BEIJING — As other countries look to China to take the lead in fighting global warming after President Trump’s rejection of the Paris climate agreement, President Xi Jinping is pushing ahead with an ambitious plan to build the world’s largest market for carbon emissions permits.

北京。美国总统特朗普拒绝巴黎气候协议后，其他国家盼着中国在应对全球变暖中挑大梁，习近平主席推动了雄心勃勃的计划，建立世界上最大的碳排放许可市场。

The start of a national carbon trading market in China by late this year has been years in the making, but is now shaping up as Mr. Xi’s big policy retort to Mr. Trump’s decision to quit the Paris accord. The Chinese government said in a greenhouse gas policy guide released on Wednesday that the 2017 start was on track.

今年末就要启动的全国性碳交易市场已酝酿数年之久，中国的大方针呛声特朗普先生决定退出巴黎协定后，碳交易市场即将出炉。周三，中国政府发布温室气体政策指导，表示将在2017年启动这一市场。

“Carbon trading on a national scale will send a signal to the world that China is serious about this,” said Wang Yi, a professor at the Chinese Academy of Sciences in Beijing who also belongs to the national legislature and advises the government on climate policy.

“在全国层面推行碳交易，这向世界发出信号，中国对此是认真的，”中国社科院教授、全国人大常委会委员王毅说，他就气候政策对政府提出建议。

But this is a high-visibility, high-stakes gamble. China seems eager to take the initiative from the United States on trade, multilateral cooperation and climate change. Its record on the environment and market reforms, though, is mixed, and China’s carbon trading plan is not a sure bet to succeed.

但这也是一场举世瞩目且筹码很高的赌博。中国想在贸易、多边合作和气候变化三方面领先美国，可中国在环保和市场改革方面的作为喜忧参半，碳交易计划也未必一定成功。

Europe and California already use this cap-and-trade approach, which sets a ceiling for greenhouse-gas emissions and allows businesses to buy and sell emissions permits in the hope of unleashing market competition to save energy and embrace clean technology. But no one has tried this on the scale the government envisions for China, the world’s leading source of carbon emissions.

欧洲和加利福尼亚州已经采取这种限额-交易方式，对温室气体排放设置上限，并允许企业买卖排放配额，希望借此鼓励企业在节约能源和推广清洁技术方面展开市场竞争，但没有国家曾在中国这么大尺度上推广碳汇市场，中国是世界最大的碳排放源。

Making the trade run smoothly could take years and test Mr. Xi’s vows to let markets expand and to curtail polluting industries. Major setbacks in the nascent market could embarrass China and undermine global support for using cap-and-trade measures to reduce the greenhouse gases that are causing warming.

碳交易的平稳运行需要数年时间，考验着中国扩大碳市场及压减污染行业的决心。这一新兴市场发生重大倒退，这可能让中国很尴尬，同时损害了运用限额-交易措施削减温室气体的国际支持。

Mr. Trump’s renunciation of the Paris agreement could also drag on China’s expansion of emissions trading by making powerful companies and industry associations more reluctant to accept pollution cuts, Mr. Wang said.

王毅说，特朗普正式放弃巴黎协议也拖累了中国扩大碳交易的努力，有实力的公司和行业协会更加不愿接受减污。

“It’s a really complicated task,” he said. “That’s precisely why China must work on this in a steady way and mustn’t fail. If China’s carbon market fails, that will be a big blow not just to China but also to global carbon markets.”

“任务确实很复杂，”他说。“这正是为什么中国必须稳步推进，不能失败。如果中国的碳汇市场失败了，不仅对中国，对全球碳汇市场都是一大打击。”

The idea behind cap and trade is that companies that cut pollution are rewarded, while laggards pay a higher price. The government sets a ceiling on the amount of pollution allowed and divides that into emissions permits issued or sold to businesses.

限额-贸易的思路是，减少污染的企业获得奖励，落后者付出高昂成本。政府为排污总量设立天花板，将排放配额分发或出售给企业。

Participating factories, power plants and other enterprises can use their permits to discharge pollution; cut pollution and sell or save leftover permits; or buy more permits, often at punishing prices, if they use up their allotment.

参与的工厂、电厂和其他企业可以使用配额进行排污，也可以减少污染并出售或保存剩余配额。如果用完了份额，就以惩罚性价格购买配额。

Governments can over time lower the allowed emissions, making permits scarcer and magnifying price pressures on companies to cut pollution.

