Yep, in the 50s and 60s climatologists told us that the Earth was heading into another ice age. This was based on pollution increasing Earth's albedo and reflecting sunlight back into space, as well as the fact that it's been 10,800 years since the last one and the average interval is every 12,000 years. When the Venus probes found unexpectedly high temperatures there, a formerly-disfavored theory about CO2 causing a greenhouse effect was resurrected to explain them. It was subsequently picked up by a few alarmists here, who noted that CO2 was higher since the industrial age began, and therefore global warming, not cooling, was going to be a problem. It's important to note that it was determined first that there was a problem, and only after that was it decided what the problem was. Cooling? Warming? Both?

To put things in perspective, the current CO2 level of 350ppm is closer to the point where plant life dies off for lack of it (100 ppm) than high levels of past eras (up to 3000 ppm.)

I saw that article about Mars experiencing a warming trend, and that it's of similar magnitude to the Earth's. One thing climatologists assume is that the sun is constant in its output. Considering what we already know about sunspot cycles and Maunder minimums, that's a pretty stupid assumption.