(In other words, even if the monthly anomalies reported
for GISTEMP, for example, were accurate to 0.00001 degrees, it wouldn't change the fact that we'd need well over a decade of readings to ascertain the long - term trend, because the variability is real feature of the system and not simply a measurement error.)
For HadCRUT, CRUTEMP and NCDC, these changes are significant at better than the 95 % CL, and
for GISTEMP and HadCRUT + C&W, they are better than the 90 % CL.
We have a further update planned for February which will address the question of why our trends are greater than
those for GISTEMP over recent years.
Bob Tisdale says: August 20, 2010 at 2:04 am Steven: Isn't 2005 the current record high year
for GISTEMP?
Since 2005 is the current record year
for GISTEMP, why are you using 1998 as your reference in the first illustration?
Let be the empirical variance estimated using tsbootstrap
for the GISTEMP series on its common support with HadCRUT4.
The numbers
for the GISTEMP curve come from the NASA GISTEMP website.
It has no bearing on the record since the record
for GISTEMP is 2005.
As
for GISTEMP, it has very well documented problems of it's own but that's another thread altogether.....
I can't say the same
for GISTEMP that estimates the temp of an entire polar region.
Regression analyses are performed as in Otto (2015), using natural and anthropogenic forcing timeseries (historical and the RCP8.5 scenario) with a regression constructed using data from 1850 - 2016 (for HadCRUT4), and from 1880 - 2016 (
for GISTEMP).
When the May figure
for GISTemp comes out (presumably) next week, the «hiatus» will most likely be no more.
In absolute probability terms, NOAA calculated that 2014 was ~ 48 % likely to be the record versus all other years, while
for GISTEMP (because of the smaller margin), there is a higher change of uncertainties changing the ranking (~ 38 %).
For the GISTEMP and HadCRUT3, the trends are 0.19 + / -0.05 and 0.18 + / -0.04 ºC / dec (note that the GISTEMP met - station index has 0.23 + / -0.06 ºC / dec and has 2010 as a clear record high).
He kindly used the same approach for the HadCRUT3v data (pictured below) and I adapted
it for the GISTEMP data as well.
Year to date numbers
for GISTEMP, NCEI, HADCRU, UAH 5.6, and RSS:
By coincidence, yesterday was also the scheduled update
for the GISTEMP July temperature release, and because July is usually the warmest month of the year on an absolute basis, a record in July usually means a record of absolute temperature too.
Not exact matches
The NASA results, calculated by Goddard Institute
for Space Studies are published monthly on the NASA / GISS website (
GISTEMP).
The 2015 temperatures continue a long - term warming trend, according to analyses by scientists at NASA's Goddard Institute
for Space Studies (GISS) in New York (
GISTEMP).
The time evolution of the Northern Hemisphere mean
for the two data sets is shown in the lower panel, showing a good agreement over most of the record, but with slightly higher
GISTEMP estimates over the last 10 years (the global mean was not shown because my computer didn't have sufficient memory
for the complete analysis, but the two data sets also show similar evolution in e.g. the IPCC AR4).
For instance,
GISTEMP uses satellite - derived night light observations to classify stations as rural and urban and corrects the urban stations so that they match the trends from the rural stations before gridding the data.
Take the
GISTEMP product
for instance.
Fig. 1 Revision history of two individual monthly values
for January 1910 and January 2000 in the
GISTEMP global temperature data from NASA (Source: WUWT)
In the graphs in my article above I used the standard
GISTEMP baseline of 1951 - 1980 since it only discusses the temperature evolution since ~ 1950, so this seems an appropriate baseline
for that discussion.
The high anomalies up in the Arctic continue
for a third month in
GISTEMP and the question of the maximum Arctic Sea Ice Extent is surely now only by how much this freeze season will be below the record low set in 2017.
The data presented in this case included both surface analyses (
GISTEMP, NCDC, and HadCRUT3) in addition to satellite products
for the lower troposphere (Microwave Sounding Unit — MSU).
Taking a longer perspective, the 30 year mean trends aren't greatly affected by a single year (
GISTEMP: 1978 - 2007 0.17 + / -0.04 ºC / dec; 1979 - 2008 0.16 + / -0.04 — OLS trends, annual data, 95 % CI, no correction
for auto - correlation; identical
for HadCRU); they are still solidly upwards.
