Fig. 1. Modeled temperature change in 2055-2060 with 10-year doubling time for freshwater flux.

Predictions implicit in “Ice Melt” paper and global implications

S.L. Marcus suggests that our paper[1] “Ice Melt, Sea Level Rise & Superstorms” would have greater appeal and impact if it featured some notable, verifiable predictions. In related vein, E. Stabenau asks what observations in the next decade or so would verify our assumptions.[2]

Indeed, there are many predictions implicit in our paper, and there is merit in highlighting these. Most revealing, in stark contrast to all IPCC models, is strong cooling of the Southern Ocean surface and in the North Atlantic, as shown in Fig. 1. These coolings are a consequence of fundamental processes induced by injection of meltwater into upper layers of the ocean.

Cooling of the Southern Ocean and North Atlantic results mainly from the stratification effect of freshwater. Lesser density of fresh meltwater, compared to salty ocean water, reduces sinking of surface water to the deep ocean. Reduced Antarctic Bottom Water formation reduces the amount of relatively warm deep water rising to the surface, where it increases heat flux to the atmosphere and space. Instead heat is kept at depth, raising deep water temperature and melting ice shelves (see diagram in Fig. 22 of our paper).

We predict not only that the Southern Ocean surface will cool, rather than warm, but also that the cooling will be largest in the Western Hemisphere. Cooling is larger there because the rate of ice shelf melt is larger there (Fig. 2; note that longitude is shifted 180° in Fig. 2 relative to Fig. 1). Our modeling assumes that warming induced meltwater is three times larger in the Western Hemisphere, stretching from the Ross Sea to the Weddell Sea, than in the other hemisphere.

What we have is a push and shove match between global warming, which warms the global ocean surface with amplification at high latitudes, and the freshwater stratification effect, which causes ocean surface cooling in the North Atlantic and Southern Oceans. IPCC simulations for the 21st century find a warming Southern Ocean with declining sea ice cover, as freshwater


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On Sept 19, 2023 ahead of the Climate Ambition Summit in New York City, climate activists gathered for a rally and civil disobedience outside Bank of America Tower in Midtown Manhattan as part of the March to End Fossil Fuels wave of actions resulting in multiple arrests. Activists demand Bank of America to “Defund Climate Chaos and Defend Human Rights” Photo: Erik McGregor (CC BY-NC 2.0 Deed)

Let’s Save Each Other

Let’s Save Each Other

Illustration by Stephanie McMillan. Used with permission