There's a lot that bothers me about this chart.

If you want numbers that sound large, use a scale that's numerically larger for the same dimension.

The interval shown goes from -1 degree F to +1 degree F.

1.8 degrees F = 1 degree C. In other words, the same scale in C would go from -0.56 C to +0.56 C. In other words, the entire range is about 1 C.

The other issue is that the color representation of the maps grotesquely exaggerate the magnitude. The visual impact from deep blue to dark brown is far greater than the 1 C range it represents. Such color range would be more accurately used to represent the delta in temperature between, say, deep winter at the cold end and a very hot summer at the hot end. I other words, it visually represents a difference that could easily be 50 C, rather than 1 C.

An honest scale would represent the range of temperatures (minima and maxima) across the US from winter to summer in a scale from, say, -30 F to +120 F and present maps colored using this scale. The problem with doing this is that this +/- 1 F delta across 120 years would be just-about imperceptible.

In addition to this, the image has no information whatsoever on what the color coding truly represents. One legend reads "Difference from average" while another says "30 year normal compared to 1901-2000".

If you look at the website, they have graphs that compare the "global temperature anomaly compared to 1901-2000". In other words, they average some temperatures (undisclosed) over that period of time, this becomes "zero" and everything is compared to this artificial zero. The temperature over this period averages out to some number and everything before a certain year looks colder than this average while everything past a certain point looks hotter.

Huh? What am I actually looking at?

Where is the map/data with absolute measurements, not this weird averaging over a period that stops twenty years ago. Why does the reference average stop in 2000, twenty one years ago and does not include the last twenty years?

Do these measurements correspond to exactly the same date and location each year? Average of what? When? How? What was the tolerance, error, reliability of the measurements? They are comparing measurements made 120 years ago on a scale with a full range of 1 C.

Let's put these numbers into context:

Hot day in Las Vegas: 48 degrees C.

Let's say we have a measurement error of +/-1%. What would that range be? Well, that's + or - 0.48 degrees C from true temperature.

And this graph is showing a range of +/- 0.56 degrees C over a period of 120 years? An measurement error of 1% across such a vast number of measurement sites, with different instruments, people and systems recording them isn't only plausible, it is very likely. In fact the error could be significantly greater than that.

Read a thermometer, not a digital one, a mercury thermometer of the kind they used to use for much of the last century. Can you read that thermometer to an accuracy/reliability of 1%? Likely not. The thing would have to be massively large for you to be able to visually interpolate that scale to such accuracy. Where are you reading it? Top of the meniscus? Bottom? Middle? How did the guy in New York read it? The one in Dallas? How was it read in years 1, 5, 10, 20, 30, etc.? Same instrument for over a century? Likely not. How were they calibrated, if at all? Who calibrated them? How often? To what standard? Etc.

I don't have a problem for making a case for environmental awareness and more responsible behavior. However, proponents need to understand that extreme honesty and accuracy in every statement being made is of paramount importance. Graphically distorted and numerically exaggerated graphs such as this one only serve to feed deniers and those who aim to increase their numbers. In other words, the reaction could be "I got you! You are lying to me!". Not a very useful outcome.

Either we are doing science or marketing. I propose only one of those will result in changing hearts and minds. Don't lie. Don't manipulate. Be accurate, precise, accountable, transparent and backup your data.