2013 Global Temperatures

[ORH_wxman]

 

This is from the authors' background material:

 

How do the results compare to other measures of global temperature?

 

The other widely quoted measures of global mean surface temperature are the GISTEMP record from the National Aeronautics and Space Administration (NASA) and the NCDC record from the National Oceanic and Atmospheric Administration (NOAA). Our results show slightly faster warming over the past 16 years than the NASA data, and significantly faster warming that NOAA. What is the reason for this discrepancy?

 

There are two known observational biases which impact recent temperature trends. Coverage bias, addressed in this paper, impacts the Met Office and NOAA data. A bias in sea surface temperature observations (arising from a recent transition from ships to buoys) is present in the NASA and NOAA data. We anticipate that when both of these biases are corrected, the resulting records will show even better agreement.

 

If the Met Office sea surface temperature corrections are applied to the NASA data, the resulting 16 year trend (i.e. 1997-2012) is 0.103°C/decade. Using the Met Office data and a similar reconstruction method we obtain a similar trend of 0.108°C/decade. Our best reconstruction including the satellite data shows a trend of 0.119°C/decade.

 

 

http://www-users.york.ac.uk/~kdc3/papers/coverage2013/background.html#compare

Thank you. So if these claims are valid, then we should shortly see revisions to the major temperature data sets to show increased warming over the last 15 years relative to current observations.

The authors' claim in the press release though troubles me:

"Trends starting in 1997 or 1998 are particularly biased with respect to the global trend. The issue is exacerbated by the strong El Niño event of 1997-1998, which also tends to suppress trends starting during those years."

There is no reason to point this out, mostly because it isn't really true. It's as if they have not heard of linear regression. The trends are essentially identical whether you start in 1998 or the year 2000 for either Hadcrut4 or GISS...neither dataset shows bias in starting time mostly because the 1999 La Nina offsets it. Keeping alive the myth that starting in 1998 is a big reason for the slower warming trend comes across as diversion. Especially if they think their claims on SST bias are robust enough to stand up to peer review.

[nflwxman]

 

Thank you. So if these claims are valid, then we should shortly see revisions to the major temperature data sets to show increased warming over the last 15 years relative to current observations.

The authors' claim in the press release though troubles me:

"Trends starting in 1997 or 1998 are particularly biased with respect to the global trend. The issue is exacerbated by the strong El Niño event of 1997-1998, which also tends to suppress trends starting during those years."

There is no reason to point this out, mostly because it isn't really true. It's as if they have not heard of linear regression. The trends are essentially identical whether you start in 1998 or the year 2000 for either Hadcrut4 or GISS...neither dataset shows bias in starting time mostly because the 1999 La Nina offsets it. Keeping alive the myth that starting in 1998 is a big reason for the slower warming trend comes across as diversion. Especially if they think their claims on SST bias are robust enough to stand up to peer review.

 

Eh, I agree that the inclusion of that language suggests they are more open to confirmation bias. However, it's not nearly as bad as some of the papers that have claimed "global warming" has stopped when merely talking about the surface temperature.  I will say as someone who has gone through the peer review process- the journal editorial board will often include and/or require language such as that in order to deem it "publishable format."

 

I don't think it's terribly alarming that it's in there.

[bluewave]

JC thinks the methodology is questionable.

 

http://judithcurry.com/2013/11/13/uncertainty-in-sst-measurements-and-data-sets/#more-13685

 

 

JC assessment

Let’s take a look at the 3 methods they use to fill in missing data, primarily in Africa, Arctic, and Antarctic.

1. 1.  Kriging
2. 2.  UAH satellite analyses of surface air temperature
3. 3.  NCAR NCEP reanalysis

The state that most of the difference in their reconstructed global average comes from the Arctic, so I focus on the Arctic (which is where I have special expertise in any event).

First, Kriging.  Kriging across land/ocean/sea ice boundaries makes no physical sense.  While the paper cites Rigor et al. (2000) that shows ‘some’ correlation in winter between land and sea ice temps at up to 1000 km, I would expect no correlation in other seasons.

Second, UAH satellite analyses.  Not useful at high latitudes in the presence of temperature inversions and not useful over sea ice (which has a very complex spatially varying microwave emission signature).  Hopefully John Christy will chime in on this.

