As we smash the record yet again for the hottest month on record, making it all but inevitable that 2016 is the warmest year on record, it seems likely that we are going to miss the target to limit global warming to within 1.5°C (2.7°F) of the average. Yet just how far back in time do we have to go to find a year when the global surface temperatures were not above the average? Well the answer is nowhere near as simple as the question belies. There are many yardsticks by which to measure the warming of the planet, something that is not helped by the fact that different organisations are using different sticks. You have to determine whether you are talking about a warming over the land, over the ocean, or over both the land and the ocean. All three will give you a different answer. Not to mention that this is then compounded by the fact that you can break it down geographically, looking at the Northern Hemisphere, Southern Hemisphere, and once again at both. More confusingly, even if you choose to look at the warming over land and sea in both hemispheres, there are still different baselines by which to measure exactly how much warmer the planet has become over the last century and a half. If we consider the baseline as being the average temperature taken between 1880 and 1899, which is generally considered when the warming of the planet really started to ramp up as the Industrial Revolution kicked off and we began burning fossil fuels and spewing millions of tonnes of carbon dioxide into the atmosphere, the last year that the global temperature was not above average was back in around 1936. This means you would have to be over 70 years old to have experienced a below-average year.
IFL Science, 19 September 2016 ;http://www.iflscience.com ;