Timothy P. Whorf

Atmospheric Carbon Dioxide, the Southern Oscillation, and the Weak 1975 El Niño

The observed rate of change of the atmospheric carbon dioxide concentration at the South Pole, Fanning Island, Hawaii, and ocean weather station P correlates with an index of the southern oscillation and with El Ni�o occurrences. There are changes at all four stations that seem to be in response to the weak 1975 El Ni�o. Thus, even poorly developed El Ni�o events may affect the atmospheric carbon dioxide concentration.

Evolution of natural and anthropogenic fluxes of atmospheric CO2 from 1957 to 2003

An analysis is carried out of the longest available records of atmospheric CO 2 and its 13 C/ 12 C ratio from the Scripps Institution of Oceanography network of fixed stations, augmented by data in the 1950s and 1960s from ships and ice floes. Using regression analysis, we separate the interhemispheric gradients of CO 2 and 13 C/ 12 C into: (1) a stationary (possibly natural) component that is constant with time, and (2) a time-evolving component that increases in proportion to fossil fuel emissions. Inverse calculations using an atmospheric transport model are used to interpret the components of the gradients in terms of land and ocean sinks. The stationary gradients in CO 2 and 13 C/ 12 C are both satisfactorily explained by ocean processes, including an ocean carbon loop that transports 0.5 PgC yr -1 southwards in the ocean balanced by an atmospheric return flow. A stationary northern land sink appears to be ruled out unless its effect on the gradient has been offset by a strong rectifier effect, which seems doubtful. A growing northern land sink is not ruled out, but has an uncertain magnitude (0.3–1.7 PgC yr -1 centred on year 2003) dependent on the rate at which CO 2 from fossil fuel burning is dispersed vertically and between hemispheres. DOI: 10.1111/j.1600-0889.2010.00507.x