The NY Times has a great article on the recent National Academies' study suggesting that CO2 emissions are not reversible without some form of atmospheric CO2 removal.
Dr. Solomon said it would be wrong to view the report as evidence that it was already too late to do much good by reducing carbon emissions. “You have to think of this stuff as being more like nuclear waste than acid rain,” she said.
Acid rain began to abate when pollution contributing to it was limited. But just as nuclear waste remains radioactive for a long time, the effects of carbon dioxide persist.
“So if we slow it down,” she said, “we have more time to find solutions.”
For example, engineers may one day discover ways to remove the gas from the atmosphere. But “those solutions are not now in hand,” Dr. Solomon said. “They are quite speculative.”