We know that the ozone disappeared from the Antarctic over a large region; during the last 20 years you have this thing called the ozone hole which appears in the spring in the Antarctic, and it doesn't yet appear in the Arctic, but if the stratosphere over the Arctic gets cooled down it's likely it's going to happen in the Arctic. And that's of course much more serious, since it happens there's a much larger population within the Arctic regions than there is within Antarctic; I mean, the Antarctic happens to be essentially empty of people, very fortunately. But when it happens in the Arctic, that's going to be a major disaster if we don't do something about it. So that's my primary concern with the carbon dioxide at the moment, but it's not what the public is worrying about. The public thinks that you have to wait until global warming is proved before you do something and of course that's completely ridiculous because the other effects which are more easily measurable are already happening anyway. So that's the kind of thing I'm doing. I'm not really doing the observation myself, but I'm pushing very hard, and also since this became a fashionable subject, JASON is also involved with the carbon dioxide and climate, so we did a study on that, in which we advised the Department of Energy to put more money into observations. Again, very limited success. The Department of Energy has a little programme called A-R-M, ARM, which stands for Atmospheric Radiation Measurements, which is an excellent programme but it has miserably small amounts of money, and meanwhile of course they put huge money into the computer models. So it's an.... so it's an endless fight, but we are making some progress. And I think the understanding of the carbon dioxide problem is still very, very far away, we have... especially the links between carbon dioxide and vegetation are very poorly understood. But when you have the understanding, when the measurements have been made, I think we can control the carbon dioxide rather easily, because it's a question of land management essentially and... so the amounts that are involved in the vegetation are so large that if you merely just change some of the forest management practices or do a little more irrigation in some places, it's quite likely you can absorb all the carbon dioxide you want, at a cost which is far less than stopping burning coal and oil. So that's essentially what I'm trying to understand.