Third, re reanalyses in the Arctic. See Fig 1 from this paper, which gives you a sense of the magnitude of grid point errors for one point over an annual cycle.  Some potential utility here, but reanalyses are not useful for trends owing to temporal inhomogeneities in the datasets that are assimilated.

So I don’t think Cowtan and Wray’s analysis adds anything to our understanding of the global surface temperature field and the ‘pause.’

The bottom line remains Ed Hawkins’ figure that compares climate model simulations for regions where the surface observations exist.  This is the appropriate way to compare climate models to surface observations, and the outstanding issue is that the climate models and observations disagree.

 

Is there anything useful from Cowtan and Wray?  Well, they raise the issue that we should try to figure out some way obtain the variations of surface temperature over the Arctic Ocean.  This is an active topic of research.

[nflwxman]

 

The GISS trend (which covers the poles) from 1997 is 0.07C per decade...so now Hadcrut4 is 0.05C more than that? Even the recently warm UAH doesn't have anything close to that high at 0.085C per decade.

This study essentially turns Hadcrut4 into a warm outlier when compared to other datasets with full coverage...assuming your 0.11-0.12C per decade trend is correct. I have not read the paper since it is paywalled, so I am not sure if they explain the difference in full.

UAH is impacted greatly by ENSO worldwide (less so in the arctic). So it's not surprising that the trend is less than an adjusted surface temperature to present.

[nflwxman]

JC thinks the methodology is questionable.

 

http://judithcurry.com/2013/11/13/uncertainty-in-sst-measurements-and-data-sets/#more-13685

 

 

JC assessment

Let’s take a look at the 3 methods they use to fill in missing data, primarily in Africa, Arctic, and Antarctic.

1. 1.  Kriging
2. 2.  UAH satellite analyses of surface air temperature
3. 3.  NCAR NCEP reanalysis

The state that most of the difference in their reconstructed global average comes from the Arctic, so I focus on the Arctic (which is where I have special expertise in any event).

First, Kriging.  Kriging across land/ocean/sea ice boundaries makes no physical sense.  While the paper cites Rigor et al. (2000) that shows ‘some’ correlation in winter between land and sea ice temps at up to 1000 km, I would expect no correlation in other seasons.

Second, UAH satellite analyses.  Not useful at high latitudes in the presence of temperature inversions and not useful over sea ice (which has a very complex spatially varying microwave emission signature).  Hopefully John Christy will chime in on this.

Third, re reanalyses in the Arctic. See Fig 1 from this paper, which gives you a sense of the magnitude of grid point errors for one point over an annual cycle.  Some potential utility here, but reanalyses are not useful for trends owing to temporal inhomogeneities in the datasets that are assimilated.

So I don’t think Cowtan and Wray’s analysis adds anything to our understanding of the global surface temperature field and the ‘pause.’

The bottom line remains Ed Hawkins’ figure that compares climate model simulations for regions where the surface observations exist.  This is the appropriate way to compare climate models to surface observations, and the outstanding issue is that the climate models and observations disagree.

 

Is there anything useful from Cowtan and Wray?  Well, they raise the issue that we should try to figure out some way obtain the variations of surface temperature over the Arctic Ocean.  This is an active topic of research.

I'm really starting to lose respect for her.  Shes become more of a hack and less of climate scientist.  She pointedly shows the issue of using UAH and other LT measurements in temperature analysis, but then constantly uses UAH and RSS in her blog posts almost daily to play up the pause and reduce the long term trend. 

[ORH_wxman]

I'm really starting to lose respect for her.  Shes become more of a hack and less of climate scientist.  She pointedly shows the issue of using UAH and other LT measurements in temperature analysis, but then constantly uses UAH and RSS in her blog posts almost daily to play up the pause and reduce the long term trend. 

 

 

UAH doesn't reduce the trend...its a warm outlier right now in all datasets.

[nflwxman]

UAH doesn't reduce the trend...its a warm outlier right now in all datasets.

Long term trend, it is one of the lowest.  Not just the last 15 years.

[tacoman25]

I think people are suspicious of this new study because it's another example of making adjustments to the past that better fit the expected outcome. The fact is that these data sets weren't questioned and re-analyzed so much when they were showing the "appropriate" warming trend. Now it feels like scientists are scrambling to find ways that the data should be adjusted - and whaddya know, now it better fits the confirmation bias.

