Efforts to deal with increasing acidification of the oceans will get a signal of support Sunday with a U.S. announcement that it will provide $1 million over the next three years to launch a global monitoring network.

The creation of the International Coordinating Office for Ocean Acidification, which will be housed within the International Atomic Energy Agency’s Environment Laboratories in Monaco, marks the first worldwide effort to track how increasing carbon emissions are making the world’s oceans more acidic.

Officials from the United States, which, along with Australia and New Zealand, will establish the office, will make the announcement Sunday afternoon at theRio+20 Earth Summit, a once-in-a-decade meeting that is convening in Rio de Janeiro this week. Also known as the U.N. Conference on Sustainable Development, the gathering aims to assess the state of the planet and take steps to solve its most critical problems.

Still, Sunday’s announcement also highlights some of the fiscal constraints global policymakers face when it comes to the environment. Scientists have estimated a robust global ocean acidification monitoring effort will cost $50 million.

The sea absorbs between 25 and 30 percent of the carbon dioxide humans release into the atmosphere, and these emissions have altered the chemical composition of the oceans so that their pH is now 0.1 lower, or 30 percent more acidic, than preindustrial levels. This could pose a serious problem for marine creatures that need calcium carbonate to form their shells, ranging from corals to tiny pteropods that are part of the basis of the food web.

Lisa Suatoni, a senior scientist at the Natural Resources Defense Council, said in a phone interview from Rio that the new initiative will help address “a silent problem” with grave repercussions.

“We really need to get probes into the water and see what’s going on,” Suatoni said. “This will help to acknowledge that ocean acidification is a major global threat to ocean resources.”

Jean-Pierre Gattuso, a French scientist who first proposed the international coordinating office, noted in an e-mail than ocean acidification research “is still in its infancy.”

“It really started about 10 years ago, and numerous questions remain unanswered,” wrote Gattuso, who is based at the Laboratoire d’Oceanographie in Villefranche-sur-Mer, France. “For example, while the increase in ocean acidity during the past two decades and its projected increase in the coming decades is an indisputable fact, the impacts on organisms and ecosystems remain largely uncertain.”

The United States launched its own national monitoring system three years ago, but it has been funded at just $6 million, a fifth of what was authorized. There is also a European Project on Ocean Acidification that has conducted some international monitoring. But it ends this month, and Gattuso said that “there is very little support available for international coordination within the current [European] national projects.”

Richard A. Feely, a senior scientist at the National Oceanic and Atmospheric Administration, said it is critical to coordinate global ocean acidification research.

“The way things are done right now, every set of measurements is different,” he said.

Erika Rosenthal, an attorney with Earthjustice’s international program, said the new commitment shows “the oceans are getting a lot of attention” in Rio. She said she and others were “heartened” by the establishment of a global monitoring system for ocean acidification, “but the amount pledged clearly falls short of what the scientists consistently have said would be needed for a serious effort. We hope that this is a first step, and both the U.S. and other countries would increase their commitments.”

In a call with reporters Friday, Kerri-Ann Jones, U.S. assistant secretary of state for oceans and international environmental and scientific affairs, said the success of the Rio summit should not be judged by how much money is pledged.

“This is about mobilizing actions at the community, state and nation level,” Jones said. “It’s really about how nations come together, and they’re sharing their experiences and they’re trying to take on the challenges together, looking to innovative ways to get at things.”

In the past few days, Australia announced the establishment of the world’s largest network of marine reserves and Mexican President Felipe Calderon canceled plans for a major resortnear Cabo Pulmo National Marine Park, an ecologically valuable marine reserve. Negotiators also are discussing how to reduce illegal fishing and overfishing.