中国中长期碳减排战略目标初探(Ⅰ)——中国分阶段温室气体减排目标的提出及其依据

A Preliminary Study on China′s Long and Medium-Term Strategic Goals for Reducing Carbon Emissions(Ⅰ)——Proposal on the Reduction Targets for 3 phases of implication in China

减少温室气体排放已刻不容缓,一系列研究显示,温升2℃是人类生活不受气候变化干扰的上限,大致550μL/L二氧化碳当量的温室气体浓度或约450～500μL/L的二氧化碳浓度对应2℃的温升。达到稳定浓度时的2005年以后的累积排放量和2005年的排碳数据一起才可以计算出最终的减排量化指标,而拐点年代和逐年排放量是可调控的动态指标。核实本世纪上半叶的累积排放量,并将排放额度分解到各个国家和地区是一项十分艰巨且很迫切的任务。我国的碳减排可分为2005～2020年的前期、2021～2035年的中期和2036～2050年的后期。权威部门曾推算了一系列数据,但与当前掌握的实际数据对比,对2010年的碳排放预测数据均偏低。有学者提出我国2005～2050年间的排碳额度为370Gt,约为全世界的28%,比例基本合理。如果2050年二氧化碳排放总量确定为140×108t,则中国为40×108t,人均2.6t,形势非常严峻。把我国2020年二氧化碳排放量控制在100×108t以内十分必要;我国碳减排中期处于拐点过渡期,我国的拐点将直接影响世界的拐点,应争取拐点出现在2025年,过渡期为2020～2030年;我国2050年与2035年的二氧化碳排放量差值应为45×108t,只要依靠非化石能源替代化石能源、采用CCS技术、最大限度地采用零碳排放甚至负碳排放的替代燃料就能得到控制,但仍然存在许多不确定因素,有待深入研究。

There is no time for delay on reducing greenhouse gas emissions.Studies have shown that 2℃ is the upper limit for temperature rise that would not affect human lives,which corresponds to about 550μL/L of carbon dioxide equivalent of greenhouse gas concentration or about 450～500μL/L of carbon dioxide concentration.Only by combining the cumulative emissions after 2005 when the concentration stabilized and the carbon emission data for 2005,can we calculate the ultimate quantified emission reduction indices.Inflection years and year-by-year amounts of emissions are dynamic indices that can be adjusted.Verifying the cumulative emissions in the first half of this century and breaking emission quotas down to all countries and regions is a very tough and urgent task.China plans to achieve its carbon emission reduction objectives in three phases-2005-2020,2021-2035 and 2036-2050.An authoritative department calculated a series of data,but its estimates of 2010 carbon emissions are slightly too low compared with the actual data currently available.Some scholars have pointed out that China′s carbon emission quota for 2005-2050 actually should be 370Gt,representing about 28% of the world′s total.This percentage is basically reasonable.If the world′s carbon dioxide emission limit for 2050 is 140×108t,China′s quota will be 40×108t,equivalent to 2.6t per capita.This will be a tough task to fulfill.It is very necessary to constrain China′s carbon dioxide emissions to a maximum 100×108t by 2020.The period 2021-2035 will be a transition period for the inflection point and the inflection point for China will directly affect the inflection point for the entire world.China should try to make the inflection point appear in 2025.If this objective is achieved,the transition period will be 2020-2030.The difference between the volumes of China′s carbon dioxide emissions in 2050 and 2035 should be 45×108t.This objective is expected to be achieved through the use of non-fossil energy sources,CCS technology and zero-emission or even carbon-negative alternative fuels although there will be many uncertainties.This issue entails further study.