Over a week of appearances at the United Nations, China tried to send the message that Beijing, not Washington, was the responsible power willing to shoulder global duties just as the United States, under President Trump, was signaling retreat.

通过一周来的联合国亮相，中国试图传递这样一个信息：在特朗普总统领导下的美国发出退却信号之际，北京——而非华盛顿——才是那个愿意承担全球责任的负责任大国。

China’s leaders used the U.N. General Assembly to roll out pledges on trade and fighting climate change that were notable less for their substance than for the image they projected of China as a pillar of stability and global cooperation.

中国领导人利用联合国大会推出了有关贸易和应对气候变化的承诺，这些承诺的引人注目之处不在于其内容，而在于它们所树立的中国作为稳定和全球合作支柱的形象。

In an apparent reference to the United States, Premier Li Qiang, China’s second-highest ranking official, said in his speech to the assembly on Friday that “the rise in unilateral and protectionist measures such as tariff hikes,” was slowing economic growth. By contrast, Mr. Li said, China had “consistently opened its door wider to the world.”

中国二号人物、国务院总理李强在周五的大会发言中表示，“关税大棒、‘筑墙设垒’等单边主义、保护主义措施增多”正在拖累经济增长，这明显是在影射美国。相比之下，他说，中国在“不断扩大对外开放”。

On Tuesday, he said that Beijing would no longer claim trade benefits reserved for developing nations at the World Trade Organization. Analysts said the announcement was intended to show China backing fairer trade at a time when the Trump administration was doing the opposite by weaponizing tariffs.

李强于上周二表示，中国将不再以发展中国家的身份在世界贸易组织享受贸易优惠。分析人士称，这一宣布旨在表明中国支持更公平的贸易，而此时特朗普政府目前正在做与此相反的事：把关税武器化。

On climate, China’s top leader, Xi Jinping, told a U.N. summit by video link on Wednesday that Beijing would commit to a detailed target for reducing greenhouse gas emissions for the first time. Mr. Xi said that going “green and low carbon” was the “trend of our time,” and he criticized countries that were “acting against” that transition, a not-so-veiled swipe at the United States.

在气候问题上，中国最高领导人习近平上周三通过视频在联合国峰会上表示，北京将首次承诺关于减少温室气体排放的详细目标。习近平表示，“绿色低碳”是“时代潮流”，并批评那些“逆流而动”的国家，这明显是在批评美国。

The contrast could not be greater. Mr. Xi’s pledge was made a day after Mr. Trump had derided climate change as the “greatest con job” that was “made by stupid people.”

对比再强烈不过了。习近平的承诺是在特朗普嘲讽气候变化是“由愚蠢的人编造”的“最大骗局”一天之后作出的。

上周二，特朗普在联合国大会上发表讲话。

The back-to-back pledges crystallized Beijing’s strategy: to position itself as an antidote to “America First.” Beijing calls its approach “true multilateralism,” which involves rhetorically embracing international organizations and treaties shunned by Mr. Trump like the United Nations, the World Health Organization and the Paris climate accord.

这一项接一项的承诺明确展示了北京的战略：把自己定位为“美国优先”的解药。北京称其做法是“真正的多边主义”，包括在言辞上拥抱特朗普所摒弃的国际组织和条约，比如联合国、世界卫生组织和《巴黎气候协定》。

The goal is to persuade other countries that China is a “moral righteous actor” so that they are more likely to take their cues from Beijing and not Washington, said Dylan Loh, an expert on Chinese foreign policy at Nanyang Technological University in Singapore.

新加坡南洋理工大学的中国外交政策专家骆明辉认为，北京的目标是说服其他国家相信中国是“正义的一方”，以使其他国家更有可能听从北京而非华盛顿的指引。

“They’re being opportunistic,” Mr. Loh said. “It’s clear that there are pockets of spaces where they see the United States leaving a vacuum in leadership, such as on climate issues, and that is where China is stepping up its game.”

“他们正在抓住机会，”骆明辉说。“很明显，他们看到在一些领域，比如在气候问题上，美国正在留下领导真空，而这正是中国加紧行动的地方。”

Whether China is doing enough to make a difference, or simply clearing the low bar of expectations set by the Trump administration’s retreat from climate science and global commitments, is an open question.

