国际研究组织称中国的灌溉体制导致二氧化碳排放增多

来源：英国《卫报》

山东的一位村民正在给麦田浇水 （环保局Wu Hong摄）

一份研究报告估计，中国农业灌溉的抽水系统，作为这个巨大的灌溉网络的支持，每年排放33兆吨二氧化碳。这相当于整个新西兰在一年中的二氧化碳排放总量。

这项研究工作的发起人是由英国和中国科学家组成的一个研究组织。这一小组旨在调研中国北方干旱地区农作物灌溉过程中常被忽视的环境污染和资源浪费状况。由于中国北方的地表河流湖泊污染严重，且工业和城市过度利用，农民只能抽取地下水源灌溉。

调研人员发现，中国作物灌溉所用的地下水已经从1950年的100亿立方米增长到现在的1000亿立方米。现已成为仅次于印度的全球第二大地下水利用国家。

造成的结果是，在一些影响严重的地区地下水位年下降速度超过2米。湖北、河南、陕西、陕西省成千上万的农民不得不把井打到地下70米才能见水。

环境研究快报的一篇论文中写到，此举会导致水能源消耗量会越来越大增大，二氧化碳释放量占全中国释放总量的0.5%。中国是全球最大的二氧化碳制造国。

东安格利亚大学、廷德尔气候变化研究中心、中国农科院的科学家组成了另一研究组织，他们的研究方向是支持出台更强有力的水资源保护政策。

组织领头人Declan Conway说：“农民们正在到处掘井抽取更深层的水源，这已经被充分证明了其不可持续性，所以必须停止。”

他还说论文提出了合理利用水资源的诸多好处，除了节约用水，我们还能同时达到节约能源的目的。

早已证明，水资源与能源之间的关系很可能成为中国经济发展的瓶颈。2012年初有报道称中国由于严重干旱，导致水利发电量比去年减少了3.5%，此事即可证明。然而，近期研究更加证实了两者之间的关系还会对粮食产量、温室气体排放造成影响。

一小片面包所用到的小麦能消耗掉500公升水，大部分来自地下深层水，钻井和用水泵抽水的过程还会消耗能量。这项研究并不包含地表输水工程，比如南水北调这样的地表水利工程。

研究提出警告，将来由于气候变化，人口增长问题和生活质量提高问题，中国在2003年到2030年的时间里，其水资源缺口可能会达到500平方公里。

中国政府已经将节约用水定为国家首要解决的问题，但要想阻止农民暗地里在自家地块打井很难。除非到能源变得非常昂贵的时候。

中国农业政策研究中心的王金霞教授说小规模的水泵使用的控制监管实施起来的确非常困难。（灌溉网编辑 崔亚静）

附原文：

China irrigation system responsible for rising emissions, research shows

A villager looks after a water pump that will irrigate a wheat field in Jimo, Shandong province, China. Photograph: Wu Hong/EPA

The irrigation of Chinese farm fields with more water <http://www.guardian.co.uk/environment/water> pumped from ever deeper underground is responsible for 33m tonnes of carbon dioxide per year - equivalent to the entire emissions of New Zealand - a new study <http://iopscience.iop.org/1748-9326/7/1/014035/article> revealed on Wednesday.

The research, carried out by a team of UK and Chinese scientists, highlights the rising but often overlooked energy <http://www.guardian.co.uk/environment/energy> and climate costs of irrigating crops in drought-plagued northern China <http://www.guardian.co.uk/world/china>, where farmers have to mine aquifers because surface rivers and lakes are increasingly polluted and over-exploited by factories and cities.

The authors found that groundwater used for crop irrigation in China has grown from 10bn cubic metres in 1950 to more than 100bn today. The country is now second only to India in tapping largely unreplenishable aquifers.

As a result, water tables in some of the worst affected areas are falling at the rate of more than two metres a year.

Millions of farmers in Hubei, Henan, Shanxi and Shaanxi are now having to pump supplies from 70m underground.

This is increasingly energy intensive and now accounts for almost half a percent of the carbon dioxide released in China, the world's biggest emitter, says the paper published by Environmental Research Letters <http://iopscience.iop.org/1748-9326>.

The authors - who include scientists from the University of East Anglia, the Tyndall Centre for Climate Change <http://www.guardian.co.uk/environment/climate-change> Research and the Chinese Academy of Agricultural Sciences - say their research underpins the need for stronger water conservation policies.

"Farmers are drilling more boreholes and pumping from every deeper depths. There are already hotspots where this is unsustainable, The signals are that this must be turned around," said Declan Conway, one of the lead authors.

He said the paper revealed a previously unaccounted for benefit from better water management: "In addition to saving water, we may get a co-beneift of saving energy."

The nexus between water and energy has previously been cited <http://www.circleofblue.org/waternews/featured-water-stories/choke-point-china/> as a likely bottleneck for China's economic development. This was underscored earlier this year by reports that China's hydropower production fell by 3.5% in 2011 <http://www.china.org.cn/business/2012-02/10/content_24601666.htm> due to unusually severe droughts. The latest study goes further than any other, however, in linking this to food production and greenhouse gas emissions that impact the global climate.

To grow the wheat for one small loaf of bread requires 500 litres of water - most of which comes from deep underground, which calls for energy for drills and pumps.

The study does not include water transferred on the surface via major hydroengineering projects such as the South-North water diversion.

In the future, it warns that demand for water in China is likely to grow by 500 square kilometers between 2003 and 2030 due to climate change, a growing population and rising living standards.

The Chinese government has identified water conservation as a national priority, but it is difficult to stop farmers from surreptitiously drilling wells on their land unless energy becomes more expensive.

"The small scale of pump operations makes regulation and control of use extremely difficult," Prof Jinxia Wang of the Centre for Chinese Agricultural Policy said.

http://www.guardian.co.uk/environment/2012/mar/14/china-irrigation-emissions