The Global Warming Challenge, aka The Climate Bet (theclimatebet.com), is a record of an experiment to test the relative accuracy of Al Gore's 2007 dangerous man made global warming "tipping point" alarming projection relative to the no-change (no-trend) forecasts of Green, Armstrong, and Soon (2009) proposed by Scott Armstrong in his challenge to Al Gore to take a bet on his claim that temperatures would become dangerously warmer over the next decade. Gore refused the bet and refused to provide specific forecasts, so we used the IPCC's then "business as usual" +3C-per-century relatively mild projection to stand for Mr Gore's tipping point. In the event, the actual temperatures were closer to the no-change than they were to the warming projection. We then extended The Challenge experiment for another decade (till end-2027) in order to further test the alternative hypotheses on which forecasting model will provide the most accurate forecasts of temperatures over the 21st century. This document will be updated periodically (mostly monthly) as new data comes in, and is directly accessible via theclimatebet.com.