Tuesday briefing: Why the oceans are on the frontline of the climate crisis

In today's newsletter: Our Seascapes editor on the dangers our seas and oceans face - and what we can do to help

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Good morning. The oceans are - according to the UN - the world's greatest ally against climate change". While many of us now understand the urgent need to take the climate crisis seriously, the focus is still very much on the land and the air. Oceans cover more than 70% of the surface of the planet, generate 50% of the oxygen we breathe, absorb 25% of all carbon dioxide emissions and capture 90% of the excess heat generated by these emissions.

Perhaps it is time we stopped to think a bit more about our seas, consider the dangers they face and look at what we can do to help. Lisa Bachelor, who edits the Guardian's Seascape series about the state of our oceans, has - if not all the answers - quite a few of them. She joins us after the headlines.

US politics | Joe Biden took the stage at the Democratic national convention Monday to deliver a reflective and optimistic address, telling the crowd: I made a lot of mistakes in my career, but I gave my best to you." Earlier, Kamala Harris made a surprise appearance to thank Biden for his lifetime of service".

Italy | UK tech entrepreneur Mike Lynch and his daughter Hannah were missing, along with Morgan Stanley International chairman Jonathan Bloomer and three others, after their yacht sank off the coast of Sicily during a violent storm. The British-flagged Bayesian was carrying 22 people when it was hit by a tornado.

Care workers | The number of foreign social care workers reporting that they are trapped in exploitative contracts has risen sixfold in the last three years, in the latest evidence of widespread abuse of migrants in the British care system.

Israel-Gaza war | The current round of ceasefire talks is maybe the last opportunity" to broker a truce and a hostage and prisoner swap, the US secretary of state has said during a visit to Israel. After a three-hour one-on-one with Benjamin Netanyahu, Anthony Blinken said that the Israeli prime minister supports" the ceasefire proposal.

Ukraine | Ukrainian forces destroyed a third bridge over the Seym River in Russia's Kursk region as part of an apparent attempt to expand what Volodymyr Zelenskiy has described as a military buffer zone" against attacks. It was the last major crossing on this part of the front.