text: The geologic component of the carbon cycle operates slowly in comparison to the other parts of the global carbon cycle. It is one of the most important determinants of the amount of carbon in the atmosphere, and thus of global temperatures.
  As the biological pump plays an important role in the Earths carbon cycle, significant effort is spent quantifying its strength.  However, because they occur as a result of poorly constrained ecological interactions usually at depth, the processes that form the biological pump are difficult to measure.  A common method is to estimate primary production fuelled by nitrate and ammonium as these nutrients have different sources that are related to the remineralisation of sinking material.  From these it is possible to derive the so-called f-ratio, a proxy for the local strength of the biological pump.  Applying the results of local studies to the global scale is complicated by the role the oceans circulation plays in different ocean regions.