In contrast, the anthropogenic signal in phytoplankton community structure, which has a lower natural variability, will emerge under RCP8.5 across 63% of the ocean by 2100 when two standard deviations are used (limited evidence) (Dutkiewicz et al., 2019).Table 3.21 | Summary of previous IPCC assessments of observed and projected abrupt ecosystem shifts and extreme events Observations Projections AR5 (Wong et al., 2014) Observations of abrupt ecosystem shifts and extreme events were not assessed in this report.‘Warming and acidification will lead to coral bleaching, mortality, and decreased constructional ability