The majority of African countries are stricken by food shortages and undernourishment, with much of the population lacking reliable access to food supplies and basic dietary requirements. In this paper, we analyze past trends of food production and consumption in Africa, both for the continent as a whole and for 52 individual countries within it. Fluctuations in the self-sufficiency ratio (SSR) are used to characterize the stability of a country's capacity to sustain its own population, and GDP per capita is taken as representative of national purchasing power. Our study shows that Africa's food self-sufficiency is lower today than it was throughout the entire study period. This is probably a result of demographic expansion, leading to a greater increase in food demand than in food production. At the national level, a decrease in SSR mainly occurred in Northern and Southern Africa, and high SSR fluctuations (i.e. low stability) always appeared in conjunction with low SSR levels. Although "low SSR-low GDP" countries face the most serious food insecurity conditions, both "low SSR-high GDP" and "high SSR-low GDP" countries also need attention.

Desertification is among the most severe global environmental and the socio-economic problems in the world. This paper is a first attempt to link scientific research to national policymaking on desertification in China. We aim to trace scientific research findings in the national policies and strategies of desertification prevention in China. One example is the large-scale plantation programme in the dust source region threatening Beijing and Tianjin since 1998. It has been suggested that the recent increased forest cover due to plantations in North China has helped reduce dust storm emissions and contributed to mitigating dust storm weather in Beijing and Tianjin. Reforestation/afforestation policy remains in the Chinese national environmental strategies for the new national forestation programme (2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018)(2019)(2020). Overgrazing during recent decades has been blamed for land degradation and desertification in Northwest China by many scholars. Small field experiments prove that vegetation in desertified/degraded land could recover if isolated from human activities. Since 1998, natural recovery has become one powerful national force to prevent land desertification and recover natural vegetation. One example is selected at Cele County, Xinjiang Uygur Autonomous Region to showcase how vegetation could thrive at large scale in natural arid and semi-arid climate if isolated from human intervention. The plantation project has pushed the stakeholders to better understand their negative impact on the environment, especially the overgrazing behaviour. After that, the household income and living level have also been significantly enhanced; however, it is not clear whether the project induced labour migration.

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