How I changed my mind… about global warming

Byron Sharp
8 min readOct 7, 2019


Most, if not all, people would consider themselves to be open-minded. Yet, if you ask someone to name an important belief that they have changed their mind about, in response to evidence and/or logic, most struggle to give even one example.

This is the first in a series of blogs where I describe how and why I changed my mind about something. I hope to encourage myself to change my mind more often. And to encourage others.

Short summary: I now worry less about global warming than I did, the scientific evidence is that it’s not going to be catastrophic. PS Our best course of action is to adapt to the effects and to invest in R&D to develop new low carbon energy.

I’ve been a “greenie” since I was a child. I raised money and marched to save the whales. I searched out all the pockets of native bush on our New Zealand farm. I became a vegetarian (although the original motivation was nutritional, not for the environment). As an adult I bought hundreds of acres of Australian bush (mallee) land and have set it aside to regenerate. When I learnt that greenhouse gas emissions were causing the climate to warm I put solar panels on the roof of my house, I sold my car and lived without one for years (until having a new baby made that impractical so I bought a small car and ran it on bio-diesel (I couldn’t afford a Prius)).

When Al Gore’s 2006 movie came out about global warming I used it to to rally my colleagues in the Ehrenberg-Bass Institute — “how could we contribute to the solution?” I asked. Being a complex problem I didn’t think it was likely it would be solved simply by legislation or technology, and I thought that we might contribute insights into consumer behaviour as well as mass communication effectiveness. Some of my colleagues pushed back (we have a culture of questioning, and not just accepting things that the director says). They said that Al Gore was exaggerating, that he sounded more like a religious zealot than a scientist, and pointed out the numerous errors he presented. I agreed, but I said he is a (religious) politician with good intentions, he’s inflating things to get attention. I quoted them more technical accounts of global warming from people like Tim Flannery (a mammalogist, author of The Weather Makers (2005)).

But then the forecasting scientists in the Institute told me that the forecasts of global warming were not to be trusted. They pointed out that climate scientists were not forecasting scientists, that climate scientists were ignorant of the established principles that help improve the very difficult business of making forecasts (ie predicting the future) in complex conditions, and that their forecasting approaches were a very long way from best practice. It’s common for experts in a field (finance, politics, physics) to assume that their expertise means they can make better forecasts than non-experts. However, research on forecasting accuracy has shown over and over that this is not true, experts are merely more sure of their forecasts, but no more accurate.

So now I had a dilemma. I respected the forecasting scientists, but I also respected the climate scientists. And emotionally I really like the idea that this global challenge might be discovered by science and then solved in a globally coordinated manner — it would be a sign of how advanced human civilization had become, and a real feather in the cap of science.

“But look at your own field”, said the forecasting scientists… “what do you think of the consensus of views among marketing academics, do you think this represents real knowledge or rather “group think?” Ouch.

Plus I knew that complex multivariate models in marketing (and elsewhere) have a miserable track record in making predictions, even in quite stable environments.

Oh dear. They certainly gave me doubts… but time will help decide things I thought, as we would see the prediction of the climate models borne out at a global scale. Indeed, in 2007 Professor Scott Armstrong challenged Al Gore to a 10 year global warming forecast competition. The losing forecaster would make a donation to charity. Al Gore declined to participate but the competition went ahead regardless. Based on the forecasting principle of “be conservative” Scott Armstrong proposed a ‘no change’ forecast, which was a bit radical given that everyone knew the climate was warming slowly. The competition wasn’t compared to Al Gore’s dramatic “tipping point” forecast, but instead to the climate science (IPCC) forecast of 3 degrees of warming over the next 100 years. Ten years later and Scott Armstrong’s forecast turned out to be more accurate.

Now ten years isn’t long enough to be definitive, but it’s important because it was a predictive test. Modellers love to play with their models, tweaking this and that, trying to get better and better fits to historic data (achieving lots of academic publications and grants along the way). This sounds sensible but there is a very high risk of “over fitting” where the model is modelling noise/error in the data, so the fit to historic data is better but it’s even worse at predicting the future, and therefore not correctly telling us what really causes what. The IPCC’s has done an assessment of climate models, which is a bit like marking your own homework but even they reported that almost every model failed to predict the slowdown in warming that occurred after 1998, in other words the models predicted more warming than occurred.

Climate scientists are now working out why their predictions were wrong:

The discrepancy between simulated and observed GMST trends during 1998–2012 could be explained in part by a tendency for some CMIP5 models to simulate stronger warming in response to increases in greenhouse gas (GHG) concentration than is consistent with observations (Section, Figure 10.4)

And others are working out how to improve them (some climate scientists claim that with a better understanding of multi-decade variations in speed of warming “the long-term warming trend in response to human emission of greenhouse gases is found remarkably steady since 1910 at 0.07°–0.08°C decade”).

