US President Donald Trump says that wind farms harm birds and whales. Scientists weigh wind power's impacts on wildlife against those of oil and gas.

Aspen Ellis, a seabird biologist at University of California, Santa Cruz, spent a decade doing field work on remote islands off the coast of the United States. She often lived for months amongst thousands of birds, becoming so immersed in their ways that she even learned to tell which predators were nearby from the birds' calls. But as she added her observations to 40 or 50 years of previous research on these colonies, she noticed a worrying pattern.

"Again and again, I just found myself logging the impact of climate change over time," she recalls, from rising sea levels that threatened breeding colonies, to fish moving to cooler areas and leaving seabird chicks starving. "Without addressing this larger issue of climate change, the seabird conversation work we were doing wasn't sufficient to save those populations," she adds. She decided to change focus – and today, studies ways to make clean-energy offshore wind farms safer for birds.

The impact of energy production on wildlife has come into the spotlight again amid US President Donald Trump's plan to pivot the country's supply from renewables such as wind, to oil and gas. In his first days in office, Trump revoked former-president Joe Biden's ban on new offshore oil and gas drilling. "We will drill, baby, drill," Trump promised when he was inaugurated, while putting the brakes on the expansion of wind farms. One of his arguments is that wind farms harm birds and whales. His executive order halting offshore wind farm development cited the importance of marine life as one of the reasons for the decision.

Renewables beyond the US

The US energy policy pivot towards fossil fuels is halting wind power developments for now, even as other nations press ahead with the expansion. China, for example, is home to almost two-thirds of the world's solar and wind power projects in construction.

After China, the UK is the world's next-largest offshore wind market. Scotland's government has described wind power expansion as a "once in a generation economic opportunity", with a pipeline of around 40GW of offshore wind capacity in addition to 3GW already in Scottish waters.

Meanwhile, the fastest-growing renewables sector of any major economy belongs to India. And in almost every country worldwide, wind and solar remain the cheapest way to add new power.

While wind farms can have some adverse effects on local wildlife in the habitats where they are sited, including through noise, Ellis and other scientists specialising in the environmental impact of wind farms challenge the claim that wind power is more damaging to wildlife than fossil fuel extraction. They describe wind energy as a powerful and necessary weapon against climate change, arguing that its impact on wildlife can be understood, managed and reduced. They contrast this with the existential risk posed by fossil fuels driving global warming – along with the ongoing noise and pollution from oil and gas production.

The debate is highlighting one of the most challenging conundrums facing renewable energy projects around the world – to what degree must they balance the impact they can have on local environments with the global effects of climate change? And how do those wind-power related impacts compare with the local effects of oil and gas drilling?

"Fossil fuels, and their effect on climate change, outweigh everything," says Beth Scott, a professor in marine ecology at the University of Aberdeen in Scotland, a nation that has become a wind energy powerhouse. "Climate change is by far, by far the worst enemy, to all wildlife, and humans." Speaking from Aberdeen, she points to her window, at a brewing storm due to batter Scotland later in the day. It's too soon to say if this particular storm has been made stronger by climate change, but the overall picture is clear – extreme weather is "only going to get worse" in a warmer world, she says.

Scott and her colleagues are studying the impact of wind power on the marine ecosystem. While that impact exists – more on it later – she also describes wind power especially useful tool in the switch to renewable, climate-friendly energy because it can be built quickly and at scale.

"Once you start construction, in less than two years, you can build a 2GW [offshore wind] farm – the equivalent of a nuclear plant," Scott says. Nuclear power plants can take over a decade to construct. "So, in terms of rapid response to climate change, there's that."

Ellis also sees wind power as especially promising. "There is a lot of consensus [among seabird experts] on the need to move from traditional energy sources to a renewable energy framework, and offshore wind has a really big potential to do that," she says. "We're seeing the industry really boom very quickly, there's a lot of interest in that........

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