied and sometimes practised, for intervening on the climate: seeding clouds, reflecting back part of solar radiation, or removing CO₂ from the atmosphere. "Chemtrails," by contrast, are a refuted thesis: no evidence of a secret chemical spraying exists, and the white trails behind aircraft are condensation trails, frozen water vapour. The real issue is not a hidden poison, but a question of governance: who has the right to touch the climate of the entire planet, and with what consent?
Geoengineering, or climate engineering, covers deliberate interventions on the climate system. Two broad families are distinguished: solar radiation management (SRM), which reflects solar energy back into space to cool, and carbon dioxide removal (CDR), which removes CO₂ already emitted. It is an established field of research, addressed by the IPCC and framed by international debates, not to be confused with the chemtrails myth.
The best-established ground, which no serious scientist disputes, is cloud seeding. In November 1946 the chemist Vincent Schaefer, in the laboratories of General Electric under the direction of Irving Langmuir (Nobel Prize in Chemistry, 1932), demonstrated that by dispersing dry ice into a supercooled cloud one triggers the formation of ice crystals, then precipitation (Schaefer, Science, 1946). His colleague Bernard Vonnegut established shortly afterward that silver iodide produces the same effect. Cloud seeding was born — not as a conspiracy, but as a published and patented discovery.
This technique is in no way secret: it is practised openly in many countries. China runs the largest known programme, mobilised notably in an attempt to clear the sky before the Beijing Olympic Games in 2008, and which it announced it would expand in 2020. The United States, the United Arab Emirates and ski resorts use it to increase precipitation or reduce hail. These are declared, contracted, sometimes subsidised operations.
That said — and this is crucial to the honesty of the file — the effectiveness of cloud seeding remains scientifically debated. The SNOWIE project (Idaho, measurements published in 2020 in PNAS) provided one of the first direct quantifications of an effect attributable to seeding, but the quantities of water obtained remain modest. The technique is real, but far from the "control of the climate" the popular imagination ascribes to it. It is onto this modest factual base that the myth then grafts itself.
The white trails behind aircraft are condensation trails, or contrails. The mechanism is known and taught: burning kerosene produces hot water vapour; at altitude, where the air is very cold (often below −40 °C) and sometimes saturated with humidity, this vapour condenses and freezes into ice crystals around the exhaust particles (NOAA / National Weather Service). It is the same physical principle as the mist of your breath on a winter morning, at 10,000 metres of altitude.
Why do some trails disappear quickly while others persist and spread out? The chemtrails thesis sees in this the proof of two different substances ("the water evaporates, the poison remains"). Physics gives a simple and verifiable explanation: persistence depends on the humidity of the air at flight altitude. In dry air, the crystals sublimate quickly; in humid, supersaturated air, they persist and can even transform into cirrus-type clouds. A single substance — ice — produces both behaviours according to the local weather. The "double trail" narrative confuses an atmospheric variation with a chemical one.
The chemtrails thesis has been examined scientifically and refuted. A 2016 study (Shearer, West, Caldeira & Davis, Environmental Research Letters) surveyed 77 specialists in atmospheric chemistry and in the geochemistry of deposition: 76 of them (98.7%) reported having encountered no evidence of a secret spraying programme, the observations advanced by proponents of the thesis being explained by the known physics of contrails. As early as 2000, several U.S. federal agencies (EPA, FAA, NASA, NOAA) had published a joint fact sheet on the nature of contrails to address the public's concerns.
There is nonetheless a real climate effect of contrails, but it has nothing of a plot. By spreading out into artificial cirrus, persistent trails trap part of the infrared radiation and contribute to warming: this is today considered a significant part of aviation's climate impact, studied openly by climatologists (Lee et al., Atmospheric Environment, 2021). The irony is complete: the sky of aircraft does have a documented effect on the climate, but it is an unintended side effect, exactly the opposite of a hidden plan.
Solar radiation management (SRM, or solar geoengineering) covers techniques aimed at reflecting back into space a fraction of solar energy to cool the planet, without touching the concentration of greenhouse gases. The most studied avenue is stratospheric aerosol injection (SAI): dispersing reflective particles in the upper atmosphere, for example sulfate compounds (National Research Council, Climate Intervention, 2015).
This idea is not science fiction: it rests on a natural precedent. In 1991, the eruption of the Pinatubo volcano injected about 20 million tonnes of sulfur dioxide into the stratosphere; the resulting aerosol veil cooled the globe's surface by about 0.5 °C for more than a year (Soden et al., Science, 2002). SAI proposes to deliberately imitate this volcanic mechanism.
