evidence: In reaching this conclusion, it is important to distinguish between changes caused by human activities altering the atmosphere’s chemistry, and climate variability caused by natural factors. [...] Excluding these natural variations, Earth’s surface temperature was generally stable from about 2,000 to 1,000 years ago. After that, the planet cooled by about 0.3°C over several centuries, before the advent of fossil fuel-based industrialisation in the 1800s. [...] If human factors are removed from the data set and only volcanic and solar factors are included, then global average surface temperatures since 1950 should have remained similar to those over the preceding 100 years. But of course they haven’t.