I think I can offer a unique perspective here as I work alongside some of the leading scientists studying this issue at one of the top institutions for atmospheric sciences in the world. My expertise is in weather prediction and severe weather, but I've had many discussions about climate as well. I don't usually talk much about climate, but I guess I will a little here.
kocher, I hope I can address some of your above points.
kocher wrote: ↑Wed Sep 06, 2017 9:15 pm
I do not have it very clearly.
In order to start discussing, you have to answer some interesting questions first. Global warming?:
- In how much time?
- Does it respond to a natural cycle?
- Where are temperatures measured?
- What series are we studying?
After:
- How do we demonstrate the cause of the warming?
- Decadal time scales (10s of years). We measure warming in ºC per decade. This is an important problem, since our natural human instincts are to protect ourselves from direct, immediate threats (like a thunderstorm), but it is harder to perceive threats a decade or two in advance.
- Think of it as a linear trend with natural cycles oscillating around the trend. The natural cycles respond to the trend, not the other way around.
- Land surface-based temperatures, upper-air balloon measurements, satellite measurements, ocean buoy measurements, deep ocean measurements... basically everywhere.
- All the above, plus historical records from ice cores, sediments, tree rings, and others. I'll link to the
5th Assessment of the IPCC, where they have detailed extensive information on what data sources are used.
- We demonstrate the cause of warming by considering our best knowledge of the physical earth-atmosphere system, and determining which physical factor(s) can produce the observed trends and correlations.
kocher wrote: ↑Wed Sep 06, 2017 9:15 pm
The scientific method is based on:
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Observation: It is to apply the senses attentively to an object or to a phenomenon, to study them as they occur in reality, can be occasional or causal.
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Induction: To extract the fundamental principle of each observation or experience.
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Hypothesis: Elaborate an interim explanation of the observations or experiences and their possible causes.
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To test the hypothesis by experimentation.
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Demonstration or refutation (antithesis) of the hypothesis.
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Thesis or scientific theory.
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Observation: We use extensive records of all of the physical parameters I noted earlier. The best observations indicate that, over the past few decades, global temperatures have been increasing at a rate never seen before in the modern record. We have also observed sea ice extent decrease, glacial mass reduction, sea level rise, water vapor concentration increases, and, of course, carbon dioxide increases at rates never before observed in the modern record. An important note should be attached here: these are global measures. Rates of temperature increase are not uniform across the globe. Some places, like the southeast United States, have even observed decreases in temperature (though not statistically significant). Others, like the Arctic, are warming very rapidly. There is a wealth of detailed information available in the IPCC report I linked earlier.
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Induction: Some mechanism, also unprecedented in the modern record, is likely to be an explanation for the unprecedented observations.
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Hypothesis: Anthropogenic emissions of carbon dioxide, a greenhouse gas, is the cause of the unprecedented observations. The physical mechanism of greenhouse-gas-induced warming is certain, the emissions of such gases by anthropogenic activity is also certain, and the correlation between CO2 and temperatures is a strong indication that this is a correct cause.
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To test the hypothesis by experimentation: The limitations of the earth-atmosphere system mean that no observations of the current system can directly link anthropogenic emissions to warming (or extreme weather events). Nevertheless, state-of-the-art global climate models, designed with our best knowledge of the physical earth-atmosphere system, have been created to test the effect of varying concentrations of CO2 on the earth-atmosphere system. These simulations statistically-significantly show that future temperature increases more rapidly with higher CO2 concentrations.
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Thesis or scientific theory: Anthropogenic emissions of greenhouse gases are
extremely likely responsible for the observed upward trend of global temperatures (and ocean heat content).
kocher wrote: ↑Wed Sep 06, 2017 9:15 pm
To my knowledge, until now, no one has proven the cause of human origin as the possible cause of global warming; despite this, most of the articles begin (by the end) admitting the cause without possibility of discussion.
My doubts (increasingly greater) on this issue, does not mean that it can be mistreated to Nature. What I question is the cause that is imposed without discussion or demonstration.
As a matter of personal curiosity, may I ask what is causing you to have increasing doubts about anthropogenic global warming?
Within the scientific community, anthropogenic global warming (AGW) is considered a theory in the sense that the "theory of general relativity" is a theory (it is virtually certain). Decades of meticulous research have been devoted to the subject.
Over 97% of published peer-reviewed papers argue in favor of AGW, an astonishing level of agreement. (Compare that to whether scientists agree that coffee or chocolate or even running marathons is good for health.) The physics are understood just as well as Newton's laws, the laws of thermodynamics, or general relativity. The evidence is undeniable.
And yet, I want to be clear about something: we scientists want nothing more than to be able to say, "nothing is wrong with our climate." In the US, unlike in other countries, scientists are often accused of promoting AGW because we "have a leftist political agenda." Nothing could be further from the truth. If any scientist can produce an idea that explains the unprecedented warming in the observational record better than AGW, and that can be proven through model simulations and be reproduced, that scientist would earn a Nobel Prize.
Thus far, there simply is no evidence for any other proposals (like solar cycles) that have been put forth.
dmgould wrote: ↑Wed Sep 13, 2017 7:51 pm
I'm in line with kocher on this. To really analyse it correctly and scientifically one would need accurate data over thousands to hundreds of thousands of years that we just don't have. That said, I think we should definitely work toward minimizing our effects on the environment. There are current trends that show warming over specific time periods, and there are current trends showing cooling over different time periods. I just don't think we have accurate data samples over a large enough time period to draw any absolute conclusions. So, the best thing to do is for all of us to lean toward green as much as we reasonably can.
It would undeniably be amazing if we could have that data! Just imagine how crazy the scientists and the news media would get. But we have to work with what we
do have. And it turns out that what we do have is a lot more than many people realize.
I'm glad though that your conclusion is that we should take care of our environment regardless. Renewable energy sources and generally "being green" are environmentally
and economically responsible. On whether AGW is wrong: "What if we make the world a better place for nothing??"
Now you've convinced me!
). In fact, this is very helpful to me because it helps me understand your point of view.