A Swiss-German team has found evidence of significantly increased precipitation in the Karakorum mountain range of Northern Pakistan since the industrial revolution, most likely due to global warming. The team, from the Swiss Federal Research Institute, Jülich Research Centre, the University of Bonn and GeoForschungsZentrum Potsdam studied juniper trees of extreme age, some with rings dating back as far as 828 AD. We know that the rings of trees provide information about the climate when the rings were laid down. Trees grow rapidly in the summer and slowly, if at all, in the winter. This effect is what creates the rings. The team used a hyper-sensitive method of examining the rings, looking at oxygen isotopes. 'This [oxygen isotope study] method is extremely complex, but permits very exact statements to be made about the humidity conditions in the year in question,' explained Professor Matthias Winiger, from Bonn's Geographical Institute. To test the accuracy of their experimental methods, the team compared information from the tree rings to meteorological data taken since 1898 under the British occupation of what was then India. 'For this period of time our method tallies remarkably well with the meteorological data,' said Professor Winiger. Content with the accuracy of the tree-ring data, the team were able to look back in time at the local climate. They found that the climate has not been constant, and that, for example, there were wet periods around 1200 and 1350, but the recent wet periods have shown higher peaks and at a greater frequency than at any other time. This also corresponds to the slow but increasing global rise in temperature during the last 150 years, due to the huge impact of the industrial revolution. The team believes that the increased temperature due to the greenhouse effect influences air currents as an additional side-effect of global warming. In mountainous areas such as the Karakorum mountains, the team believes that this will have had a significant influence not only on the local climate, but also on the local people, and their lives. '[I]n these sub-tropical and peripheral tropical regions changes in the precipitation rate and distribution and thus in the water balance would have a much greater impact on people's well-being and changes in the eco-systems than the change in temperature on its own,' concludes the paper.