Challenges in Quantifying Changes in the Global Water Cycle

TitleChallenges in Quantifying Changes in the Global Water Cycle
Publication TypeJournal Article
Year of Publication2015
AuthorsHegerl, Gabriele C., Black Emily, Allan Richard P., Ingram William J., Polson Debbie, Trenberth Kevin E., Chadwick Robin S., Arkin Phillip A., Sarojini Beena Balan, Becker Andreas, Dai Aiguo, Durack Paul J., Easterling David, Fowler Hayley J., Kendon Elizabeth J., Huffman George J., Liu Chunlei, Marsh Robert, New Mark, Osborn Timothy J., Skliris Nikolaos, Stott Peter A., Vidale Pier-Luigi, Wijffels Susan E., Wilcox Laura J., Willett Kate M., and Zhang Zuebin
JournalBulletin of the American Meteorological Society
Volume96
Number6
Pages1097-1115
Date Published07/2015
Abstract / Summary

Human influences have likely already impacted the large-scale water cycle but natural variability and observational uncertainty are substantial. It is essential to maintain and improve observational capabilities to better characterize changes.

Understanding observed changes to the global water cycle is key to predicting future climate changes and their impacts. While many datasets document crucial variables such as precipitation, ocean salinity, runoff, and humidity, most are uncertain for determining long-term changes. In situ networks provide long time-series over land but are sparse in many regions, particularly the tropics. Satellite and reanalysis datasets provide global coverage, but their long-term stability is lacking. However, comparisons of changes among related variables can give insights into the robustness of observed changes. For example, ocean salinity, interpreted with an understanding of ocean processes, can help cross-validate precipitation. Observational evidence for human influences on the water cycle is emerging, but uncertainties resulting from internal variability and observational errors are too large to determine whether the observed and simulated changes are consistent. Improvements to the in situ and satellite observing networks that monitor the changing water cycle are required, yet continued data coverage is threatened by funding reductions. Uncertainty both in the role of anthropogenic aerosols, and due to large climate variability presently limits confidence in attribution of observed changes.

URLhttp://doi.org/10.1175/BAMS-D-13-00212.1
DOI10.1175/BAMS-D-13-00212.1
Journal: Bulletin of the American Meteorological Society
Year of Publication: 2015
Volume: 96
Number: 6
Pages: 1097-1115
Date Published: 07/2015

Human influences have likely already impacted the large-scale water cycle but natural variability and observational uncertainty are substantial. It is essential to maintain and improve observational capabilities to better characterize changes.

Understanding observed changes to the global water cycle is key to predicting future climate changes and their impacts. While many datasets document crucial variables such as precipitation, ocean salinity, runoff, and humidity, most are uncertain for determining long-term changes. In situ networks provide long time-series over land but are sparse in many regions, particularly the tropics. Satellite and reanalysis datasets provide global coverage, but their long-term stability is lacking. However, comparisons of changes among related variables can give insights into the robustness of observed changes. For example, ocean salinity, interpreted with an understanding of ocean processes, can help cross-validate precipitation. Observational evidence for human influences on the water cycle is emerging, but uncertainties resulting from internal variability and observational errors are too large to determine whether the observed and simulated changes are consistent. Improvements to the in situ and satellite observing networks that monitor the changing water cycle are required, yet continued data coverage is threatened by funding reductions. Uncertainty both in the role of anthropogenic aerosols, and due to large climate variability presently limits confidence in attribution of observed changes.

DOI: 10.1175/BAMS-D-13-00212.1
Citation:
Hegerl, GC, E Black, RP Allan, WJ Ingram, D Polson, KE Trenberth, RS Chadwick, PA Arkin, BB Sarojini, A Becker, A Dai, PJ Durack, D Easterling, HJ Fowler, EJ Kendon, GJ Huffman, C Liu, R Marsh, M New, TJ Osborn, N Skliris, PA Stott, P Vidale, SE Wijffels, LJ Wilcox, KM Willett, and Z Zhang.  2015.  "Challenges in Quantifying Changes in the Global Water Cycle."  Bulletin of the American Meteorological Society 96(6): 1097-1115, pp. 1097-1115.  https://doi.org/10.1175/BAMS-D-13-00212.1.