I'd think if they use a different baseline (norms?), to compare the same readings to, that they'd get different "answers."
In terms of the individual anomalies you'd be correct. That's not the issue here - as I said, I expected there to be a difference between the anomalies. Different norms, different anomalies.
But I'm talking about the trend of the anomalies. The difference between the two datasets should remain the same (regardless of the normal selected) for every time interval within that 6 years -
provided that they are calculating similar global temperatures.
Now, what the graph is showing, is that the difference between NOAA and Hadley is NOT staying the same, but is actually increasing. This is despite using the same orginal data.
Isn't the y-axis showing a ~0.5 degree "anomoly" from some supposed baseline? Isn't that the critical point?
No - that's not the critical point here. The critical point is NOAA is showing global temperatures
continuing to increase over the past 6 years, while Hadley has shown temperatures to flatten.
So with NOAA - the past warming is continuing. With Hadley, the past warming has greatly slowed or stopped.
I see the graph as a 6 year snapshot of a much longer line that may trend up or down by 10-20% (~0.1degree), and over decades may trend up or down "overall" (again, limited by the time range).
Again - the issue is that here we have two respected, leading edge institutions, and they can't agree if temperature is increasing or has stabilized over the past 6 years.
Isn't this focusing on a discrepancy that is small compared to the main point of the graph?
This is not a small issue. NOAA is showing temperature to be increasing at phenomenal rate. 0.8 C over 6 years. That's huge. It's a warming rate of 13.3 C/100 years (obviously this rate can't continue, I just scaled it up for illustrative purposes). Is there this much uncertainty in our estimates of global average temperature?
Let me repeat from previous post:
"You say the Hadley data shows 'almost no increase' over 6 years.
Do you mean- except for the 'plus' ~0.5 degree anomoly?" -samwik
Once again - I'm not concerned about the +0.5 degree anomaly. I'm talking about the fact that the start of the linear trend line for Hadley is at 0.44 C, and ends at 0.45 C (
a difference of 0.01 C), and the start of the linear trend line for NOAA is at 0.51 C, and ends at 0.59 C (
a difference of 0.8C).
0.8 is much higher than 0.1, which means the NOAA rate of warming over the past 6 years is 8 times what Hadley is showing.
They could present global temperatures as absolute values, and get away from the complicating factor of differing means, but the end result would be the exact same thing. Over the past 6 years global temperatures estimated by NOAA are increasing much, much faster than global temperatures estimated by Hadley. And they're using the same climate data!