The researchers find ‘a significantly declining AA effect on the millennial time scale’ — but then attempt to link that to anthropogenic forcing in recent times, according to the article at least. That seems illogical if the argument is that humans are playing a part. In any case if the effect has been shown to occur over at least a millennium, that in itself casts doubt on claims that humans must be the prime (or any) cause of the most recent observed changes.
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The recent amplified warming in the Arctic during the last decades has received much attention, says Phys.org.
But how Arctic amplification (AA) has varied on longer time scales and what drives these variations remain unclear.
Recently, a study has provided a new perspective on the AA effect during the past millennium based on the best available paleoclimate data and novel data assimilation methods.
The study was published in Nature Communications on April 6.
It was conducted by researchers from the Northwest Institute of Eco-Environment and Resources of the Chinese Academy of Sciences (CAS), the Institute of Tibetan Plateau Research of CAS, the Lund University and the University of Gothenburg.
The researchers produced a new millennium-long temperature reconstruction over the Northern Hemisphere by combining climate model simulations with newly available paleoclimate proxy records from the Past Global Changes 2k Network (PAGES2k) consortium, resulting in physically consistent and spatiotemporally continuous temperature fields.
Additionally, to quantify the variations in the strength of the AA, the researchers reconstructed a millennial AA index series, which revealed a significantly declining AA effect on the millennial time scale.
The millennial AA index series revealed that AA exhibited strong variations over a broad range of time scales, which can be explained, to a large part, by the phase of the Atlantic Multi-decadal Oscillation (AMO) and recent anthropogenic greenhouse gas forcing.
Full article here.
via Tallbloke’s Talkshop
April 12, 2022 at 11:31AM