It’s ironic that as scientific evidence on climate change and vaccines have become more compelling, public opinion on social media appears more divided. Five billion people use social media globally, and millions of posts are shared on Meta (Facebook) every minute. While a virtual life can be fun and informative, it can also be harmful. Misinformation about climate science is rife. So, too are conspiracy theories and disinformation about vaccine science, as we witnessed during the COVID-19 pandemic. This misinformation not only undermines trust in science but actively threatens public health: The World Health Organization has named vaccine hesitancy, along with air pollution and climate health, among the top 10 global health threats of our time. The evidence shows that vaccines save lives, and that climate change is strongly linked to rising water temperatures, sea level rise, shrinking polar ice caps, loss of biodiversity and more extreme weather events. 2023 was the hottest year on record. Greenhouse gas emissions hit record highs. The Earth is sounding its distress call. But ironically, as the scientific evidence has become more compelling, public opinion appears to be more divided. This hesitancy and denial appear to be founded in a misconception of how science works. Vaccines save millions of lives every year, and with improved technology, the accepted view on climate change has changed, with unequivocal data showing increases in CO2 and higher temperatures are linked to the burning of fossil fuels. This is science in action. But opponents on social media, and other outlets, claim the scientific evidence for both is undecided and conflicting. Oppositional viewpoints are often supported by a few vocal scientists in white coats spreading misinformation, uncertainty and doubt. The fossil fuel industry also plays a part in undermining science, by emphasising this so-called “dissent” within the scientific community. This tactic is not new: for decades, the industry has created shell organisations and companies to fund climate science-denial and muddy public understanding of climate science. More recently, the fossil fuel industry and other major polluters have used social media to gain new audiences. One analysis found that 16 of the world’s biggest polluters were responsible for placing more than 1700 false and misleading ads on Facebook in 2021. There will always be a few scientists who challenge the accepted view. However, more than 97 percent of professional medical and climate scientists, having reviewed the existing evidence, agree that vaccines are safe, and that human activity is increasing CO2 and warming the Earth’s surface. The key message the public needs to hear is: What matters is the preponderance of evidence, not one person’s opinion. Facts are considered true because they are based on the preponderance of evidence, whereas opinions may be true or not. It is easy to see how social media — which platforms opinions and untruths, and does away with traditional gatekeepers of knowledge such as news editors — can facilitate an impression that the science around climate change and vaccines is unsettled or “controversial.” This is especially the case because 80 percent of social media platforms do not have a content moderation policy that includes a comprehensive, universal definition of climate misinformation, according to a September 2023 report by the Climate Action Against Disinformation Coalition. Artificial intelligence (AI) can further support high quality oppositional opinions in new ways to deceive and cast doubt. AI algorithms can mean someone who clicks on one anti-vax post is then fed a steady diet of anti-vax and other anti-science content. Similarly, AI can be used to target misinformation to vulnerable audience sectors. And AI programs trained to write text using vast data sets have automated fake news generation with increased persuasive potential. Bridging the consensus gap between science believers and deniers requires education. Learning about the scientific method is important, but — in an age of conspiracy theories, misinformation and “alternative facts” — so too is critical literacy and philosophical inquiry. Broadening school curricula to help students navigate complex ideas and virtual digital realities, and to make sense of their increasingly complex world, could help. Since children engage with social media from a young age, it makes sense for our education system to help them develop new skills in assessing truths and falsehoods when confronted with new information.