As if global warming wasn’t disturbing enough, there’s still a thundercloud hanging over our heads: As more meltwater ends up in the Atlantic Ocean, we’ll have to deal with more heat waves and warmer, drier summers in Europe, according to Search. . New search.

How does this happen, explains researcher Marilena Oltmans Scientias.nl: “Fresh water is lighter than sea water because it contains less salt. Therefore, fresh water remains above the deep salty ocean water, which prevents heat exchange between the atmosphere and the cold deep ocean water. She continues: “It has been known for a long time that fresh water affects Large-scale ocean circulation, sometimes called AMOC.This new study now shows that freshwater also has rapid and direct consequences on atmospheric circulation and thus on our weather.

Wind, Gulf Stream, and temperature differences
Oltmans explains how there is a large temperature difference in winter between parts of the ocean that contain and do not contain fresh water. “These temperature differences lead to stronger westerly winds – or jet stream – between the North Atlantic, where most fresh water is located, and the warmer subtropical ocean. These stronger winds cause the Gulf Stream to deflect northward and extend it. North Atlantic Stream: a strong current that bends From the west to the east of the North Atlantic. In later summers, wind strength decreases, but variable ocean currents remain, amplifying the temperature difference in the ocean. Greater temperature contrast develops along the coast, where land warms more Faster in spring and summer.This causes winds to bend north over the North Atlantic and along the European coast, resulting in warmer and drier weather on the continent.

More predictable weather
So we can count on warmer and drier summers as well as more heat waves. In this way, European summer weather can be predicted in advance based on the amount of fresh water in the Atlantic Ocean. Oltmanns, who worked for the British National Oceanographic Center The work cites next summer as an example: “While northern Europe had an unusually cold and wet summer last year, it was very warm in Greenland. This has led to an increase in fresh water in the North Atlantic Ocean. This means we will see a relatively warm and dry summer in southern Europe this year. Depending on the path of freshwater, we also expect warm, dry summers in northern Europe within five years. “We can estimate this better in the winter before it happens.”

It is unclear exactly how large the effect is. “This is because current climate models still have difficulty accounting for the impact of freshwater changes in the ocean, and thus underestimate the impact. But I expect southern Europe to be the most affected. It will become warmer and drier. Northern Europe will see more extremes.” , although a lot of things are still uncertain about this.

On top of the normal warm-up
The more ice melts, the more fresh water flows into the North Atlantic Ocean. Reduced sea ice also disrupts natural ocean currents, changing the global climate. Researchers expect heat waves and droughts to become more severe in the future. Europe is warming due to fresh water in the ocean as well as global warming.

“Our findings show how important it is to include what is happening in the oceans in climate models in order to achieve better weather forecasts. This is a step forward towards better models that help policymakers and companies plan for the future. “Think about adjustments in agriculture, fuel consumption,” the researcher explains. Expected and prepared for floods.

A bit scary
You may wonder why this effect has not been included in climate models before. “That’s because it’s complicated. On the one hand, freshwater is an indicator of climate change, because more warming leads to more meltwater in the ocean, but on the other hand it’s also an important driver of that. This creates complex feedback loops, especially in the northern Atlantic, and we have not yet been able to capture it properly in models.

The researcher was amazed by the results. “Remote processes of the climate system appear to be interconnected: melting ice in the Arctic affects ocean and atmospheric circulation, and thus our climate and weather. This is exciting and offers new opportunities for better predictions, but it is also a bit scary.”