This week’s good news is that the East Antarctic Ice Sheet (EAIS), by far the world’s biggest ice mass, was largely intact during the entire Pliocene epoch. The Pliocene was slightly less than three million years in length, and preceded the Pleistocene, the epoch of the ice ages.
The implications for human-caused warming from enhanced carbon dioxide are enormous. The good news was published in the same issue of Nature that carried an article about the loss of slightly less than three trillion metric tons of Antarctic ice since 1992.
These things are best viewed in a larger perspective. By itself, that ice loss would raise sea level by about a third of an inch, something probably impossible to detect with land-based tidal gauges. But it was also likely somewhat balanced by the probability of enhanced snowfall over the continent thanks to a (very) slightly warmed surrounding ocean. But the melting of the EAIS would be apocalyptic, itself raising sea level by 175 feet.
Even though this seemed like a very remote possibility, we can now confidently say that human-induced climate change cannot make it happen.
Global temperatures during the Pliocene averaged around 2-3⁰C higher than the 20th century average. But the massive thermal inertia of Antarctica means it probably wasn’t that much warmer there. Let’s be very conservative and say it was about one degree warmer.
The Pliocene heat load over the EAIS then becomes:
3,000,000 years X 1⁰ = 3,000,000 degree-years.
Now let’s also be conservative about how long human-induced climate change might last, say, 1000 years. But again, climate change is attenuated over the vast ice-covered continent, so let’s posit we induce a global warming of 5⁰ (which is probably too large), and Antarctica warms half as much.
The maximum heat load over Antarctica then is:
1,000 years X2.5⁰ = 2,500 degree-years.
The Pliocene heat load was 1,200 times what humans could possibly exert on the EAIS, and it still remained largely intact. Because of that, fears about the ultimate climate catastrophe can no longer even be entertained.