Feb 2, 2012

Near-Surface Salinity as Nature’s Rain Gauge to Detect Human Influence on the Tropical Water Cycle

Laurent Terray and Lola Corre
AMS Journal of Climate
  • States that changes in the global water cycle are expected as a result of anthropogenic climate change, but large uncertainties exist in how these changes will be manifest regionally, especially the case over the tropical oceans
  • States one approach is to examine changes in near-surface salinity
  • Uses datasets of observed tropical Pacific and Atlantic near-surface salinity combined with climate model simulations to assess the possible causes and significance of salinity changes over the late twentieth century
  • Applies two different detection methodologies to evaluate the extent to which observed large-scale changes in near-surface salinity can be attributed to anthropogenic climate change.
  • Shows that basin-averaged observed changes enhance salinity geographical contrasts between the two basins: the Pacific is getting fresher and the Atlantic saltier
  • Finds that while the observed Pacific and interbasin-averaged salinity changes exceed the range of internal variability provided from control climate simulations, Atlantic changes are within the model estimates
  • Finds that spatial patterns of salinity change, including a fresher western Pacific warm pool and a saltier subtropical North Atlantic, are not consistent with internal climate variability, but are similar to anthropogenic response patterns obtained from transient twentieth- and twenty-first-century integrations, therefore suggesting a discernible human influence on the late twentieth-century evolution of the tropical marine water cycle
  • Finds that changes in the tropical and midlatitudes Atlantic salinity levels are not significant compared to internal variability