Atmospheric CO2 Not So Scary - Wheel Out Ocean 'Acidification'

There are two articles of interest from a climate point of view in this week's Science magazine. The first is entitled: 'Large and Rapid Melt-Induced Velocity Changes in the Ablation Zone of the Greenland Ice Sheet' by R. S. W. van de Wal et al.

The Abstract states:

Continuous Global Positioning System observations reveal rapid and large ice velocity fluctuations in the western ablation zone of the Greenland Ice Sheet. Within days, ice velocity reacts to increased meltwater production and increases by a factor of 4. Such a response is much stronger and much faster than previously reported. Over a longer period of 17 years, annual ice velocities have decreased slightly, which suggests that the englacial hydraulic system adjusts constantly to the variable meltwater input, which results in a more or less constant ice flux over the years. The positive-feedback mechanism between melt rate and ice velocity appears to be a seasonal process that may have only a limited effect on the response of the ice sheet to climate warming over the next decades.

The report concludes:

Longer observational records with high temporal resolution in other ablation areas of the ice sheet are necessary to test the importance of the positive-feedback mechanism between melt rates and ice velocities. At present, we cannot conclude that this feedback is important. We do see a significant increase of the ablation rate (Fig. 2), which is likely related to climate warming, but it remains to be seen if this is likely to be amplified by increasing annual ice velocities.

Moving on to Perspectives, Oceans: Carbon Emissions and Acidification by Richard E. Zeebe et al:

Much of the scientific and public focus on anthropogenic carbon dioxide (CO2) emissions has been on climate impacts. Emission targets have been suggested based primarily on arguments for preventing climate from shifting significantly from its preindustrial state. However, recent studies underline a second major impact of carbon emissions: ocean acidification. Over the past 200 years, the oceans have taken up ~40% of the anthropogenic CO2 emissions. This uptake slows the rise in atmospheric CO2 considerably, thus alleviating climate change caused by anthropogenic greenhouse gas emissions. But it also alters ocean chemistry, with potentially serious consequences for marine life.

The authors conclude:

To monitor and quantify future changes in ocean chemistry and biogeochemical fluxes, intensified global-ocean carbon dioxide surveys in combination with carbon-cycle modeling will be necessary. Awareness must be raised among the public and policy-makers of the effects of ocean acidification and the steps required to control it. Ocean chemistry changes, and not only climate effects, should be taken into consideration when determining CO2 emission targets; such consideration is likely to weigh in favor of lower emission targets.

Meanwhile, join the red dots between the dates of James Hansen's testimony to Congress in June 1988 and June 2008 - see if you can spot a tipping point:

Figure lifted from Climate Audit.