全球人口發(fā)展趨勢

According to the UN Population Fund， over the next 20 years， the global population is expected to grow by a quarter -- that's an extra 1.5 billion mouths to feed. This is at a time when， even though we can grow enough to feed everyone， 800 million people will be malnourished.

Meat production continues to soar， with China taking over the mantle of biggest meat eater from the U.S. While soybean production has rocketed， the fish catch looks to have peaked. About 60 per cent of ocean fisheries are now being exploited at or close to capacity.

Grain production per capita is static， but land area per capita for growing grain is falling. This is partly due to the rising population but also reflects urban encroachment5 on farmland and， more positively， the replanting of marginal6 soils with more sustainable crops. Soil continues to be squandered7， with 5 to 6 million hectares a year being lost to soil degradation.

Water is also under pressure as never before. Today， some 500 million people do not have enough water. By 2025， that number is expected to hit 2.5 billion.The World Resources Institute in Washington DC estimates that 160 million cubic metres more water is pumped from aquifers each year than is flowing into them.

This is enough to grow grain for 480 million people. So， these people are being fed from a source that cannot be sustained.

根據(jù)聯(lián)合國人口基金預(yù)測，在未來的20年內(nèi)，全球人口將增長四分之一，也就是說世界上會(huì)多添出15億張嘴嗷嗷待哺。到那時(shí)，即使我們種出來的糧食足夠養(yǎng)活每一個(gè)人，仍然將有8億人口面臨營養(yǎng)不良。

隨著中國取代美國成為世界上最大的肉類消費(fèi)國，肉類產(chǎn)量持續(xù)猛增。大豆產(chǎn)量已經(jīng)飛速增長，與此同時(shí)全球捕魚總量似乎已經(jīng)達(dá)到頂峰?，F(xiàn)在，大約60%的海洋漁場正以最高極限量或接近最高極限量進(jìn)行生產(chǎn)。

人均糧食產(chǎn)量保持不變，但是人均種糧地面積卻在減少，其部分原因是人口的不斷增長，但是也反映出城市開發(fā)對農(nóng)田的占用。一個(gè)積極的發(fā)展是貧瘠土地的再利用，即改種較易存活的作物。土地資源繼續(xù)遭到浪費(fèi)，每年平均有500萬到600萬公頃的土地退化。

水資源也面臨前所未有的壓力?，F(xiàn)在世界上有大約5億人口缺水。到了2025年，這個(gè)數(shù)字將達(dá)到25億。據(jù)設(shè)于美國華盛頓市的世界資源協(xié)會(huì)估計(jì)，每年從地下蓄水層中抽取的水比流人的水多1.6億立方米。這個(gè)水量足夠種植供4.8億人口消費(fèi)的糧食。所以說，養(yǎng)活這些人口的水資源將無法可持續(xù)獲得。