Climate change is one of the most fundamental challenges ever to confront humanity. Its impacts are already showing and will intensify over time __21__ left unchecked. There is overwhelming scientific evidence, __22__ shown in the Fourth Assessment Report (第四次评估报告的综合报告)of the Intergovernmental Panel on Climate Change (IPCC) 政府间气候变化专门委员会(IPCC), that climate change will threaten __23__ growth and long-term prosperity, as well as the very survival of the most vulnerable populations. IPCC projections indicate that if emissions continue to rise at their current __24__ and are allowed to double from their pre-industrial level, the world will face an average temperature__25__ of around 3°C this century. Serious impacts are associated __26__ this scenario (情景), including sea-level rise, shifts in growing seasons, and an __27__ frequency and intensity of extreme weather events such as storms, floods and droughts.
The United Nations Climate Change Conference in Copenhagen in December in 2009 offers a __28__ opportunity to step up international action on climate change. A Copenhagen deal is __29__ the global transition into green economic growth, and, most urgently, to help the world, especially the most vulnerable, to adapt to impacts __30__ are now inevitable.