References to the ousted President Bashar al-Assad and his father, who ruled Syria before him, have been removed, as have images of pre-Islamic gods. The definition of a martyr has been changed, and it now means someone who has died for God, not one’s country. A Roman-era queen has been taken out of some textbooks.

Just weeks after a coalition of rebels toppled the Assad regime, the interim government they have set up in Damascus has moved quickly to order a raft of changes to the country’s school curriculum. The modifications cover subjects ranging from English and history to science and Islamic studies.

The move has been criticized by teachers and other Syrians who object not only to the nature of some of the changes but also to the fact that they were decided upon so quickly, with no transparency and no guidance from teachers and the general public.

Critics say that the changes, and the unilateral way in which they were ordered, are worrying signs of how the new Syrian government plans to govern a diverse country.

Some of the changes, which were detailed in nine pages released by the Education Ministry on social media last week, have been broadly welcomed, like removing glorification of the Assad regime from textbooks.

But some Syrians question why other changes were a priority, given the more pressing issues, like insecurity, sectarian tensions and an economic crisis, that still confront the country.

“The modifications should be restricted to only the things that involved the previous regime,” Rose Maya, 45, a high school French teacher, said at a small protest against the changes outside the Education Ministry on Sunday. “But there is no need for all the other changes.”

Ms. Maya was joined by about two dozen other people — among them teachers, students, doctors and artists — holding signs expressing various objections to the changes. Next to her was another teacher, Muayid Muflih, with a sign that read: “Power belongs to the people, not over the people.”

Mr. Muflih said that until recently he taught about nationalism, a subject that was widely seen as serving the agenda of the Assad regime. It has now been eliminated completely from the curriculum.

Ms. Maya, referring to Nazir Mohammad al-Qadri, the education minister, said that “as an interim minister he shouldn’t make changes.” And she said there needed to be transparency regarding the committees the ministry said it formed to review textbooks and suggest the changes. “There should be teachers involved,” she said.

The ministry has defended the changes and pushed back against suggestions that the alterations were Islamist, or a nod to Salafism, a conservative branch of Sunni Islam to which many of the country’s new leaders belong.

“The modifications were needed after the liberation of Syria,” Mr. al-Qadri said in an interview on Sunday. “These modifications were not changes to the curriculum but modifications of some of the slogans and symbols that used to glorify the previous regime.”

Mr. al-Qadri was part of the education ministry in Idlib, the province in northwest Syria run by the Islamist rebel group that now heads the interim government, Hayat Tahrir al-Sham.

Specialized committees involving both members of the Hayat Tahrir al-Sham-led government in Idlib Province and members of the Assad-era education ministry reviewed the textbooks and suggested changes, he said.

Mutasem Syoufi, executive director of the Day After, a nonprofit group, said that the interim government was trying to impose its vision not just on the political system of Syria but also its public life. The Day After was founded in 2012 by members of the Syrian opposition to plan for a transitional phase in Syria after the eventual fall of the Assad regime.

“The changes are a clear reflection of a very narrow reading of Islam, and again it reminds us of the background of the group which is in charge of Syria today,” he said. “There is no inclusive viewpoint.”

The speed with which the curriculum changes were made suggests they had been prepared before the interim government took power, Mr. Syoufi said.

Across Syria, even as people celebrate the toppling of a brutal and autocratic regime, there is some trepidation about the future of the country under a government headed by Islamist rebels.

Syria’s de facto new leader, Ahmed al-Shara, recently said it could take two to three years to draft a new constitution and up to four years to hold elections, alarming some Syrians who have expressed fear that they have traded one authoritarian leader for another.

Several people at the protest questioned why removing a Roman-era queen was such a priority for the new Syrian leadership, which is already overwhelmed with suddenly running a whole country, and rebuilding the state.

On page 19 in the third-grade Islamic Studies textbook a reference to Zenobia, a queen in the Roman colony of Palmyra, in present-day central Syria, has been removed. An ambiguous notation in the ministry’s list of changes has been read by many as proof that it sees her as a fictional person.

Mr. al-Qadri said she had not been removed from history textbooks. He said she had been deleted from the Islamic Studies textbook because she had lived and ruled in a pre-Islamic period.

“We don’t deny that Zenobia was present in history,” he said. But, he said, “we object to her inclusion in this book.”

The deletion of the female leader from the textbook has nevertheless worried some Syrians, who see it as an attack on the storied history of Syria.

“If we teach this generation that she was a fictional character, then we lose our connection to the past,” Ms. Maya said. “It means that we don’t have a past. And those that don’t have a past don’t have a future.”

Such changes, some Syrians say, should await the writing of a constitution and elections. They should also be part of a broader dialogue between different parts of Syrian society, made up of various religions, sects and ethnicities, they said.

