Fall in San Francisco: Jim Renwick’s AGU report

Jim RenwickI took part in the 2015 AGU Fall Meeting, held at the vast Moscone Center in San Francisco, 14-18 December. As always, it was an absolute cornucopia of everything to do with the Geo/Earth Sciences, from exoplanets to the earth’s core to climate change and science policy, delivered by over 20,000 geoscientists. The Fall Meeting is always a blast, a real mind-expander.

This year, I was committed to chairing sessions first thing on Monday morning and then again on Friday. Monday’s session was “Evaluating Reanalysis: What Can We Learn about Past Weather and Climate?” with my sub-session having a focus on polar regions. The Thu/Fri session was “Precipitation over Mountainous Terrain: Observations, Understanding, Modeling, and Future Prospects”. In between, I soaked up as much as I could, wandering the halls to hear and see fascinating presentations on climate history, science communication, sea ice, and designing climate change musicals for primary school children. Here’s a few highlights, my personal “tip of the iceberg” from this year’s meeting.
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The Climate Show #31: Doha! Doha! Doha!

It’s the run up to Christmas, and the annual ritual repeats. Diplomats gather in Doha to discuss and debate action on climate change, so Glenn and Gareth talk to their correspondent on the spot, New Zealand climate media strategist Cindy Baxter to find out what’s happening in the oil kingdom’s echoing halls. At the Fall AGU meeting in San Francisco, NOAA has published its 2012 Arctic Report Card (grim reading, it has to be said). Plus Gareth talks about truffles as a bellwether for Europe’s changing climate, and the boys get all enthusiastic about nanophotonics and steampunk.

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Arctic records tumble as ice melts: 2012 Arctic report card released at AGU

The latest Arctic Report Card was published yesterday at the American Geophysical Union’s Fall Meeting in San Francisco, and it makes grim reading. Apart from last summer’s new record low sea ice minimum, all the indicators of warming are pointing in the wrong direction. The Arctic is making a rapid transition to a new climate state. Highlights of the report (from the press release):

  • Snow cover: A new record low snow extent for the Northern Hemisphere was set in June 2012, and a new record low was reached in May over Eurasia.
  • Sea ice: Minimum Arctic sea ice extent in September 2012 set a new all-time record low.
  • Greenland ice sheet: There was a rare, nearly ice sheet-wide melt event on the Greenland ice sheet in July, covering about 97 percent of the ice sheet on a single day.
  • Vegetation: The tundra is getting greener and there’s more above-ground growth. During the period of 2003-2010, the length of the growing season increased through much of the Arctic.
  • Wildlife & food chain: In northernmost Europe, the Arctic fox is close to extinction and vulnerable to the encroaching Red fox. Massive phytoplankton blooms below the summer sea ice suggest that earlier estimates of biological production at the bottom of the marine food chain may have been ten times lower than was occurring.
  • Ocean: Sea surface temperatures in summer continue to be warmer than the long-term average at the growing ice-free margins, while upper ocean temperature and salinity show significant interannual variability with no clear trends.
  • Weather: Most of the notable weather activity in fall and winter occurred in the sub-Arctic due to a strong positive North Atlantic Oscillation, expressed as the atmospheric pressure difference between weather stations in the Azores and Iceland. There were three extreme weather events including an unusual cold spell in late January to early February 2012 across Eurasia, and two record storms characterized by very low central pressures and strong winds near western Alaska in November 2011 and north of Alaska in August 2012.

It’s well worth digging down beyond the executive summary to look at the individual reports for key elements in the Arctic — there’s a lot of detail to digest, all of it fascinating, much of it sobering, if not downright scary. This is rapid climate change, happening now. I wonder if anyone in Doha will notice?

A ton too far (more bad news)

At the Climate Futures Forum in Wellington a couple of weeks ago, David Karoly discussed the idea of considering carbon emissions as a “stock” problem, not a “flow” problem. If we want to give ourselves a 75 percent chance of coming in below a 2ºC rise in the global average temperature, then we (as in all humanity) can emit around one trillion tonnes of CO2 (for more see Meinshausen et al here, discussed in the context of emissions targets at HT in this post). It doesn’t much matter when we do the emitting, because CO2 hangs around in the atmosphere for a long time, but stick to that limit we must if we’re serious about avoiding damaging warming. I like that way of thinking about the issue, as I noted in my report on the Forum, but it seems that I may have been rather optimistic about the height of the ceiling we’re living under, and our chances of hitting a 2ºC target. A new study by a team of Canadian climate modellers, Arora et al, Carbon emission limits required to satisfy future representative concentration pathways of greenhouse gases in Geophysical Research Letters, 38 (5) DOI: 10.1029/2010GL046270 (pdf here), suggests that:

…we have already surpassed the cumulative emission limit and so emissions must ramp down to zero immediately. The unprecedented reduction in fossil‐fuel emissions implied by either of these scenarios suggests that it is unlikely that warming can be limited to the 2°C target agreed to in the 2009 Copenhagen Accord.

Bugger.

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The Climate Show #4: Peter Gleick, the AGU, and climate sensitivity

Our last show for 2010, and it’s over an hour of podcast/video goodness: featuring Peter H Gleick of the Pacific Institute discussing the news from the Fall AGU conference in San Francisco last week, John Cook discussing how we work out how sensitive the climate system is to the addition of heat, plus a roundup on Cancun, how French vignerons are looking to old vines to help them adapt to a warming climate, and London’s black cabs set to go electric.

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Show notes below the fold.

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