It is well known that the equilibration timescale for the isotopic ratios 13C/12C and 14C/12C in the ocean mixed layer is on the order of a decade, 2 orders of magnitude slower than for oxygen. Less widely appreciated is the fact that the equilibration timescale is quite sensitive to the speciation of dissolved inorganic carbon (DIC) in the mixed layer, scaling linearly with the ratio DIC/CO2, ...

A number of observational studies indicate that carbon sequestration by terrestrial ecosystems in a world with an atmosphere richer in carbon dioxide and a warmer climate depends on the interactions between the carbon and nitrogen cycles. However, most terrestrial ecosystem models being used in climate-change assessments do not take into account these interactions. Here we explore how carbon/ni...

Carbonate carbon (CC) represents an important fraction of atmospheric PM10 along with organic carbon (OC) and elemental carbon (EC), if specific sources (e.g. street abrasion, construction sites, desert dust) contribute to its composition. However, analytical methods for an easy and unambiguous determination of CC in atmospheric aerosols collected on filter matrices are scarce. We propose here ...

The amplitude of the CO(2) seasonal cycle at the Mauna Loa Observatory (MLO) increased from the early 1970s to the early 1990s but decreased thereafter despite continued warming over northern continents. Because of its location relative to the large-scale atmospheric circulation, the MLO receives mainly Eurasian air masses in the northern hemisphere (NH) winter but relatively more North America...

We develop a dynamic model to investigate the optimal time paths of carbon emissions, sequestration, and the carbon stock. We show that carbon sinks should be utilized as early as possible, and carbon flow into sinks should last until the atmospheric carbon concentration is stabilized. We rule out any cyclical patterns of carbon sequestration and release. We propose and assess three mechanisms ...