15:45 〜 16:00
[ACG35-08] Future changes in the vertical structure of temperature extremes may reshape marine biome dynamics
★Invited Papers
The vertical structure of ocean temperature extremes (1st and 99th quantiles) is an important driver for marine ecosystems, shaping the vertical extension of marine biomes through the thermal tolerance for marine species. However, our understanding of the physical mechanisms behind the fluctuations in ocean temperature extremes is limited to the ocean surface. The lack of global-scale high-frequency observations and model outputs prevents a thorough investigation of those fluctuations across the water column over recent years and of their future evolution in response to climate change.
Here, we use long-term (>8 years) high-frequency (daily) high-quality in situ measurements of temperature across the water column at several locations of the world ocean extracted from the Ocean Sites (OS) network to assess the performance of the Earth System model CNRM-ESM2-1 at simulating extremes in ocean temperature across the water column. Model future projections under the ssp585 high-emission scenario are further explored using the Time of Emergence (ToE) metrics, which determine the timing at which changes in the extremes of ocean temperature exceed the magnitude of the natural variability. Comparisons between observed and modelled trends in ocean daily temperature extremes help to assess the level of reliability of the predicted ToE for those ecosystem drivers. Such comparisons inform us on when and where marine ecosystems are likely to be threatened by climate change. Our results show that the ToE for the extremes in sea surface temperature across selected OS locations ranges from year 2015 to 2090, while ToE for ocean temperature extremes at subsurface (~100 m) ranges from year 2024 to 2100. Therefore, our study suggests there is a need to account for differences in the emergence of alterations in extreme temperatures in the vertical layers to predict changes on marine biome dynamics.
Here, we use long-term (>8 years) high-frequency (daily) high-quality in situ measurements of temperature across the water column at several locations of the world ocean extracted from the Ocean Sites (OS) network to assess the performance of the Earth System model CNRM-ESM2-1 at simulating extremes in ocean temperature across the water column. Model future projections under the ssp585 high-emission scenario are further explored using the Time of Emergence (ToE) metrics, which determine the timing at which changes in the extremes of ocean temperature exceed the magnitude of the natural variability. Comparisons between observed and modelled trends in ocean daily temperature extremes help to assess the level of reliability of the predicted ToE for those ecosystem drivers. Such comparisons inform us on when and where marine ecosystems are likely to be threatened by climate change. Our results show that the ToE for the extremes in sea surface temperature across selected OS locations ranges from year 2015 to 2090, while ToE for ocean temperature extremes at subsurface (~100 m) ranges from year 2024 to 2100. Therefore, our study suggests there is a need to account for differences in the emergence of alterations in extreme temperatures in the vertical layers to predict changes on marine biome dynamics.