Gokul43201 said:
I disagree with this, and I imagine, so would Andre. Over the last 30 years, there is an unarguable increase in the global anomaly, even if you look at only the least convincing dataset: the satellite data for lower tropospheric temperatures (MSU2LT).
I refer you to Andre's post with the linear regression fits for the different datasets:
https://www.physicsforums.com/showpost.php?p=1677418&postcount=42
The satellite data shows an increase of about 1.4K/century from 1979 to 2007. This is a greater slope than for any other dataset over the last 100 years, which give numbers like 0.5K/century. The other datasets have slopes greater than 1.5K/century for the last 30 years.
Ok, now let's take the numbers from that post:
Period:...1979-2007...1998-2007
GHCN:...0.193...0.199
NOAA:...0.170...0.127
HADCRUT:..0.170...0.041
MSU2LT...0.142...0.057
If I understand well, the numbers are degrees per decade for 4 different estimators of global temperature. Now, what do we see ? 3 out of 4 of them have a LOWER value of the set 1998-2007 than for the set 1979-2007, which means that the slope is DECREASING. If the CO2+feedback+whatever panic scheme were right, then the slope should be INCREASING, as in the mean time, the CO2 level has been increasing, and all the positive feedback had more time to act.
Simple maths: if between x1 and x3, the slope is s1, and between x2 and x3, the slope is s2, then we have: total increase is d3 = (x3-x1) x s1 ; increase between x2 and x3 is d2 = (x3-x2) x s2, so the increase between x1 and x2 is d1 = d3 - d2 = (x3-x1) x s1 - (x3-x2) x s2
or the slope between x1 and x2 is: s3 = [ (x3-x1) x s1 - (x3-x2) x s2 ] / (x2 - x1).
If you do that naively to the numbers above, then we find as slopes between 1979 and 1998:
GHCN:...0.190
NOAA:...0.190
HADCRUT:..0.231
MSU2LT...0.182
Now, I know that we are talking about regression coefficients with a lot of noise and so on, but it seems clear from these data that the temperature increase between 1979 and 1998 was stronger than between 1998 and 2007. So it's getting hotter less fast between 1998 and 2007 than between 1979 and 1998. That's absolutely not in agreement with "more CO2, more warming".
I'm pretty sure the last IPCC reports made falsifiable predictions saying (approximately): if we maintain a Z(t) CO2 emission rate (t=time), we will see an increase in temperature over the next X years at a rate of about Y degrees per decade*. I think the early predictions for the scenarios of constant/decreased CO2 emissions may be somewhat off because back then, there was a somewhat poorer quantization of the amplitude of multi-decadal oscillations compared to what has come from papers in the last 1-2 years.
Was there a clear prediction of a *slowing down* of the increase of temperature between 1998 and 2007 BEFORE these data were available ? In other words, a *real* prediction ?
Because if not, then the increase between 1979 and 1998 which was then enhanced by any kind of oscillation might otherwise have been taken as "calibration" and justification for the "flat" response.
Could you provide a reference? I hope you are not comparing the measured deep sea temperature decrease in sub-Arctic waters with the predicted surface water temperature increase.
Well, have a look at Andre's post: https://www.physicsforums.com/showthread.php?t=239131
and then there is http://data.giss.nasa.gov/gistemp/graphs/Fig.A4.pdf
EDIT: just not to be misunderstood, I'm NOT saying that AGW is not a potential issue. And I DO think that there are many reasons to get away from fossil fuels. But I'm against all this irrational fear mongering. It can only lead to irrational decisions, and a lot of unnecessary problems. I'm also claiming that these things are far less understood than the fear mongerers (and also the negationists) claim. The real answer is that we really don't know what's going to happen 100 years from now, and that there is a potential for warming.