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水資源是氣候變化解決方案的重要組成部分

 (English version below)

聯(lián)合國《世界水發(fā)展報(bào)告》于3月22日發(fā)布

巴黎/日內(nèi)瓦，3月22日——最新發(fā)布的聯(lián)合國《世界水發(fā)展報(bào)告》警示，氣候變化將影響滿足人類基本需求所需的水的供給、質(zhì)量和體量，從而損害數(shù)十億人享有安全飲用水和衛(wèi)生設(shè)施的基本權(quán)利。報(bào)告呼吁各國為應(yīng)對這一挑戰(zhàn)做出更具體的承諾。

情況的惡化會(huì)阻礙可持續(xù)發(fā)展目標(biāo)6的實(shí)現(xiàn)。這一目標(biāo)是《2030年可持續(xù)發(fā)展議程》的一部分，它要求在十年內(nèi)確保所有人獲得安全飲用水和衛(wèi)生設(shè)施。這將是一個(gè)巨大挑戰(zhàn)——目前全球仍有22億人無法獲得安全的飲用水，42億人（占世界人口的55%）沒有合乎要求的衛(wèi)生設(shè)施。

一個(gè)世紀(jì)以來，人類的用水量增加了6倍，并仍在以每年1%的速度增長。然而據(jù)估計(jì)，氣候變化以及風(fēng)暴、洪水和干旱等極端事件的頻率和強(qiáng)度日益增加將使目前已經(jīng)面臨“水資源緊張”的國家的處境更加惡化，并將目前尚未受到嚴(yán)重影響的地區(qū)置于類似境地。此外，報(bào)告還指出，水管理不善往往會(huì)加劇氣候變化對水資源和整個(gè)社會(huì)的影響。

聯(lián)合國教科文組織總干事阿祖萊強(qiáng)調(diào)：“水帶來了一些問題，但也能提供解決方案。水可以為減緩和適應(yīng)氣候變化的努力提供支持?！?/p>

聯(lián)合國水機(jī)制主席、國際農(nóng)業(yè)發(fā)展基金會(huì)主席洪博說:“如果我們想要將全球氣溫上升幅度限制在2攝氏度以下，并在2030年實(shí)現(xiàn)可持續(xù)發(fā)展目標(biāo)，那么我們必須立即采取行動(dòng)。以更加協(xié)調(diào)的方式管理水和氣候是可以做到的，這需要社會(huì)各界共同參與。留給我們的時(shí)間不多了。”

氣候變化影響健康，威脅生物多樣性

水溫升高和溶解氧減少將影響水質(zhì)，導(dǎo)致淡水流域水體的自凈能力下降。洪水或干旱期間污染物的聚集將增加水污染和病原體污染的風(fēng)險(xiǎn)。除了糧食生產(chǎn)之外，人類身心健康也可能受到相當(dāng)大的影響，原因有疾病、傷害、經(jīng)濟(jì)損失和人民流離失所等。

多種生態(tài)系統(tǒng)——特別是森林和濕地——也面臨生物多樣性減少的威脅。不僅是農(nóng)業(yè)（占淡水使用量的69%），還有工業(yè)、能源生產(chǎn)甚至漁業(yè)的水供給都將受到影響。

風(fēng)險(xiǎn)最高的地區(qū)：群島、山區(qū)、熱帶和極北

氣候變化對水資源的大部分影響將在熱帶地區(qū)凸顯，大多數(shù)發(fā)展中國家位于這一地區(qū)，小島嶼國家甚至可能遭受毀滅性的打擊，其中一些可能會(huì)從地圖上消失。由于山地冰川和雪蓋的存在，山區(qū)也特別容易受到影響，而世界上幾乎所有地方的山地冰川和雪蓋都呈現(xiàn)消退趨勢。然而報(bào)告亦提及，由于地方一級降雨模式的季節(jié)性變化等原因，一些不確定性仍然存在。

解決方案建議：適應(yīng)與減緩

面對這些威脅，報(bào)告指出了2項(xiàng)應(yīng)當(dāng)實(shí)施的相輔相成的戰(zhàn)略——適應(yīng)和緩解：

• 適應(yīng)包括一系列自然、技術(shù)和科技選擇的組合，以及社會(huì)和體制措施，以減輕氣候變化帶來的損害和利用氣候變化的有限積極影響。這一戰(zhàn)略可能收效迅速，尤其在地方一級。