“Their focus at this point should be just enforcing security and making it clear how they came into power and what their plans are,” said Malak Muhammad Suleiman, a dentist.

Another of the curriculum changes that has Syrians worried concerns the translation of a verse of the Quran. The final verse in the first chapter of the Muslim holy book refers to “those who are astray.”

In the previous first-grade Islamic studies book, the phrase was defined as “those who have moved away from the right path.” Under the new government’s changes, the phrase is now defined as “Christians and Jews.”

Manwella al-Hakim, a 60-year-old abstract painter and observant Muslim who wears the hijab, held up a sign at the protest objecting to this new interpretation.

“We don’t want things that will divide us,” she said. “Syria has always had all the religions and all the beliefs.”

Near her, Ziyad al-Khoury, a 61-year-old retired journalist, held up two signs, one of which read: “I am a Christian and not astray.”

Mr. al-Khoury said he was shocked when he first heard of the change.

“It felt like a message from the new government that we aren’t part of this country,” he said.

As the world grapples with climate change, population growth and dwindling supplies of fresh water, more people are set to rely on treated wastewater to sustain their daily lives.

But wastewater, even after treatment, contains high levels of harmful “forever chemicals” that are already contaminating the drinking water of millions of Americans, researchers said in a study published on Monday that analyzed wastewater samples nationwide.

The study, led by researchers at Harvard and New York University, found elevated levels of six types of chemicals known as PFAS, or per- and polyfluoroalkyl substances, in the samples. The chemicals, which have been linked to cancer and other diseases, are known as forever chemicals because they don’t break down in the environment. Last year, the Environmental Protection Agency started to regulate PFAS in drinking water.

The researchers found that the samples contained an even greater quantity of organofluorines, a wider group of chemicals that includes PFAS and is used in pharmaceuticals, refrigerants, and nonstick coatings. The majority of those chemicals are unregulated and the health consequences of exposure to many of them are still unknown.

“What are all of these other compounds? Are they other PFAS that we’re not measuring, that the industry has shifted toward?” said Bridger Ruyle, assistant professor of environmental engineering at New York University, who led the research. “What does that mean for exposure?”

The study, published in the Proceedings of the National Academy of Sciences, found that wastewater treatment facilities do not effectively remove these compounds from wastewater. At most sites, in fact, PFAS in wastewater became more concentrated after treatment, the researchers found.

The contamination is of particular concern, the researchers said, given that water scarcity across many regions of the United States means wastewater is being reused or is being released into rivers and lakes. And if that wastewater isn’t diluted enough before re-entering the drinking water supply, a concern that is growing as water flows dwindle because of overuse and climate change, “you have a contamination issue,” Professor Ruyle said.

About 50 percent of the country’s drinking water supplies are downstream of one or more wastewater sites, he added. The study used modeling to show that PFAS from wastewater was already contaminating the drinking water of up to 23 million people in the United States.

The results “emphasize the importance of further curbing ongoing PFAS sources,” the researchers concluded.

The new study highlights how widespread contamination is complicating efforts to reuse wastewater, which includes sewage from households as well as polluted water from businesses and factories. The sludge that is left over after wastewater treatment is also used to fertilize farmland across the country, and PFAS contamination of that sludge is also raising concerns over the practice.

Prime Minister Justin Trudeau of Canada said on Monday that he would step down in the coming months, bowing to an angry electorate at a time of uncertain economic prospects and political infighting.

The announcement, which came amid a gridlocked Parliament, left Canada in political flux just as the incoming Trump administration has vowed to impose punishing tariffs on Canadian imports.

“It’s time for a reset,” Mr. Trudeau told reporters outside his residence on a frigid morning in Ottawa, the capital. Mr. Trudeau said that he had suspended Parliament until March 24 and that he would stay on as Liberal Party leader and prime minister until his replacement had been chosen through a nationwide party election.

“I truly feel that removing the contention around my own continued leadership is an opportunity to bring the temperature down,” he said.

Mr. Trudeau, 53, who rose to power nearly a decade ago and quickly became seen as a progressive icon, is the latest leader in the West to be swept aside by a mood of anti-incumbency, a backlash against immigration and anger at the lingering effects of a spike in inflation during the Coronavirus pandemic. Although inflation in Canada has receded to below 2 percent, unemployment remains high, at above 6 percent.

General elections must be held by October, a timetable that Mr. Trudeau referred to on Monday.

“It’s become obvious to me with the internal battles that I cannot be the one to carry the Liberal standard into the next election,” he said.

Mr. Trudeau has faced weeks of mounting pressure from inside his party’s ranks.

