Changing Climate Increases Turbulence
	
The Naked Scientists
Wed, 10th Apr 2013
Ben Valsler

Increasing atmospheric carbon dioxide could lead to more "clear air turbulence", leading to bumpier and more expensive transatlantic flights.

Turbulence may make a flight less comfortable for passengers, but the cost to airlines is far higher.  Injury to passengers and structural damage to planes resulting from turbulence is thought to cost at least tens of millions of pounds.  The biggest problem is clear-air turbulence, which cannot be seen by pilots or detected by satellites or on-board radar.

Now, publishing in the journal Nature: Climate Change, Paul Williams and Manoj Joshi argue that increasing atmospheric carbon dioxide concentration could significantly increase the incidence and strength of these turbulence events, making transatlantic flights bumpier, slower and more expensive.

Despite over half a century of powered flight, the mechanisms that cause aircraft turbulence are still not fully understood.  Convection causes up- and down-drafts around clouds, but clear air also contains instabilities that lead to local changes in wind speed and direction.  Spotting large clouds with radar and satellite technology allows pilots to navigate around the worst of the convention currents, but clear-air turbulence is only forecast on large scales, using algorithms similar to those used for forecasting the weather.

Anecdotal reports of increased turbulence since the turn of the century and a suggested increase in the prediction data since the 1950s prompted Willams and Joshi to use climate models to see if a changing climate could increase the amount of turbulence pilots may experience.

They modelled air flow and atmospheric jet streams for two different situations - comparing pre-industrial revolution CO2 levels with concentrations twice as high, which we are estimated to reach around the middle of this century.

Their models predict, at standard cruise altitudes, there will be an increase of 10-40% in the average strength of turbulence, and a 40-170% increase in the frequency of turbulence.

This is just one research project, possibly the first to look at the effect of climate change on aviation turbulence, and only looks at clear-air turbulence, one of many factors to affect the cost and comfort of transatlantic flight, but it looks like the "fasten your seatbelts" lights might need to be left on in future...