• 緩解包括采取行動(dòng)減少溫室氣體排放，同時(shí)利用碳匯減少大氣中二氧化碳和其他溫室氣體的含量。這一戰(zhàn)略可以覆蓋較廣的地理區(qū)域，但可能需要數(shù)十年時(shí)間方能取得成效。然而，在水資源管理中應(yīng)用這一戰(zhàn)略的可能性在很大程度上仍然沒有得到承認(rèn)。

改善廢水處理

廢水處理同樣加劇氣候變化，因?yàn)樗a(chǎn)生溫室氣體。據(jù)估計(jì)，其排放量占溫室氣體排放總量的3-7%。這些排放來自廢水處理的能源消耗和生化工序。但是由于其中含有的有機(jī)物質(zhì)的分解，未經(jīng)處理的廢水也是甲烷——一種典型的溫室氣體——的主要來源。該報(bào)告指出，廢水所含的能量超過了對其進(jìn)行處理所需的能量。當(dāng)然，前提是人類能夠?qū)ζ渲泻械哪芰考右岳?。?jù)估計(jì)，全世界80-90%的廢水未經(jīng)任何形式的處理便被排放到環(huán)境中去。

具體而言，實(shí)現(xiàn)水資源的最優(yōu)管理意味著投資現(xiàn)代加工技術(shù)，以便從有機(jī)物中提取甲烷，然后利用這種生物氣體提供廢水處理過程所需的能源。約旦、墨西哥、秘魯和泰國等缺水國家已將其付諸實(shí)踐。這些技術(shù)使相關(guān)公用設(shè)施能夠減少數(shù)千噸二氧化碳的排放，同時(shí)節(jié)省資金和提高服務(wù)質(zhì)量。

報(bào)告還提到了收集霧水等創(chuàng)新的水資源管理措施，或者濕地保護(hù)等更傳統(tǒng)的措施，以及已被證實(shí)有效的“保護(hù)性耕作”技術(shù)。這些措施使得在降雨量較少的情況下保護(hù)土壤結(jié)構(gòu)、有機(jī)物和水分成為可能。同樣，只將廢水做部分處理以便“再利用”于農(nóng)業(yè)和工業(yè)，而不必使其達(dá)到飲用安全標(biāo)準(zhǔn)，是另一個(gè)值得考慮的方法。

將水列入優(yōu)先事項(xiàng)

令人擔(dān)憂的是，報(bào)告指出，雖然人們普遍認(rèn)識到通過改善水循環(huán)管理來應(yīng)對氣候變化的重要性，但這一認(rèn)識并沒有轉(zhuǎn)化為現(xiàn)實(shí)?！啊@個(gè)字很少出現(xiàn)在國際氣候協(xié)定中?！卑⒆嫒R評論道。各國在《巴黎協(xié)定》下提交的”國家自主貢獻(xiàn)”仍然是一般性的，沒有提出具體的水管理計(jì)劃。雖然大多數(shù)國家在其“一攬子行動(dòng)”中承認(rèn)水的重要性，但很少有國家實(shí)際計(jì)算了這些行動(dòng)的成本，提出具體項(xiàng)目的國家更少。同時(shí)，適應(yīng)和緩解措施之間協(xié)同增效的可能性也常常被忽視。

獲取氣候資金

顯然，融資問題至關(guān)重要。報(bào)告指出，水資源管理以及供水和衛(wèi)生設(shè)施缺乏資金，需要各國予以更多關(guān)注。他們認(rèn)為，目前有越來越多的機(jī)會(huì)將適應(yīng)和緩解計(jì)劃系統(tǒng)性地納入與水有關(guān)的投資，以使得這些投資對捐助者們更具吸引力。

斯里蘭卡的“綠色氣候基金”項(xiàng)目是一個(gè)良好的案例。該方案旨在改善脆弱農(nóng)村社區(qū)的灌溉系統(tǒng)，并在3個(gè)河流流域推廣氣候智能型農(nóng)業(yè)做法，既能將氣候變化適應(yīng)與減緩相結(jié)合，又能保護(hù)水和飲用水源。

各種水和氣候變化倡議還可以產(chǎn)生連帶效益，如創(chuàng)造就業(yè)機(jī)會(huì)、改善公共衛(wèi)生、減少貧困、促進(jìn)性別平等和改善生計(jì)等，這提高了它們對捐助者的吸引力。

