Old Scientist
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Comments by "Old Scientist" (@OldScientist) on "How scientists are hoping to save our coral reefs - The Climate Question podcast, BBC World Service" video.
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As regards ocean acidification, it is estimated that the ocean’s global mean surface pH may have declined (i.e., become less alkaline and thus more “acidic”) by -0.07 to -0.08 in the last 200 years — from pH8.12 during pre-industrial times to 8.04 to 8.05 today (Wei et al, 2015). N.B. The decline in pH occurred before 1930.
However, and very importantly when you look the data after CO2 emissions began rising precipitously in the 1930s, the oceans have become less “acidic”!!!
By way of comparison, from one season to the next, or over the course of less than 6 months, pH levels naturally change by ±0.15 pH units, or twice the overall rate of the last 200 years. On a per-decade scale, the changes are even more pronounced. Oceanic pH values naturally fluctuate up and down by up to 0.6 U within a span of a decade, with an overall range between 7.66 and 8.40. This decadal rate of pH change is larger than the overall 200-year span (0.07-0.08) by a factor of 8. Indeed the daily noted maximum pH range of 0.7 (Santos et al. 2011) is far greater than the overall change predicted between now and the end of the century.
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