Climate science is totally inaccessible to lay people. All we can do is trust. I'm a science teacher and when I teach climate change, it's just the bare basics and a few subjective facts. We can make cardboard greenhouses and draw pictures of IR rays getting absorbed in the atmosphere. But that's not what's in doubt. That's the stuff everyone's accepted for decades. The part people don't trust is the "it'll destroy the world". For that, I haven't got the faintest clue how right it is beyond trust. In most of high-school science, you can measure forces yourself, you can mix the chemicals yourself, you can observe stuff doing what the text book says it should. But not climate science.
Unless it can be made accessible to even science graduates to actually reproduce the results from a critical point of view, it's always going to have a lot of sceptics. Not everyone has so much faith in scientists.
My understanding is that there isn't really a scientific consensus that "it'll destroy the world". But there is a consensus that "human activity is causing global warming" - yet this is something that a significant minority of people do not believe.
EPA has a website describing the mid and long term effects of climate change in N America. With plenty of citations a dedicated student or teacher could follow up on. Very accessible, and did not include "will destroy the world".
Incidentally, your critique also applies to literally most science, including very good and obviously successful science.
Can you really prove to your students that Intel doesn't have magic pixie dust it uses to speed up its processors? Probably not without expensive equipment your classroom cannot afford.
And can you reproduce the LHC experiments? Of course not.
The National Climate Assessment in particular is presented in the form of a slick website with hundreds of citations into the literature for curious readers: http://nca2014.globalchange.gov/report
The information is there, in extremely digestible form, and at the top of google search results. Naturally, reproducing the results of literally hundreds of cited papers is going to take you a while, but in most cases, there's nothing actually stopping you...
It's also worth noting that scientists are usually fairly transparent about when they're guessing WRT effects of climate change and when they're pretty certain. The near-term stuff (~hundred years) is largely guess work based on simulations -- we can't do much better. The most certain prediction is that weather will become harder to predict. The longer-term stuff (~hundreds to thousands of years) is much more well-understood because there're historical records relating GHG levels to climate.
The biggest greenhouse gas by far is water vapor, not CO2. So it makes no sense to call a plot of CO2 a plot of "greenhouse gas concentrations". This type of "information" is low quality and will only make people not trust them.
Ah, I see now it is a plot of CO2 equivalents... that ignores water vapor while the others (BC, OC, CH4, Sulfur, NOx, VOC, CO and NH3) are rather negligible (which is why the ppm values are close to those for CO2 alone).
Anyway you can deny what I am telling you, but it is usual for people to go to supposed authoritative site like that, then check wikipedia and see H20 is the biggest greenhouse gas.[1] As a result they just shrug and figure no one knows what they are talking about, since they can't get the story straight.
> Ah, I see now it is a plot of CO2 equivalents... that ignores water vapor while the others (BC, OC, CH4, Sulfur, NOx, VOC, CO and NH3) are rather negligible (which is why the ppm values are close to those for CO2 alone).
Unless you're planning on boiling an ocean or great lake some time soon, humanity isn't directly effecting the amount of H20 in the atmosphere at appreciable levels as a first order effect. It's not a parameter under variation.
C02 equivalents are a parameter under significant variation, and as a first-order effect of human action.
We are interested in the dynamics of the system as we vary a parameter that we can, and are, directly manipulating.
Larger atmospheric, oceanic and whole system models then incorporate H20 and other effects in a simulation as the parameter we actually control is varied.
If this were explained on the page, you'd complain it was too technical.
> Anyway you can deny what I am telling you, but it is usual for people to go to supposed authoritative site like that, then check wikipedia and see H20 is the biggest greenhouse gas.[1] As a result they just shrug and figure no one knows what they are talking about, since they can't get the story straight.
Is that really common? I mean, there are actually a large population of people who will read [1] but don't bother to click on the link right under the graphic and see how the graphed data is used in climate predictions?
I'm highly suspicious that there's actually a significant population of people who are open to being convinced but make such a sophomoric mistake in their reasoning.
Someone can always find reasons to be uncharitable and dismissive if that's their predisposition. People with that predisposition and willingness and disregard evidence for even the most superficial of complaints aren't going to be convinced anyways.
The reasoning is simple. A warming is said to be due to the "greenhouse effect", the major portion of which is due to "water vapor in atmosphere". If you show me a chart of "greenhouse gas concentration" and leave out water vapor, something is not making sense.
I don't know whats going on with that chart, whatever. I am just telling you the end result of showing it to me, and doubt I am alone.
The meaning and purpose of the chart is extremely clear. They're varying C02 and similar gasses, and looking at what happens. Water vapor is held constant as a first order effect and so isn't plotted.
I don't draw straight lines on all my plots relating constants to (in)dependent variables. Even fifth grade science experiments follow this convention in their plots. It's an extremely common practice. Water vapor isn't being varied, so isn't plotted. Again, nearly every fifth grade science fair project follows this convention in their plots. It really does count as basic literacy.
For someone with some basic scientific literacy, the author's intent is obvious and confirmable by reading the literature. OBVIOUSLY the authors are aware of water vapor concentrations, and you can confirm this awareness with a superficial investigation into how this metric is used in models.
Sorry, but I do not believe a non-antagonistic reader would jump to the conclusion that climate scientists are unaware of tyoical atmospheric H20 concentrations. That's so far from the realm of reasonability.
At some point, the readers' good faith must be assumed or the entire expository enterprise is pointless. I think this plot is by far on the correct side of that line.
Yeah, warming increases atmospheric water vapour slightly so a simplified model that assumes it remains constant is going to slightly underestimate the total warming caused by a given amount of non-water-vapour emissions. Models don't have to take into account every detail to be useful, though.
Unless it can be made accessible to even science graduates to actually reproduce the results from a critical point of view, it's always going to have a lot of sceptics. Not everyone has so much faith in scientists.