One of the world’s main number crunchers released its latest economic report on Tuesday. But the middling forecast from the International Monetary Fund doesn’t begin to capture the helter-skelter ride the global economy is on.

全球主要经济数据分析机构之一周二发布了最新经济报告，但国际货币基金组织(IMF)给出的折中预测远未能反映出全球经济正经历的剧烈动荡。

Even as the I.M.F. was preparing its report, a flurry of developments were already altering the picture. New U.S. tariffs on imported wood, furniture and kitchen cabinets that are expected to drive up the cost of home building took effect on Tuesday. So did the opening round of higher port entry fees that China and the United States will impose on each other’s vessels.

就在IMF筹备报告期间，一系列新动态已在改变当前局势。美国对进口木材、家具及橱柜加征的关税已于周二正式生效，此举预计将推高住宅建造成本。同日，中美两国相互加征的首轮船舶港口费也同步落地。

Tuesday’s turn of the trade wheel was just one click in a series of repercussions set in motion by President Trump’s vow to smash the world’s economic order. More will follow.

周二的贸易局势变动不过是特朗普总统誓言打破全球经济秩序所引发连锁反应中的一个环节，后续还将有更多变动。

Last week, Beijing decided to sharply step up curbs on its export of rare earth metals, materials that are essential for the manufacturing of semiconductors, cellphones, wind turbines and nearly every other modern gadget. New restrictions on equipment needed to produce batteries for electric cars are also scheduled to take effect next month.

上周，中国政府决定大幅加强对稀土金属的出口管制。稀土金属是制造半导体、手机、风力涡轮机及几乎所有现代电子产品的关键材料。此外，针对电动汽车电池生产所需设备的新限制措施，也定于下月正式生效。

Mr. Trump’s initial fury softened over the weekend, after his response led to the sharpest decline in stocks since April, when the president’s initial barrage of tariffs was announced. Still, his threat to slap an additional 100 percent tariff on Chinese imports was left dangling.

特朗普最初的怒火在上周末有所缓和，此前他的回应导致股市出现自4月首次宣布大规模加征关税以来的最剧烈下跌。尽管如此，他威胁要对中国进口商品额外加征100%关税的提议仍是悬而未决。

中美贸易紧张局势正引发全球连锁反应：中国出口限制措施冲击欧洲汽车制造商，美国对中国制造船舶的收费则影响外国船运企业停靠美国港口。

“The U.S.-China relationship is highly volatile,” said Richard Portes, a professor at the London Business School. “One doesn’t really know what to expect from one day to the next, and that is typical of the current administration.”

“美中关系极不稳定，”伦敦商学院教授理查德·波特斯表示，“人们根本无法预测第二天会发生什么，而这正是本届政府的典型特征。”

The souped-up tension between the two economic superpowers is catching other countries — that is, almost every country — in the crossfire. China’s restrictions on metals and magnets, for instance, would affect European automakers that use those materials and ship them across borders within Europe. And the levies on ships made in China apply even to non-Chinese shipping companies stopping at American ports.

这两个经济超级大国之间不断升级的紧张局势正使其他国家——几乎是所有国家——陷入夹缝之中。例如，中国对金属和磁体的出口限制，将影响到使用这些材料并在欧洲内部跨境运输的欧洲汽车制造商；而针对中国制造船舶的收费，即便对停靠美国港口的非中国航运企业也同样适用。

On Tuesday, the Chinese government ratcheted up the retaliation by adding five American subsidiaries of the South Korean shipping company Hanwha to its sanctions list, accusing the subsidiaries of “supporting and assisting” the United States in its moves in the shipbuilding industry.

周二，中国政府进一步加大报复力度，将韩国航运企业韩华集团的五家美国子公司列入制裁名单，指控这些子公司“支持和协助”美国在造船业的相关行动。

Beijing and Washington are also essentially pressuring nations around the globe to take sides. Mexico, one of the world’s biggest buyers of Chinese cars, proposed a 50 percent tariff last month on those vehicles after heavy lobbying from the Trump administration.

北京和华盛顿实质上还在迫使全球各国选边站。作为全球最大的中国汽车买家之一，墨西哥在特朗普政府的大力游说后，于上月提议对中国汽车加征50%的关税。

India, meanwhile, has moved closer to China since the White House, piqued by New Delhi’s continued purchase of Russian oil, imposed tariffs up to 50 percent on Indian goods. In August, Prime Minister Narendra Modi visited China for the first time in seven years to attend a security and economic conference — a public display by India’s leader that his country has plenty of allies should the Trump administration continue to single it out for punishment.

