A relatively mild winter in Europe helped stave off an energy crisis there this past winter, but the warm weather itself is now threatening the energy system in other ways.

"At the moment, we are in a more comfortable position than expected at the beginning of the winter: gas prices came down by over 80% compared to their August highs, and storage levels are more than double the ones in the same period last year," Gergely Molnar, Gas Analyst at the International Energy Agency (IEA), told DW.

"But caution is needed," he added. 

The European and global gas markets remain fragile. "Any exogenous risk can destabilize them. This year, there is not much flexibility left in the system," Molnar explained.

Gas demand in the European Union fell 13% year-on-year in 2022, the biggest on record. Meanwhile, electricity generated by hydropower, which is made from water flowing into turbines, registered a 20% drop in 2022, according to an IEA analysis. Without this decline, Europe could have saved even more gas, a necessity after major producer Russia cut off flows to the bloc last year. 

Less hydropower means more fossil fuels

The fall in hydropower production led to an increase in gas consumption, Molnar said . Historically, hydropower is Europe's second-largest renewable electricity source. It provided 17% of the EU's electricity in 2020, according to Eurostat.

Currently, the amount of water in the European reservoirs is almost 15% higher than levels registered in 2022, despite the dry winter in France and the little snow in the Alps, says Molnar.

"But water reservoir levels can fluctuate significantly," he explained. "There is a lot of uncertainty around hydropower output."

The International Hydropower Association (IHA) says that significant investments are needed for water facilities to support the energy transition, while acting like climate mitigators and adapters. "The need for grid-level flexibility is only going to increase with the rise of solar and wind technologies," Alex Campbell, IHA's head of research and policy, told DW. New infrastructures can help manage floods and summer droughts, he added. 

Water temperatures threaten nuclear power 

Lower water levels and higher water temperatures over the summer can influence nuclear power production as well, as river water is often used to handle the nuclear waste heat discharge.

"If the temperature of the rivers goes over certain levels, it can impact the nuclear fleet. We saw it last year, but also in the previous years, both in France and Belgium,” said Molnar.

Rivers are also central for coal shipping. "Once the Rhine levels drop, it can cause logistical issues to coal plants, but coal operators usually have stocks, so low water levels do not immediately translate into issues, " the IEA analyst said.

Snow melt difficult to predict

These long-term trends require attention and a profound rethinking of energy systems, says Carlo Buontempo, Director of Copernicus Climate Change Service (C3S). January 2023 was the third warmest January on record in Europe, but this itself would not mean that much, Buontempo told DW.

"2022 was one of the eight warmest years, " he said, "and the other seven all occurred in the last eight years. Winters in Europe are getting warmer, and there are consequences."

Accounting for snow melt requires an element of predictability in the energy field, as it accumulates in winter and is then available in summer. But over the last 30 years, the ice thickness of Europe's glaciers has decreased by 30 meters on average. The amount of snow, which includes snow in glaciers and other mountain sections, is equally alarming for water levels going forward.

"This year, we are not in a situation dissimilar to last year. With respect to last year, there is an extra challenge: we are coming from a rather dry year, many parts of Europe are still in near-drought conditions," said Buontempo.

More power needed for cooling in summer 

Summer weather, alongside spring precipitation, is another key factor that will impact river levels. High summer temperatures increase water temperatures and evaporation while also pushing up electricity demand, especially in Northern Europe.

"The rising temperatures demand air conditioning in cities and new geographies," said Buontempo. "Peak domestic energy demand in northern Europe occurs in winter, but we are now seeing a second peak in summer."

Unexpected climate events are additional risks for the EU's energy security. Buontempo recalls how Europe experienced a wind drought in 2021. "We can dig deep into our risks, using the worst-case scenario, and start from there as a reference point,” he said.

Risk modeling and reliable data are particularly relevant to be prepared.

"We have to leverage the information we have about what could happen this year, one being the snow in the Alps,” the C3S director said. "The April-May forecasts could then give us better guidance for the summer. "

Edited by: Kristie Pladson