we hear it all the time – ‘the surf was way better a couple of years ago’, or ‘I didn’t need a wetsuit when I grew up’. Are these statements only subjective, or is there actually more to it ? And if so, where will you go for your surf trip in the future ? The latest special report on the Ocean and Cryosphere in a Changing Climate has the answer !
Every couple of years, the Intergovernmental Panel on Climate Change (IPCC) identifies where there is agreement in the scientific community and prepares a report that summarises the state of our knowledge, and where further research is needed. The cool thing is that it also comes with a summary for policy makers, that is easy to understand and a key input into international negotiations to tackle climate change. But what does that have to do with surfing ?
Absolutely everything ! Aside from providing the latest estimates about sea-level rise as well as projections of global temperature increase – the IPCC report holds valuable information on where to catch a wave with your future kids. But why should you care about Antarctica, which seems so far away from any tropical beach ? It is because Antarctica holds enough water to raise global sea level by 70 m if it were all to melt. And all this fresh water modifies the global ocean circulation and thus weather patterns far offshore – which produce the swell that surf. Satellite measurements show that the ocean surface is currently rising by 3.6 mm per year. And the latest IPCC report identifies that melting ice is with 1.8 mm per year, the dominant source of sea-level rise and has now exceeded the effect of thermal expansion of ocean water (water expands as it gets warmer) with 1.4 mm per year. So how much warmer is the ocean ?
It is virtually certain that the global ocean has warmed since 1970 and has taken up more than 90% of the excess heat in the atmosphere. Since 1993 the rate of ocean warming has more than doubled and is attributed to ‘anthropogenic’ forcing (a fancy expression for human activity). Most of this heat uptake occurred in the Southern Ocean surrounding Antarctica, where ice loss has tripled since the millennium. The reason for that is an acceleration of ice discharge in the Amundsen Sea Embayment of West Antarctica – where the onset of an irreversible feedback mechanism might already be at play… but we will get to that. Ok, if the ocean gets warmer, do you need a thinner wetsuit ?
Computer simulations can be used to predict global mean surface temperatures. If we significantly limit our greenhouse gas emissions and develop the technologies to pull carbon back out of the atmosphere, we are already committed to 1.6 °C temperature change by 2100. In the absence of policies to combat climate change and keeping business as usual, the temperature change will be 4.3 °C. Unfortunately this is exactly where we are heading to at the moment. These simulations, in turn, underline the importance of timely climate action to lower our carbon emissions before the year 2050.
By that time, wave heights are projected to decrease over the North Atlantic and the Mediterranean Sea. But, significant wave heights are projected to increase not only in the Southern Ocean, but also in the tropical eastern Pacific ! Associated changes in tides can locally act enhancing. This means that waves are getting bigger – but do they also occur more often ? Extreme sea-level events, like local sea levels that historically occurred only once per century are projected to become at least annual events at most locations during the 21st century.
So is climate change good or bad for surfing ? As always, nature is not a binary system of yes and no… it depends where you live and what you want… ‘Honey, I guess a trip to the Galapagos Islands is upcoming !’