As early as 1912, some warned of the effects of massive CO 2 emissions into the atmosphere by the new industrial era. As early as the late 1970s, internal studies of the fossil
fuel industries made accurate projections linking global warming to CO 2 emissions, predicting “dramatic environmental effects by the year 2050”. Meanwhile, these same companies, especially ExxonMobil, tried to convince the public that a causal link between fossil fuel use and global warming was impossible because the models used to model climate response were too uncertain.

Since the 1970s, advances in climate science have provided an increasingly clear statement of the reality of global warming (see IPCC Group I Report, Chapter 1), while the 2021 IPCC Report states that “it is unequivocal that human influence has warmed the atmosphere, ocean and land”.

As global warming intensifies in every region of the world (2022 being an emblematic year) and its impacts worsen, this is a critical decade to make a determined commitment to reducing greenhouse gas emissions. Despite this, we are witnessing an increase in the activity of online denialist and climate-skeptic groups and an upward revision of the emission targets of most of the oil majors that have just announced record annual profits (e.g. BP).

In France, the intensification of denialist activism has been particularly marked since July 2022 with a triple climate news: a series of extreme events, the holding of the COP27 with a strong weight of fossil industries, and finally the convergence of the stakes of global warming with those of the security of oil and gas supply due to the war in Ukraine.

Other equally worrying trends are observed in countries like the United States, with a strong increase in the proportion of bots in the denialist information space.
This study describes some of the strategies implemented by climate skeptic and denialist activists on Twitter worldwide, quantifies their effects and highlights potential geopolitical motivations alongside the political and economic dimensions already present. It is based on methodologies developed at the CNRS at CAMS and at the Complex Systems Institute of Paris Île-de-France.

Beyond “fact-checking”, this study aims at a better understanding of the circulation of different narratives related to climate change and in particular those related to disinformation.

Here are the main results and conclusions:
At the global level

• The global climate change debate on Twitter is highly bipolarized with about 30% climate denialists among Twitter accounts that address climate issues over the period
  2019-2022,
• The COVID-19 pandemic has distracted public opinion from climate change issues for several months,
• Experts from the IPCC and pro-climate communities focus their messages on their areas of expertise while the denialist community presents inauthentic forms of ex-
  pertise: a core group of accounts speaks on a multitude of topics, concentrate presumed expertise, and fabricate the majority of the denialists narratives in circulation.
  Some of the denialists’ favorite topics reveal an active agenda setting uncorrelated with current events.
• Exchanges on climate change issues are largely organized around human-to-human interactions. However, the proportion of Twitter accounts with inauthentic behaviors in the exchanges has increased significantly since 2019 on a global scale, pointing to possible astroturfing operations.
• The denialist community has an overrepresentation of accounts with inauthentic behaviors of +71% compared to pro-climate communities, with 6% of accounts “probably bot”. This phenomenon is particularly pronounced in the United States where there has been a steady increase since February 2022 in the overrepresentation of denialist accounts with inauthentic behavior (likely bots), which has exceeded 400% in 2023.
• Since spring 2022 Twitter has become an active place of conversion to climate skepticism while losing at the same time its status as a globalized space for the expression of opinions on climate change.
• Pro-climate accounts flee from Elon Musk’s Twitter. After Elon Musk’s takeover of the platform in Oct. 2022, about one third of core pro-climate accounts left the network while the activity of these communities was halves.
• The proportion of climate skeptics has been steadily increasing on Twitter over the past two years. This increase accelerated sharply following Musk’s takeover, with the proportion of climate skeptics reaching 50% by March 2023.

The case of France (extended version only)

• While the French twittersphere had been relatively unaffected by climate skepticism until now, a large French denialist community was structured in the summer
  of 2022 on Twitter.
• A higher proportion of accounts “likely bot”. The proportion of inauthentic accounts in the French denialist community is 2.8 times higher than in the French IPCC community. The proportion of accounts suspended by Twitter is ten times higher.
• The denialist community produces or relays 3.5 times more toxic messages than the IPCC community.
• The main influencer of the French denialist community is a newcomer to the cause after a period spent campaigning against government measures against the COVID-
  19 pandemic. The transition was made at the time of the invasion of Ukraine and he relayed pro-Putin propaganda for a time. The account was dormant since 2012 and
  woke up in 2021.
• Apart from some accounts involved in the informational sphere of Reconquête! (French far-right), the major part of the denialist community is not composed of political activists from traditional parties (LFI, PS, EELV, Renaissance, LR or RN).
• The denialist community on Twitter is mostly composed of accounts that have participated in numerous anti-system protest campaigns during the pandemic. Moreover, out of 10 000 accounts, nearly 6000 have relayed Kremlin propaganda about the war in Ukraine.
• The issue of the fight against global warming and the characteristics of denialist activists make this societal issue a particularly favorable terrain for foreign inter-
  ference operations of the subversion type.
• A causality analysis shows that in the medium term, the publication of IPCC leads the debate on Twitter around climate issues.
• Twitter discourse from the denialist and technosolutionist communities likely hinders the dissemination of scientific knowledge and IPCC findings by negatively affecting the online activity of climate science and climate change scientists.