与此同时，印度与中国的关系愈发紧密。此前，白宫对新德里持续购买俄罗斯石油不满，对印度商品加征最高50%的关税。8月，印度总理莫迪七年来首次访华，出席一场安全与经济会议——印度领导人借此公开表明，若特朗普政府继续针对印度实施惩罚性措施，印度仍有众多盟友。

北京和华盛顿正施压各国选边站队。在美国游说下，中国汽车的主要买家墨西哥上月提议对中国汽车征收50%的关税。

Since Mr. Trump took office, shifts in global trade policy have happened both at high speed and in slow motion, reverberating in broad and unpredictable ways.

自特朗普上任以来，全球贸易政策的变动既有快速的推进，也有缓慢的发酵，其影响广泛且难以预测。

When Mr. Trump announced his plan this summer to slap 50 percent tariffs on most steel and aluminum coming into the United States, British steel makers felt lucky. Their government had already struck a deal that their steel would be tariffed at only half that amount — 25 percent.

今年夏季，当特朗普宣布计划对大多数进口钢铝加征50%关税时，英国钢铁制造商曾感到庆幸——英国政府已与美方达成协议，其钢铁产品仅需缴纳半数关税，即25%。

But the mood in Britain darkened considerably last week when the European Union announced its own set of punishing tariffs on steel imported into its 27-nation bloc. The policy delivered a gut punch to Britain’s steel industry, which sends nearly 80 percent of its exports to the European Union.

但上周，欧盟宣布对进口至其27个成员国的钢铁征收惩罚性关税后，英国业界的情绪急剧恶化。该政策给英国钢铁业带来沉重打击，因为英国钢铁近80%的出口流向欧盟。

Britain, though, wasn’t the target of the policy — just a bystander to moves aimed at Beijing and Washington.

然而，英国并非该政策的目标——这些举措的矛头指向北京和华盛顿，英国只是被波及的旁观者。

The 50 percent E.U. tariff was directed at China, which has been accused of dumping underpriced steel on the global market. The tax was also designed with an eye to putting the European Union in a better negotiating position with the United States.

欧盟此次加征的50%关税主要针对中国，中国被指向全球市场倾销低价钢铁。该关税政策的另一目的是使得欧盟在与美国谈判时占据更有利地位。

“The Union is ready to work with like-minded countries with a view to ring-fencing their economies from global overcapacity,” the European Union’s executive arm said last week. “We will continue exploring ways of working together with the U.S.”

“欧盟准备与志同道合的国家合作，保护本国经济免受全球产能过剩的影响，”欧盟执行机构上周表示，“我们将继续探索与美国的合作途径。”

全球两大经济体之间的贸易冲突正引发连锁反应——中国制造的船舶在停靠美国港口时面临额外收费。

The protectionist impulse is also going viral, with Canada, Brazil and Mexico taking steps to shield their homegrown steel makers.

保护主义的势头也在蔓延，加拿大、巴西和墨西哥均已采取措施保护本土钢铁企业。

Despite the frequent swerves in trade policy, though, the global economy will remain highly integrated, said Lucrezia Reichlin, a professor at the London Business School, even as the center of gravity shifts toward Asia and away from the West.

不过，伦敦商学院教授卢克雷齐娅·赖希林表示，尽管贸易政策频繁变动，全球经济仍将保持高度一体化，即便经济重心正从西方转向亚洲。

For now, growth is slowing in both the United States and China, while a pervasive unpredictability characterizes the short- and long-term outlooks.

目前，美国和中国的经济增长均在放缓，短期和长期前景均充满普遍的不确定性。

Mr. Portes at the London Business School summed up the dynamic between the world’s two largest economies: “China has stable, clear and determined objectives. The Trump administration changes from day to day, in its views and its policies.”

伦敦商学院的波特斯如此总结全球两大经济体之间的态势：“中国的目标稳定、明确且坚定，而特朗普政府的观点和政策每天都在变化。”

“The degree of uncertainty is huge,” he added, “and that has consequences for the global economy.”

“当前的不确定性程度极高，”他还说。“这无疑会给全球经济带来影响。”