ESA Says Earth-Observing Spacecraft Crucial To Track Oceans’ Increasing Acidification

The same week that the U.N. World Meteorological Organization announced that greenhouse gas concentrations in earth’s atmosphere had reached yet another high, the European Space Agency (ESA) also announced that it’s now possible to effectively monitor global ocean acidification levels on a global scale.

Although ocean temperatures are important and often steal the climate change headlines, acidification in the world’s oceans is arguably an even larger threat to our planet’s environmental health than sea level rise. 

“Acidification, resulting from the ocean uptake of Carbon Dioxide (CO2) in dissolved form, has in some quarters been referred to as “climate change’s evil twin,” Mark Drinkwater, Head of ESA’S Earth and Mission Science Division, told me.

The rise in atmospheric CO2 content therefore has enormous consequences for sustainability of marine life, he says.

The natural chemical buffering needed to keep the oceans’ pH stable can’t keep up with the excessive uptake from atmospheric CO2, says Drinkwater. This results in a pH reduction of the oceans’ surface waters, making seawater less alkaline and in turn more acidic. As these surface waters are mixed down, so the deeper ocean becomes impacted, he says.

But Drinkwater says that satellite measurements are becoming increasingly important for monitoring ocean carbonate chemistry, especially in remote waters which are difficult to sample.

A paper just published in the journal Remote Sensing of Environment describes how researchers are using ESA’s SMOS Earth-orbiting spacecraft as well as the merging different datasets to estimate and ultimately monitor ocean acidification, says the space agency.  

Seawater is supersaturated with respect to calcium carbonate minerals which means that there are abundant building blocks for calcifying organisms to build their skeletons and shells, the National Oceanic and Atmospheric Administration (NOAA) says.

Even so, acidification is causing many parts of the ocean to become undersaturated with these minerals, says NOAA. Thus, it says lower environmental calcium carbonate saturation states can have a dramatic effect on some calcifying species, including oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton.

NOAA says that increasing ocean acidification has also been shown to significantly reduce the ability of reef-building corals to produce their skeletons.  In fact, it notes, that by the end of this century, coral reefs may erode faster than they can be rebuilt. If so, this could impact an estimated one million species that depend on coral reef habitat.

It gets worse.

Since the beginning of the Industrial Revolution, ocean acidity has increased by some 30 percent says NOAA. Projections are that if no remedy is implemented for these levels of co2, by century’s end surface waters of the ocean could have acidity levels nearly 150 percent higher, it says. This could result in a pH that the oceans haven’t experienced for more than 20 million years, says NOAA.

But at least now scientists have a fighting chance of monitoring the problem.

There is an ever-increasing need to easily identify areas of the ocean which are most at risk from acidification, says Drinkwater.