Tuesday, December 15, 2009

Environmental change happening faster than predicted

A consistent theme that has emerged in science-based presentations in Copenhagen is that the rates of environmental change that have been observed over the last decade exceed the upper boundaries of those predicted by models. Perhaps fundamentally is that atmospheric CO2 concentrations have been increasing at rates beyond the business-as-usual trajectory, which is commonly taken to be the upper boundary of development pathways.

Observations of oceans, for example - as described by head NOAA administrator Jane Lubchenco this morning, show that their heat content is accelerating. The annual appearance of hypoxic zones in the most productive parts of the oceans (such as off the California and South American coasts) has been unprecedented over the last 8 years – with as much as 2/3 of the water column depleted of oxygen, with severe impacts (mortality) propagating through the food web. Expansion of low productivity zones, especially in the western equatorial Pacific, has grown 15%. And ocean acidification (see earlier post) is rapidly emerging as a new “surprise” not considered much in understanding of greenhouse gas impacts just a few years ago. Conversely, the uptake of CO2 by the oceans has slowed over the past decade – bad news because up until now ¼ of carbon emissions have been removed from the atmosphere by the oceans (another ¼ by terrestrial ecosystems). This disrupts the assumptions the negotiators are working with when translating the quantity of emissions to atmospheric CO2 concentrations.

The evidence that Lubchenco and Scott Doney (Woods Hole) presented this morning point to fundamental changes in environmental processes – specifically the patterns of circulation of the atmosphere and ocean, that produce consequences like reduced upwelling in productive zones, or in the case of the accelerating circumpolar winds around Antarctica, drawing CO2 up from the deep ocean, and actually venting it to the atmosphere there.

The presentations by US scientists over the past week are clearly at the forefront of global understanding of environmental change – and most of them are alarming, with the alarms becoming even louder. It’s therefore extremely disheartening to see US policy and public opinion at the other end of the global spectrum – dragging far behind the consensus.

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