Understanding Global Climate Change
Ocean Acidification, Ocean Temperature

http://edu-observatory.org/olli/Climate/Week2.html



IPCC Special Report on the
Ocean and Cryosphere in a Changing Climate (SROCC)
  https://www.ipcc.ch/srocc/
  https://www.ipcc.ch/srocc/chapter/chapter-5/

  The ocean is continuing to acidify in response to ongoing
  ocean carbon uptake. The open ocean surface water pH is
  observed to be declining (virtually certain) by a very
  likely range of 0.017-0.027 pH units per decade since the
  late 1980s across individual time series observations longer
  than 15 years. The anthropogenic pH signal is very likely to
  have emerged for three-quarters of the near-surface open
  ocean prior to 1950 and it is very likely that over 95% of
  the near surface open ocean has already been affected. These
  changes in pH have reduced the stability of mineral forms of
  calcium carbonate due to a lowering of carbonate ion
  concentrations, most notably in the upwelling and
  high-latitude regions of the ocean.

  There is a growing consensus that the open ocean is losing
  oxygen overall with a very likely loss of 0.5-3.3% between
  1970-2010 from the ocean surface to 1000 m (medium
  confidence). Globally, the oxygen loss due to warming is
  reinforced by other processes associated with ocean physics
  and biogeochemistry, which cause the majority of the
  observed oxygen decline (high confidence). The oxygen
  minimum zones (OMZs) are expanding by a very likely range of
  3-8%, most notably in the tropical oceans, but there is
  substantial decadal variability that affects the attribution
  of the overall oxygen declines to human activity in tropical
  regions (high confidence).






Ocean Acidification (Wikipedia) https://en.wikipedia.org/wiki/Ocean_acidification Of the extra carbon dioxide added into the oceans, some remains as dissolved carbon dioxide, while the rest contributes towards making additional bicarbonate (HCO3-) (and additional carbonic acid). This also increases the concentration of hydrogen ions. Many ocean plants and animals build shells and skeletons out of two chemicals that exist in seawater, calcium and carbonate. Organisms combine calcium and carbonate to form hard shells and skeletons out of the mineral calcium carbonate. Therefore, the plants and animals that use calcium carbonate for structure and protection are called calcifying organisms. Increased acidity slows the growth of calcium carbonate structures, and under severe conditions, can dissolve structures faster than they form. Changes in ocean chemistry can have extensive direct and indirect effects on organisms and their habitats. One of the most important repercussions of increasing ocean acidity relates to the production of shells and plates out of calcium carbonate (CaCO3). This process is called calcification and is important to the biology and survival of a wide range of marine organisms. Calcification involves the precipitation of dissolved ions into solid CaCO3 structures. After they are formed, such structures are vulnerable to dissolution unless the surrounding seawater contains saturating concentrations of carbonate ions (CO32-). 2010 TED Talk (18+ Minutes) Rob Dunbar: Discovering Ancient Climates in Oceans and Ice https://www.ted.com/talks/rob_dunbar_discovering_ancient_climates_in_oceans_and_ice https://www.youtube.com/watch?v=evfgbVjb688 Rob Dunbar hunts for data on our climate from 12,000 years ago, finding clues inside ancient seabeds and corals and inside ice sheets. His work is vital in setting baselines for fixing our current climate -- and in tracking the rise of deadly ocean acidification.

Warming Oceans can't hold as much Oxygen NOVA scienceNOW | Mass Extinction (6- Min) NOVA scienceNOW: Mass Extinction from 2006 https://www.pbs.org/wgbh/nova/teachers/viewing/3318_01_nsn.html Host Neil deGrasse Tyson joins a team of investigators hot on the trail of a mass murderer--one that knocked off its victims 252 million years ago when it wiped out the majority of life on our planet. Hydrogen Sulfide (H2S) Toxicity Mass Extinction in Earth's Oceans Could Begin by 2100 https://www.scientificamerican.com/article/mass-extinction-in-earth-rsquo-s-oceans-could-begin-by-2100/ The amount of carbon in our planet's oceans has varied slowly over the ages. But 31 times in the past 542 million years the carbon level has deviated either much more than normal or much faster than usual. Each of the five great mass extinctions occurred during the same time as the most extreme carbon events. In each case, more than 75 percent of marine animal species vanished. Earth may enter a similar danger zone soon. Five [Clinate Related] Mass Extinctions (excludes the Cretaceous-Tertiary Mass Extinction due to impact) https://phys.org/news/2017-06-mass-extinctionsand-planet-today.html The Late Permian mass extinction around 252m years ago dwarfs all the other events, with about 96% of species becoming extinct. This included more trilobites, corals, and whole branches of species of terrestrial animals. The extinction was triggered by a vast eruption of the Siberian Traps, a gigantic and prolonged volcanic event that covered much of modern day Siberia, which led to a cascade of environmental effects. A greenhouse effect rapidly took hold in the atmosphere, while the oceans suffered acidification and oxygen depletion. The ozone layer was partially destroyed, meaning lethal levels of UV radiation reached the Earth's surface. The recovery took almost 10m years and even then, the unstable environment this catastrophic crisis created meant the subsequent Triassic period saw intermittent bursts of heightened extinction. So, are we currently in the middle of a mass extinction? If we really are, this time the cause is not a meteorite impact or volcanic eruptions. It is the work of a single species: Homo sapiens. Habitat destruction and climate change from rising carbon dioxide levels has driven extinction rates to levels reminiscent of the mass extinctions of the ancient past. The similarities between today and the past are uncanny. The majority of past extinctions are associated with carbon dioxide from volcanoes causing rapid global warming, which led to a number of environmental cascade effects. The cause may be different, but the results will be the same. sam.wormley@gmail.com