What is the connection between climate change and football? Apart from the fans standing in the driving rain and supporting their team, there is very little. But dig a bit deeper and you will find an interesting comparison.
Imagine it is the start of a new football season and you are beginning to think about how well your team will perform. Will they win the league? To assess their chances, you will take into account a wide range of factors: buying and selling players over the summer, strengths of the coach and background staff, size and quality of the squad, strengths and weaknesses of the other teams in the league, and so on. With all these factors bubbling in your head, mixed with gut feeling, you come up with a 50% chance of them winning the league. After about 10 games your team is 2nd in the league with 8 wins, 1 draw, and 1 loss. At this point you ask yourself a few questions: How likely is this table position if your team is really a title contender? How likely is your team not a title contender? Based on your answers, you revise your estimates to a 75% chance of winning the league. Of course table position isn’t enough because the first 10 games may have been against weaker teams; therefore, it is weak evidence that your team will win the league. At midseason your team has dropped to 5th position and injuries are piling up; therefore, your estimate may fall back to, say, 50%. As the season progresses, you are gathering more information and update your beliefs about the success of your team.
So what does all this have to do with climate change? Climate science follows the same process but with many more factors: laws of physics covering the effect of the sun on the earth; the motion of winds and the jet stream and their effect on the earth; historical climate data; future CO₂ emissions; economic and population growth; the list goes on. These factors and many more are combined to give an estimate of, say, a 70% chance that the five-year average warming for 2025-2029 will be more than 1.5°C. After a few years various measurements such as atmospheric CO2, emissions, surface temperature, radiation measurements, etc. are used to assess whether the original estimate has to be updated.
The link between football and climate change is that you start with lots of different types of information and come up with your best estimate. As more information arrives, you update your estimate to give a better estimate. In the case of football, it is the performance of the team assessed against its position in the league table. For climate change it is the new information coming from the latest measurements from around the world.
Next time you are trying to work out if your football team is going to win the league, give a thought to the complex problem that climate scientists work on, whose predictions we all depend on.
The Reverend Thomas Bayes showed how rational belief should be updated in light of new evidence, and his theorem now underpins fields ranging from statistics and machine learning to medicine, physics, climate science, economics, and everyday decision-making.