One of the speakers at this year's Explorer Yachts Summit is Sebastian Wache, senior meteorologist at WetterWelt GmbH, which produces highly individualised weather forecasts using constantly updated technology to generate high-precision weather analyses and forecasts. Ahead of the summit on 13 November at the Yacht Club De Monaco, we discuss the effects of climate change, how it could affect maritime traffic and his predictions for the years ahead.
Tell me about your company and what you do…
"WetterWelt is a weather company specialising in providing private maritime weather forecasts. We founded 25 years ago, starting with forecasts for radio stations and TV broadcasts, and later branched out into forecasting for world class sailors, from Ellen MacArthur and Roland Jordain to Roman Pazschke, Jörg Riechers and several international Olympic Sailing Teams.
Along with routing for sailors and shipping, we now also offer special software (Meteopilot) for motor vessels to sail safe and fast through the weather patterns, making it possible to calculate fuel consumption precisely based on weather and currents. Nowadays, thanks to the effects of climate change, our work as specialised weather routers is becoming more necessary and challenging."
"My typical day is to first check the weather apps and then get together with my colleagues where we talk about the weather situation in Germany and what is happening worldwide. When I have a specific client, I will go into the different weather models and check the situation in detail. I don't calculate the models personally, my job is to analyse the data and translate complex weather systems into easy words for the people outside. It depends on the client; sometimes the weather needs to be broad, sometimes incredibly detailed and localised. This week, for example, we have Travemünde Week, which is an international regatta taking place in Travemünde. There are 12 different race courses, and they all need exact forecasts."
How is climate change having an impact on our maritime weather?
"First we need to understand global weather patterns, so let’s start with the basics. There are three different cells over the northern and southern hemispheres called the Polar Cell, the Ferrel Cell and Hadley Cell. These three cells produce our winds. Northern Europe is situated around 60°N, where you see the meeting of the Ferrel and Polar Cells. This clash of cells produces a strong contrast in temperatures, which in turn creates a strong wind band called the jet stream which normally blows west to east.
In the last few years we have seen the jet stream decrease. The reason for this is climate change and a warming planet, which has led to fewer temperature differences between the colder air zones and warmer air zones, especially in the summertime. As a consequence, we are seeing the jet stream become more wavy - these we call ‘Rossby Waves’ - and they transport warm air masses to the north and cold air to the south. While it’s not unusual to see Rossby Waves, which normally dissipate and revert back to a normal west-east flow, what is unusual is to see so many over the last few years.
More waves mean more extreme weather patterns. If you have a Rossby wave going from south to north it can lead to very stable high pressure fronts forming and these tend to stick around and increase in temperature. In summertime we see a lot of heat domes, which are very dangerous for people because of the extreme high temperatures. It also blocks any cooler low pressure fronts moving from north to south.
If you have a wave going the other direction, from north to south, we tend to see unstable weather conditions which force heavy rain showers, flooding stronger winds and low pressure systems."
How do rising sea temperatures affect the weather?
"Globally, we are seeing rising water temperatures and in some areas, they’re off the scale - if you look at the area from 60°N to 60°S around the globe there has been a jump in temperature of over one degree more, around 21.5 degrees. Warmer ocean temperatures and higher sea levels means more moisture in the air which increases the frequency and intensity of hurricanes and tropical storms. This year we saw Hurricane Beryl form on 24 June, one of the earliest-ever and strongest hurricanes."
How do you see climate change affecting the Arctic and Antarctic regions?
"It’s clear we are seeing ice melt caused by warmer temperatures. What is interesting is how it is impacting areas south (or in the case of the Antarctic, north) of that. In the south of Greenland, for example, the melting of the Greenland Ice Shield means an introduction of cold fresh water, which reduces the strength of the winds and creates more low-pressure areas, causing more storms. So in contrast to what we’re seeing elsewhere, it could be that we see very hard winters as a consequence. This winter, in Northern Sweden, we saw the coldest temperatures measured there, minus 40 degrees.
While the world is getting warmer and the ice is melting, everyone thinks it will be easier for vessels to pass through areas such as the Northwest Passage. But this is not the case. It’s true that the ice is melting, but instead of turning into water straight away it’s breaking off in smaller chunks; into icebergs, bergy bits and growlers. A storm can blow these together into packed ice fields and this can turn into a very dangerous situation for a ship."
And what about the typical charter season… for example, the Caribbean from December to April; the Mediterranean from May to October?
"I believe the seasons and months will have to shift. With the increasing heat and 40 degree heat waves in Southern Europe we are already seeing a change in the mindset of tourists. A lot of people I’ve met are starting to think about holidaying somewhere cooler, like Scandinavia, or changing their holidays to different months.
In the Caribbean, a few years ago we knew when the hurricane season would happen and could plan around that, but climate change has made the weather so unpredictable that the maritime industry is going to have to be prepared for more events like Hurricane Beryl. It's really hard to predict what certain areas can expect in the next few years. But what I would say is to expect everything!"
The Explorer Yachts Summit will take place on 13 November 2024 at the Yacht Club de Monaco. Tickets are available now.
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