Time will tell, but for now it’s clearly good news that the climate doesn’t seem to have reacted to greenhouse gases quite the way we feared.

Meanwhile there is other evidence that has changed my mind about the seriousness of global warming and the best courses of action to take to mediate its effects. It’s not that global warming isn’t a problem, but the problem has been misrepresented, and over-hyped (by people with good intentions). And simplistic, unfeasible solutions have been embraced, while more feasible zero-carbon solutions such as nuclear power are mostly ignored. Most concerning is how preoccupied people are about “what side you are on?” rather than wanting to discuss facts.

Global warming is not a existential threat. Global warming means the world is getting hotter (milder winters, hotter summers). Which is of most concern for those who already live in hot places (like Adelaide or Dubai) but probably quite welcome if you live in Northern Europe, China, or America. Each year far more people die due to cold than from heat, even in Australia six times more deaths are due to cold than heat. And most of this isn’t from extremes but rather simply cold winters, and global warming means warmer winters (that’s something the climate scientists all agree upon).

Contrary to reports in the popular press, climate scientists have not been reporting more hurricanes, flood, fires and so on due to Global Warming. There are concerns that extreme weather events might increase but not for a long while yet, and maybe not. Equally importantly United Nations data shows that deaths due to extreme weather events have declined a staggering 96% over the past century, and that’s in spite of population growth. Why? How? Largely due to better buildings and infrastructure, better emergency services, better hospitals and so on. In other words, human technology and wealth levels, both of which continue to improve. So even predictions of increased deaths due to a warmer planet seem far fetched, while the idea that global warming means “the end is nigh” is sheer apocalyptic fantasy.

This is pretty important to know because there are many things we’d like to fix (literacy, poverty, antibiotic resistant bacteria, cancer, clean water, endangered species etc), and efforts and money put into one problem often does nothing for another. We need to have a proper sense of the magnitude of each threat, each problem, and then the options to solve the problem and what their costs and feasibility are.

Anyway, decide for yourself, be open-minded. Here are a few important climate science articles that don’t get much coverage in newspapers (which prefer bad news):

The world is getting substantially greener. This is a positive effect of CO2. Also as the world become richer (and cleverer) people stop cutting down forests, and start planting trees.

Wildfires are not increasing, “Instead, global area burned appears to have overall declined over past decades, and there is increasing evidence that there is less fire in the global landscape today than centuries ago”. Globally, the total acreage burned by fires declined 24 percent between 1998 and 2015. It appears that changes in agricultural practices are more than offsetting the increased fire risk now that they world is 1 degree warmer.

The world’s beaches are not disappearing. Most are stable, some are shrinking, but slightly more are growing. And Pacific and Indian Ocean atolls aren’t shrinking.

Oceans are rising. This article says the trend is less than 2mm a year (or 20 centimeters per Century). Here is an articlewhere a climate scientist explains the error of newspapers of reporting the very unlikely forecast of a one metre rise this Century.

NASA says that an increase in Antarctic snow accumulation that began 10,000 years ago is currently adding enough ice to the continent to outweigh the increased losses from its thinning glaciers. This is not without controversy, however… the Antarctic is huge and while it’s clearly losing in some places and gaining in others, working out the overall change, and how much is due to heating from the earth’s crust, and how much from global warming is complicated! The work continues, with advances in measuring technology. The good news is that the latest estimates of the contribution of ice melting to sea level rise is less than previous estimates (again, less than 2mm rise a year).

There has been no increase in North Atlantic tropical cyclone flooding. Nor tornadoes in the USA. Tropical cyclones in Australia tend to also show a small declining trend.

And even though most Australians believe that there are more droughts, there is actually no drying trend over the past hundred years, according to Bureau of Meteorology data. Professor Andy Pitman (Director of the Australian Research Council Centre of Excellence for Climate Extremes, and a Lead Author for the IPCC) says there is no reason to think global warming will cause more droughts in Australia (at 1hr, 11 minutes).

And, in spite of newspaper speculation, climate change isn’t causing wars.

So because of the evidence, I’ve gone from being a climate alarmist to a climate realist. I hope that both ‘alarmists’ and ‘deniers’ will do likewise. Then we can all move on to working out feasible solutions that don’t harm people and the environment while trying to save them.



Byron Sharp

Professor of Marketing Science & Director Ehrenberg-Bass Institute, University of South Australia. Tweets marketing, science, sceptical thinking.