When I first started looking into climate change some twenty years ago, there were a few things I didn’t understand. I didn’t see how an average temperature increase of 1.5 or 2 degrees Celsius was so dangerous. Sea level rise was also puzzling. How could rising sea levels of mere centimetres pose any kind of risk?
Current world events are providing a tragically useful explanation. The politics of climate change often centres around trends and averages, but that’s not how it is experienced. We experience the damage of climate change as events. The warming trend is one of several factors that generates these events, making extremes more likely and more serious.
Take the heatwaves currently affecting many parts of the world. All dangerous heatwaves are a combination of factors. Climate change adds one more, an underlying base layer of risk. The current record heat in Southern Europe combines all of these:
- Weather – starting at the most local and most variable, wind and weather affect the likelihood of extreme heat. Heatwaves are associated with slow-moving high pressure weather systems, and as the US city of Phoenix is experiencing, local and regional weather will affect how long it lasts.
- Summer – the seasons come into play too, naturally. Heatwaves are most likely when the world is at its warmest, and so there’s a timing element here.
- El Nino – there are a number of long-running natural cycles that affect conditions on earth, including glacial, solar and orbital cycles. The best known is the ocean cycle of El Nino and La Nina events, which I remember learning about at school in 1998, when there were a series of related storms and floods. Because it’s a recurring pattern, we can spot El Nino events in history – there’s a theory that it contributed to the French Revolution, for example. The heat records in 2023 owe a lot to El Nino.
- Global heating – all of the above has been going on since time immemorial. What’s new is 150 years of rising temperatures from the release of greenhouse gases – mainly from fossil fuels. Extreme weather events still occur when other factors combine. What’s different is that they are now combining in a warmer world, and so the effects are more likely to be extreme. Without this underlying warming, a heatwave is just another heatwave. Because they are now occuring in a warmer world, we get ever higher temperatures and keep breaking records.
We could write a similar list of factors around sea level rise. It’s not that the sea slowly creeps up the land and you end up underwater. Like heat, the dangers of sea level rise are mainly experienced as events. Floods and storm surges become common enough that it isn’t worth rebuilding, or insurers won’t pay for it.
The chances of an inundation combine local weather conditions – a storm and its trajectory. It includes timings around the tide, and the lunar timings that give us bigger tides at certain points. Season matters, as storms can be more severe at different points of the years, depending on where you are in the world. Climate change and sea level rise once again form an underlying base layer of risk.
Storm winds have always combined with high tides to create devastating storm surges from time to time. Now they do it in a context of incrementally higher sea levels.
This is something I didn’t get initially, and I still often see people misunderstand climate change along these lines. So one of the best ways to think about it is as a threat multiplier. We still roll the dice on any given day, with a combination of results giving us the weather conditions for that day. Global warming subtly loads those dice against us, but we might not notice until they combine and deliver an extreme event.
The Earthbound Report 
All very true. Must say, at page 124 of Climate Change is Racist, I laughed out loud. Well-written. Am sending my copy to friends in Chicago. Hope to give a few more to others soon, too.
And thank you, also, for recommending The Boy Who Harnessed the Wind. Looks like a good one.
*one meaning “one movie.”