For me personally it is about glaciers.
I can go to a great many places in the North Cascades right out my door where thirty or even twenty years ago I would go skiing on a Labor Day weekend above the firn line on glaciers. Many of those glaciers are now gone. Some of them are still there but dramatically reduced in size. If you read a little bit that is a worldwide phenomenon -- by some estimates 99 percent of the world's glaciers are rapidly receding.
Glaciers are a good proxy for average temperatures over time, as from a geophysical standpoint what makes a glacier is having a location that has more snowfall on average than snowmelt. So if temperatures rise you will likely have less snowfall (because some of that snow will become rain, and rain doesn't make glaciers) and obviously snow melts faster with warmer temperatures.
The tiny minority of glaciers that are not receding appear to be in locations where the increased average temperatures produces more precipitation, which in the case of those lucky glaciers produces more snowfall in the accumulation zone. Whether over the long term those glaciers will continue to expand or not is a larger question.
This isn't really a question of "belief". That is the wrong word. We all can observe what is happening. Maybe we need some help getting there but the most reasonable hypothesis is that the planet is warming. It is very likely warming more rapidly than it has in all of recorded history, and possibly more rapidly than at any time in the last several million years. The most likely reason for this situation is because of human activity that is increasing the level of CO2 in the atmosphere, mainly use of fossil fuels but also industrial and agricultural activity by humans.
The effect of CO2 on climate has been
well-understood for over a century.
We know that CO2 is increasing because we have observatories that have tracked atmospheric CO2 since the 1950s.
We can be pretty darned certain that the increase of CO2 in the atmosphere is mostly caused by fossil fuels, because the carbon isotope mix in atmospheric CO2
would be different if it was from a biological source and we don't have any evidence of large-scale volcanic activity(*) that could cause such a consistent and dramatic rise in CO2 levels in recent decades.
In order to argue that climate change is not happening or is not likely caused by human activity (which to my mind is about as deranged as arguing that the sky is pink, not blue) you need to argue that at least one of the previous points is not correct. If you want to argue that climate change is not happening what happened to my skiing?
(*) By "large-scale" volcanic activity I do not mean one volcano erupting. To produce the sustained and consistent CO2 increases we have seen would require a large volcanic province, like the Deccan Traps or Columbia River Basalts. Somebody would have noticed.
Thank you , Mr. Coffee, for that well done, encompassing writing. It's well put together. Thank you.
(I edited my reply many times for mistakes and added things as I thought of them.)
First, I think everyone who believes that the basic science can be taken for granted, would be correct in thinking so. "Belief" is the correct word, I think. It might be thought of as a dimunition of "knowledge", but it isn't intrinsically a dimunition of knowledge, because much much more is contained in the AGW concept than simply the knowledge of the physics of radiation. Oceans disappearing relatively soon, for Earth to be like Venus, for example, is one aspect that isn't simply about basic physics. AGW belief is a big wide bundle, and beliefs DIFFER significantly about projections and predictions. Those are not knowledge.
Agreed? Neither projections nor predictions are themselves knowledge, but they are part of the bundle. Neither is trust in expert opinion, itself, knowledge. There's nothing but belief in layers. It is belief and nothing
wrong with calling it what it is. I believe my doctor if he tells me what the lab saw in a test result.
So for you it's what you can see...disappearing glaciers being a prime example of a proxy for increased global temperatures.
Then there are proxies for glacier retreat, such as river sediments deposits. The variation of river and lake sediments are a proxy for the proxy for variation in temperatures. The proxy for the proxy.
What if they turned a proxy graph upside down from what they claim and recognize as right side up? Would that bother you?
It would bother me if my doctor turned my graph upside-down from the orientation that is recognized by Medicine and interpreted it opposite way from true "by accident" repeatedly. They do that. In what field of climate science? Glacier study. Hence the mention of the proxy for the proxy. They turn it upside-down when it suits them and that is often. The sediments are used upside down from the scientifically recognized orientation. A lot.
To be fair, in preliminary, here's an article that offers argument that denies in a strange way, that what I said above is true.
TEA is the original authoring of the sediment proxy record. MEA Is hockey stick Michael Mann and friends. M&M is McIntyre taking them to task.
Note that they exclaim proudly that they've proven it's false to say it's upside-down.
...before it got turned upside-down...
Now that it is established that the data in MEA input (in the ppd-file) is in same way as in TEA
>
Note (September 8, 2016): The article below contains some false statements. I have overlined the false parts. See the discussion below for further information. Arthur Smith wrote about the Mann/Til…
agwobserver.wordpress.com
The funniest part of all this is that some authors now use it upside-down, are sometimes ground down to finally admit fault, then forced to correct their paper, then they do the same thing on the next paper. That's all become part and parcel of the belief system, a critic could spend years getting them to admit fault which they might do while they work on more papers doing it again. Nobody reads the small correction a year later.
"disappearing ice"? First Issue: one needs to know what happened in the time BEFORE the time you were worried looking at it. For example, was it GROWING in 1960s-1970s when you were a bit younger? What if it only reached its highest recorded extent of ice in 1870? Just sayin'. Perspective is everything, in this arena.
When did AGW "kick in", due to human fuel use emissions, assuming we follow IPCC thought? Would that be a fair place to mark? 1950 or so?
Just as an aside, what do you notice that is odd about the angle of the upward slopes on this graph below, and the temperature spiking with vertical lines over the earlier part of the century from just before 1920 to 1930's if you compare the highest 30's spikes of monthly averages and the extreme angle of the slope there compared to what they wanted to highlight as drastic modern times using the line they drew on it for the 20 year modern trend? BTW, it's not from a bad site, it's from a prestigious university study, taken from NASA site. It's not fully up to date, of course.
https://earthobservatory.nasa.gov/features/ArcticIce/arctic_ice3.php
How is that possible? Why is this graph so out of tune with everything else we believe we know about arctic AGW temperatures? Guesses? Why is this graph not worrisome at all, to look at? Simply ups and downs, with more drastic and higher in the earlier part of the century before AGW kicked in?
Why did they begin a 60 year trend line right after that mountain? And why didn't NASA address this earlier BIGGER spike? In the century's graph. It's a veritable mountain of heat right there in the open to see if you study the moon itself and not the finger-pointing. Which mountain is the biggest if you're on your bike? Yet, no slope line drawn. No % per decade rise figures. No mention of the record temperature peaks of the century. Nary a word.
, and water. 
