Experts have mixed reactions to the recent U.N. climate talks in the Amazon.

The return of Brazil’s president Luiz Inácio Lula da Silva to UN climate talks was hoped to spur nations to meet a self-imposed early deadline for progress on tough issues.

The Paris agreement is complex and works in a slow bureaucratic manner.

In the past few months United Nations-sponsored negotiations to tackle climate change, plastic pollution, loss of global species and a growing number of deserts have either outright failed or come out with limited outcomes that didn’t address the scale of the problems.

The annual New York City Climate Week and United Nations General Assembly that's just about to start are emphasizing how to generate trillions of dollars that will be needed to help poorer countries move away from gas, oil and coal, fuels that release greenhouse gases and heat the planet.

Teams of veteran negotiators fanned out Friday at the United Nations climate conference with orders to get the strongest, most ambitious agreements possible, especially on the central issue of the fading future of fossil fuels in a dangerously warming planet.

Officials say a target for rich countries to provide poor nations with $100 billion in aid each year to tackle global warming will be missed, dealing a blow to the upcoming U.N. climate talks in Glasgow.