There are at least two potentially serious consequences to the amount of carbon we've been pumping into the atmosphere. The first is global warming. The second is the chemical and biological changes in the oceans.
Though it's difficult to compare the likely impact of phenomena this big and complex, the second problem is arguably on a level with the first, a point driven home in the LA Times' Pulitzer-winning series on the subject:
As industrial activity pumps massive amounts of carbon dioxide into the environment, more of the gas is being absorbed by the oceans. As a result, seawater is becoming more acidic, and a variety of sea creatures await the same dismal fate as Fabry's pteropods.And we haven't even gotten to the primeval toxic slime (you really do need to read the whole series).
The greenhouse gas, best known for accumulating in the atmosphere and heating the planet, is entering the ocean at a rate of nearly 1 million tons per hour — 10 times the natural rate.
Scientists report that the seas are more acidic today than they have been in at least 650,000 years. At the current rate of increase, ocean acidity is expected, by the end of this century, to be 2 1/2 times what it was before the Industrial Revolution began 200 years ago. Such a change would devastate many species of fish and other animals that have thrived in chemically stable seawater for millions of years.
Less likely to be harmed are algae, bacteria and other primitive forms of life that are already proliferating at the expense of fish, marine mammals and corals.
In a matter of decades, the world's remaining coral reefs could be too brittle to withstand pounding waves. Shells could become too fragile to protect their occupants. By the end of the century, much of the polar ocean is expected to be as acidified as the water that did such damage to the pteropods aboard the Discoverer.
Some marine biologists predict that altered acid levels will disrupt fisheries by melting away the bottom rungs of the food chain — tiny planktonic plants and animals that provide the basic nutrition for all living things in the sea.
Given their common origin, comparable severity and potential for synergistic effects, topics like acidification should show up frequently in stories about global warming. Not all the time, but I would expect to see it in at least fifteen or twenty percent of the stories. It is simply a pairing that journalists to make on a fairly regular basis, but while a search of the last twelve months of the New York Times for "climate change" produces 10,509 hits, a search on '"climate change" acidification' over the same period produces 15.
(If we do a quick, back-of-the-envelope hypothesis test on the null that most journalists are well-informed, hard-working, independent thinkers...)
The specific tragedy here is that, for all the ink that's been spilled on the impacts of carbon emissions, all we really get in the vast majority of cases are simply the same handful of stories endlessly recycled. We read dozens of articles but since the writers have converged on a tiny number of narratives we remain ill-informed.
The general tragedy is that this is the way almost all journalism works these days. Through a lack of independent thinking (often augmented by laziness and a lack of rigor), journalists quickly settle on a small number of templates which they seldom stray from, even though these templates leave out important aspect of the larger story. Stories on the environmental impacts of carbon leave out the oceans; stories on the economics of cable don't mention broadcast television; stories about the free spending ways of countries like Greece and Spain omit the fact that Spain was running a surplus before the crisis.
It would be easy to find more examples. Finding counter-examples is the tough one.