Marine Heatwaves
Overview
Marine heatwaves (MHWs) are periods of extreme warm ocean temperature that persist for days to months, extend over thousands of kilometers, and penetrate multiple hundreds of meters into the deep ocean[1]. These events have significant impacts on marine ecosystems, as well as on physical and human system. (Figure 1).
Marine heatwaves have become an urgent issue regarding climate risks du due to their increase in frequency, duration, magnitude, and spatial extent. The number of MHW days has doubled between 1982 and 2016[2], and they have become more longer-lasting, more intense, and more extensive -- 8 of the 10 most severe recorded events have taken place in the past decade[3]. MHWs are projected to further increase with global warming. Climate models project increases in the frequency of marine heatwaves by 2081-2100, relative to 1850–1900, by approximately 50 times under RCP8.5 and 20 times under RCP2.6. The intensity of marine heatwaves is projected to increase about 10-fold under RCP8.5 by 2081–2100, relative to 1850–1900[1].
Data
Definition of MHW: Our group developed a definition of MHWs (Hobday et al. 2016), which has been widely adopted by researchers and other users. A MHW is defined as a period when seawater temperatures exceed a seasonally-varying threshold (usually the 90th percentile) for at least 5 consecutive days. Successive events with gaps of 2 days or less are considered part of the same MHW. In a subsequent study (Hobday et al. 2018) we extended the definition to introduce categories of severity, based on multiples of the threshold being exceeded. [4]
Historical:
Observations: MHW tracker:
past events of California MHW: https://www.integratedecosystemassessment.noaa.gov/regions/california-current/california-current-marine-heatwave-tracker-blobtracker
SST Datasets at PSL[5]
- NOAA OI SST Daily High Resolution. From 1982, a gridded high resolution daily dataset from NOAA that continues to present.
- NOAA ERSST V5 From 1865, a gridded consistently analyzed monthly dataset from NOAA that continues to present. V3 and V4 are also available
- COBE SST
- COBE-2 SST
- ICOADS
- Kaplan SST
- NOAA OI V2
- NODC 1994 and 1998 atlasses
Forecast:
- ↑ 1.0 1.1 Collins M., M. Sutherland, L. Bouwer, S.-M. Cheong, T. Frölicher, H. Jacot Des Combes, M. Koll Roxy, I. Losada, K. McInnes, B. Ratter, E. Rivera-Arriaga, R.D. Susanto, D. Swingedouw, and L. Tibig, 2019: Extremes, Abrupt Changes and Managing Risk. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate [H.-O. Pörtner, D.C. Roberts, V. Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, A. Alegría, M. Nicolai, A. Okem, J. Petzold, B. Rama, N.M. Weyer (eds.)]. Cambridge University Press, Cambridge, UK and New York, NY, USA, pp. 589-655. https://doi.org/10.1017/9781009157964.008.
- ↑ Frölicher, T.L., Fischer, E.M. & Gruber, N. Marine heatwaves under global warming. Nature 560, 360–364 (2018). https://doi.org/10.1038/s41586-018-0383-9
- ↑ Smith, Kathryn E., et al. "Socioeconomic impacts of marine heatwaves: Global issues and opportunities." Science 374.6566 (2021): eabj3593.
- ↑ https://www.marineheatwaves.org/mhw-overview.html
- ↑ https://psl.noaa.gov/marine-heatwaves/#