I think this part of the debate hinges critically on whether or not you think that core samples can be used to project temperature samples. If so, the data available to the models is vast and conclusive. If you reject that, the amount of climate data we have covers only hundreds of years.
In order to verify if the current data can predict temperature or other key metrics accurately, more data needs to be collected, which needs time, in the order of a few decades. But a wait of that long, may bring more changes, which would render the model inefficient or incorrect. A very tricky systems optimization problem!
It seems tome that no amount of evidence will ever be sufficient for folks such as yourself, no matter how many predictive milestones are passed.
To get to the level of co-operation needed, a significant investment needs to made in educating people of all mindsets, about the benefits of this co-operation. That itself is going to take a couple of generations.
Regarding the data, it's not very conclusive. Given the scale of time over which data has been collected, is it sufficient to create a reliable model and predict the future changes in climate?
Even if we were to assume that everyone agreed that human activities are the cause of climate change, it would still require huge amount of participation and co-operation among countries across the globe to fix it. That is impossible.