"The science is stark: as carbon emissions continue to rise, so do average global temperatures— and this is happening at a pace much faster than projected. Ice melt and sea-level rise are accelerating beyond modelled predictions. Tipping points once thought to be a century away may occur within our lifetimes.To prevent warming of more than 2°C—considered a dangerous threshold by scientists—atmospheric concentrations of greenhouse gases cannot exceed 450 parts per million (ppm). This will require cutting annual emissions by at least 30 billion tons (30 gigatons) by 2030, or roughly what the world emits today. The task is as ambitious as it is essential; but continuing with 'business as usual' is likely to lead to catastrophic and irreversible consequences. Given the unacceptable risks of inaction, our most urgent objective is to identify realistic opportunities to reduce emissions and then seize those opportunities."