Why do people keep voting for climate change deniers?

The rise of Mike Johnson to US House Speaker is a disturbing development as the world lurches towards existential crisis

Like many scientists I was perturbed by the recent election of Republican representative Mike Johnson to the position of speaker in the House of Representatives, the third most powerful position in US politics.

Johnson has made no secret of his deep scepticism concerning the phenomenon of man-made climate change. He has stated on many occasions that there is no reason to believe the global heating we are now experiencing is any different from natural variations in climate the Earth has experienced in the past.

This view remains depressingly common among conservative politicians in the US, although it flies in the face of a mountain of evidence to the contrary. Reading Johnson’s various statements on the topic, I was prompted to imagine how one might try to change such a mindset.

In the first instance it is a logical fallacy to assume that because the Earth’s climate underwent natural changes in the distant past, any variations in the current climate must also be natural in origin. A moment’s reflection should reveal that the first statement does not imply the second.


Secondly, scientists have spent many years carefully investigating whether the current changes in the Earth’s climate could be linked to natural cycles such as variations in the sun’s output, variations in the Earth’s orbit, changes in the angle of tilt of the Earth and other phenomena. No such natural cycles have been found to correlate with the timescale of the warming we are experiencing – a warming that is increasingly manifest as devastating droughts, wildfires and floods around the globe.

Emissions of greenhouse gases continue to rise globally despite a plethora of international agreements and targets

On the other hand the warming matches well a non-natural effect predicted by basic climate science. It has long been known that the Earth’s temperature is regulated by certain trace gases in the atmosphere. Known as greenhouse gases, they keep our world warm by trapping heat radiated outwards by the Earth. Decades of measurements show a steady increase in the concentration of greenhouse gases in the atmosphere caused mainly by the burning of fossil fuels.

When compared directly, this man-made rise in the concentration of atmospheric greenhouse gases correlates closely with the increase in global surface temperatures we have seen over the same period.

Many other pieces of evidence link an increase in the concentration of atmospheric greenhouse gases with global warming. For example, satellite measurements of the heat radiated by the Earth into space show an increased atmospheric absorption of heat at exactly the wavelengths associated with greenhouse gases. These measurements also indicate a warming that is far more pronounced in the lower parts of the atmosphere, effectively ruling out external causes.

All in all there is a mountain of evidence to suggest that the bulk of the warming we have been experiencing is caused mainly by the burning of fossil fuels. However, it has taken a very long time for this message to be accepted, and an even longer time to convince governments of the urgent need to replace carbon-intensive energy sources such as oil, coal and gas with alternative energy sources such as wind, solar and tide.

Today most governments concede the need for a transition to renewable energy sources, but change has been very slow. Emissions of greenhouse gases continue to rise globally despite a plethora of international agreements and targets.

One reason for this is the problem of vested interests. The global fossil fuel industry is an industry with extremely deep pockets and it has been extremely active in lobbying governments to continue to award licences for drilling and to continue to subsidise the extraction of fossil fuels. Sadly the largest fossil fuel companies have made remarkably little effort to transition to more sustainable technologies despite a great deal of advertising to the contrary.

This problem is particularly marked in the US, where large businesses spend vast sums of money lobbying politicians. It is no great surprise to learn that Johnson, who has received substantial funding from big US oil and gas companies, lost no time in passing a Bill earlier this month that severely weakened President Joe Biden’s recent climate legislation.

As the devastating effects of global warming become more apparent year on year, one wonders how long ordinary citizens will continue to elect politicians who deny the reality of man-made climate change.

Dr Cormac O’Raifeartaigh lectures in physics at the South East Technological University (Waterford) and is a visiting associate professor of physics at University College Dublin