"The seafloor sediment cores provided researchers with geochemical and ecological data stretching back 800 years.
For most of those 800 years, researchers noted the Arctic Ocean's temperature and salinity were relatively stable. But the geochemical signatures began to shift around the beginning of the 20th century, revealing a significant uptick in temperature and salinity."
The Arctic Ocean has been warming since the beginning of the 20th century, fueled by a process known as Atlantification, according to a new study published Wednesday in the journal Science Advances.
www.upi.com
The industrial revolution started around 1760. By 1900 there was a significant uptick in both atmospheric CO2 and CH4. Since nothing had happened in the previous 700 years, only after there was the increase in GHGs, I would say that is further proof of AGW, and an indication that the planets sensitivity to GHGs is more than previously thought.