撒哈拉沙漠环境安全问题 - Note

• 分类
  • 规模：large-> sub-Sahara, Rwanda
  • 气候影响因素：arable land, access to fresh water
  • 程度：fragile? vulnerable? stable?
    • 若是fragile --> 注意TASK2要求
    • 若是vulnerable--> 注意TASK3要求
  • 干涉措施

background 可引用

1. how to influence?
   =>"Developing states are more susceptible to environmentally triggered violent conflict because they are, characteristically, more dependent on the environment for their economic productivity, have higher concentrations of subsistence farming(自给自足的农业), burgeoning population(新兴人口) and manifest weak governance(Homer-Dixon 1999; Galgano 2007) . "
2. Weak Governance
   =>“ Pervasive political instability and a lack of government control generally means that these states characteristically lack effective institutions and the financial and material resources to mitigate the effects of non-sustainable practices that degrade the environment or safeguard the population from the effects of environmental stress .”
3. Social effects
   =>" They are more vulnerable to the consequences of environmental stress and typically suffer from four causally related social effects: 1) reduced agricultural production;
   => Index: table1

2. economic decline; 3) population displacement(人口迁移); and 4) civil disruption（骚乱） "
   4.Rwanda -“fragile”

   • causes: population density and the spiral of ecosystem degradation it caused(data见p7)

   => " However, by 1994, population growth and non-sustainable farming practices dangerously degraded the environment by reducing soil productivity, and consequently diminished food output beyond sustainable levels . Rwanda’s population growth meant that there was little useful arable land left for cultivation ."

   • Drought
     deforestation->
     " Thus, by 1985, all arable land in Rwanda was under cultivation (Percival and Homer-Dixon 1995) . Forests were clear-cut, exposing slopes to runoff and erosion, limiting the percolation(渗滤) of precipitation(沉淀) into the ground water table . Fallow(休耕) periods were shortened resulting in soil exhaustion . Deforestation led to severe soil erosion and a lowering of the water table to the extent that streams began to run dry . Thus, when the climate began to change into a decadal drought cycle, the ability to irrigate was lost"
     5.sub-Saharan Africa
     => " Water resources are also a critical component of mining, hydropower generation, tourism, and livestock production, all of which are important to healthy African economies"
     =>"fresh water is threatened by overuse, poor management, pollution, and stresses caused by climate variability ."
     ->very likely to trigger violence as Rwanda
     6.MODEL IN THE PAPER
     -> 自变量(independent variables)： arable land per capita ； access to improved water
     -> 应变量(dependent variable): Political stability and non-violence
     7.DATA

• arable land: Food and Agriculture Organization (FAO, 2009),
• population data : the World Bank (World Bank, 2010) .
• water access data： the U .N . Millennium Development Goal Database (U .N . 2009) .
• Political Stability, 2005 : For countries included in the model (Data from Kaufmann, et al ., 2008)
• model specification
  PSV = α+ β1 ait + β1 wit + β1 awit+µit
  =>"In which PSV is political stability and non-violence, a is arable land per capita, w is percent of population with access to improved water, and aw is a multivariable which accounts for the interaction between arable land per capita and percent of population with access to improved water . The regression error is represented by µ, regression coefficients are α and β."
• 阈值：
  =>" the model suggests that there is a threshold at which arable land per capita and access to improved water predicts stability . When arable land per capita is at 0 .5 hectares/capita, access to improved water no longer has any positive correlation to political stability . We assume that this represents the threshold at which access to improved water no longer positively correlates with government stability ."