A substantial portion of the rising atmospheric carbon dioxide dissolves into the ocean and increases ocean acidity. The effects this acidification will have on marine organisms is a topic of research. One researcher at UC Merced finds slight acidification changes caused substantial reduction in nitrogen metabolism by microbes in the oceans.
“Microbial nitrification rates decreased in every instance when pH was experimentally reduced at multiple locations in the Atlantic and Pacific oceans,” wrote researchers led by University of California, Merced, biogeochemist J. Michael Beman in the Dec. 21 Proceedings of the National Academy of Sciences. “Our results suggest that ocean acidification could reduce nitrification rates by 3 to 44 percent within the next few decades … fundamentally altering nitrogen cycling in the sea.”
That's not good. Via our fossil fuels burning we are conducting a massive real life experiment on ocean acidity. This is the aspect of rising CO2 emissions that worries me most. We can always find ways to quickly and cheaply cool the planet. But if more CO2 dissolved in the oceans will cause big shifts in marine ecosystems it is hard to see how to reverse it quickly.
Ocean acidification is a bigger problem than global warming because we can turn the planet into an ice box for cheap. Push comes to shove we can cool the planet to prevent the melting of Greenland and Antarctica. But higher CO2 concentrations will dissolve into the oceans and continue to increase their acidity. Some U Southampton researchers took a look at scenarios for CO2 emissions and ocean acidification.
Emissions of carbon dioxide are causing ocean acidification as well as global warming. Scientists have previously used computer simulations to quantify how curbing of carbon dioxide emissions would mitigate climate impacts. New computer simulations have now examined the likely effects of mitigation scenarios on ocean acidification trends. They show that both the peak year of emissions and post-peak reduction rates influence how much ocean acidity increases by 2100. Changes in ocean pH over subsequent centuries will depend on how much the rate of carbon dioxide emissions can be reduced in the longer term.
Corals are often brought up in discussions about the damage that higher acidity might cause.
“The oceans absorb around a third of carbon dioxide emissions, which helps limit global warming, but uptake of carbon dioxide by the oceans also increases their acidity, with potentially harmful effects on calcifying organisms such as corals and the ecosystems that they support,” explained Dr Toby Tyrrell of the University of Southampton’s School of Ocean and Earth Science (SOES) based at the National Oceanography Centre, Southampton.
But the ocean is a big place with lots of organisms. The biggest problems might show up with other organisms and food chains.
We've already moved the needle on ocean acidity. But changes in the next 100 years could be even bigger.
Global mean ocean surface pH has already decreased from around 8.2 in 1750 to 8.1 today (remember than a decrease in pH corresponds to an increase in acidity). The simulations suggest that global mean ocean pH could fall to between 7.7 and 7.8 by 2100 if carbon dioxide emissions are not controlled.
“As far as we know, such a rate of change would be without precedent for millions of years, and a concern must be whether and how quickly organisms could adapt to such a rate of change after such a long period of relative stability in ocean pH,” said Tyrrell.
However, if an aggressive emissions control scenario can be adopted, with emissions peaking in 2016 and reducing by 5% per year thereafter, the simulations suggest that mean surface ocean pH is unlikely to fall below 8.0 by 2100. But even that represents a large change in pH since the pre-industrial era.
The only aggressive emissions control scenario I see on the horizon will come as world oil production goes into decline. CO2 emissions from coal will continue to grow until another electric power source becomes cheaper than coal electric power
I watch for ideas for preventing ocean acidification in the presence of high atmospheric concentrations of CO2.