Researchers reconstruct a new history of ocean warming
PostedSep 4, 2020
Globally, average sea level has risen over the past several decades as ocean waters have warmed. While the ocean as a whole has absorbed a huge amount of heat from the warming atmosphere, ocean currents transport that heat differently across regions, contributing to significant regional variations in the amount of sea level change. Understanding changes in ocean heat content and the role of currents in shaping patterns of warming is critical to assessing current and future global and regional climate change, sea level rise, and coastal flooding risk.
Before the 1990s, however, most ocean temperature measurements were limited to the upper ocean (above 700m), presenting an incomplete picture of past ocean heat content. To help address this gap, researchers funded in part by NASA combined NOAA and NASA satellite and field data with a model of heat transport within the ocean to reconstruct patterns of ocean warming over the industrial era. Their method provides a global, full-depth estimate of ocean warming dating back to 1871.
The study also demonstrates that changes in heat transport by ocean circulation have produced significant regional variations in ocean heat content, and consequently, sea level rise. In particular, a stronger convergence of warm ocean currents in the Atlantic Ocean has contributed to the accelerated warming observed in the region over the past six decades. These findings show that analysis of ocean dynamics and circulation can help explain trends in ocean warming and sea level rise and yield clues about future climate and regional sea level change.
1 USGCRP, 2017: Climate Science Special Report: Fourth National Climate Assessment, Volume I. Wuebbles, D. J., D. W. Fahey, K. A. Hibbard, D. J. Dokken, B. C. Stewart, and T. K. Maycock, Eds. U.S. Global Change Research Program, Washington, DC, USA, 470 pp. https://doi.org/10.7930/J0J964J6
2 Zanna, L., Khatiwala, S., Gregory, J. M., Ison, J., & Heimbach, P. (2019). Global reconstruction of historical ocean heat storage and transport. Proceedings of the National Academy of Sciences, 116(4), 1126–1131. https://doi.org/10.1073/pnas.1808838115
Highlight Agency:Department of Commerce, National Aeronautics & Space Administration