evidence: This provides much-needed context to the current phase of warming. In fact, scientists estimate the Earth hasn't been this hot for about 125,000 years. [...] They reveal there would have been little global warming - and possibly some cooling - over the 20th and 21st Centuries, if only natural factors had been influencing the climate. [...] For many years, groups of so-called climate "sceptics" have cast doubt on the scientific basis of global warming.