政府可以随着时间的推移降低排放总量，让配额越来越少，增加企业的价格压力，促使其减少污染。

“Every ton of emissions that’s going up the stack becomes potentially money lost,” said Dan J. Dudek, vice president for Asia of the Environmental Defense Fund, who has advised the Chinese government on its market. “It changes people’s minds about what was once fundamentally free.”

“多排一吨排放量就意味着可能亏钱，”为中国政府提供碳汇市场咨询的环境防卫基金亚洲副主席丹·杜德克说。“这改变了人们的思维，以前排放基本是免费的。”

Before Mr. Dudek began working with China, he spent decades advising American politicians on using cap and trade to limit pollution, among them President George H. W. Bush, who used it to reduce the sulfur dioxide and nitrous oxide causing the acid rain that was harming forests.

杜德克开始为中国工作前，数十年间为美国政客提供咨询，指导其使用限额-贸易限制污染，其中包括老布什总统，后者运用该机制降低二氧化硫和氧化氮的排放，两种污染物导致酸雨，酸雨对森林造成危害。

But creating a government-mandated market has rarely been easy. Even mature economies have encountered problems in setting the rules for greenhouse gas markets. Chinese policy makers have studied Europe, as well as California, which started its emissions trading program in 2013.

但创立政府指令性市场并不容易，甚至成熟的经济体为温室气体市场制定规则时都遭遇诸多问题。中国决策者研究了欧洲和加州的情况，两个地方自2013年起启动排放交易项目。

Moreover, China has a huge industrial sector dominated by state conglomerates that can outgun regulators and ignore laws. Officials habitually meddle in markets. Local protectionism often stymies domestic competition, and pollution and energy data can be unreliable or outright fake.

此外，中国拥有由庞大的国有集团控制的工业部门，这些部门比监管者还强势，无视法律。官员也习惯于干预市场，地方保护主义还常常阻挠国内竞争，污染和能源数据不可靠甚至根本就是伪造的。

“One of the problems they have had is getting realistic numbers,” said Deborah M. Lehr, a senior fellow at the Paulson Institute who has advised Chinese officials on climate-friendly financial policies. “To move to emissions trading, you need to have realistic numbers on how to start to price these emissions.”

“其中一个问题是获得真实的数据，”为中国官员提供气候友好财政政策咨询的保尔森研究所高级研究员黛博拉·莱尔说。“推动排放贸易，你需要有真实的数据，从而决定如何对排放定价。”

If China gets past these problems, it will create the world’s biggest emissions market, overshadowing the European Union’s, and that could deepen China’s influence over developing new energy technology, Chinese policy advisers said.

如果中国解决了这些问题，它将创立世界上最大的排放市场，让欧盟都位置逊色，这会深化中国在开发新能源技术方面的影响力，中国政策咨询者说。

“A successful start of a carbon market will greatly enhance China’s international standing in responding to climate change,” said Zhang Xiliang, a professor at Tsinghua University in Beijing who is advising the government on the market.

“碳汇市场的成功启动将极大增强中国应对气候变化的国际站位，”为政府提供碳汇市场咨询的清华大学张希良教授说。

For now, Chinese officials are planning a relatively modest start and have retreated from their initially high ambitions.

目前，中国官员要启动的计划比最初的远大设想更为温和。

After 2015, when China announced a national emissions trading plan as part of a formal pledge with the Obama administration to support a new climate agreement, policy makers in Beijing assembled plans for a market that would at first cover eight sectors, including steel, petrochemicals and construction materials.

2015年后，中国宣布一项全国排放贸易计划，那是与奥巴马政府共同支持新气候协议的正式承诺。，北京的政策制定者汇总了碳汇市场计划，最初涵盖八个部门，包括钢铁、石化和建筑材料等。

But several months ago, the National Development and Reform Commission, the government agency preparing for the market, decided that it still lacked reliable information for many industries, according to experts involved in the planning.

据筹备专家称，几个月前，筹备碳交易市场的政府机构国家发改委认为，许多行业仍缺少可靠信息。

The commission abruptly reduced the number of industries most likely to join at the start to just three: coal-fired power plants, cement and aluminum, according to experts and preparatory remarks from local governments.

专家和地方政府的筹备讲话透露，发改委突然把最初加入这一市场的行业数量削减到三个：火电厂、水泥和电解铝。

These industries have relatively simply production processes, making it easier to collect data. Aviation may also be included.