In December, Mr. Trudeau’s deputy prime minister and finance minister, Chrystia Freeland, abruptly stepped down, issuing a stinging rebuke of his leadership and stewardship of the country. Ms. Freeland, who had been a close ally of the prime minister, accused Mr. Trudeau of having engaged in “costly political gimmicks” and being ill-prepared to face the challenge posed by Mr. Trump.

Her resignation incited a growing chorus of voices from Liberal parliamentarians asking him to step aside for the sake of the party, and let someone else lead the party in general elections.

Mr. Trudeau also had been under pressure from a resurgent Conservative Party, which in recent surveys has drawn a commanding double-digit lead over the Liberal Party. The Conservative leader, Pierre Poilievre, posted a video on social media on Monday promoting an alternate vision of governing: “ax the tax,” referring to Trudeau’s unpopular carbon tax, “build the homes,” “fix the budget” and “stop the crime.”

The upheaval comes as Canada is debating how best to deal with Mr. Trump’s pledge to impose tariffs that would upend a trade agreement among Canada, the United States and Mexico. (Mr. Trump has also threatened tariffs on Mexico and says he wants both countries to address the flow of drugs and undocumented migrants into the United States).

Tariffs would be potentially ruinous for Canada’s economy, which is heavily dependent on exports, particularly of oil and automobiles. The United States and Canada are each other’s biggest trading partners.

Mr. Trudeau visited Mr. Trump at Mar-a-Lago, his private club and residence in Florida, in late November, and his government had been in talks to address the president-elect’s concerns about border security in hopes that he would reconsider his tariff threat.

The talks do not appear to have been fruitful. In early December, Mr. Trump mocked Mr. Trudeau in a social media post, describing the Canadian prime minister as “Governor Justin Trudeau of the Great State of Canada.”

On Monday Mr. Trump responded to Trudeau’s resignation by again suggesting that Canada should become America’s “51st state,” saying on social media that if Canada merged with the U.S. that taxes would decrease and that there would be no tariffs.

Among possible replacements for Mr. Trudeau are Ms. Freeland, the former deputy prime minister and finance minister; Dominic LeBlanc, who became finance minister when Ms. Freeland resigned; Mélanie Joly, Canada’s top diplomat since 2021; and Mark Carney, the former governor of the Bank of Canada, who also led the Bank of England.

Mr. Trudeau, whose government has been hamstrung by its lack of a majority in Parliament, said on Monday that the legislative body had been “totally seized by obstruction, and filibustering and a total lack of productivity.”

In his comments in French, he painted an even starker picture of a Parliament that “no longer functions.”

The suspension of Parliament, a process known as prorogation, will give his party time to pick a new leader, which Mr. Trudeau said would be through a “robust, nationwide, competitive process.” A new — and perhaps more popular leader — could put the Liberals on firmer footing in the upcoming national election.

Suspending Parliament wipes out all pending legislation but does not affect the government’s day-to-day operations.

Mr. Trudeau spent a decade building a political brand around being a feminist, an environmentalist, and an advocate for refugees and Indigenous people, pursuing the same message of change and hope as Barack Obama. But analysts say Mr. Trudeau’s brand, which appears antithetical to Mr. Trump’s, is no longer working for him.

“He caught a wave on his way in, and when you catch a wave, it can lift you up,” Darrell Bricker, a seasoned pollster and chief executive of Ipsos Public Affairs, said. “But on the other side, if you don’t get off, it will ground you.”

An Ipsos poll, published in late December, found that the Liberals trail the Conservatives by 25 percentage points.

Although the next election must be held by October, a vote could be called or forced earlier.

The Liberal government under a new prime minister could be short lived. And shortly after the new session begins, the Liberal government is likely to face a vote of confidence. It would likely lose such a vote, as it only commands a minority of the seats in Parliament and it has lost the support of all other parties. That would prompt a federal election.

The prime minister also has the power to dissolve Parliament at any time, which would also prompt an election.

When Elon Musk asked his 211 million followers on X to vote on whether “America should liberate the people of Britain from their tyrannical government,” it seemed as if the post could only be tongue-in-cheek.

But coming after a barrage of strident posts about Britain by Mr. Musk — assailing the Labour prime minister, Keir Starmer; demanding the release of a jailed far-right agitator; and breaking with a hard-right leader, Nigel Farage — it came off less as a joke than a flex by a powerful man relishing his ability to roil the politics of another country.

Mr. Musk’s posts, which popped up on X throughout the holiday like unwelcome guests at a Christmas party, have thoroughly hijacked the political debate in Britain at the start of 2025.

On Monday, Mr. Starmer used a news conference about fixing Britain’s National Health Service to deny Mr. Musk’s allegations that he had not acted when he was Britain’s chief prosecutor more than a decade ago against gangs that sexually abused girls.

