Critical Facts 7. Climate models that have focused on CO2 have been very poor at hind-casting Earth's known climate history as well as their recent forecast of the future.
Climate models that have focused on and been tuned to demonstrate a significant impact by CO2 on Earth's climate have generally failed the test of simply explaining the changes that have occurred in Earth's past climate where the answers are already known. Couple this with the fact that the forecasts of the International Panel on Climate Change (IPCC) models of the past 19 years have already failed in their projections of early 21st century global cooling (see figure below). The current global temperatures fall below even the the lowest rise projected by the IPCC models. These forecasts of the last many years are no longer called forecasts (since they have failed) but are now being called just possible scenarios. Regardless, none of the models or scenarios allowed for what is actually occurring. The most likely cause of the failure of the IPCC models is that the modelers were charged with finding the manmade signal in the climate and, given the lack of preciseness of the many factors that go into the models and the modeler's inability to choose the magnitude of the effect of many factors, it is likely that none of the modelers wanted (or expected) to show no significant effect by manmade CO2 . Astonishingly, the modelers were even told by the leaders of the IPCC to ignore variations in solar effects which would include not only variations in solar intensity but also in the possible effect of solar magnetic variations on shielding the Earth from the potential influence of cosmic rays in cloud generation that could help cool the earth.
Note the monthly global temperatures; up, down, steep rise, low rise, etc. all this despite a steady increase in CO2 that is in Earth's atmosphere 24/7, worldwide.