Living with climate change: Can we limit global warming to 2°C?
来源：未知 作者：齐嗝群 时间：2019-04-04 03:16:03
Patrick Kovarik/AFP/Getty By Olive Heffernan AT THE core of the Paris climate change agreement is the aspiration to “[hold] the increase in the global average temperature to well below 2°C above pre-industrial levels”. At current rates of greenhouse gas emissions, we have 20 years before such a rise is inevitable. To avoid it, we need emissions to peak as soon as possible – preferably by 2020 – before making their way to zero by about 2070. There are some grounds for optimism: energy and industry emissions may already be peaking as the world moves away from the dirtiest of fossil fuels, coal (see “Living with climate change: Turning the corner“). But this needs to be seen in context. We are still emitting almost 42 gigatonnes of carbon dioxide each year. Change is not yet happening fast enough or on a large-enough scale to meet the world’s growing energy demand. Besides, closing coal mines and investing in renewables for electricity generation is the easy part. Generating electricity accounts for only a quarter of global greenhouse gas emissions, with emissions from agriculture, forestry, industry and transportation making up the rest. Oil, the primary fuel for transport, is particularly difficult to replace. Cars and buses can be made to run on electricity, but powering planes will require the large-scale development of renewable, sustainable jet fuel. The current global production,