The current talks “simply cannot deliver the change at exponential speed and scale, which is essential to ensure a safe climate landing for humanity,” a number of influential figures, including former U.N. Secretary General Ban Ki-moon, wrote in a letter to the United Nations as the Baku summit was underway.

United Nations climate negotiators agreed on a funding formula to help developing countries cope with the effects of climate change early Sunday in Azerbaijan after two weeks of intense negotiations.

It’s not near the full amount of $1.3 trillion that developing countries were asking for, but it’s three times a deal of $100 billion a year from 2009 that is expiring.