The United Nations says levels of greenhouse gases responsible for global warming have reached a record high. According to the United Nations’ World Meteorological Organization, the concentration of carbon dioxide in the atmosphere rose by nearly three parts per million from 2012 to 2013, the largest single-year increase since detailed records began three decades ago. Last year, concentrations of carbon dioxide reached nearly 400 parts per million, the highest level in at least 800,000 years. As oceans absorb the increased carbon, ocean acidification has reached a rate that is “unprecedented at least over the last 300 million years.” In a press release, WMO Secretary-General Michel Jarraud called the data a “scientific base” for global action on climate change. “We are running out of time,” he said. The report comes ahead of the U.N. climate summit and the People’s Climate March in New York City later this month.