Recent Atlantic ocean warming unprecedented in nearly 3,000 years

https://www.eurekalert.org/pub_releases/2020-10/uoma-rao101420.php

News Release 14-Oct-2020
UMass Amherst, Canadian research uses ancient lake sediments to extend climate record

University of Massachusetts Amherst

Taking advantage of unique properties of sediments from the bottom of Sawtooth Lake in the Canadian High Arctic, climate scientists have extended the record of Atlantic sea-surface temperature from about 100 to 2,900 years, and it shows that the warmest interval over this period has been the past 10 years.

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The researchers report that their newly reconstructed record is significantly correlated with several other independent sediment records from the Atlantic Ocean ranging from north of Iceland to offshore Venezuela, confirming its reliability as a proxy for the long-term variability of ocean temperatures across a broad swath of the Atlantic. The record is also similar to European temperatures over the past 2,000 years, they point out.

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Climate warming in the Arctic is now twice or three times faster than the rest of the planet because of greenhouse gas emissions from burning fossil fuels, warming can be amplified or dampened by natural climate variability, such as changes in the surface temperature of the North Atlantic, which appear to vary over cycles of about 60-80 years.

Lapointe, who has carried out extensive fieldwork in the Canadian Arctic over the past decade, notes that "It has been common in recent summers for atmospheric high-pressure systems - clear-sky conditions - to prevail over the region. Maximum temperatures often reached 20 degrees Celsius, 68 degrees Fahrenheit, for many successive days or even weeks, as in 2019. This has had irreversible impacts on snow cover, glaciers and ice caps, and permafrost."

Bradley adds that, "The surface waters of the Atlantic have been consistently warm since about 1995. We don't know if conditions will shift towards a cooler phase any time soon, which would give some relief for the accelerated Arctic warming. But if the Atlantic warming continues, atmospheric conditions favoring more severe melting of Canadian Arctic ice caps and the Greenland ice sheet can be expected in the coming decades."

In 2019, Greenland Ice Sheet lost more than 500 billion tons of mass, a record, and this was associated with unprecedented, persistent high pressure atmospheric conditions."

Lapointe notes, "Conditions like this are currently not properly captured by global climate models, underestimating the potential impacts of future warming in Arctic regions."