First let's get a disclaimer here that I hope everyone reads and allows to soak in. To say something is scientific is not to say that it is true or false. I repeat, being scientific has nothing to do with being true or false. 2=2=4 is not scientific, but it is true.
Here are the standards that any scientific theory must meet. It must first be testable and second it must be falsifiable.
Testability is important because it will root the theory in the natural world. We can't test supernatural hypotheses. Falsifiability is the check on the power of testability. For instance, if an astrologer predicts that "you will meet someone interesting today" that is not falsifiable, but it is testable.
So a theory must be testable, i.e. in the natural world, and falsifiable, i.e. it must make predictions that can possibly be falsified in the experiments.
Can Global Warming meet that criteria? If not, then to call it science is wrong or to seek to change the definition of what counts as science.
Let me again reiterate that I'm not concerned with whether the theory of Global Warming is true. The collection of data on the environment and climate can lead reasonably to the deduction of man made global warming. But the scientific status is a totally different question. The scientific status of Global Warming hinges on two questions already outlined: can we form experiments to test Global Warming and does it make predictions that are falsifiable?
One thing to remember is that at its core Global Warming as a theory is a cause-effect theory. Global Warming theory advocates the increase in pollutants causing an increase in global temperature. It gets deep and is backed by much data, but the basic hypothesis is accessible to anyone. Let's look at what this implies.
To test Global Warming, it seems we would have to know all the factors that move the climate and a way to recreate them to test the introduction of heightened entities in that climate. First, we don't know the full causal picture of climate. We know of countless causal factors, but we don't know the complete picture. This is a problem for science. How do we test this theory? We can't physically test it in ideal experimental conditions because we can't recreate a climate, and even if we could physically do it we don't know the causal climate picture. We don't know what percentage of impact sun spots, currents, pollution, urban jungles, etc etc have on the climate.
And what about the predictions of Global Warming? I googled a couple of things to illustrate the problem of falsifiability in regards to Global Warming predictions:
If you look at the search results for "Global Warming may" it is clear that the predictions are all across the map including predicting localized cooling There is also a prediction that Global Warning may stop.
From the links respectively:
Global warming may include some periods of local cooling, according to a new study by researchers at the University of California, Berkeley. Results from satellite and ground-based sensor data show that sweltering summers can, paradoxically, lead to the temporary formation of a cooling haze in the southeastern United States.
Researchers studying long-term changes in sea temperatures said they now expect a "lull" for up to a decade while natural variations in climate cancel out the increases caused by man-made greenhouse gas emissions.
So let's get this straight on predictions. Global Warming may cause local cooling and it may stop. So...how do we falsify that? Because science is adversarial and theories are supposed to take severe tests. But if you look at these predictions you see that a drop in temperatures or a halt in rise in temperatures both prove the Global Warming predictions posed here. Now isn't that a good set-up for a theory? If the planet gets warmer you are right, if the planet gets cooler then you are right, and if the temperature stays the same you are right. This is fundamentally not falsifiable.
I also googled Global Warming could:
This is an example of the sort of predictions that come out of a theory that is so broad that it can encompass everything and this is why I think we must jealously guard what we consider scientific.
Examples of what Global Warming "could" do:
This is one the Global Warming community wish they could have back because as of yet it has been sort of falsified as much as a vague prediction can be:
Global Warming could create stronger hurricanes.
Global Warming could make you sick.
Global Warming could increase terrorism.
These are just a small sample of what type of predictions swirl around a theory that is free-wheeling.
One last example.
I googled Global Warming might.
Here are some things Global Warming "might" do:
Global Warming might benefit certain crops.
Counter this with what Global Warming could do: Cause World Crop Collapse.
From the links respectively:
Citing scientific reports, the agency allowed that some crops will initially benefit from rising temperatures and carbon dioxide levels. But the agency said yields of corn and other commodities could fall as the climate continues to warm and some areas experience more frequent droughts.
With the U.N.-affililated Food and Agriculture Organization (FAO) already warning of declining grain harvests due to extreme weather, a U.S. study released last week suggests that global warming could cause world agricultural systems to face possible collapse by 2080, with countries in the south being the hardest hit.
More that Global Warming might do: affect Hawaii? Aren't they a part of the globe?
Global Warming might eliminate warm weather clouds.
Now what is the point of all this? Science requires testability and falsifiability for good reason. The reason is to force the hand of potential theories.
For anyone it should be a problem when a theory can predict all of the above (and this is just the tip of the melting iceberg). But also note the ease with which "researchers", "scientific studies", and the like throw around predictions using words like "may", "might" and "could". These are qualifiers not predictors. That is to say that even if we could falsify these predictions that the advocates would just say they said it was possible. This is not science. It could be true, but it is not science.
I'm not saying we should burn the candles at both ends in regards to the environment. I'm not saying we don't need regulation. I'm not saying we don't need energy independence and a greener economy. I'm just saying Global Warming does not appear to meet the criteria for science.