With respect to the two publications mentioned above, a seemingly contradictory publication was made in 'Science'. Based on satellite and surface observation, the conclusion is reached that the ice cover of the Arctic Ocean has diminished in surface area. Subsequently, simulations were made using the Geophysics Fluid Dynamics Laboratory and Hadley Centre climate models, to see whether these observations could be explained by natural variability. In 'Geophysics Research Letters', the results of ice thickness measurements were presented. Research in this intriguing field will go on.
Many issues are still unresolved.
However, it shows that there are possible non-linear responses of 'the weather machinery' which a couple of decades ago were hardly imaginable. The last evidence from research on climate change related subjects starts to show that this is at least to some extent not the case. These are bound to happen sooner or later anyway and maybe even irrespective of global warming. This is also part of the problem for policy makers.