News brief

Scientists reported record levels of carbon dioxide in the atmosphere. Researchers at Hawaii’s Mauna Loa Observatory calculated a monthly average of more than 430 parts per million for May. Before the world began burning fossil fuels for energy, scientists say the average atmospheric concentration was a fraction of that, at 280 parts per million. Carbon dioxide traps heat in the Earth’s atmosphere. Despite widespread awareness about global warming, global emissions continue to rise. The U.S. has slowly reduced its emissions for the past 20 years. Still, Americans are responsible for the most carbon emissions per person. – Staff