If you agree that climate change is a global problem that requires a global solution, then the recent agreement achieved in Cancun, Mexico is reason for hope – and succeeded in a few areas where the much more lauded conference in Copenhagen last year failed.

What happened in Copenhagen? Was it unprecedented progress (Barack Obama) or a disappointing failure (Gordon Brown)?

Let’s break it down.

Question: What was unprecedented about Copenhagen?

Today the U.S. delegation here in Copenhagen continued with a sustained and impressive charm offensive as ministers and heads of state began arriving. Tomorrow, Secretary of State Hillary Clinton is scheduled make it to the Bella Center, followed on Friday by President Obama himself.

Today Rajendra Pachauri, leader of the Nobel-prize winning UN climate science  process, spoke in Copenhagen with confidence in the bedrock of science on which our understanding of global warming rests.

Meanwhile the opposition continues to try to squeeze the last few drops of doubt out of a few email lemons stolen from East Anglia University.

Here's a simple question for our climate negotiators in Copenhagen: As we seek to highlight the need to preserve the carbon in the vast but shrinking forests in other countries, how are we doing here at home?