For the low low price of 300 billion we could 'buy up to 20 years of time to fix the global crisis'...that isn't fix the problem money but we could buy some time.
Sure the worst polluters like China and India won't try at all to help us and their polluting will only get worse...and yes most of this money is basically the Western World giving money to poor countries whose governments are corrupt and only a small fraction will actually go to intended purposes (Russell Kirk was arguing in the 1970's that environmentalism was nothing more than wealth redistribution from rich to poor countries)...
And yes we are already spending untold billions on the problem...but dammit guys this 300 billion will be the difference. Of course they will be saying they need 500 billion more in a few years but that is irrelevant...we must act now!
Sounds more like "line our pockets and we will tell you you have 20 more years, then in 20 years we'll tell you 300 billion wasn't enough, give us another 200 billion and we will give you an extra 10 years, so we can continue this charade into perpetuity.