Arctic sea ice time bomb ticking: the bang’s gonna be huge

Arctic2013July14Reading this press release about a new paper in Palaeogeography, Palaeoclimatology, Palaeoecology spoiled my day. It might not be obvious to a casual reader just glancing through the morning news — but a couple of paragraphs leapt out at me:

Atmospheric carbon dioxide concentrations recently reached 400 parts per million for the first time since the Pliocene Epoch, three million years ago. During this era, Arctic surface temperatures were 15-20 degrees Celsius warmer than today’s surface temperatures.

Ballantyne’s findings suggest that much of the surface warming likely was due to ice-free conditions in the Arctic. That finding matches estimates of land temperatures in the Arctic during the same time. This suggests that atmospheric carbon dioxide concentrations of 400 ppm may be sufficient to greatly reduce the spatial extent and seasonal persistence of Arctic sea ice.

In other words, losing Arctic sea ice brings huge warming to the lands around the Arctic Ocean. This is extremely bad news for a number of reasons:

Continue reading “Arctic sea ice time bomb ticking: the bang’s gonna be huge”

Arctic summer 2013: fragile ice pack feeling the pressure

Arctic2013July14

Looking down on the North Pole from satellite, NASA’s Arctic mosaic image for July 14 shows an unusually cloud-free view of the sea ice covering the Arctic Ocean. Click on the image to see the bigger original, and to zoom in on interesting regions. So far this year the sea ice melt has lagged behind last year’s record-setting performance, but in the last few weeks the rate of melt has increased significantly and the two years are moving closer together.

Arcticextent2013July13

The NSIDC’s sea ice extent graph (above, for July 13) clearly shows the increase in melt, but there is still a substantial gap — over 0.5 million km2 — between the two years. This is, however, the time of year when the melt season goes into overdrive, with sunshine pouring energy into the Arctic 24 hours a day.

Continue reading “Arctic summer 2013: fragile ice pack feeling the pressure”

Planet waves, and the big heat

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It’s certainly hot in the southwestern USA at the moment — a dome of heat has established itself under a persistent high pressure ridge, and temperatures are pushing up towards all-time highs. Wildfires are running out of control. One caused the tragic death of 19 firefighters at Yarnell Hill in Arizona yesterday. One more extreme weather event to add to this year’s growing list, and as with most of the others, there’s a clear sign of a link with rapid climate change. That heat dome is being held in place by a large, slow-moving northward loop in the jetstream — and that jetstream pattern is beginning to look very much like the characteristic fingerprint of rapid warming in the northern hemisphere, as Jennifer Francis explains in this video, recorded at a Climate Desk event in Washington last month. It’s just about the clearest explanation of what’s going on that I’ve encountered — particularly in her description of why the jetstream exists in the first place, and why warming is changing the way it behaves. If you want to understand what’s going on, you have to watch this.

There’s a full recording of the Climate Desk event here, including a talk by Weather Channel meteorologist Stu Ostro. Ostro used to be a confirmed sceptic, but began to see changes in weather patterns that he traced back to the effects of warming — specifically, an increase in the “thickness” of the atmosphere, the very thing that’s driving the changes in jetstream behaviour.

NZCCC 2013: Barry Smit on adaptation – Inuit, wine and uncertainty

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Kicking off the afternoon sessions on the first day of this year’s NZ CCC conference, Professor Barry Smit of the University of Guelph in Canada launched his keynote — titled From theory to practice, from impacts to adaptation (abstract) — with a rousing climate version of Let It Be. I caught up with him during the evening reception, but didn’t ask him to sing…

Sensitivity and consensus; theory and practice

97So Cook et al ((Yes, that Cook — the one from Skeptical Science and The Climate Show. Quantifying the consensus on anthropogenic global warming in the scientific literature, John Cook et al 2013 Environ. Res. Lett. 8 024024
doi:10.1088/1748-9326/8/2/024024)) confirms that there really is a consensus in climate science: 97% of the peer-reviewed literature over the last 20 years supports the fact that humans are responsible for the warming. It’s a solid result, confirming the earlier work of Oreskes and others, but its importance lies in the fact that public perceptions of that consensus lag behind reality. As John puts it:

Quite possibly the most important thing to communicate about climate change is that there is a 97% consensus amongst the scientific experts and scientific research that humans are causing global warming. Let’s spread the word and close the consensus gap.

Indeed. Count this as my small contribution. Meanwhile, another recent paper very nicely demonstrates that the existence of a consensus on the basic facts of warming does not mean that scientists have to agree about everything. Continue reading “Sensitivity and consensus; theory and practice”