Cross‐regional prediction of long‐term trajectory of stream water DOC response to climate change

There is no scientific consensus about how dissolved organic carbon (DOC) in surface waters is regulated. Here we combine recent literature data from 49 catchments with detailed stream and catchment process information from nine well established research catchments at mid‐ to high latitudes to examine the question of how climate controls stream water DOC. We show for the first time that mean annual temperature (MAT) in the range from −3° to +10° C has a strong control over the regional stream water DOC concentration in catchments, with highest concentrations in areas ranging between 0° and +3° C MAT. Although relatively large deviations from this model occur for individual streams, catchment topography appears to explain much of this divergence. These findings suggest that the long‐term trajectory of stream water DOC response to climate change may be more predictable than previously thought. Key Points Stream DOC on a regional scale is controlled by mean annual temperature (MAT) Topography is important for DOC concentration as a secondary control Long‐term trajectory of stream water DOC to climate change is predictable