Global emissions of carbon dioxide were at a record high in 2011 and are likely to take a similar jump in 2012, scientists reported Sunday

The amount of heat-trapping pollution the world spewed rose again last year by 3 percent — the latest indication that efforts to limit such emissions are failing.

Global emissions of carbon dioxide were at a record high in 2011 and are likely to take a similar jump in 2012, scientists reported Sunday.

Emissions continue to grow so rapidly that an international goal of limiting the ultimate warming of the planet to 2 degrees, established three years ago, is on the verge of becoming unattainable, said researchers affiliated with the Global Carbon Project.

Josep G. Canadell, a scientist in Australia who leads that tracking program, said Sunday in a statement that salvaging the goal, if it can be done at all, “requires an immediate, large and sustained global mitigation effort.”

Yet nations around the world, despite a formal treaty pledging to limit warming — and 20 years of negotiations aimed at putting it into effect — have shown little appetite for the kinds of controls required to accomplish those aims.

In 1997, most of the world agreed to an international treaty, known as the Kyoto Protocol, that required developed countries such as the United States to reduce greenhouse-gas emissions by about 5 percent when compared with the baseline year of 1990. But countries that are still developing, including China and India, were not limited by how much carbon dioxide they expelled. The United States never ratified the treaty.

Delegates from nearly 200 nations are meeting in Doha, Qatar, for the latest round of talks under the treaty, the U.N. Framework Convention on Climate Change. Their agenda is modest this year, with no new emissions targets and little progress expected on a protocol that is supposed to be concluded in 2015 and take effect in 2020.

Because emissions of the key greenhouse gas have been rising steadily and most carbon stays in the air for a century, it is not just unlikely but “rather optimistic” to think that the world can limit future temperature increases to 2 degrees, said the study’s lead author, Glen Peters at the Center for International Climate and Environmental Research in Oslo, Norway.

Three years ago, nearly 200 nations set the 2-degree temperature goal in a nonbinding agreement. Negotiators in Doha are trying to find ways to reach that target.

Last year, all the world’s nations combined pumped nearly 38.2 billion tons of carbon dioxide into the air from the burning of fossil fuels such as coal and oil, according to new international calculations on global emissions published Sunday in the journal Nature Climate Change. That’s about a billion tons more than the previous year.

The total amounts to more than 2.4 million pounds of carbon dioxide released into the air every second.

The new figures show that emissions are falling, slowly, in some of the most advanced countries, including the United States. That apparently reflects a combination of economic weakness, the transfer of some manufacturing to developing countries and conscious efforts to limit emissions, like the renewable power targets that many American states have set. The boom in the natural-gas supply from hydraulic fracturing is also a factor, since natural gas is supplanting coal at many power stations, leading to lower emissions.

But the decline of emissions in the developed countries is more than matched by continued growth in developing countries like China and India, the new figures show. Coal, the dirtiest and most carbon-intensive fossil fuel, is growing the fastest, with coal-related emissions leaping more than 5 percent in 2011, compared with the previous year.

The overwhelming majority of the increase was from China, the world’s biggest carbon-dioxide polluter. Of the planet’s top 10 polluters, the United States and Germany were the only countries that reduced their carbon-dioxide emissions.

“If we’re going to run the world on coal, we’re in deep trouble,” said Gregg H. Marland, a scientist at Appalachian State University who has tracked emissions for decades.

Overall, global emissions jumped 3 percent in 2011 and are expected to jump another 2.6 percent in 2012, researchers reported in two papers released by scientific journals on Sunday. It has become routine to set new emissions records each year, although the global economic crisis led to a brief decline in 2009.

The level of carbon dioxide, the most important heat-trapping gas in the atmosphere, has increased about 41 percent since the beginning of the Industrial Revolution, and scientists fear it could double or triple before emissions are brought under control. The temperature of the planet has already increased about 1.5 degrees since 1850.

Further increases in carbon dioxide are likely to have a profound effect on climate, scientists say, leading to higher seas and greater coastal flooding, more intense weather disasters and an extreme acidification of the ocean. The earliest effects are already being seen, many experts believe, but they are projected to worsen.

The latest pollution numbers, calculated by the Global Carbon Project, a joint venture of the Energy Department and the Norwegian Research Council, show that worldwide carbon-dioxide levels are 54 percent higher than the 1990 baseline.