Guardian: Twenty five months ago, working with my colleague, a climate scientist, Dr Victoria Johnson, and others, I decided to find out how long it would take before, on the best data available, we would begin to cross red lines where climatic instability and extremes were concerned. A quarter of that time has now passed. To minimise the danger of alarmism, but without hiding from the facts, we set our parameters to assume that humanity would be on the lucky end of the spectrum of …