For example, scientists at the Leibniz Institute of Marine Sciences at the University of Kiel in Germany recently discovered that plankton consumes more carbon at higher atmospheric concentrations of CO2. "The plankton were carbon-enriched," says marine biologist Ulf Riebesell, who conducted the study. "There weren't more of them, but each cell had more carbon."
This could mean that microscopic ocean plants may potentially absorb more of the carbon emitted into the atmosphere. Unfortunately, other research (from the Woods Hole Oceanographic Institution) has shown that such plankton does not make it to the seafloor in large enough amounts to sequester the carbon in the long term.
Further, such carbon-heavy plankton do not begin to appear until CO2 concentrations reach twice present values—750 parts per million (ppm) in the atmosphere compared with roughly 380 ppm presently (a level at which catastrophic change may be a certainty)—and they are less nutritious to all the animals that rely on them for food. "This mechanism is both too small and too late," Riebesell says. "By becoming more carbon-rich, zooplankton have to eat more phytoplankton to achieve the same nutrition" and, therefore, "they grow and reproduce more slowly."
The IPCC notes that there are cost-effective solutions, such as retrofitting buildings for energy efficiency, but says they must be implemented in short order to stem further damage. "We are 25 years too late," Schneider says. "If the object is to avoid dangerous change, we've already had it. The object now is to avoid really dangerous change."