Climate-induced drivers fluctuate on time scales ranging from diurnal to annual, with potential consequences for organismal responses , but these fluctuations are commonly not incorporated experimentally. Experiments that simulate natural fluctuations in drivers, especially beyond tidal or diel cycles, can result in more detrimental impacts than those based on quasi-constant conditions , but can also ameliorate effects , confirming that the influence of environmental variability requires evaluation . Marine heatwaves exacerbate the impacts of rising mean temperatures, with major ecological consequences  . Higher temperature variability decreased phytoplankton growth and calcification in Emiliania huxleyi relative to a stable warming regime . Diel fluctuations  in carbonate chemistry superimposed on current and future pCO2 levels influenced diatom species differently, depending on their habitat . CO2 fluctuations overlaid on changing mean values also altered phenotypic evolutionary outcomes of picoeukaryotic algae . In the bivalve Mytilus edulis, fluctuating pH regimes exerted higher metabolic costs , while salinity fluctuations might be more influential than pH fluctuations in other bivalves . The amplitude of diel and seasonal pH and CO2 changes are projected to increase in the future due to lowered CO2 seawater buffering capacity  , which can impose additional stress on organisms.
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report