Dear Secretary-General, Climate change science is in a period of ‘negative discovery’ - the more we learn about this exceptionally complex and rapidly evolving field the more we realize how little we know. Truly, the science is NOT settled. Therefore, there is no sound reason to impose expensive and restrictive public policy decisions on the peoples of the Earth without first providing convincing evidence that human activities are causing dangerous climate change beyond that resulting from natural causes. Before any precipitate action is taken, we must have solid observational data demonstrating that recent changes in climate differ substantially from changes observed in the past and are well in excess of normal variations caused by solar cycles, ocean currents, changes in the Earth’s orbital parameters and other natural phenomena. We the undersigned, being qualified in climate-related scientific disciplines, challenge the UNFCCC and supporters of the United Nations Climate Change Conference to produce convincing OBSERVATIONAL EVIDENCE for their claims of dangerous human-caused global warming and other changes in climate. Projections of possible future scenarios from unproven computer models of climate are not acceptable substitutes for real world data obtained through unbiased and rigorous scientific investigation.