中国是做出了足以带来真正改变的行动，还是仅仅因为特朗普政府在气候科学和全球承诺方面的退缩导致人们的期待值很低，仍是一个悬而未决的问题。

Take Mr. Xi’s climate targets. Experts say China would need to reduce its greenhouse gas emissions by 30 percent from peak levels over the next decade for there to be a realistic chance of limiting global warming to 1.5 degrees Celsius, or 2.7 degrees Fahrenheit, above preindustrial levels, the main goal of the Paris climate accord. What they got instead from China, the world’s top polluting nation, was a pledge to cut between 7 and 10 percent.

以习近平的气候目标为例。专家表示，中国需要在未来十年将温室气体排放量从峰值水平减少30%，才有可能将全球变暖幅度限制在比工业化前水平高出1.5摄氏度以内——这是《巴黎气候协定》的主要目标。但他们从中国——世界上最大污染国——得到的承诺只是削减7%到10%。

“The headline target announced by President Xi has disappointed environmentalists and falls short of the climate leadership the world urgently needs,” said Li Shuo, director of the China Climate Hub at the Asia Society Policy Institute. Mr. Li held out hope that China would eventually exceed its targets on the backs of its growing electric vehicle and wind and solar energy industries.

“习近平主席宣布的这一主要目标令环保人士失望，未能展现出世界迫切需要的气候领导力，”亚洲协会政策研究所中国气候中心主任李硕说。李硕仍然认为中国有望在不断壮大的电动汽车、风能和太阳能产业的推动下，最终超额完成目标。

China has long resisted making more ambitious climate pledges, saying such commitments would stunt its economic growth.

中国长期以来一直拒绝做出更具雄心的气候承诺，称这种承诺会阻碍其经济增长。

There is a similar tension in how China defines itself as a developing country, a description that reinforces its ties to the world’s less developed nations, even as its nearly $19 trillion economy is already the world’s second largest.

在中国将自己定义为发展中国家这一点上也存在类似的矛盾。这种定义强化了中国与欠发达国家的联系，尽管该国近19万亿美元的经济体量已使其成为世界第二大经济体。

Mr. Li’s trade pledge on Tuesday — saying China would no longer seek certain benefits at the W.T.O. — appeared aimed at narrowing that gap. Such benefits include being given more time to carry out trade agreements, for instance.

李强周二的贸易承诺——表示中国将不再在世贸组织寻求某些优惠待遇——似乎是为了缩小这一鸿沟。这类优惠待遇包括给予更多时间履行贸易协定等。

But Li Yihong, China’s top envoy to the trade body, told reporters in Geneva that China would “always be a part of the developing world.”

但中国驻世贸组织首席代表李毅红在日内瓦对记者表示，中国将“永远属于发展中国家”。

The United States has long criticized China for failing to uphold promises it made when it joined the W.T.O. in 2001, and the Trump administration argues that “developing nation” status has long allowed China to game global trading rules.

美国长期以来一直批评中国未能兑现其在2001年加入世贸组织时作出的承诺，特朗普政府认为，“发展中国家”身份长期以来让中国得以玩弄在全球贸易规则。

“China is trying to have its cake and eat it, too,” said Stephen Olson, a former U.S. trade negotiator and a senior visiting fellow at Singapore’s ISEAS-Yusof Ishak Institute. “It does not want to lose its ‘membership card’ in the Global South, which it aspires to lead.”

“中国想要两头都占，”美国前贸易谈判代表、新加坡尤索夫伊萨东南亚研究所高级访问研究员斯蒂芬·奥尔森说。“它不想失去自己在全球南方的‘会员卡’，又渴望领导这些国家。”

The change in policy should not deflect from some of China’s objectionable trade practices, Mr. Olson added, including its subsidizing of Chinese exports that make goods produced elsewhere in the world less competitive.

奥尔森补充说，这一政策转变不应掩盖中国一些令人反感的贸易做法，比如对中国出口的补贴，这种补贴降低了世界其他地方生产的商品的竞争力。