Climate change is getting in the way of the much-loved tour of tours.

Today it is exactly 25 years ago that the last Elfstedentocht was held. And many will wonder when it will finally happen again. No one can answer that question, but what we do know is that the chance of an Elfstedentocht is heavily negatively influenced by global warming.

Halved

All in all, the warming since 1901 has even halved the chance of an Eleven Cities Tour, according to the KNMI. a press release. Researchers at the Royal Netherlands Meteorological Institute have come to this conclusion after examining the ‘Eleven Cities Weather’ in the past century. No fewer than 13 of the 15 trips took place during a period in which the temperature in De Bilt was on average below -4.2 degrees Celsius in a period of 15 days. That is apparently very favorable weather for an Elfstedentocht.

But how is the chance of that favorable Elfstedentocht weather influenced by climate change? To answer that question, the researchers examined how high the temperatures would have been leading up to and during previous Eleven Cities Tours if they had had the climate of today (see graph below). And guess what? Instead of 13 periods in which the temperature is below -4.2 degrees Celsius on average for 15 days in a row and which culminate in the Elfstedentocht, there are suddenly only seven periods in which temperatures were low enough to ride an Elfstedentocht. “This shows that since 1901 warming has roughly halved the chance of an Eleven Cities Tour,” the researchers conclude.

Image: KNMI.

Bad luck

The fact that we have already had to wait 25 years – or 9131 days – for an Eleven Cities Tour, cannot be entirely blamed on climate change. That’s just a bit of bad luck. On average, in the current climate, an Elfstedentocht could be held every 12 years. “That is to say: every year there is a chance of about 8 percent that it will be cold enough for an Eleven Cities Tour,” researcher Geert Jan van Oldenborgh explained last year. Scientias.nl from.

Unfortunately, the chance of an Elfstedentocht will probably become even smaller in the coming years. “If we can quickly reduce greenhouse gas emissions – mainly CO2 – and thus limit warming to below two degrees, as agreed in Paris, the chance remains about 5 percent per year,” said Van Oldenborgh. In that scenario, an Eleven Cities Tour is held on average once every twenty years. And then we can count ourselves lucky, because if we do nothing, the very last Elfstedentocht will really be ridden this century, said Van Oldenborgh. “With unbridled warming and a continued shift to more westerly winds, it looks bad, one or two more trips and then it’s over.”