Highs and lows

So, here's a chart of average carbon dioxide measurements in September this year from a mountain top in Hawaii, as we can see the level (measured in parts per million) never falls below 400. This is the first time this has ever happened, normally levels are lower at this time of year. For reference the average level of carbon dioxide prior to the industrial revolution (which we can measure in ice cores) was around 280 ppm a massive increase like this is unprecedented and no one knows for sure what will happen, it's likely that we will surpass the Paris target of 2 degrees average temperature rise before 2100, however the chances that the effect will be zero is about that, i.e. zero.