Offshore wind turbines are a vital weapon in the fight against climate change.
But they also incite battles we can’t see. Crises continue long after the massive hydraulic hammers are done slamming into the seabed.
After the underwater acoustic blitz has permanently altered the marine habitat on the seabed, the disruption moves to the sky.
How do you justify saving the planet from climate change if it completely rewrites ecosystems?
How the crisis continues long after the hammering is done
Offshore wind energy is booming in response to the demand for clean power.
But it comes with a price. And it’s local ecosystems that have to pay.
Wind turbines generate so much acoustic pollution during the pile-driving phase that some wildlife flees and never returns.
The physics of underwater noise makes it remarkably efficient. Water is denser and less compressible than air, so sound travels nearly 4.5 times faster underwater. Acoustic waves also reach immense distances.
These acute sound fields are seriously risky for fish. Behavior is disrupted, and wildlife is displaced due to physiological trauma.
Marine mammals, specifically, can suffer from temporary threshold shifts. This is a temporary loss of hearing, or even permanent injury.
There are ways to mitigate the trauma, for example, with bubble curtain technology. But this doesn’t come close to undoing the ecological footprint of installing the massive wind farms.
And it’s not all happening below the surface. It turns out the aerial corridors are also under siege by turbine noise.
Evidence of ecological exclusion: Measuring the marine footprint
The Danish North Sea is the home of the Horns Rev offshore wind farms I, II, and II. They are pioneering sites for long-term marine environmental monitoring.
Incredible insights have been delivered over their 26 years of data collection. The farms were tracked from construction through operation, providing exceptional longitudinal data.
Shifts in species abundance and distribution were studied across vast areas using aerial surveys, digital imaging, and advanced spatial modeling.
The data show that species reactions, like that of seals, are seldom instantaneous or uniform, but unfold across several years in different ways.
Stressors don’t affect all fish the same way.
This is why it was vital to track the data over the long term. Researchers also had to filter out natural variables like prey availability or climate fluctuations to make sure they got it right.
The results showed that underwater, species were amazingly resilient. After the pile-driving died down, the environment started stabilizing and adapting to the operational soundscapes.
But above the waves, completely different, more permanent displacement was taking place, according to the Pacific Northwest National Laboratory.
Looking to the skies: What’s going on with the avian life?
You’d imagine that once the construction racket is over, it’s business as usual for nature.
Unfortunately not. At the Horns Rev farms, researchers picked up that the turbines were triggering musical chairs in the sky, says the DCE Nationalt Center for Miljø og Energi.
It turns out that it was not a case of “birds hate wind farms.” The drama that resulted between species completely reshaped the avian ecosystem.
Some highly sensitive species became “avoiders,” like divers and common scoters. For them, the turbines had a total barrier effect, and they abandoned their feeding grounds.
Some species were noted as the “attractors.” Opportunistic types like gulls and cormorants saw the turbines as inviting luxury resorts with the perfect perches for resting and scouting out easy meals.
The take-away is a great eye-opener for the future of green energy. Fighting underwater noise is only half the battle.
Even a completely silent wind farm permanently changes the seascape, such as creating new reefs. The balance has to be even on both sides of the water if we want to avoid more green vs. green wars down the line.