報(bào)告的作者們總結(jié)道，采取綜合的適應(yīng)和緩解措施是一個(gè)雙贏的做法。顯然，它們有利于水資源的可持續(xù)管理，有利于保障享有安全飲用水和衛(wèi)生設(shè)施的人權(quán)。它們還直接作用于氣候變化的原因和后果，包括對極端天氣事件的響應(yīng)。最后，它們有助于許多項(xiàng)可持續(xù)發(fā)展目標(biāo)的實(shí)現(xiàn)。

聯(lián)合國《世界水發(fā)展報(bào)告》是聯(lián)合國水機(jī)制關(guān)于水和衛(wèi)生問題的旗艦報(bào)告，每年關(guān)注一個(gè)不同的主題。該報(bào)告由教科文組織代表聯(lián)合國水機(jī)制發(fā)表，其編制工作由教科文組織世界水評估計(jì)劃負(fù)責(zé)協(xié)調(diào)。該報(bào)告在世界水日當(dāng)天發(fā)布，為決策者提供制定和實(shí)施可持續(xù)水政策的知識和工具。

教科文組織媒體聯(lián)系人：

Bernard Giansetto

b.giansetto@unesco.org

33 (0)1 45 68 17 64

聯(lián)合國水機(jī)制：

Daniella Bostrom Couffe

daniella.bostrom@unwater.org

41 79 159 92 17

Water resources an essential part of the solution to climate change

Launch of the UN World Water Development Report on 22 March

Paris/Geneva, 22 March — Climate change will affect the availability, quality and quantity of water needed for basic human needs, thus undermining enjoyment of the basic rights to safe drinking water and sanitation for billions of people, warns the latest UN World Water Development Report. The authors call on States to make more concrete commitments to address the challenge.

Such a deterioration of the situation would only hinder achievement of Sustainable Development Goal 6 which is part of the 2030 Agenda for Sustainable Development, according to which access to safe drinking water and sanitation must be guaranteed for all within ten years. This will be a considerable challenge – 2.2 billion people currently do not have access to safely managed drinking water, and 4.2 billion, or 55% of the world's population, are without safely managed sanitation.

Water use has increased sixfold over the past century and is rising by about 1% a year. However, it is estimated that climate change, along with the increasing frequency and intensity of extreme events – storms, floods and droughts, will aggravate the situation in countries already currently experiencing ‘water stress’ and generate similar problems in areas that have not been severely affected. Furthermore, the report highlights the fact that poor water management tends to exacerbate the impacts of climate change, not only on water resources but on society as a whole. 

The Director-General of UNESCO, Audrey Azoulay, stresses “that water does not need to be a problem – it can be part of the solution. Water can support efforts to both mitigate and adapt to climate change.”

The Chair of UN-Water, and President of the International Fund for Agricultural Development (IFAD), Gilbert F. Houngbo, says : “If we are serious about limiting global temperature increases to below 2°C and achieving the Sustainable Development Goals by 2030, we must act immediately. There are solutions for managing water and climate in a more coordinated manner and every sector of society has a role to play. We simply cannot afford to wait.”

Health effects, threat to biodiversity

Indeed, water quality will be affected by increased water temperatures and a decrease in dissolved oxygen, leading to a reduction in the self-purification capacity of freshwater basins. We will see increased risks of water pollution and pathogen contamination caused by floods or higher concentrations of pollutants during periods of drought. In addition to the impact on food production, the effects on physical and mental health – linked to disease, injury, financial loss and the displacement of people – are therefore likely to be considerable.

Many ecosystems, particularly forests and wetlands, are also under threat, reducing biodiversity. Water supplies will be affected, not only for agriculture – which accounts for 69% of freshwater withdrawals – but also for industry, energy production and even fisheries.

Areas most at risk: archipelagos, mountains, tropics and Far North

Much of the impact of climate change on water resources will be manifested in the tropics, where most developing countries are located, with potentially apocalyptic consequences for small island states, some of which could be wiped off the map. Mountainous areas are also exceptionally vulnerable through impacts on mountain glaciers and snowcaps, which show a decreasing trend almost everywhere in the world. The authors recognize, however, that a number of uncertainties remain, particularly at the local level and due to the seasonal variability of rainfall patterns.