这些行业生产流程相对简单，更容易收集数据。航空也有可能包括进来。

“It’s a good idea to start with a narrow range of sectors, even if that wasn’t the original plan,” said Stian Reklev, a Beijing-based co-founder of Carbon Pulse, which provides information on greenhouse gas markets and climate change policy.

“从相对狭窄的几个部门开始是个好主意，虽然这和最初预想的不一样，”位于北京的碳脉搏共同创始人斯蒂安·雷克列夫说，公司为温室气体交易市场和气候变化政策提供信息。

“It’s still going to be a massive challenge to make it work,” he said. “Anyone who thinks that the Chinese scheme will be effective in making big cuts in emissions from the start is going to be disappointed.”

“让市场运行仍起来然是一个巨大的挑战，”他说。“任何以为中国方案一开始就能大幅削减排放的人可能会失望。”

Still, China is by far the world’s leading carbon dioxide emitter — releasing about 10.4 billion metric tons of the gas from factories and other human sources in 2015. And even in its scaled-back form, the fledgling market will cover roughly half of those emissions, Mr. Dudek said.

中国目前是世界最大的二氧化碳排放国，2015年世界范围内的工厂和其他人类活动排放了104亿公吨气体。杜德克说，即便中国减排，蓬勃发展的市场也占排放的近半数之多。

A basic challenge will be persuading thousands of Chinese companies to put their trust and capital in a limited market for carbon dioxide, which most have discharged without weighing the environmental cost.

基本的挑战是劝说成千上万家中国企业把信誉和资本放在一个受限的二氧化碳市场中，让大多数排放不增加环境成本。

Since 2013, China has run seven pilot carbon-trading programs, including in Beijing, Shanghai and the central province of Hubei. (Fujian Province on the east coast announced an eighth last year.)

2013年以来，中国运行了七个试点碳交易项目，包括北京、上海和中部省份湖北。（东部沿海的福建去年成为第八个试点。）

Some observers said that even with this trial run, China’s lax statistics and enforcement of rules could hobble the national market. But others said the trade itself would amplify pressure for reliable numbers.

有观察者表示，即便有这些试点，中国统计数据松弛和执法不严可能会让全国市场运行不佳，但也有人表示交易本身就会为提供可靠数据加压。

“You start to create vested interests in local government, in industry associations and in other parts of the private sector for more accurate data,” said Huw Slater, research and projects manager for China Carbon Forum, a group in Beijing that monitors emissions trading. “In China, you can’t really wait until you’ve got perfect data, because it will never happen.”

“你开始让地方政府、行业协会和其他私营部门成为利益体，他们努力去提供更精确的数据，”在北京监测碳交易的中国碳论坛研究和项目经理休·斯雷特说。“在中国，你不能等到数据完美后再行动，因为永远都不完美。”

Even now, though, many company managers outside the pilot programs have little idea how the market will work, and could bridle at the paperwork and inspections used to monitor emissions, said Wang Ke, a professor of environmental economics at Renmin University of China in Beijing, who has been advising officials.

即便直到现在，试点项目外的公司管理者对这个市场如何运作一无所知，对用于监测排放的公文和检查不屑一顾，为官员提供咨询的中国人民大学环境经济学教授Wang Ke说。

After the national market officially opens, it will be more a test exercise until around 2020, while officials and companies work out how to allocate permits and regulate the market. 

全国市场正式开启后，到2020年左右，更多是一种测试，官员和公司共同探索如何分配配额及管理市场。

Companies are likely to receive generous initial allocations of permits, meaning that they will have to buy or bid for only a fraction of the allowances they need to emit. Market purchases will expand only gradually.

公司一开始可能配额比较多，意味着他们只需购买和出价一小部分所需排放额，市场购买行为将逐步扩大。

Several experts advising the Chinese government said that officials have resisted proposing a carbon tax in the face of public resentment over current tax burdens. 

为中国政府提供咨询的一些专家表示，当下公众对税负不满，因此官员抵制新设立碳税。

Last year, China’s legislature authorized a new environmental tax that will start from 2018, but policy makers resisted including the explicit authority for a carbon tax.

去年，中国立法机构批准了新的环境税，2018年将开始征收，但决策者抵制真正意义上的碳税。

“The realities of the political process are that a carbon tax is unlikely in the short term,” Mr. Wang said. “Politically, this is more difficult than launching the carbon market.”

“政治进程的真实情况是，碳税短期内不会出台，”王说。“从政治上看，这比启动碳汇市场更难。”