We all know about the heat trapping effect of atmospheric CO2 on the surface temperature of the earth. What is less known is that up to half of the CO2 emitted by burning fossil fuels has been dissolved in the ocean. Less global warming sounds good, doesn’t it. Well, no it isn’t good for the oceans. It has already made the sea 30% more acidic and by the end of this century it could be more than twice as acidic as it was. That’s more acidic than it has been for at least 20 million years.
So, why does this matter?
First, it matters because the ocean is really, really big. It covers 70 per cent of the planet and, because of its depth, makes up 99 per cent of the living space, so when it is sick, all other life that ultimately depends on its health is also at risk.
Marine life has evolved to thrive at a level of acidity that has been remarkably stable for millions of years. The current rate of change is so extreme that most marine organisms cannot evolve quickly enough to adapt and marine ecosystems are badly out of balance.
The increased acidity means that shellfish expend more energy building their shells leaving less energy to grow and reproduce. This leaves them smaller, weaker, and more vulnerable to illness. Other sea creatures that feed on them are stressed in their turn and populations decline.
This is particularly bad for coral reefs. Although coral reefs cover less than 1% of the ocean floor they support about 25% of all marine life. Their well being is threatened by a double whammy of water that is both warmer and more acidic. According to the WWF report “Living Blue Planet“, reef ecosystems have declined by 50% in the last 30 years and may completely disappear by 2050. Some 850 million people depend directly on coral reefs for their food security. What are they going to eat?
What can we do? Unfortunately there’s not enough Alka-Seltzer to relieve this serious ailment. Some geoengineering solutions have been proposed but they are not promising. The only antacid available is to stop burning fossil fuels as soon as we possibly can.