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Résumé |
Global warming – meaning the increase in globally-averaged surface temperature – is happening now and will continue if greenhouse gases continue to be added to the atmosphere, as is almost certain. The response of the atmosphere and ocean that may be regarded as thermodynamic are becoming reasonably well understood – for example, the diminishing of sea ice extent, an enhanced warming in the tropical upper atmosphere and, less obviously, an increase in the height of the tropopause. However, the dynamic responses remain less well understood and, as a result, less certain. For example, the expansion of the Hadley Cell is predicted by some theories but observational verification has been hard to come by. Similarly, a shift in the position of the mid-latitude westerlies is seen in some models but there is no well-accepted theory. In the colloquium I will discuss these issues, saying what the problems are and how we might make progress. |
