The carbon dioxide (CO2) spewing from human activities is not only changing Earth’s atmosphere, it’s also rapidly acidifying the planet’s oceans. In 50 years, that acidification could reduce the oceans’ ability to absorb CO2 by 10% as it takes a toll on phytoplankton

... Nevertheless, it’s still too early to conclude that the projected declines in phytoplankton will inevitably reduce CO2 uptake by the world’s oceans, Church and others caution. It’s still possible the declines could be offset by higher plankton growth rates at high latitudes and other global processes involved in carbon cycling. However, Church says, “It certainly doesn’t help.”