Greenhouse gases in the Earth’s atmosphere reached another grim milestone earlier this year as carbon dioxide levels surpassed the symbolic threshold of 400 parts per million across much of the planet, the premier global meteorological association confirmed in a report to be released Monday. Figures compiled by the World Meteorological Organization showed strong growth — and new records — in the concentrations of all three of the most important heat-trapping gases, continuing a long-term trend with ominous implications for climate change, the group said. The report is likely to add to concerns about global warming in a year that climate experts say is almost certain to surpass 2014 as the hottest year in recorded history. “We are moving into unchartered territory at a frightening speed,” WMO Secretary General Michel Jarraud said of the […]