GISTEMP uses HadISST
for pre-Satellite SST.
So I don't think it is unreasonable to use HadCRUT
for analyzing global temperatures and not bother comparing the results to
GISTEMP.
Who performs the underlying corrections used
for the in situ (pre 1982) data in the current
GISTEMP analysis?
For an example of how that «citizen science» can really work, look at what Ron Broberg and Zeke Hausfeather are doing with the weather station data — they aren't sitting around declaring that «it can't be done» or that the
GISTEMP / CRU / NCDC methods are fixed, they are going into the data, making choices, seeing what impact they have and determining what is robust.
GISTEMP was 0.19 (0.17
for HadCRUT3v) on the same baseline.
The time evolution of the Northern Hemisphere mean
for the two data sets is shown in the lower panel, showing a good agreement over most of the record, but with slightly higher
GISTEMP estimates over the last 10 years (the global mean was not shown because my computer didn't have sufficient memory
for the complete analysis, but the two data sets also show similar evolution in e.g. the IPCC AR4).
GISTEMP uses Smith et al (1996) and Reynolds & Smith (1994)
for SST, but those papers document SST interpolation methods.
GISTEMP has posted
for January, kicking off the new year with a global anomaly of +0.78 ºC, the 5th warmest January on record after 2016 (+1.16 ºC), 2017 (+0.97 ºC), 2007 (+0.95 ºC) and 2015 (+0.81 ºC).
For instance,
GISTEMP uses satellite - derived night light observations to classify stations as rural and urban and corrects the urban stations so that they match the trends from the rural stations before gridding the data.
The question from the audience was along the lines of «the senator has asked
for empirical proof that humans are largely responsible
for recent warming, will someone give it to him» and Dr Cox's response was to wave around a smoothed
GISTEMP LOTI graph?
As is usual, today marks the release of the «meteorological year» averages
for the surface temperature records (
GISTEMP, HadCRU, NCDC).
For instance, the regression of the short - term variations in annual MSU TLT data to ENSO is 2.5 times larger than it is to
GISTEMP.
The reluctance of
GISTEMP to follow HADCRUT and publish offsets
for monthly data rather than just an offset
for the annual data might be overcome by publishing monthly offsets relative to the annual figure.
I've generated a graphic using the latest
GISTEMP data that plots the anomaly over decadal average bars
for decades 2005 - 2014, 1995 - 2004, and so on.
I was very interested to read that the annual mean UHI adjustment was applied
for all months in the
GISTEMP data.
Last Saturday, Steve McIntyre wrote an email to NASA GISS pointing out that
for some North American stations in the
GISTEMP analysis, there was an odd jump in going from 1999 to 2000.
GISTEMP uses HadISST
for the pre-satellite era, and so long - term trends may be affected there too (though not the more recent changes shown above).
For Figure 1, global mean temperatures are plotted from the HadCRUT4 and GISTEMP products relative to a 1900 - 1940 baseline, together with global mean temperatures from 81 available simulations in the CMIP5 archive, also relative to the 1900 - 1940 baseline, where all available ensemble members are taken for each mod
For Figure 1, global mean temperatures are plotted from the HadCRUT4 and
GISTEMP products relative to a 1900 - 1940 baseline, together with global mean temperatures from 81 available simulations in the CMIP5 archive, also relative to the 1900 - 1940 baseline, where all available ensemble members are taken
for each mod
for each model.
The same index is then calculated
for the 2005 - 2014 period and the historical 1880 - 2000 period in the HadCRUT4 and
GISTEMP datasets.
As far as I can see you got the tied
for 10th highest
GISTemp anomaly part right (I assume you have the Land - Ocean Temperature Index in mind, not the land only numbers) but my spreadsheet disagrees with your claim that the average anomaly
for 2013 to date would put it in 3rd place — I get 9th.
This is the basis
for the combined seasonal anomaly plots that are now published on the
GISTEMP website.
The climatology
for 1981 - 2010 is 287.4 ± 0.5 K, and the anomaly
for 2016 is (from
GISTEMP w.r.t. that baseline) 0.56 ± 0.05 ºC.
The models overestimated warming from 1979 - 2011, but if you look at
GISTEMP for example you can see that the East Pacific is cooler in 2011 than it was in 1979 and the models did not capture that as they have no PDO in the correct phase and are not expected to because PDOs are transient changes.