Big money to respond to climate change is key to the United Nations talks underway in Azerbaijan. Vulnerable nations say they need as much as $1.3 trillion to cope with damage they've already suffered from extreme weather events,

A report backed by current G20 leader Brazil proposed a global minimum tax of 2% of wealth for the world's roughly 3,000 dollar-billionaires, to raise about $250 billion a year. Other options could include changing the threshold at which the tax kicks in and the rate at which it is applied.