The dangers if governments ignore efforts to limit warming to 1.5C are more grave than the summary makes outA report by the Intergovernmental Panel on Climate Change confirms the enormous wisdom that governments showed in Paris in December 2015, when they agreed to the goal of “pursuing efforts” to limit global warming to 1.5C. The report’s summary for policymakers paints a sobering picture of the potentially terrible impacts of allowing global mean surface temperature to rise by 2C compared with pre-industrial levels: more extreme weather, sea level rise and ocean acidification, with detrimental effects on wildlife, crops, water availability and human health. But the policymakers, or at least their aides, should make the effort to read the whole report. Incredibly, the stark summary is still a relatively conservative assessment of the consequences we might face if global warming does exceed 1.5C.The report is a comprehensive review of the published evidence painstakingly compiled by hundreds of authors and reviewers over the past two and a half years. The summary of the report was approved line by line by governments, including the US, Australia and Saudi Arabia, during long and intensive discussions last week in South Korea. It is written in matter-of-fact language, but it omits some of the biggest risks of climate change, which are described in the full text. For instance, the summary indicates that warming of 2C would have very damaging impacts on many parts of the world. But it does not mention the potential for human populations to migrate and be displaced as a result, leading to the possibility of war.This is a risk that many governments around the world have already recognised, with climate change often highlighted in national security assessments as a “threat multiplier”, which could increase the chances of political instability and conflict.