The climate deniers' equivalent of "speak to the hand" is to haul out their favourite line - the climate has always been changing. It's their version of 'nothing to see here, move along.'
It works because those who accept the climate science have to agree with it, in part. Yes, the climate has always been changing - over millennial timespans - tens of thousands or sometime hundreds of thousands of years. Not this severely, not in the span of just two centuries. The deniers dismiss that as nitpicking.
Now it's time to drive another nail in the deniers' coffin.
Earth's natural cycles can't account for the recent warming seen over the past 100 years, new research suggests.
In one of three new studies published in the journals Nature and Nature Geoscience, researchers found that previous periods of climate change such as the Little Ice Age and the Medieval Warming Period were regional and not a global phenomenon.
In contrast, the warming that has occurred over the past century has been far-reaching and global in nature.
...In the case of the Little Ice Age, the researchers found that different parts of the planet experienced changes at different times.
The central and eastern Pacific regions experienced their coldest temperatures in 2,000 years during the 15th century. But in northwestern Europe and southeastern North America, the coldest temperatures occurred during the 17th century. For everywhere else, it occurred during the 19th century.
In contrast, the warming we are seeing today spans 98 per cent of the planet.
h/t John Klein, Saskboy