Carbon dioxide emissions, from the burning of fossil fuels and production of cement, registered record increases last year, according to researchers with the Global Carbon Project, which reported a 5.9 percent increase.

Carbon dioxide emissions are usually measured by the weight of carbon they contain. The report, published on Sunday in Nature Climate Change, is based on preliminary estimates of global CO2 emissions.

Taking action to reverse current trends is urgent, said Corinne Le Quere, director of Britain's Tyndall Center for Climate Change Research and co-author of the report. She also said these emissions were at the high end of projections, used by the Intergovernmental Panel on Climate Change, showing temperatures could rise by more than 2 degrees by the end of the century.

The report also states there was a short-lived drop in global emissions due to the financial crisis of 2008-09; unfortunately, they climbed back up the next year.

Many saw the global financial crisis as an opportunity to move the global economy away from persistent and high emissions growth, but the return suggests the opportunity was not exploited, said Glen Peters of the Norwegian Center for International Climate and Environmental Research.

The rates of emissions were highest in developing countries, including China (10.4 percent), Brazil (11.6 percent) and India (9.4 percent); those in developed countries like the U.S., Russia and the European Union were 4.1 percent, 5.8 percent and 2.2 percent, respectively.

The United States, however, is the world's second largest emitter of greenhouse gases and pumped 1.5 billion tons of carbon into the atmosphere last year. The largest is China, which releases more than 2 billion tons every year.