Why 'unprecedented' weather no longer shocks us (and why that's dangerous)

When Britain recorded its hottest summer on record this year, beating a record set just 12 months earlier, the news barely registered. Another hot summer, another flooded street, another crop failure. We are accepting extraordinary deterioration as normal, and that complacency is staggering.

Linguists have a term for what is happening to the word unprecedented: semantic bleaching, the gradual erosion of a word's original meaning through overuse. Used to describe unprecedented heat, unprecedented rain, unprecedented drought and unprecedented wildfires, the word is losing its punch. The extraordinary is starting to sound ordinary, the unprecedented almost routine.

What does 'unprecedented' actually mean now?

The dictionary definition has not changed. Unprecedented still means something that has never happened before. And the events described above have indeed represented a ratcheting up of severity. But when climate-related records keep being smashed, it raises a question: what do we actually find remarkable?

Research from the University of California, Davis suggests our yardstick for what counts as normal is constantly shifting. In a study analysing more than 2 billion weather-related social media posts, economist Frances Moore and colleagues found that unprecedented temperatures feel less remarkable when we have experienced similar ones in the previous few years. We do not make judgments based on historical precedents or childhood memories, but on what we have lived through recently.

In other words, something can be historically unprecedented but psychologically precedented.

Shifting baseline syndrome: how we normalise environmental decline

Ecologists call this phenomenon shifting baseline syndrome. The term was originally coined in the context of fisheries, when marine biologist Daniel Pauly noted that successive generations of fisheries scientists accepted increasingly depleted fish populations as their baseline. We now realise the phenomenon is widespread, applying not just to biodiversity loss but to pollution, environmental degradation and the climate crisis.

But Moore's study contained a twist. Although extreme temperatures became less remarkable with repeated exposure, the negative feelings they provoked did not fade. We may stop finding unprecedented temperatures remarkable, but that does not mean we find them tolerable. We are not necessarily becoming blase about the climate crisis. We can still recognise that something is unpleasant without realising how unusual it is.

The boiling frog parable gets it wrong

You have probably heard the parable of the boiling frog. When the unfortunate amphibian is placed in a pot of slowly warming water, it supposedly fails to notice the gradual rise in temperature and stays put until it croaks. The parable is meant to illustrate how we fail to respond to gradual threats.

But as it turns out, the old parable gets it completely wrong. No healthy frog would sit idly in a warming pan of water. They feel the heat and respond to it. When the temperature crosses a threshold, they hop out.

So maybe that is the question we should be asking ourselves. If we can no longer recognise how remarkable these uncomfortable temperatures are, what will it take for us to do what the frog does: respond to the heat?

Why language matters in the climate crisis

One place to start is with the words we use to describe what is happening. Awesome became ordinary because we kept using it for ordinary things, such as warm bread and marmalade. Climate extremes are different: the events themselves have not become ordinary, even if our experience of them is becoming more familiar.

Unprecedented is in danger of becoming a synonym for really extreme. It should not be. The word tells us that we have crossed into territory humanity has never experienced before. It is important we retain that historical meaning.

Perhaps one of the most unsettling things about a heating world is not that unprecedented weather keeps happening. It is that unprecedented is beginning to sound like a perfectly normal thing to say.

What can be done to break the cycle of complacency?

Recognising the psychological mechanism at work is the first step. If we know our baselines are shifting, we can consciously compare current conditions to historical records rather than recent memory. This matters for policy: if the water feels normal, we may be less likely to demand that the heat be turned down.

For Namibia, a country already experiencing the realities of a warming planet, the lesson is direct. Our sense of what needs fixing depends on what we perceive as broken. Keeping the historical meaning of unprecedented intact is not just a matter of linguistic precision. It is a matter of survival.