Since when we are sure? Just a few weeks ago some scientist on BBC was talking about extreme events and was careful not to insist that they are a direct consequence of climate change (though there finally appears to be a link). I am aware about consensus on climate change, but not about direct link between it and more frequent or more severe occurrences of extreme weather events. Pretty much all agree that it is likely that changing climate "may likely" bring more of such events but are careful not to directly link any particular case with it.