Climate change and global warming are often used interchangeably, but in fact they have very distinct meanings.
Climate change describes a set of changes to the climate that can happen at either a local or a global level, while global warming refers to the rise of temperature in the Earth’s climate system. However, climate change is one cause of global warming.
These definitions are going to be handy as we look at the results of a recent study by University of Harvard researchers David Keith and Lee Miller, which was published in energy-focused journal Joule.
The study has caused very strong reactions in the wind community as it has shown that, if all electricity demand in the US was supplied only by wind farms, the turbines would contribute to increase US surface temperature by 0.24°C. This has prompted some to criticise the study for giving the impression that building more wind farms leads to global warming. But is this right? We spoke to Lee Miller to find out more.
He explained to us that wind farms affect climate change in two opposing ways.
First – and this is the effect that we all know and love – wind reduces future global climate change by reducing greenhouse gas emissions compared to a fossil-fuel based energy mix. But second, wind farms also cause climatic impacts on a local scale – and this is the effect the Harvard researchers analysed in their study.
The researchers have analysed data from 28 operational wind farms in the US and assumed they all use 3MW wind turbines, which are evenly spaced over the wind farm region. They found that wind turbines contribute to redistributing heat, meaning that some areas get warmer and some cooler after the deployment of wind turbines.
Miller said locally-warmer surface temperatures was one key effect of wind power.
He said: “Wind beats fossil fuels under any reasonable measure of long-term environmental impacts per unit of energy generated. However, assessing the environmental impacts of wind power is relevant because, like all energy sources, wind power causes climatic impacts.”
This is not the first study to show that wind turbines affect local climate. For example, a study published in 2014 by a group led by Robert Vautard, a senior scientist at France’s National Centre for Scientific Research, showed that wind power influenced temperatures and chances of rain, depending on where it was located in Europe.
This is where the definitions of climate change and global warming are important. Climatic impacts of wind farms are local and immediate, while climate benefits given by accumulated emission reductions are long-lasting. The longer the time horizon, the less important wind power’s impacts are compared with its benefits in terms of global warming, the study has shown. That is good news for the wind industry.
However, it is also an easy point to misinterpret or misrepresent. There is a risk that these studies can have consequences on how wind power is perceived – in other words, people can claim wind farms cause global warming – even when that isn’t the point at all. Indeed, we’ve already had wind sceptics sharing it with us on Twitter.
Now consider this. Arguably, the main reason for the success of wind power over the last decade is that governments and companies around the world have decided to invest in it because it contributes to fight global warming. This means that corporates have used wind power purchase agreements as a way to lower their emissions, and for that same reason governments have sustained the deployment of wind power.
But if the message that comes out from these studies gets misinterpreted, and seen instead as a demonstration that wind turbines negatively affect global warming rather than contribute to fight it, it could have a negative impact on the industry.
This doesn’t mean that we can ignore or discard these studies. Rather, we should be aware of them and promote a proper understanding of them.
If we want wind to play a key role in the future of the global energy mix, it is essential to understand its limits, including its potential environmental and climatic impact, so that we can address them. Well-informed decisions are the only way to achieve this.
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