Friday’s top story: Biden clashes with Warren and Sanders as frontrunners finally share a stage. Plus, the 100 best films of the 21st century

This article is more than 1 year old

This article is more than 1 year old

This article is more than 1 year old

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Good morning, I’m Tim Walker with today’s essential stories.

Top 2020 candidates disagree on healthcare and immigration

Joe Biden at last shared a debate stage with his biggest rivals for the Democratic presidential nomination on Tuesday night in Houston, demonstrating clear differences with Bernie Sanders and Elizabeth Warren on healthcare, immigration and foreign policy. But all 10 candidates in the largely conciliatory exchange aimed their ire most squarely at a single target: Donald Trump. Joan E Greve outlines the debate’s key takeaways, while the Guardian’s panel of experts fails to identify a clear winner.

Weak and strong. Richard Wolffe says Biden has a big lead but no momentum, which made him both the strongest and weakest candidate on stage. Bhashkar Sunkara says his dominance is a reminder that the Democratic party is still centrist at its core.

Death threat? After the debate, Twitter removed a tweet by a Texas GOP lawmaker, in which he took aim at Beto O’Rourke’s gun control stance, warning “my AR is ready for you”.

Trump’s border wall construction begins in Unesco reserve

Facebook Twitter Pinterest The Organ Pipe Cactus national monument in Arizona’s Sonora Desert. Photograph: Alamy

To the dismay of environmental groups, construction has begun on a section of Donald Trump’s coveted US-Mexico border wall along the southern edge of Arizona’s Organ Pipe Cactus national monument, a federally protected wilderness area and Unesco-recognized reserve. Amanda Munro of the Southwest Environmental Center said the planned barrier would require “bulldozing one of the most biologically diverse regions” in the US, calling it “a colossal mistake and a national tragedy”.

Wetlands protection. The Trump administration has revoked an Obama-era regulation shielding many US wetlands and streams from pollution. Farmers and developers claimed the rule dented economic development and infringed on property rights.

Crew slept as California boat caught fire, say investigators

Facebook Twitter Pinterest The burned hull of the Conception is brought to the surface by a salvage team. Photograph: Brian van der Brug/AP

Federal investigators say all six crew members aboard the doomed diving boat Conception were asleep when the vessel caught fire off the coast of southern California in the small hours of 2 September, killing 34 people who were trapped below deck. The information was revealed on Thursday in a preliminary report by the National Transportation Safety Board, and could lead to charges under a statute known as seaman’s manslaughter.

Keeping watch. The law stipulates that at least one crew member ought to have been awake and keeping watch overnight. All but one of the six crew survived the blaze, the cause of which is yet to be determined.

How the UK’s Brexit drama became a crisis

Facebook Twitter Pinterest The Speaker of the House of Commons, John Bercow, says he will block an unlawful no-deal Brexit. Photograph: Yui Mok/PA

The outgoing Speaker of the UK’s House of Commons, John Bercow, has said he will tear up traditional parliamentary procedure to prevent the prime minister, Boris Johnson, dragging the country out of the EU without a deal on 31 October. His pledge to enforce MPs’ will comes as Johnson was forced to deny misleading the Queen about his reasons for suspending parliament until mid-October. Jon Henley, the Guardian’s Europe correspondent, tells the full story of an extraordinary 10 days in the Brexit crisis.

‘Misleading’ campaign. Opposition MPs have condemned the Johnson government’s £100m “Get ready for Brexit” advertising campaign, ostensibly intended to prepare the British public for no deal on 31 October, as “redundant and misleading”.

Cheat sheet

The progressive Democratic congresswoman Alexandria Ocasio-Cortez has condemned a Republican TV ad broadcast during the debate in Houston, which described her as “the face of socialism” while showing a burning photograph of her face.

Gregory Cheadle, the black man to whom Trump referred as “ my African American ” during a campaign rally in California in 2016, has quit the Republican party, citing the president’s “white superiority complex”.

Brazil’s controversial environment minister, Ricardo Salles, is to meet representatives from the Competitive Enterprise Institute, a rightwing US group that denies climate change , in Washington in the run-up to the UN climate action summit.

A 14-year-old Kenyan girl who had her period during a lesson killed herself after a teacher allegedly called her dirty and expelled her from the classroom. The case has reignited a national debate about “period shaming” and access to menstrual products.

Must-reads

Facebook Twitter Pinterest ‘Are you not entertained?’ Russell Crowe in Gladiator, one of the Guardian’s 100 best films of the century. Photograph: DreamWorks/SportsPhoto/Allstar

The greatest films of the century… so far

The Guardian’s film writers have compiled a list of the 100 best films of the 21st century, guaranteed to enthuse and enrage in equal measure. The director of their No 1 pick reacts to the honour, Peter Bradshaw explains why it’s a masterpiece and some of the other film-makers listed select their own favourites.

Kentucky mixes church and state – in schools

Christians in Kentucky have succeeded in what seems a modest aim: mandating the state’s schools to prominently display the words “In God we trust”. But critics say it’s part of a nationwide effort by conservative Christian nationalist groups to inject religion into society, as Josh Wood reports from Louisville.

Should we clarify our pronouns when we say hello?

The trans YouTube star Natalie Wynn provoked the internet’s ire after tweeting that she wasn’t always fond of “pronoun introductions”, whereby people say their preferred pronouns when offering their names. It’s often a positive step to a better understanding of gender, but Arwa Mahdawi agrees it’s complicated.

How a podcast about celebrity became a ‘recipe for joy’

The podcast Who? Weekly is devoted to explaining the fame of minor, wannabe “Who?” celebrities to its baffled listenership, which includes real “Them” celebrities Lena Dunham and Busy Phillips. “‘Who?/Them’ is not actually a value judgment. It’s literally just a categorisation,” its co-host Lindsey Weber assures Steph Harmon. “It’s totally out of love.”

Opinion

The EU has nominated a minister with responsibility for protecting the “European way of life”, a job that incorporates the management of migration. It may be intended to keep nationalism at bay, but instead it is a gift to the far-right, says Daniel Trilling.

This is received political wisdom among the technocrats who have dominated politics in western Europe for years: take a tough stance on border control to address the “legitimate concerns” of “ordinary people” and the populists will lose their sting. Unfortunately, it is a bogus solution based on a fundamental misunderstanding.

Sport

The Patriots won everything last year, confirming their place as the most fearsome franchise not only in the NFL, but in all US sports. And somehow, with a 42-year-old quarterback and without the greatest tight end to ever play the game, they look even more dominant this year, says Oliver Connolly.

Unbeaten Leicester City are everyone’s tip to break up the Champions League cartel this year, and on Saturday they could stay in the top four by beating a vulnerable Manchester United at Old Trafford. That’s one of 10 things to look out for in the Premier League this weekend.

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