These posts include a brief mention of a number of news items relating to climate change. They don’t preclude treating any of these topics at more length in a separate post.
They can also serve as an open thread so that we can keep each other informed on important climate news.
Hansen and Sato say that limiting human-made warming to 2°C and CO2 to 450 ppm is a prescription for disaster
They say we could be looking at sea level rise of up to 5 metres by 2100.
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:
We’ll know in 20 years whether we are on that path. If so only an actual cooling of the planet will stop it.
A two-metre sea level rise is inevitable
The only question is how fast it will happen according to Stefan Rahmstorf of the Potsdam Institute. He reckons:
“The crux of the sea level issue is that it starts very slowly but once it gets going it is practically unstoppable.”
“There is no way I can see to stop this rise, even if we have gone to zero emissions.”
We have to cool the planet.
Sound familiar? But his best guess was a one meter rise this century and up to five meters over the next 300 years.
We left a safe climate behind when the increase was 0.5°C above pre-industrial
Spratt draws the lesson from the Hansen and Sato paper, which is actually in the original. Beyond 0.5°C we are likely to get amplified polar feedbacks and an “albedo flip”. Considering ice loss from the ice sheets doubled from 2003-2008, we are off to a flying start. Spratt provides this useful graph of temperatures in the Holocene, which I’ve enlarged for your benefit:
We’ve left the Holocene comfort zone.
Greenland ice sheet is safer than scientists previously thought
Yep, not everyone sings from the same song sheet.
Hansen and Sato do go into the various aspects of ice sheet decay. I’m sure they would say that Professor Shepherd focuses too much on one aspect. But time will tell. You bet against Hansen at your peril. He’s been right for three decades.
More than 50 per cent of observed glaciers in the Karakoram region in the northwestern Himalaya are advancing or stable
That’s perhaps what the headline of the article should have said.
The critical factor is whether the surface is strewn with debris, which seems to provide protection from warming.
It doesn’t imply that global warming has been cancelled.
Debris-covered glaciers are common in the rugged central Himalaya, but they are almost absent in subdued landscapes on the Tibetan Plateau, where retreat rates are higher.
Record melting in 2010 for the Greenland ice sheet
There was plenty of melting in Greenalnd in 2010:
“This past melt season was exceptional, with melting in some areas stretching up to 50 days longer than average,” said Dr. Marco Tedesco, director of the Cryospheric Processes Laboratory at The City College of New York.
Summer temperatures up to 3°C above the average were combined with reduced snowfall.
The capital of Greenland, Nuuk, had the warmest spring and summer since records began in 1873.
Northern Canada has a heat wave
Or more accurately a staggering mildness.
Imagine having temperatures 21°C above average for over a month. Just as well the average was about -30°C.
Polar bear’s nine-day swim
Swam 687km looking for sea ice, she did, which they need to hunt seals.
Not a happy story. She lost 22% of her body fat in two months and her yearling cub. This was presumably at a time of the year when she should have been increasing body weight to hibernate and breed.
Healthy and back to work
That’s me. The ankle has lost it’s suspected cellulitis and I’m back to work in the blazing sun. Collecting posts about ice has been therapeutic. I promise to have an ice-free zone in the next edition of CC.