Most of the discussion around climate change naturally revolves around temperature, but have wind speeds increased and become more variable? It seems to me that they have.
• In the past decade, a lot of research has focused on the practical consequences of climate change and wind has not been neglected. Studies have looked both at dangerously high winds and at the breezes that drive wind turbines.
Some studies of particular regions have reported a decrease in surface winds, but that might be partly due to regrowth of forests. Some computer models indicate an increase in the number and strength of the most severe hurricanes and typhoons. They also project that storm tracks will shift, bringing stronger gusts in some regions and weaker ones in others.
Advertisement
All this remains uncertain, because the observational record is spotty and it is difficult to model wayward winds. What is certain is that with the Arctic warming faster than the tropics and land warming faster than oceans, weather patterns must change.
Spencer Weart, Hastings-on-Hudson, New York, US
• Globally, wind speed is determined by temperature gradients. Because the poles are warming faster than equatorial regions, these gradients are decreasing, and wind speeds are decreasing to match.
However, these general trends don’t hold true at all times for all areas of the globe, with local variations due to seasonal effects, local topography and the impact of variable rates of heating and cooling between oceans and land masses.
Some countries, like the UK, are predicted to become windier over the next few years, whereas others, like Spain, India and China, are predicted to become less windy. Most states in the US are expected to have windier winters and less windy summers.
Lewis O’Shaughnessy, St John’s College, Oxford, UK
• With so much publicity given to the increased frequency of extreme weather events, it might be surprising to learn that winds have slowed down by up to 15 per cent in the last 30 years, a trend that is expected to continue with global warming. The best guess is that across half a century of warming, the wind will slow by 0.7 metres a second. This could be the result of a reduced temperature gradient between the tropics and the poles, but some scientists believe that a reduced thermal gradient should reduce the intensity of storms – the opposite of what is observed.
A warmer world might increase the surface area of water, as a result of which a bigger proportion of solar energy might be used to evaporate water, which would leave less available to drive surface convection (or wind).
An alternative idea is that moving air is encountering more friction, either because more trees are being planted or vegetation is growing at a faster rate, in response to increased concentrations of atmospheric carbon dioxide, or because of urbanisation, when the wind has to spin more turbines or blow around buildings.
Overall, evidence suggests that wind speed is increasing over the oceans, while wind speeds over land are slowing. But the evidence has to be greeted with caution as there is a paucity of data and global coverage is poor. The apparent slowing could simply be the result of shifting weather patterns.
Mike Follows, Sutton Coldfield, West Midlands, UK
We pay £25 for every answer published in ¿ìè¶ÌÊÓƵ. To answer this question – or ask a new one – email lastword@newscientist.com.
Questions should be scientific enquiries about everyday phenomena, and both questions and answers should be concise. We reserve the right to edit items for clarity and style. Please include a postal address, daytime telephone number and email address.
¿ìè¶ÌÊÓƵ retains total editorial control over the published content and reserves all rights to reuse question and answer material that has been submitted by readers in any medium or in any format.
You can also submit answers by post to: The Last Word, ¿ìè¶ÌÊÓƵ, 25 Bedford Street, London WC2E 9ES.