Paleoclimate data indicate there was less Arctic sea ice during the pre-industrial period than in modern times, or when CO2 concentrations were 100 ppm lower than today (280 vs. 380 ppm).
Scientists (Diamond et al., 2021) assert that during the 18th and 19th centuries Arctic sea ice extent minimum (September) values averaged 5.54 million km². Though modern sea ice losses are often characterized as dangerously low, satellite data indicate the 2002-’06 five-year average minimum sea ice extent was 5.92 million km², which is 0.38 km² above the 1700s and 1800s or pre-industrial (PI) levels. ...
Several other studies also affirm the sea ice losses observed via satellite in recent decades are not unusual or unprecedented when compared to past centuries.
CNN: The Arctic Ocean has been warming since the onset of the 20th century, decades earlier than instrument observations would suggest, according to new research. The study, published Wednesday in the journal Science Advances, found that the expansion of warm Atlantic Ocean water flowing into the Arctic, a phenomenon known as "Atlantification," has caused Arctic water temperature in the region studiedtoincrease by around 2 degrees Celsius since 1900.
Francesco Muschitiello, an author on the study and assistant professor of geography at the University of Cambridge, said the findings were worrisome because the early warming suggests there might be a flaw in the models scientists use to predict how the climate will change. "The reconstructions suggest a substantial increase in the Atlantic Ocean heat and salt transport into the Nordic Sea at the beginning of the 20th century, which is not well simulated by (climate models)," Rong Zhang, a senior scientist at NOAA's Geophysical Fluid Dynamics Laboratory, who was not involved with the study, told CNN. "It's important to understand the cause of this rapid Atlantification, as well as the discrepancies between the model simulations and the reconstructions."
Scott Adams: "Fake News Play of the Year: CNN posts an article that debunks human-caused climate change (or at least the models), so they do it on Thanksgiving so no one notices and give it a misleading framing to conceal it."