Scientists at the UN are sounding the alarm in a new report. “Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts,” concluded the report by the United Nations’ Intergovernmental Panel on Climate Change (IPCC). The report says that government must decide soon whether to take dramatic steps, or face “abrupt and irreversible changes” to the atmosphere and oceans. The report represents a five-year effort to take into consideration the latest in climate change science and evidence. It is the final document out of five assessments made since 1990, and is intended for use by world leaders working on an inter nation climate treaty in Paris next year.