Good morning, this is Helen Sullivan bringing you the main stories and must-reads on Tuesday 22 January.

Top stories

The California senator Kamala Harris has officially launched her presidential campaign for 2020, joining an already crowded field of Democratic hopefuls. Harris, 54, the daughter of immigrants from India and Jamaica, follows fellow senators Elizabeth Warren of Massachusetts and Kirsten Gillibrand of New York into the contest, as well as Hawaii congresswoman Tulsi Gabbard and former housing secretary Juilán Castro. Harris is presenting herself as a criminal justice reformer, an ally of Black Lives Matter, and a defender of America’s most vulnerable citizens, but her record as a prosecutor in California complicates her progressive image.

Sir David Attenborough has warned that “the Garden of Eden is no more”, as he urged political and business leaders to make a renewed push to tackle climate change before the damage is irreparable. Speaking at the start of the World Economic Forum in Davos, Switzerland, the 92-year-old naturalist and broadcaster warned that human activity has taken the world into a new era, threatening to undermine civilisation. “We need to move beyond guilt or blame, and get on with the practical tasks at hand,” Attenborough warned.

Yellow crazy ants are threatening Queensland’s wet tropics, the world heritage area known as the oldest continuing rainforest. The ants are one of the world’s most invasive species, but the state and federal governments have still not committed to funding the program that is holding them at bay. The Wet Tropics Management Authority is asking for a $6m a year package for the next seven years – enough, the authority says, for it to finish the job of eradicating the pest. Without further funding, the money will run out in June.

World

A collapsed building of Afghanistan’s intelligence office in Wardak, where dozens were killed in a Taliban attack. Photograph: Jawad Jalali/EPA

The Taliban have killed dozens of Afghan security personnel at a military compound in central Maidan Wardak province, according to a senior defence official. One official said the death toll was as high as 126.

The UK government will waive a planned £65 ($117) fee for EU nationals seeking post-Brexit settled status, Theresa May has said. The prime minister called the minimal concession one of six lessons from a week of talks with other parties after her Brexit deal was voted down by a vast majority last week, but essentially entrenched her position on the intractable Brexit process.

More than 140 former diplomats and leading China experts have called on Xi Jinping to release two Canadian citizens who were detained last month, as a diplomatic standoff between Ottawa and Beijing escalates.

A no-deal Brexit and a sharper slowdown in China are the biggest risks to global economic growth in 2019, the International Monetary Fund has warned in its latest economic outlook. The Washington-based organisation said global growth would weaken from 3.7% in 2018 to 3.5% this year, down 0.2 percentage points from its prediction last October.

Nicaragua’s best-known journalist has gone into exile in Costa Rica after armed police raided and ransacked his newsroom in what experts have called the latest chapter of the country’s slide into autocracy under President Daniel Ortega.

Opinion and analysis

A man walks along the beach at Wye River, Victoria. Photograph: Julian Smith/AAP

On Victoria’s chilly beaches, no one has a tan, writes Brigid Delaney. “Before I moved to Sydney I would look at Max Dupain’s famous Sunbaker photo and think: I do not recognise that beach. Where, for example, is the person in the overcoat and beanie? Growing up in Warrnambool, there were only two hot days a year and even then the water was rough and freezing. Southerly blusters would barrel down the beach. You hardly ever saw anyone sit on the sand – it was like having a mini microdermabrasion.” Everyone has a different reason to love their favourite beach – there are now only three days left to vote in Guardian Australia’s best beaches poll.

The scare campaign on negative gearing and other tax measures is gathering pace. It didn’t work in 2016, but sure, why not try it again, asks Greg Jericho: “Even with falling house prices there is little reason to believe the ALP’s policy is less popular than it was at the last election. Apparently 26% of investors who were happy with a policy in 2016 now might decide they dislike the policy enough to change their vote, even though the changes would be grandfathered and thus would not affect them. Fear and logic do not make for good bedfellows.”

Sport

The Socceroos have stumbled into the Asian Cup quarter-finals after a gritty but unconvincing penalty shootout victory over Uzbekistan. Two saves from Mat Ryan helped Australia through to the last eight, where they will play the hosts, United Arab Emirates.

The last time Serena Williams came to Melbourne, she was five weeks’ pregnant and went on to win the Australian Open for the seventh time. On day eight of the 2019 championships, two years older at 37, she used a sliver of her old magic to defeat world No 1 Simona Halep 6–1, 4–6, 6–4. Meanwhile, Novak Djokovic has stepped into the void left by the departure of Roger Federer, with a 6-4, 6-7, 6-2, 6-3 win against 22-year-old Daniil Medvedev.

Thinking time: ‘The ultimate destruction of our culture’

Walgett in rural NSW has run out of water. The two rivers that run through the town, the Barwon and the Namoi, are both dry. Photograph: Carly Earl/The Guardian

Gamilaraay people and farmers rarely agree, but they are all worried the town of Walgett has only six months to live if it doesn’t get more water. Guardian Australia’s Indigenous editor Lorena Allam and picture editor Carly Earl visited the north-western NSW town, where the Barwon and the Namoi rivers meet. They are major tributaries in the Murray-Darling system, but both are empty. Gamilaraay and Yuwalaraay elders say they have never seen it as bad as this, and they doubt it can ever be recovered. “This to me is the ultimate destruction of our culture,” Gamilaraay elder Virginia Robinson says.

A few weeks ago, the Keepit Dam upstream released a series of “environmental” flows that started to trickle down into this part of the Namoi during Guardian Australia’s visit. “A couple of farmers have come down to the boat ramp outside Walgett to see if the river has risen overnight, but it looks like it’s pooling at the weir and won’t reach the town pumps,” Allam writes. “After this flow, the Keepit Dam is down to 0.5% capacity; there will be no more water coming down the river unless it rains. Walgett will have to live on bore water indefinitely. But bore water is high in mineral content, especially sodium – it’s not a long-term solution.”

Media roundup

The Sydney Morning Herald says Alice Thompson, a former adviser to Malcolm Turnbull, is set to challenge Tony Abbott as an independent in his seat of Warringah. The West Australian reports that the WA government says BHP owes the state back royalties of up to $300m. Clive Palmer has shifted control of most of his business empire to New Zealand and is threatening to sue Australian taxpayers for $45bn, according to the Australian.

Coming up

A directions hearing into a series of deaths at music festivals across the state will be held at the NSW coroner’s court.

The quarter finals of both the women’s and men’s singles begin at the Australian Open.

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