Suggested solutions: adaptation and mitigation

In the face of these threats, the report highlights the two complementary strategies to be implemented – adaptation and mitigation: 

• Adaptation encompasses a combination of natural, technical and technological options, as well as social and institutional measures to mitigate damage and exploit the few positive consequences of climate change. It is likely to have very rapid benefits, mainly at the local level.

• Mitigation consists of the human actions needed to reduce greenhouse gases (GHGs) emissions while exploiting carbon sinks to reduce the amount of CO2 and other GHGs in the atmosphere. It can involve large geographical areas, but with gains that may spread over decades. However, the possibilities for mitigation in water management remain largely unrecognized.

Improved wastewater management

Wastewater treatment also contributes to climate change as it generates GHGs, accounting for an estimated 3% to 7% of all emissions. These emissions arise from both the energy required for wastewater treatment and the biochemical processes used. But because of the decomposition of the organic matter it contains, untreated wastewater is also a major source of methane, a powerful greenhouse gas. The report points out that wastewater harbours more energy than is needed for its treatment, provided, of course, that it is harnessed. It is estimated that worldwide, between 80% and 90% of wastewater is discharged to the environment without any form of treatment. 

In concrete terms, the optimal management of water resources means investing in modern treatment techniques that allow for the extraction of methane from organic matter and then use this biogas to generate the energy needed to run the process, as is already done in water-scarce countries such as Jordan, Mexico, Peru and Thailand. These techniques have enabled the public utilities concerned to reduce emissions by thousands of tonnes of CO2, while making financial savings and improving the quality of the service.

The report also mentions innovative water management interventions such as fog capture, or more traditional ones such as wetland protection, as well as proven ‘conservation agriculture’ techniques. These make it possible to preserve soil structure, organic matter and moisture, despite lower rainfall. Similarly, the ‘reuse’ of partially treated wastewater for agriculture and industry, without necessarily making it safe to drink, is another interesting approach.

Prioritizing water

Unfortunately, note the authors, while the need to combat climate change through better management of the water cycle is well recognized, it is not being translated into reality. “The word 'water' rarely appears in international climate agreements,” observes Audrey Azoulay. The ‘nationally determined contributions’ submitted by States under the Paris Agreement remain general in nature, without proposing specific plans for water. While a majority of countries recognize water in their 'portfolio of actions', few of them have actually calculated the costs of these actions and even fewer have put forward specific projects. Meanwhile, the possibilities for synergies between adaptation and mitigation measures are often neglected.

Accessing climate funds

The question of finance is obviously crucial. The authors point out that water resources management and water supply and sanitation services are underfunded and require greater attention from States. They argue that there are increasing opportunities to systematically integrate adaptation and mitigation planning into water-related investments, in order to make them more attractive to donors. 

A good example of this is a Green Climate Fund project in Sri Lanka. This aims to improve irrigation systems in vulnerable village communities and promote climate-smart agricultural practices in three river basins, offering both climate adaptation and mitigation benefits, while conserving water and protecting drinking water sources.

Various water and climate change initiatives can also bring co-benefits such as job creation, improved public health, poverty reduction, promotion of gender equality and improved livelihoods, further enhancing their attractiveness to donors.

The adoption of integrated adaptation and mitigation measures is a win-win proposition, conclude the authors of the report. They are clearly beneficial for the sustainable management of water resources and for the human right to safe drinking water and sanitation. They also directly address the causes and consequences of climate change, including in terms of the response to extreme weather events. Finally, they contribute to the achievement of several of the Sustainable Development Goals.

The United Nations World Water Development Report is UN-Water’s flagship report on water and sanitation issues, focusing on a different theme each year. The report is published by UNESCO, on behalf of UN-Water and its production is coordinated by the UNESCO World Water Assessment Programme. Launched in conjunction with World Water Day, the report provides decision-makers with knowledge and tools to formulate and implement sustainable water policies.

Media contact for UNESCO: 

Bernard Giansetto

b.giansetto@unesco.org

33 (0)1 45 68 17 64

UN-Water: 

Daniella Bostrom Couffe

daniella.bostrom@unwater.org

41 79 159 92 17

More information:

World Water Day

https://en.unesco.org/commemorations/waterday

來源：聯(lián)合國教科文組織