Climate change conference to "present a challenge" says US

That's right the conference will pose a challenge.

Actual climate change? Golly we just don't know!

A statement from the EPA web site:

Like many pioneer fields of research, the current state of global warming science can't always provide definitive answers to our questions. There is certainty that human activities are rapidly adding greenhouse gases to the atmosphere, and that these gases tend to warm our planet. This is the basis for concern about global warming.

The fundamental scientific uncertainties are these: How much more warming will occur? How fast will this warming occur? And what are the potential adverse and beneficial effects? These uncertainties will be with us for some time, perhaps decades.

Global warming poses real risks. The exact nature of these risks remains uncertain. Ultimately, this is why we have to use our best judgement – guided by the current state of science – to determine what the most appropriate response to global warming should be.