December 11, 2017

expert reaction to research on the impact of global warming on wind energy in the northern hemisphere

A new study, published in Nature Geoscience, models the impact of global warming on available wind energy.

Dr David Brayshaw, Associate Professor in Climate Science and Energy Meteorology at the University of Reading, said:

“This study provides an important new perspective on how climate change may impact upon global patterns of wind power resources.   A key message that emerges is that there is considerable uncertainty in how future wind patterns may – or may not – change and that further research is needed to establish a firm basis for understanding and estimating them at regional scales.

“While significant changes in regional wind climate cannot be ruled out, it is obviously important to be cautious about overinterpreting the results of any single climate model or study – indeed the results presented by the authors suggest that ‘averages’ taken over groups of climate models may not always be a good guide in some cases (e.g., in this case for the Central US).  This study therefore confirms that further research is needed to understand large-scale changes in wind patterns and the diversity in climate model projections.”

Prof Sir Brian Hoskins, Chair of the Grantham Institute at Imperial College London and Professor of Meteorology at the University of Reading, said:

“It is important to try to estimate how climate change is likely to influence all our activities. This paper is a good example of using climate model data to evaluate how the production of electricity from wind may change. The model data used is for monthly averages and on a coarse scale, and the paper gives an evaluation of how all this averaging might affect calculations of today’s wind power. The results of the paper for the future suggest that by the period 2020-2040 there will be a general small decrease of a few per cent in wind power in the middle latitudes of the Northern hemisphere. However, the geographical variation is a large, and almost no change is found near the UK.

“Because wind power is proportional to the cube of the wind speed, it is likely that any changes in the variability of the wind from day to day, associated with changes in weather, will actually be more important than changes in the average monthly mean wind.”

Dr Dave MacLeod, Postdoctoral Research Assistant at the University of Oxford, said:

“The size of the wind energy resource is important and modelling can provide a clue about potential future changes. The authors use modelling output to estimate wind resources, and suggest decreases in wind energy potential will decrease in the Northern Hemisphere.

“There are two significant issues with the method of the paper which cast doubt on the conclusions.  The resolution of the models is only around 100-200km – this is not very accurate.  Also they use monthly average data from the models, which ignores day-to-day variations.

“The authors are quite clear about these limitations, but they claim that they are not sufficiently severe to undermine their results. They back up this claim by testing a method against results obtained by using daily data from a single wind farm over four years. For this single location they find an acceptably small difference in results, and extrapolate that the method is suitable for application globally and that the limitations will not affect the results.

“This is quite an assumption. There are many kinds of atmospheric processes interacting with all kinds of complex terrain. To claim then that these limitations are not significant anywhere – based on a single location – is quite a leap.

“Global climate models are too low-res to simulate smaller scale processes and complex topography smaller than 100km.  So there is a limit to how much can be said about the influence of anthropogenic climate change at this scale.

“In addition, there is other research which directly contradicts this new research.  One recent study used higher resolution atmospheric models and found that several regions over the US experienced an increase in wind energy of around 2%.

“Personally I have serious doubts we can rule out future increases or decreases in wind energy over the UK.”

Dr Iain Staffell, Lecturer in Sustainable Energy Systems at Imperial College London, said:

“This study is not going to alarm the UK wind industry.  It shows that in the worst-case scenario, with no effort to reduce carbon emissions, wind power in the UK could be 2–3% less productive in 40 years’ time.  Businesses worry about profits over the coming 10 or 20 years, so I can’t see this would affect the decision to build more wind farms today.

“A 2–3% change in wind farm output will be lost in the noise – the cost of building wind farms has halved in the last few years, and power prices vary dramatically from one year to the next.  The uncertainty in future costs and revenues will be more important for businesses and consumers.

“A key problem for scientists conducting this kind of study is that the global climate models they use are best at estimating the impacts of carbon emissions on temperature and rainfall; their ability to calculate the long-term impact on wind speeds is much less understood.”

* ‘Southward shift of the global wind energy resource under high carbon dioxide emissions’ by Kristopher Karnauskas et al. published in Nature Geoscience on Monday 11 December 2017. 

Declared interests

None received.