France, Nov. 6 -- World leaders arrive in the Brazilian Amazon on Thursday for a high-stakes test of global climate promises, with vulnerable nations demanding far greater financial support and scientists warning the world is still veering off track.

The two-day Belem Climate Summit takes place in the humid port city at the mouth of the Amazon River - a symbolic prelude to the UN's Cop30 conference that begins there next week. Together they mark 10 years since the Paris Agreement and bring global attention back to the planet's most vital carbon sink.

For Brazil, it is a moment to show that protecting forests and reducing poverty can go hand in hand. For much of the world, it is a chance to prove that promises made in Paris can still del...