The concept of negation is often associated with unfavorable or restrictive meanings, and the history of science offers numerous examples of this. From the condemnation of Galileo for defending heliocentrism to the harsh criticism received by Darwin for proposing human evolution from common ancestors with primates, many revolutionary ideas were initially rejected before becoming fundamental pillars of modern science.

In certain ultraconservative sectors of the United States and Europe , we are witnessing today a phenomenon that seems to take us back centuries: the deliberate denial of proven and widely accepted facts has become an act of vindication.

Under the premise of “swimming against the tide” or “not following the herd,” some present the rejection of evidence as a sign of critical thinking and intellectual courage. This dangerous tendency has even challenged the credibility of scientific knowledge, calling into question issues that have been empirically proven, but which perhaps do not fit with certain political interests. One of the most alarming examples is the denial of climate change.

The climatic reality of the planet

In 2024, the world faced a series of events that highlighted the severity of the global climate emergency. Heat waves , droughts , fires and floods hit regions around the world, causing significant economic and human losses.

A report by the British organization Christian Aid places hurricanes Milton and Helene as the most expensive natural disasters of the year, with a combined impact of more than 100 billion dollars, followed by other events such as Typhoon Yagi in southwest Asia (13 billion), storm Boris in central Europe (5 billion) and Dana in Valencia (4 billion).

In September, Arctic sea ice hit record lows . And a recent study published in Nature Communications predicts that the first ice-free day in the region could occur before 2030.

In addition, global warming has reached record levels, cementing 2024 as the warmest year in millennia .

The denialist arguments

Amid this disheartening reality, climate denialism relies on misinformation and the manipulation of scientific evidence to hinder or delay the measures needed to address the climate crisis.

Three of the most recurrent arguments in his speech are the following:

1. “Climate change has always existed”

This argument holds that climate change is a natural phenomenon that has occurred throughout the Earth’s history and should therefore not be considered alarming or attributed to human activity.

While it is true that the Earth’s climate has changed naturally over time, current climate change is distinguished by its unprecedented speed: in just a few decades, it has generated changes that, under natural circumstances, would take thousands or even millions of years to occur.

The main cause has been clearly identified: the dramatic increase in greenhouse gases due to human activities such as burning fossil fuels, deforestation and intensive agriculture. Ice core records have confirmed that current carbon dioxide concentrations exceed any natural variation over the past 800,000 years.

2. “There is no scientific consensus on climate change”

Those who argue that there is no scientific consensus on climate change often cite documents signed by “numerous” scientists who reject human influence on this phenomenon.

One of the most frequently mentioned documents is the World Climate Declaration: There is No Climate Emergency, signed by, among others, two Nobel Prize winners in physics. However, of the more than 1,800 signatories, the majority – including the Nobel Prize winners – have no scientific publications on climate or climate change. For example, among the 21 Spanish signatories, only three have published studies in this field .

The perception of a lack of consensus is largely due to disinformation campaigns and media representation that gives disproportionate weight to minority opinions, creating a false equivalence in public debate.

3. “Carbon dioxide is not a pollutant”

This argument is based on a simplistic interpretation of the chemistry of carbon dioxide (CO₂) and its biological role. It is true that CO₂ is a natural gas essential to the carbon cycle and processes such as photosynthesis and cellular respiration. At normal concentrations, it is not toxic to humans or ecosystems.

However, CO₂ is classified as a pollutant under the Kyoto Protocol and the Paris Agreement, international agreements that seek to reduce its emissions to mitigate its impact on the climate and the environment. Presenting it as harmless because of its natural origin ignores its role in the climate crisis and perpetuates misinformation.

It is vitally important that society commits to a global response based on science. The decisions we make today are crucial to building a safer, fairer and more balanced future for future generations, ensuring the health of our planet and the well-being of its inhabitants.

Author Bios: Jose Manuel Rico Ordas is Professor of Ecology, co-director of the Chair of Climate Change and Paula Izquierdo Muruais has a PhD in Biogeosciences both at the University of Oviedo