Where I ended up after a series of happenings as described below, is concluding that we need a paradigm shift in our climate change aspirations. Instead of trying to limit warming to a point where we can avoid dangerous climate change, we need to recognize that we’ve already gone too far, that the climate is already dangerous, so we should aim to ratchet down GHG concentrations in the atmosphere to attain a safe climate.
1. Germans look to 7.4 trillion tons of fake snow to save the West Antarctic Ice Sheet
Perhaps the most striking characteristic of Pliocene climate reconstructions is that low latitude ocean temperatures were very similar to temperatures today. High latitudes were much warmer than today, the ice sheets smaller, and sea level about 25 m higher (Dowsett et al., 2009 and references therein). Atmospheric CO2 amount in the Pliocene is poorly known, but a typical assumption, based on a variety of imprecise proxies, is 380 ppm (Raymo et al., 1996).
We conclude that Pliocene temperatures probably were no more than 1-2°C warmer on global average than peak Holocene temperature.
But it was considerably warmer at the poles, with consequent loss of ice sheets bulk. The effect is sometimes known as polar amplification. This involves a strong albedo feedback which could produce a doubling of ice loss every 10 years. The cumulative effect is shown in this graph: Continue reading Climate clippings 13→