The northern North Atlantic’s sea ice records derived from ice cores and marine sediments consistently affirm there was far less sea ice during the Early/Mid Holocene than in 2000 CE. Even 17th to 19th century sea ice coverage was similar to (or less than) today’s.
A 2020 study (Geirsdóttir et al.) indicated peak Holocene warmth at least “?3–4 °C above modern in Iceland” prevailed throughout much of the last 8000 years in this region of the northern North Atlantic.
Image Source: Geirsdóttir et al., 2020
A new study indicates there has been “a clear increase of sea ice” throughout the last 4,000 years extending to today (2000 CE, or “yr b2k”) in the northern North Atlantic region.
Fram Strait and North Icelandic shelf sea ice reconstructions derived from ice cores and marine sediments consistently show modern sea ice is nearly the highest extent of the last 10,000 years. The last few centuries – which include the Little Ice Age cold period – were similar to or had even less sea ice than the year 2000 CE.
Image Source: Maffezzoli et al., 2021
Another new sea ice reconstruction (Wang et al., 2021) from this region published in Nature also depicts modern sea ice coverage as nearly the most extensive of the last 10,000 years. (Notice the contrasting inverted scale, as ? directionality indicates less sea ice.)
Image Source: Wang et al., 2021
A closer look at the northern North Atlantic trends during the 20th and 21st centuries indicates summer sea surface temperatures have been declining and sea ice has been growing since in the 1930s (Weckström et al., 2020).
So, once again, there is nothing unprecedented or even unusual about the modern sea ice extent in the northern North Atlantic.