4 ms·

This visualisation is misleading because the visual area covered increases quadratically as the radius increases, and (less misleading) the velocity of the 'pen

by veltas 4y ago

This visualisation is misleading because the visual area covered increases quadratically as the radius increases, and (less misleading) the velocity of the 'pen' increases linearly too. But it's measuring a difference (not an absolute quantity): so velocity and (especially) area are arbitrary. I could take the same graph and apply it to the period between 1890 and 1945 and it would seem just as concerning, with a different scale.

alfor 4y ago
The change of color also and the fact that it’s temperature anomalies, not average temperature. I wonder what is actually behind ’temperature anomalies’, what does it mean, how is it calculated?
- veltas 4y ago
  https://en.wikipedia.org/wiki/Temperature_anomaly https://en.wikipedia.org/wiki/Temperature_anomaly As I understand it, this is a more useful number when trying to measure changes of average temperature over time.
  - alfor 4y ago
    Ok, I found the answer: it’s supposed to be the average of the difference of temperature over close to a million of region on the earth.
- turtledove 4y ago
  Here's the data source, which includes links out to papers on how the data is collected and calculated. https://data.giss.nasa.gov/gistemp/ https://data.giss.nasa.gov/gistemp/
titzer 4y ago
It could be misleading the other way too, if the starting radius was extremely large and the increments very small, then it could be made to look like no big deal. But that's the thing with temperature. We rarely start graphs at absolute zero (-273C), so what's your point again?
- veltas 4y ago
  My point is if you want to inform people about climate changes, be accurate with visualisations (i.e. don't equate something quadratic with something linear without being very transparent about this). If you want it to not be arbitrary, put some context with the numbers/scale. Like maybe plot temperature changes vs CO2 over time on a linear scale, and compare with changes that led to previous ice ages on that same scale. Or something of this vein.
mrow84 4y ago
In what way are you trying to interpret the area, or indeed the velocity (indeed the angular velocity is constant)? As I understand it, the intent of the visualisation is simply to make clear the temperature (anomaly) trend, which is encoded in the radius - that is all you need to consider to understand what is being shown. Also, the fact that it uses anomalies isn't of much consequence, given that there is widespread understanding of "normal" temperatures, to which the anomalies can be compared - this is unlike many situations where readers might not have an understanding of usual absolute values, making the plotting of differences prone to being misleading. According to [0] the anomaly difference for 1890-1945 is 0.44 K, whereas for 1880-2021 it is 1.01 K, so presumably someone who was concerned by the former would be (approximately) doubly concerned by the latter. [0] https://climate.nasa.gov/vital-signs/global-temperature/ https://climate.nasa.gov/vital-signs/global-temperature/
- veltas 4y ago
  Angular velocity is not velocity, the velocity increases because the angular velocity was remaining constant as the radius increased. It's encoded in the radius, but the area is visually more impactful - to me anyway - until the end when it's shown from the side, which was good. The point about comparing up to 1945 is that since the scale is arbitrary I can have it end at the same radius.
  - mrow84 4y ago
    I didn't suggest that angular velocity is the same as linear velocity, I asked how you were interpreting the area and velocity, and parenthetically observed that the angular velocity was constant. You say that the area is impactful - what do you understand it as meaning? The scale is not arbitrary, it covers the range of anomalies over the chosen period, in units of temperature change in degrees Celsius, and is labelled as such, with the anomaly reference period described in the text. If you were to use absolute values then the scale would similarly cover the range of absolute values over the chosen period - there is no "unbiased" choice of data range, except perhaps that which covers all of the data in question, which this does. As I noted, the impact of the anomalies is with reference to "normal" temperatures - it is relatively easy for anyone to see that 1 C (/K) is quite a large temperature increase, relative to "normal" temperatures. Surely you can agree that if the largest anomaly shown was 0.01 C then the graph would have far less impact, and if it was 100 C then the graph would have far more impact?
deleted 4y ago
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by veltas 4y ago

alfor 4y ago

The change of color also and the fact that it’s temperature anomalies, not average temperature. I wonder what is actually behind ’temperature anomalies’, what does it mean, how is it calculated?

veltas 4y ago
https://en.wikipedia.org/wiki/Temperature_anomaly https://en.wikipedia.org/wiki/Temperature_anomaly As I understand it, this is a more useful number when trying to measure changes of average temperature over time.
- alfor 4y ago
  Ok, I found the answer: it’s supposed to be the average of the difference of temperature over close to a million of region on the earth.
turtledove 4y ago
Here's the data source, which includes links out to papers on how the data is collected and calculated. https://data.giss.nasa.gov/gistemp/ https://data.giss.nasa.gov/gistemp/

titzer 4y ago

It could be misleading the other way too, if the starting radius was extremely large and the increments very small, then it could be made to look like no big deal. But that's the thing with temperature. We rarely start graphs at absolute zero (-273C), so what's your point again?

veltas 4y ago
My point is if you want to inform people about climate changes, be accurate with visualisations (i.e. don't equate something quadratic with something linear without being very transparent about this). If you want it to not be arbitrary, put some context with the numbers/scale. Like maybe plot temperature changes vs CO2 over time on a linear scale, and compare with changes that led to previous ice ages on that same scale. Or something of this vein.

mrow84 4y ago

In what way are you trying to interpret the area, or indeed the velocity (indeed the angular velocity is constant)? As I understand it, the intent of the visualisation is simply to make clear the temperature (anomaly) trend, which is encoded in the radius - that is all you need to consider to understand what is being shown. Also, the fact that it uses anomalies isn't of much consequence, given that there is widespread understanding of "normal" temperatures, to which the anomalies can be compared - this is unlike many situations where readers might not have an understanding of usual absolute values, making the plotting of differences prone to being misleading. According to [0] the anomaly difference for 1890-1945 is 0.44 K, whereas for 1880-2021 it is 1.01 K, so presumably someone who was concerned by the former would be (approximately) doubly concerned by the latter. [0] https://climate.nasa.gov/vital-signs/global-temperature/ https://climate.nasa.gov/vital-signs/global-temperature/

veltas 4y ago
Angular velocity is not velocity, the velocity increases because the angular velocity was remaining constant as the radius increased. It's encoded in the radius, but the area is visually more impactful - to me anyway - until the end when it's shown from the side, which was good. The point about comparing up to 1945 is that since the scale is arbitrary I can have it end at the same radius.
- mrow84 4y ago
  I didn't suggest that angular velocity is the same as linear velocity, I asked how you were interpreting the area and velocity, and parenthetically observed that the angular velocity was constant. You say that the area is impactful - what do you understand it as meaning? The scale is not arbitrary, it covers the range of anomalies over the chosen period, in units of temperature change in degrees Celsius, and is labelled as such, with the anomaly reference period described in the text. If you were to use absolute values then the scale would similarly cover the range of absolute values over the chosen period - there is no "unbiased" choice of data range, except perhaps that which covers all of the data in question, which this does. As I noted, the impact of the anomalies is with reference to "normal" temperatures - it is relatively easy for anyone to see that 1 C (/K) is quite a large temperature increase, relative to "normal" temperatures. Surely you can agree that if the largest anomaly shown was 0.01 C then the graph would have far less impact, and if it was 100 C then the graph would have far more impact?

deleted 4y ago

[deleted]