A secure energy supply depends on identifying global developments at an early stage and assessing their impacts on energy systems. Weather phenomena such as El Niño vividly illustrate how closely weather, supply chains and energy markets are interconnected today: events on the other side of the world can affect transport routes, move markets and thus indirectly shape energy supply in Europe. For Alpiq, analysing these interdependencies and understanding their relevance to the energy sector is therefore essential. In this interview, Alpiq meteorologist Martin Bolliger explains why El Niño is far more than just a weather phenomenon and what it reveals about the opportunities and challenges of an increasingly interconnected energy system.
There is currently a great deal of talk about a possible “Super El Niño”. What exactly makes this phenomenon so exceptional, and why are meteorologists around the world, including you, paying such close attention to it?
El Niño is a coupled ocean-atmosphere anomaly in the tropical Pacific that occurs every two to seven years. A strong warming of Pacific sea-surface temperatures alters atmospheric circulation patterns. The result is weather anomalies around the world. Examples include heavy rainfall in South America, fewer tropical cyclones in the Atlantic and a tendency towards warmer global temperatures. The current El Niño is strengthening and will probably reach its peak intensity towards the end of the year.
What is special this year is that the current El Niño is extremely strong compared with historical events, which means an increased risk of weather extremes around the world. A strong El Niño is characterised by exceptionally pronounced warming of the ocean in the central and eastern Pacific, with temperature anomalies of more than two degrees Celsius above the long-term average.
For us meteorologists in the energy sector, El Niño events are significant because they influence weather worldwide and thus affect global, interconnected energy markets.
Europe is not directly within El Niño’s main sphere of influence. What effects could a strong El Niño event nevertheless have on the weather in Switzerland?
The statistical relationship between El Niño and European weather is weak. The reason is that El Niño occurs in the tropical Pacific, so its effects would have to propagate all the way to Europe. That is a long way, with many intervening factors that can weaken a potential signal. I would therefore also be cautious about saying that this year’s period of drought and heat in Europe is linked to the El Niño that is still strengthening.
What we can observe, however, and what is very consistent with historical observations, is that El Niño tends to suppress Atlantic hurricane activity. That is clearly the case at present. These tropical cyclones also often recurve over the Atlantic and then become embedded in the prevailing westerlies. When originally tropical systems are incorporated into the Atlantic westerly flow, they can increase forecast uncertainty for weather in Europe, for example when predicting whether conditions will be very windy or relatively calm. We are not entirely free of that tropical induced forecast uncertainty this year, but the situation is considerably less challenging.
El Niño is not only a weather topic, but also an energy issue. How can droughts, heatwaves and changes in precipitation patterns affect global electricity supply and energy markets?
For us meteorologists in the energy sector, El Niño events are important because they influence weather around the world. Weather, in turn, affects energy markets because these markets are highly interconnected globally. Since the war in Ukraine, the global maritime transport of liquefied natural gas (LNG) by tanker has become increasingly important. Here too, weather plays a role and can affect supply chains.
One example is Gatún Lake, an artificial lake in Panama that forms a central part of the shipping route linking the Atlantic and Pacific oceans via the Panama Canal. During El Niño events, the region tends to receive less rainfall, which affects water levels in Gatún Lake. During the 2023/2024 El Niño, water levels fell so low that fewer vessels were able to transit the Panama Canal. This disrupted supply chains for goods transported by sea and increased transport costs, as many ships had to take longer alternative routes. The situation there is currently more relaxed: despite El Niño, there has so far been sufficient rainfall. This shows that the precise impacts of an El Niño event can vary.
How are El Niño and global climate change actually connected, and can their effects reinforce one another?
That is an interesting question, but one I would prefer to leave to the scientists. The reason is that the effects of climate change are currently intensifying and overlapping with natural climate variability, such as the fluctuations associated with El Niño. The question is therefore how climate change interacts with natural climate variability. Does it amplify anomalies in certain regions, or could it even weaken them?
The magnitude of the anomalies makes the assessment even more difficult. The more extreme they are, as with this year’s El Niño, the harder it becomes to place the impacts in a historical context. This means that the weather signals associated with a similarly strong El Niño in the last century most probably cannot simply be applied one-to-one to the present day, because the atmosphere is now in a different state.