The calculus of unsustainability.
The calculus of unsustainability.
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DOI：
10.1021/es2038118
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发表时间：
2011-12
影响因子：
11.4
通讯作者：
J. Schnoor
中科院分区：
文献类型：
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作者：
J. Schnoor
可持续性是一个模糊的术语，并且很难在公共政策中实施。当我向公民团体和学生演讲时，经常有人问我：“到底什么是不可持续的？”也许根本问题是公众对物质存量和流量、积分和衍生品，即不可持续性的计算缺乏了解。在美国，我们似乎根本不明白这一点。今年10月31日，据联合国统计，全球人口达到70亿（http://www.unfpa.org/public/home/news/pid/7597）。多么具有里程碑意义啊！当我出生时，地球上有 25 亿人，所以在一位（老）编辑的一生中，我们的人口几乎增加了两倍。但温室气体排放量增加得更多，自那时以来增加了六倍多。如图所示，排放量的变化率（导数）导致大气中温室气体大量积累（来源：Scripps-NOAA，2010）。显然，辐射重要的微量气体的这种积累（曲线下的积分面积）从长远来看是不可持续的。就是这么简单。好消息是人口变化率正在下降，人口统计学家告诉我们，到 21 世纪中叶的某个时候，人口数量可能会达到 90 亿左右的稳定水平。坏消息是，这种平稳期也可能无法持续——这取决于我们如何利用我们的资源。资源利用（土地、劳动力、资本）决定了我们的经济。我最喜欢的经济学家是赫尔曼·戴利（Herman Daly），他在马里兰大学因生态经济学而闻名。戴利 (Daly) 撰写了《稳态经济》(A Steady State Economy) (http://www.sd-commission.org.uk/publications.php?id=775)，但似乎没有人对这本书给予过多的政策关注。如果经济学真的是“令人沮丧的科学”，那么环境科学一定是“自杀式的令人沮丧的科学”。
Sustainability is a squishy term—and difficult to operationalize for public policy. As I give talks to civic groups and students, I am often asked,“Exactly what is it that is not sustainable?” Perhaps the underlying problem is the public’s lack of understanding about material stocks and flows, integrals and derivatives, ie, the calculus of unsustainability. In the US, we simply do not seem to get it.On October 31 of this year, according to the United Nations, the global population reached 7 billion (http://www. unfpa. org/public/home/news/pid/7597). What a milestone! When I was born there were 2.5 billion people on earth, so we’ve almost trebled population in one (old) editor’s lifetime. But emissions of greenhouse gases have increased even more, greater than 6-fold since that time. That rate of change in emissions (the derivative) makes for a huge accumulation of greenhouse gases in the atmosphere as shown in the figure (Source: Scripps-NOAA, 2010). Clearly, such accumulation (the integral—area under the curve) of a radiatively important trace gas is not sustainable over the long run. It is as simple as that. The good news is that the rate of population change is decreasing, and demographers tell us we may reach a plateau around 9 billion people sometime in the middle of the 21st century. The bad news is that the plateau is likely to not be sustainable either—it depends on how we use our resources. Resource utilization (land, labor, capital) defines our economics. My favorite economist is Herman Daly, of ecological economics fame at the University of Maryland. Daly is the one who wrote A Steady State Economy (http://www. sd-commission. org. uk/publications. php? id= 775) to which no one seems to have paid much policy attention. If economics really is the “dismal science”, then environmental science must be “depressing science on a suicide watch”.