Global warming hypotheses mostly cannot be tested. If I remember correctly, the overarching IPCC hypothesis is that the planet will experience 4 to 8 *C of warming and X feet of seal level rise over the next century. How do you propose that you or I test that hypothesis?
We do the same thing we do to test tomorrow's weather forecast of rain: we see what tomorrow brings.
Likewise, GW theory is testable. We have been testing it for decades. Each year, we collect more and better data from real time measurements of temperature, precipitation, sea levels, ocean pH and other data.
Each year, the data supports the theory: Earth - both atmosphere and oceans - is heating, climate is changing, ocean pH is decreasing.
Even the relatively conservative (scientifically speaking, meaning not previously prone to making radical claims)
World Meteorological Organization (WMO) admits that weather is changing in ways that cannot be explained without invoking the heating theory.
We will continue to test the theory during this century.
We also retrodict: that is, we look at patterns of change in the past and attempt to explain them using science. Patterns of change reflected in ice cores, tree rings, pollen studies, deep sea floor cores and other sources are analyzed statistically. In particular, researchers seek relationships between carbon gases and temperatures. That evidence is extremely strong, and as close to "proof" as one can get that the temperature and carbon gases CO2 and CH4 are tightly coupled: when one increases, so do the others. And I'll say again: it does not matter which increases first.
We build sophisticated super computer models based on the best real world data we have, then start those models with conditions from decades, centuries and millennia past (into the last ice age) to see if they reproduce today's conditions. That is hypothesis testing: they test whether the explanatory model accurately represents reality. If they do, it's viewed as support for the hypothesis or (now) theory.
Neither the models nor the data are perfect. That will always be the case. Data collection can never capture every aspect of the picture, and a model is always necessarily simplified. But they've come a long way, and our confidence in them is strong.
The three biggest problems in modeling now are: 1) insufficient data on the role of clouds (especially high v low clouds, which have different effects on heating, and clouds are notoriously difficult to model because they are so dynamic); 2) ocean currents (still poorly mapped); and most importantly, the models still do not adequately represent positive feedbacks, the ones that amplify and accelerate changes. That's why the IPCC models under estimate the predictions consistently. Within a couple of years after every IPCC report, scientists are already saying, "We didn't expect change in {insert variable here} would be so fast. It is changing much faster than predicted." This is now an almost cliche refrain.
Obviously, the people involved in this discussion have glaring differences in their interpretation of the data that continues to amaze me. It's hard for me to understand how anyone that really looks at the supporting data as presented by Weart, Pearce, and RealClimate can fail to understand that this is a serious problem. But that's the state of things.
In some cases, there is undoubtedly an element of denial based in psychology (not wanting to believe that Earth is changing in ways that we cannot control) or politics (which is why I just don't deal with the political component).
The problem is that these hypotheses are nothing more than speculation, supported by other speculation, supported by yet more speculation, all of it untested and probably untestable. Such a mess is NOT a sound basis for acquiring knowledge.
Speculation is fundamentally different from hypothesis. Speculations are guesses based on no data, and usually with no model.
Hypotheses are based on data and models.
Spencer Weart, Fred Pearce & RealClimate discuss tons of real data and models about this issue. You choose to ignore them.
Now, science can be proven. We have ample proof of scientific laws, and we have a myriad of theories (theories in the context of the scientific method) that we know to be true as far as they go.
My comments about "proof" and "disproof" in science have a basis in probability theory. In my science classes, I counsel my students that in science, we can never say that something is "proven" or "disproven", only "supported" or "rejected". It's a technicality, but an important one, based on the asymptotic nature of probability distribution functions that never reach a point of probability 0 or 1.
We can only make probability statements about natural phenomena, not absolute statements about "proof" and "disproof".
Until then, I'll oppose anyone who claims that AGW is fact.
Patterns in global heating and climate change are being observed and are consistent with predictions except that both are consistently occurring faster than predicted.
I'll especially oppose anyone who claims that we need to give up our standard of living and our liberties in order to fight AGW.
I make no claims at all about what people should or should not do about this. I make no assertion that you should, let alone must, change your life style, let alone give up your liberty. Do what you want. It's your decision, and I have no intention of trying to force you to do anything about it. I own an F-250 diesel. I'm not planning to sell it. I don't drive it much these days because fuel is so expensive, but I'm not selling it over this issue.
As for me, I'm planning contingencies, because it's clear to me - based on sound evidence (see Weart, Pearce & RealClimate) that the problem is real, accelerating and will get much worse
very quickly.
And that is a testable hypothesis.
