排放与森林碳汇作用下云南省碳净排放量估计

以云南省为例,用马尔科夫链计算能源结构,在经济增长模型基础上基于动态最优化理论估计能源消费碳排放,并基于CO₂FIX模型计算云南省森林碳汇,预测在能源消费碳排放和森林碳汇共同作用下的从2008到2050年碳净排放量。研究发现云南省能源消费碳排放量和碳净排放量曲线都呈"倒U"型,在2035年达到高峰,高峰值分别为和129.71 MtC和118.89 MtC;在森林碳汇中,原有森林的碳汇作用在现在和未来一段时间内处于主导地位,但新造林有着巨大的碳汇潜力,所以在保护原有森林的同时要植树造林,从生态学角度抵消碳排放;森林碳汇只能减少小部分碳排放,更主要的是改善云南省的能源结构,加快技术进步速度,开发水电等新能源,从根本上减少温室气体的排放。

Predictions of net carbon emissions based on the emissions and forest carbon sinks in Yunnan Province

This study calculated the energy structure of Yunnan Province by using a Markov chain, estimated carbon emissions from energy consumption based on an economic growth model and dynamic optimization theory, computed forest carbon sinks based on the CO₂FIX model, and predicted net carbon emissions from 2007 to 2050. Furthermore, we analyzed the factors which influenced carbon emission reduction and the contribution of forest carbon sinks, and then investigated a low-carbon economy. The results showed that the curves of carbon emissions from energy consumption and net carbon emissions were an inverted "U" shape, with a peak value of 129.71 MtC in 2035 and 118.89 MtC in 2035. The percentage of coal in the energy structure of Yunnan decreased year by year, while oil, natural gas and non-carbon energy increased slowly, with the non-carbon energy component increasing the fastest among the three thus allowing the energy structure of Yunnan to probably reach a steady state in 2042. In addition, according to emissions targets required in China, an annual decreasing rate of energy intensity of 2.7% is needed. However, our models show that the predicted energy intensity of Yunnan does not reach these targets in the short term. This means that it is currently not possible to achieve the goal of our nation. If the non-carbon energy component in Yunnan's energy structure is improved to 20% in 2050, carbon emissions can be reduced by 12.3% and this is greater than the amount of carbon sinks in 2050, but lower than its peak. The construction of carbon sinks and the use of non-carbon energy are very effective ways to reduce carbon emissions. In terms of forest carbon sinks, the original forest plays a valuable role now and in the immediate future. But, any new forest also has a huge potential as a carbon sink, so afforestation should be encouraged while protecting the original. However, new forests have a growing period, so they cannot reach their full capacity as a carbon sink for many years. Therefore, from the standpoint of carbon sink accumulation, the original forest sinks are still an important part, and are irreplaceable. But these trees can only offset a portion of the provinces' total carbon emissions; what is more important is to radically reduce greenhouse gas emissions by improving the energy structure of the economy, by increasing the speed of technological progress being made and developing hydropower and other (in particular renewable) energy sources. It can also be shown that the per capita net carbon emissions have the same trend along with total carbon emissions, with a peak of 2.18 tC/person in 2035. The amount of per capita emissions is 1.17 tC globally, 1.12 tC in China, and 5.18 tC in the United States. However, in 2009 the amount of per capita emissions is 0.77 tC in Yunnan, below the national level, and is far lower than that of the United States. By 2020, the amount of per capita net carbon emissions will likely be 1.40 tC in China, and that of Yunnan, 1.69 tC, which is 0.29 tC more than that for the whole country.