Mr. Farage, for his part, faced questions about his future as the leader of the right-wing anti-immigration party Reform U.K. after Mr. Musk declared on X on Sunday that “Farage doesn’t have what it takes.” A day later, Mr. Farage posted a call for a national inquiry into the cases of child sexual abuse, picking up on one of Mr. Musk’s favorite causes.

“Musk has a very distorted understanding of British politics, and yet he’s got a megaphone,” said Robert Ford, a professor of politics at the University of Manchester. “When he says this stuff at 3 a.m. on a Sunday night, it disrupts Labour’s whole N.H.S. press conference on Monday.”

The long-term effect of Mr. Musk’s erratic crusade was harder to predict, Professor Ford said, but some of his moves could backfire. His rupture with Mr. Farage, for example, could redound to Mr. Farage’s benefit.

The likely cause of the split was Mr. Farage’s refusal to back Mr. Musk’s demand for the release of the far-right agitator Tommy Robinson. Mr. Robinson, whose real name is Stephen Yaxley-Lennon, is serving a prison sentence for defying a court order by repeating a libel against a young Syrian refugee. He has multiple criminal convictions and a record of racist and Islamophobic statements.

In Britain, Professor Ford said, “Tommy Robinson is political kryptonite. There’s a reason that Farage doesn’t want to have anything to do with him, and never has.”

By rejecting Mr. Robinson in defiance of Mr. Musk, he said, Mr. Farage could make himself more palatable to mainstream voters on the right who are disenchanted by the Conservatives. Mr. Musk, he added, will also find that there aren’t clear alternatives for party leader to Mr. Farage, an architect of Brexit and a fixture in right-wing British politics for decades who galvanized Reform U.K. during last year’s election campaign.

For Mr. Starmer, who returned from a rare vacation that had to be postponed because of the death of his brother, Mr. Musk’s intervention was another setback after a glitch-ridden start to his fledgling government. With his personal ratings plunging in opinion polls, Mr. Starmer was hoping to begin 2025 by rolling out a plan to reduce patient waiting times at the N.H.S.

Instead, reporters asked him about Mr. Musk, who had falsely claimed that Mr. Starmer had covered up the abuse and exploitation of girls in the 2000s and 2010s by gang members, many of whom were of British Pakistani heritage. “Prison for Starmer,” Mr. Musk wrote in one post on Monday morning.

“It probably irritated him beyond description that he has to deal with this kind of thing,” said Steven Fielding, an emeritus professor of political history at the University of Nottingham. The prime minister, he said, was trying to avoid “a street fight” with Mr. Musk and focus on governing.

Mr. Starmer noted that when he was director of the Crown Prosecution Service, between 2008 and 2013, his office brought the first of several cases against a grooming gang and drafted guidelines for the mandatory reporting of child sexual abuse. He had tackled the scandal “head on,” he said.

The prime minister became visibly angry as he defended Jess Phillips, a minister for safeguarding and violence against women and girls, from Mr. Musk’s charge that she was a “rape genocide apologist” because she pushed back on calls for a national inquiry into child sexual exploitation in Oldham, a town near Manchester.

Ms. Phillips had instead called for an investigation to be run by Oldham’s authorities rather than the central government. Mr. Starmer said she had done “a thousand times more than they’ve even dreamed about when it comes to protecting victims of sexual abuse.”

Elizabeth Pearson, the author of a book about Britain’s far-right, “Extreme Britain,” said Mr. Robinson, who had been convicted of assault and fraud, was fortunate to draw “the attention of one of the most powerful people in the West.”

She and other analysts are more puzzled about what Mr. Musk stands to gain from supporting a reviled figure who has occupied the sometimes violent margins of British politics. Daily users of X in Britain have declined since Mr. Musk took over the platform formerly known as Twitter; championing Mr. Robinson’s cause, experts said, is not likely to reverse that trend.

“It is foreign interference in our system,” said Dr. Pearson, a senior lecturer at Royal Holloway, University of London. “I do feel, at the moment, that Musk is becoming a bad actor seeking to destabilize our system.”

Professor Fielding said Mr. Musk was probably catering to his audience in the United States. The risk, he said, was that “anyone who is serious in the U.S. administration will think this man is creating fires that are absolutely unnecessary.”

Mr. Musk’s activism has drawn alarm in other European countries, like Germany, where he endorsed a far-right party with neo-Nazi ties. On Monday, President Emmanuel Macron of France told a diplomatic audience, “Ten years ago, who would have imagined that the owner of one of the world’s largest social networks would be supporting a new international reactionary movement.” He did not mention Mr. Musk by name.

Likewise, Mr. Starmer showed no appetite to single out Mr. Musk, a close ally of President-elect Donald J. Trump, with whom Mr. Starmer and his aides have tried to cultivate relations. “This isn’t about America or Musk,” he said to a reporter on Monday. “I’m talking about our politics.”