Climate variability and change, their impacts on marine life and ecosystems

PAN, JERÓNIMO; MAENZA, REINALDO A.

Marine Biology: a functional approach to the oceans and their organisms

CRC Press/Taylor & Francis Group

Lugar: Boca Ratón, FL; Año: 2022; p. 349 - 373

1. Human activities related to agricultural and industrial development and based on fossil fuels have altered Earth?s subsystems and biogeochemical cycles, leading to a new geologic Epoch in the Quaternary, the Anthropocene.2. Climate change became a matter of interest to society only recently, despite the disregard of its importance and impacts from certain sectors. The current environmental agenda is based on Sustainable Development Goals. Global Climate Models are used to produce projections of the future climate under different scenarios.3. The climate system is made up of five subsystems, with coupling mechanisms represented by feedback processes between its components. Internal and external forcers produce changes in the climate system.4. The global atmospheric circulation transfers heat from tropical to polar regions; it is made up of the Hadley, Ferrel and polar circulation cells. At low levels in the troposphere, the descending branches of each one of these cells create the trade, westerlies and easterly polar winds.5. Variations in Earth?s orbital parameters (eccentricity, obliquity and precession), known as Milankovitch cycles, are an example of external astronomical forcers responsible for the alternation of glacial and interglacial periods.6. El Niño-Southern Oscillation (ENSO) is an example of the variability in atmospheric circulation and ocean-atmosphere interactions; it comprises three phases: El Niño (large-scale warming of surface waters in the central-east equatorial Pacific), La Niña (surface cooling) and a normal phase.7. The depletion of stratospheric O3 promotes a radiative imbalance with an increase in short-wave UV radiation; exposure to UV elicits different responses in marine organisms.8. The anthropic alteration of the concentrations of greenhouse gases (GHGs: CO2, methane, and NO2) results in a greater retention of long-wave energy, producing the recent global warming. The average air temperature increased globally by 1°C in relation to pre-industrial values. In the oceans, this has manifested as increased surface thermal stratification, and focalized, steep SST rise (marine heatwaves).9. In marine ecosystems, warming has impacted the distribution range of organisms, led to temperature and stratification-induced changes in phytoplankton, and altered the phenology of marine communities.10. The rate of CO2 absorption by seawater is currently high in relation to the supply of carbonate ions, resulting in a decreasing pH trend (ocean acidification), which affects marine organisms differentially. Seaweed physiology might contribute to the modulation of seawater pH at local scales.11. The biological pump and Blue Carbon ecosystems have been regarded as natural mechanisms/environments to effectively trap excess atmospheric CO2, and palliate the effects of climate change.