Muilwijk et al. (2023) Divergence in Climate Model Projections of Future Arctic Atlantification

M. Muilwijk, A. Nummelin, C. Heuzé, I.V. Polyakov, H. Zanowski, and L.H. Smedsrud (2023), Divergence in Climate Model Projections of Future Arctic Atlantification. Journal of Climate, vol 36, pp 1727–1748. doi:10.1175/JCLI-D-22-0349.1

In the companion paper Heuzé et al. (2023), we showed that the CMIP6 models are extremely biased in the Arctic Ocean. This study investigates whether it matters, focussing on stratification.

TL;DR: yes, biases matter. They’re so strong that models do not agree regarding the future of Arctic stratification, and that matters for the future of sea ice.

Stratification is changing in the Arctic. We show that since the 1970s, it has increased in the Amerasian Arctic but weakened in the Eurasian Arctic.

Using a new method, more adapted to biased climate models during climate change runs than the standard ones based on fixed thresholds, we compute the stratification of the upper ocean, all around the Arctic, until 2100 in the historical and SSP5-8.5 runs.

And we see things like this:

Stratification changes in two basins of the Arctic, until 2100, for each CMIP6 model in this study. Adapted from Muilwijk et al. (2023)

That is, a strong agreement among models that stratification will continue to increase in the Amerasian Arctic, but no agreement whatsoever in the Eurasian Arctic. This is because of different rates of changes in properties in the upper ocean vs the Atlantic layer, which, besides, are both differently-biased in the different models.

Finally, unsurprisingly, the models that project an Atlantification of the Eurasian Arctic (decrease in stratification) also project a strong sea ice decline.

Download the full-text here.

One thought on “Muilwijk et al. (2023) Divergence in Climate Model Projections of Future Arctic Atlantification

  1. Pingback: Heuzé et al. (2023) The deep Arctic Ocean and Fram Strait in CMIP6 models | Dr Céline Heuzé

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