To date, SRM is very largely a matter of research, modelling and experimentation, not of deployment. In 2021, the U.S. National Academies of Sciences, Engineering, and Medicine recommended a public, transparent and framed research programme, funded at 100 to 200 million dollars over five years, while insisting that research must not amount to a commitment toward deployment (Reflecting Sunlight, 2021). Research therefore exists, and it is in part public.
The risk most cited by researchers has a name: the termination shock. If one were to deploy an aerosol veil to mask the warming without otherwise reducing CO₂ emissions, an abrupt halt of the device (failure, war, political decision) would cause an extremely rapid catch-up warming, far more dangerous than a gradual warming (Robock, Bulletin of the Atomic Scientists, 2008). SAI does not treat the cause; it masks a symptom, creating a potentially irreversible dependence. The real vertigo is not secrecy: it is irreversibility and the absence of consent.
To grasp the governance problem concretely, a precise case is worth more than an abstraction. The SCoPEx project (Stratospheric Controlled Perturbation Experiment), led by researchers at Harvard University, aimed at a modest experiment: raising a stratospheric balloon to release a very small quantity of matter (on the order of a kilogram, for example calcium carbonate) and study its behaviour in real conditions — a research step, not a deployment.
A first preparatory technical flight was envisaged in Sweden, from the Esrange space base near Kiruna, in 2021. It never took place in that form: faced with the opposition of environmental groups and, decisively, of the Saami Council — representing the indigenous Saami people, who had not been consulted and refused solar geoengineering tests on their territory — the project's independent advisory committee recommended cancelling the planned flight (Nature, "Harvard solar geoengineering experiment paused," 2021).
In March 2024, the Harvard team announced the definitive abandonment of the SCoPEx project (MIT Technology Review, March 2024). A real experiment, funded and technically ready, was therefore stopped not by a scientific failure, but by an objection bearing on the consent of the populations concerned. SCoPEx is the exact opposite of the chemtrails fantasy: here, no secrecy, but public protocols — and it is precisely because the process was public that it could be contested and stopped.
Geoengineering is not limited to manipulating light. Carbon dioxide removal (CDR) covers techniques aimed at removing the CO₂ already present in the atmosphere: reforestation, direct air capture, bioenergy with carbon capture and storage (BECCS), enhanced mineral weathering or geological storage. Unlike SRM, CDR tackles the greenhouse-gas concentration itself (National Academies, Negative Emissions Technologies, 2019).
The IPCC explicitly addresses these techniques. In its sixth assessment report and in its 2018 special report on a warming of 1.5 °C, it states that almost all trajectories limiting warming to 1.5 °C rely, to varying degrees, on a recourse to CO₂ removal, while underlining the uncertainties, costs and risks of these technologies at large scale. CDR is not a marginal whim: it is integrated, cautiously, into the official climate scenarios.
The IPCC clearly distinguishes CDR from SRM: it considers CO₂ removal as a possible and complementary component of emissions reduction, while it approaches SRM with markedly greater caution, because of its systemic and governance risks. Neither of the two families could substitute for the reduction of emissions at the source. Lumping CDR and SRM together blurs judgement: removing CO₂ is a slow and costly repair with mostly economic risks; masking the Sun is a rapid, cheap and systemic intervention with planetary and irreversible risks.
The real subject is not chemical; it is political and democratic. As early as 2009, a group of researchers gathered at the University of Oxford formulated the Oxford Principles, the first governance framework proposed for geoengineering (Rayner et al., Climatic Change, 2013). They hold notably that geoengineering should be regulated as a public good, that decisions must involve the public, that research must be transparent and published, and that an independent assessment of impacts is necessary before any deployment. The principle of consent is central there — and it is, to this day, largely unmet.
At the international level, the United Nations Convention on Biological Diversity (CBD) adopted in 2010 a decision (X/33) inviting States to refrain from geoengineering activities likely to affect biodiversity, in the absence of an adequate scientific basis and control mechanisms — a text often described as a de facto "moratorium," although not legally binding. In 2019, an attempt to have the United Nations Environment Assembly (UNEA) adopt a resolution calling for an assessment of geoengineering technologies failed, for lack of consensus among States (Nature, 2019). The governance vacuum is not a hypothesis: it is observed.
The problem of consent arises at several nested scales: consent of indigenous peoples (the Saami case of SCoPEx), consent of the populations of the Global South, the most exposed to the monsoon disruptions that a poorly calibrated SRM could provoke, and intergenerational consent, since a deployment would commit future generations with no say in the matter. Here is the true "without consent": not that one acts in hiding, but that one could act legally, openly, and yet without democratic mandate, because no institution is empowered to gather the consent of those whom the decision would affect.
