A wide consensus of climate scientists agrees on the many underlying facts around climate science, but these facts are not widely accepted by policy-makers or the general public. Addressing this issue, the American Statistical Association formed an Advisory Committee on Climate Change Policy, with the objective of improving communication of statistical issues associated with climate change. This committee has been active in giving public lectures, writing nontechnical articles, and participating in visits to Congress. This symposium will focus on uncertainty. The public and policy-makers sometimes equate uncertainty with ignorance and miss the reality that statistically calculated uncertainty is a form of knowledge that can help clarify responses to environmental risks. The three speakers are statisticians with extensive published research in climate change. Their talks address uncertainties in observations and climate models, strategies for formulating policies, and methods for communicating uncertainty to decision-makers. The discussant is an author and journalist who has been writing for more than 20 years on climate science and policy. The objectives of the session are to provide information about recent scientific developments, as well as discuss the challenges of formulating climate science for policy-makers and the general public. This symposium will be one of the activities of Mathematics of Planet Earth 2013.