WMO: Status of Atmospheric Greenhouse Gases

CO2 UPInstructors in climate change courses looking for the latest statistics on greenhouse gas emissions (including its implications for ocean acidification, the “other” CO2 problem) should check out the World Meteorological Organization’s September Greenhouse Gas Bulletin.
Among the primary findings in the Bulletin:

1. Total radiative forcing in the NOAA Annual Greenhouse Gas Index was 34% higher at the end of 2013 relative to 1750, with total radiative forcing of all long-lived greenhouse gases equivalent to 479ppm;
2. Carbon dioxide is responsible currently for 65% of radiative forcing by long-lived greenhouse gases, and 84% of the increase in radiative forcing in the past decade. Atmospheric concentrations of CO2 have risen 142% above pre-industrial levels, reaching a globally averaged atmospheric concentration of 396ppm at the end of 2013;

a. Recent increases in fossil fuel emissions can’t explain the inter-annual variability in carbon dioxide growth rates; it’s possible that this is attributable to changes in photosynthesis and respiration or amounts of biomass burning

3. Methane currently accounts for 17% of radiative forcing by long-live greenhouse gas forcing. Atmospheric concentrations reached 253% of pre-industrial levels in 2013 and rose from 1650ppb in the early 1980s to 1825ppb in 2013;
4. Chloroflourocarbons and minor halogenated gases contribute 12% to radiative forcing, with CFCs and most halons declining, while hydrocloroflurocarbons and hydrofluorocarbons are increasing at relatively high rates;
5. Nitrous oxide contributes 6% to radiative forcing, with concentrations reaching 325.9ppb in 2013, a 121% increase above pre-industrial levels;
6. In the context of ocean acidification:

a. Oceans are currently taking up approximately 4kgs. of carbon dioxide per person per day, a rate “unprecedented at least over the last 300 million years;”
b. Ocean surface pH has declined in recent years by an average rate of -0.0011 yr-1 to -0.0025 yr.-1

The report also includes some excellent diagrams for Power Point presentations, including plotting of radiative forcing, graphs of greenhouse gas growth rates and times series of surface seawater pH.

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