Understanding this architecture of decision joins a broader thread: that of simplification or the digital panopticon, where the same question recurs — who decides, for whom, and with what democratic control? To follow this thread of consent across the great contemporary systems, the full investigation of the L'Appel de l'Éveil collection extends this panorama.
Belief in chemtrails is measurable and far from marginal. A 2011 survey covering three countries (United States, Canada, United Kingdom) estimated that about 2.6% of the people surveyed "completely" believed in the existence of a secret spraying programme, and nearly 14% believed in it "in part" (Mercer, Keith & Sharp, Environmental Research Letters, 2011). Some researchers actually working on geoengineering even report receiving threats from proponents of the thesis.
The paradox is cruel. By looking for a plot where there is none (the aircraft trails), the myth diverts civic attention from the place where vigilance would be legitimate: the governance of SRM research, the absence of an international framework, the consent deficit. Disinformation is not only false, it is counterproductive: any legitimate questioning of geoengineering risks being reflexively filed under "conspiracy theory" and dismissed. Debunking chemtrails is therefore not a sceptical luxury: it is the condition for the real question — who decides the planetary thermostat? — to be able at last to be posed in a clear voice.
Do chemtrails exist? No. The thesis of a secret chemical spraying by aircraft has been examined scientifically and refuted: 98.7% of the specialists surveyed in 2016 found no evidence of such a programme (Environmental Research Letters). The white trails are contrails, frozen water vapour.
Why do some trails persist for a long time? Because of the humidity of the air at altitude. In dry air, the ice crystals sublimate quickly; in humid, supersaturated air, they persist and can form cirrus. It is a weather variation, not a variation of substance.
Is geoengineering real? Yes, but it is very different from the myth. Cloud seeding has existed since 1946, and research on SRM (reflecting solar radiation) and CDR (removing CO₂) is documented, in part public, and addressed by the IPCC. Large-scale deployment of SRM has not taken place.
What is the SCoPEx project? A research experiment by Harvard University on stratospheric aerosol injection. A test flight planned in Sweden in 2021 was cancelled after the opposition of the Saami Council, and the project was definitively abandoned in March 2024 — a textbook case of governance and consent.
What is the real risk of geoengineering? Not a hidden poison, but a governance deficit. No global institution is today empowered to decide, with the consent of the populations concerned, on techniques (such as SAI) that could affect the climate of the entire planet. The termination shock and moral hazard are the major risks.
This synthesis rests on real and verifiable sources (Science, PNAS, Environmental Research Letters, NOAA, National Academies, IPCC, CBD, Nature). It never validates the chemtrails thesis, because it is false. For the complete investigation into climate science, its real grey areas and the question of democratic consent, the ebook of the L'Appel de l'Éveil collection extends this panorama, distinguishing throughout the myth from the mandate.
No. The thesis of a secret chemical spraying by aircraft has been examined scientifically and refuted: 98.7% of the specialists surveyed in 2016 found no evidence of such a programme (Environmental Research Letters). The white trails are contrails, frozen water vapour.
Because of the humidity of the air at altitude. In dry air, the ice crystals sublimate quickly; in humid, supersaturated air, they persist and can form cirrus. It is a weather variation, not a variation of substance.
Yes, but it is very different from the myth. Cloud seeding has existed since 1946, and research on SRM (reflecting solar radiation) and CDR (removing CO₂) is documented, in part public, and addressed by the IPCC. Large-scale deployment of SRM has not taken place.
A research experiment by Harvard University on stratospheric aerosol injection. A test flight planned in Sweden in 2021 was cancelled after the opposition of the Saami Council, and the project was definitively abandoned in March 2024 — a textbook case of governance and consent.
Not a hidden poison, but a governance deficit. No global institution is today empowered to decide, with the consent of the populations concerned, on techniques (such as SAI) that could affect the climate of the entire planet. The termination shock and moral hazard are the major risks.
No. Patent US 4,686,605 (Eastlund, 1987) describes a theoretical method of heating the ionosphere that has never been built at that scale. Its assignee APTI was indeed HAARP's first contractor — that is the only documented link —, but HAARP is a 3.6-megawatt research facility, operated by the University of Alaska Fairbanks since 2015, which does not apply the patent.
No. HAARP briefly heats small regions of the ionosphere, above 50 km in altitude; weather forms in the troposphere, below 12 km. NOAA judges the facility incapable of influencing surface weather, and the official UAF FAQ puts the energy disproportion in the billions of years.
Dossier : Géo-ingénierie & modification du climat
MINI12: La Géo-Ingénierie Sans Consentement
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