With all due respects to both sides of the, “My scientists are better than your scientists” debate, you’re all engaging in pretty unscientific argumentation.
Science isn’t a popularity contest. There are plenty examples from the history of science where the overwhelming majority of scientists happened to be wrong. This especially happens when a new theory comes along which challenges a widely held orthodoxy.
The science should stand on its own. And here’s where the problem comes in - the reason you can find so many eminent scientists on both sides of the question is that the science in this case is not clear cut. I think all climatologists and earth science types would admit that our understanding of climate and of the earth’s long-term response to changes in climate are incomplete. There’s no experiment we can run which will categorically tell us whether the earth will be a certain temperature 50 years from now, even within very wide margins of error. We don’t have two Earths, so we can’t run controlled experiments. All we can do is mine historical data and try to piece together cause and effect, and build models which we hope will predict future events.
In a way, it’s a lot like the study of history. We have evidence that the rise of philosophy X caused result Y. We can speculate what might have happened in Hitler had been killed in WWI, or if Napolean had decided Moscow was too cold for his liking and had stayed home. But in the end, human events are chaotic and unpredictable, and lessons from the past are filled with many confounding variables and factors that no longer exist, so extrapolating them into the future is dicey.
And yet, that doesn’t stop us from drawing certain reasonable conclusions, such as believing that Hitlers are generally bad for the planet and human freedom is generally a productive force. But there’s enough wiggle room that you can still find people on all sides of every political debate.
I don’t mean to downplay the actual science involved in climate study - I believe there’s plenty of it, and that it points to a future that will likely be warmer with man’s CO2 emissions than it would be without them. It’s just that there’s enough wiggle room in the data and the models, and enough confounding variables and randomness in climate change, that there’s room for equally good scientists to still disagree about what’s going on.
My personal position is that yes, there is clearly a greenhouse mechanism for C02, and all else being equal, a planet with more CO2 in the atmosphere will be hotter than one with less CO2. From that standpoint, man-made global warming is occurring.
The question is whether all else is equal. If we had two identical earths, and we pumped a few trillion kg of CO2 into one of them, what would happen over the next 50 years? Would we still have two identical earths, except one is hotter than the other? Or would the injection of CO2 kick of changes that would bring back an equilibrium? Maybe they’d be identical again, except one would have more C02 locked up in the ocean floor from increased algae blooms and sequestration. Or perhaps the earth with more CO2 would go through a cycle of increased vegetation growth, which would over time wind up sequestered as fossil fuel. Maybe it would take a million years to sequester the CO2, or maybe it would be done in 20.
I think these are where the big unknowns are. What’s the earth’s response going to be to the increased CO2? What feedback mechanisms does the Earth employ, and how long do they take?
In my opinion, the farther you get from the basic science of CO2 causing warming, the shakier the science gets. There’s an awful lot about long-term climate that’s still a mystery, with major new discoveries being made all the time.