Climate change has major impact on oceans

These same greenhouse gas emissions also are creating dramatic buildup of atmospheric carbon dioxide, which is rapidly making the world’s oceans more acidic, said panelist Scott Doney of the Woods Hole Oceanographic Institution. Current CO2 levels of 380 parts per million already are 30 percent higher than pre-industrial values and many scientific models predict that those rates will triple by the end of the century under “business as usual” scenarios.

While much of the scientific attention on ocean acidification has looked at the impact of coral reefs, the potential danger to other marine ecosystems is equally severe, Doney said.

“Ocean acidification harms plants and animals that form shells from calcium carbonate,” he said. “Calcifying organisms include not just corals, but many plankton, pteropods (marine snails), clams and oysters, and lobsters. Many of these organisms provide critical food sources or habitats for other organisms and the impact of acidification on food webs and higher trophic levels is not well understood.

“Newly emerging evidence suggests that larval and juvenile fish may also be susceptible to changes in ocean pH levels,” Doney added. “Ocean acidification is rapidly becoming a real problem.”

Michael Behrenfeld, an oceanographer from Oregon State University, is studying relationships between climate and the global activity of ocean plants called phytoplankton.

“Phytoplankton are of tremendous human importance because their photosynthesis yields oxygen for us to breathe and they are the base of the ocean food webs that support our global fisheries,” Behrenfeld said. “Using NASA satellites, we can track changes in phytoplankton on a global basis and what we find is that warming ocean temperatures are linked to decreasing photosynthesis. Satellites are one of the most important tools we have for understanding the link between climate and ocean biology because they provide measurements of the whole planet on a daily basis, which could never be accomplished by ship.

“Unfortunately,” he added, “it is at this very time when we need satellites most that we are facing the end of NASA ocean biology satellites because of budget cutbacks or new priorities. This is a serious issue that needs to be addressed.