"...In the global climate models (GCMs) most of the warming that has taken place since 1950 is attributed to human activity. Historically, however, there have been large climatic variations.Temperature reconstructions indicate that there is a ‘warming’ trend that seems to have been going on for as long as approximately 400 years. Prior to the last 250 years or so, such a trend could only be due to natural causes..."Wrong.
The past natural warming cycle started about 50,000 years ago and melted off the glaciers that covered most of North America.
We are about 10,000 years after the natural warming cycle ended and the next cooling cycles started.
Your claim there was a warming starting 400 years ago is just false.
Temperature Plateau Likely Due to Deep Ocean Warming | Climate Central
Climate skeptics have seized on a pause in warming over the past five years, but the long-term trend is still upwards.www.climatecentral.org
Obviously it was actually slightly cooling until around 1900 or so.
https://www.ssb.no/en/natur-og-milj...594b9225f9d7dc458b0b70a646baec3339/DP1007.pdf