[tacoman25]

Long term trend, it is one of the lowest.  Not just the last 15 years.

 

You're missing the point. It's the last 15 years that this study greatly increases the trend for.

[nflwxman]

I think people are suspicious of this new study because it's another example of making adjustments to the past that better fit the expected outcome. The fact is that these data sets weren't questioned and re-analyzed so much when they were showing the "appropriate" warming trend. Now it feels like scientists are scrambling to find ways that the data should be adjusted - and whaddya know, now it better fits the confirmation bias.

 

No reason not to be suspicious and skeptical.  I've always been suspicious of the missing arctic temperatures from all datasets, however. Arctic sea ice hasn't blasted away the last 10 years for no reason. The circumstantial evidence is there.

[nflwxman]

You're missing the point. It's the last 15 years that this study greatly increases the trend for.

Read my post above. That was not the point I was making.  My point is that Judith Curry has turned into a sideshow more than a scientist, not about the paper itself.

 

Not so different than Mann.  They have picked "sides" rather than letting the science speak for itself.

[ORH_wxman]

JC thinks the methodology is questionable.

 

http://judithcurry.com/2013/11/13/uncertainty-in-sst-measurements-and-data-sets/#more-13685

 

 

JC assessment

Let’s take a look at the 3 methods they use to fill in missing data, primarily in Africa, Arctic, and Antarctic.

1. 1.  Kriging
2. 2.  UAH satellite analyses of surface air temperature
3. 3.  NCAR NCEP reanalysis

The state that most of the difference in their reconstructed global average comes from the Arctic, so I focus on the Arctic (which is where I have special expertise in any event).

First, Kriging.  Kriging across land/ocean/sea ice boundaries makes no physical sense.  While the paper cites Rigor et al. (2000) that shows ‘some’ correlation in winter between land and sea ice temps at up to 1000 km, I would expect no correlation in other seasons.

Second, UAH satellite analyses.  Not useful at high latitudes in the presence of temperature inversions and not useful over sea ice (which has a very complex spatially varying microwave emission signature).  Hopefully John Christy will chime in on this.

Third, re reanalyses in the Arctic. See Fig 1 from this paper, which gives you a sense of the magnitude of grid point errors for one point over an annual cycle.  Some potential utility here, but reanalyses are not useful for trends owing to temporal inhomogeneities in the datasets that are assimilated.

So I don’t think Cowtan and Wray’s analysis adds anything to our understanding of the global surface temperature field and the ‘pause.’

The bottom line remains Ed Hawkins’ figure that compares climate model simulations for regions where the surface observations exist.  This is the appropriate way to compare climate models to surface observations, and the outstanding issue is that the climate models and observations disagree.

 

Is there anything useful from Cowtan and Wray?  Well, they raise the issue that we should try to figure out some way obtain the variations of surface temperature over the Arctic Ocean.  This is an active topic of research.

 

 

NCEP/NCAR renalaysis also shows warming in Antarctica and surrounding southern ocean while satellite data, and O'Donnell et al (in the Steig rebuttal paper) showed cooling. A recent paper by Thompson et al tried to link the recent cooling to the ozone hole.

 

So clearly there are discrepancies within the peer reviewed literature versus NCEP/NCAR reanalysis over that part of the globe...which is pretty significant when filling in missing data over the southern hemisphere.

[ORH_wxman]

Long term trend, it is one of the lowest.  Not just the last 15 years.

 

 

Well you are splitting hairs at that point if you are talking back to 1979...the datasets in general agree pretty well. UAH is +0.136C per decade, RSS is +0.126C per decade, GISS is +0.158C per decade, and Hadcrut4 is +0.154C per decade.

 

The satellites have always been cooler on their trendline.

[tacoman25]

No reason not to be suspicious and skeptical.  I've always been suspicious of the missing arctic temperatures from all datasets, however. Arctic sea ice hasn't blasted away the last 10 years for no reason. The circumstantial evidence is there.

 

Yes, but the thing is that those datasets were missing the Arctic data long before 1997-98. Long before the big melts of the past 5-10 years. How would that affect past trends?

[Jonger]

I think people are suspicious of this new study because it's another example of making adjustments to the past that better fit the expected outcome. The fact is that these data sets weren't questioned and re-analyzed so much when they were showing the "appropriate" warming trend. Now it feels like scientists are scrambling to find ways that the data should be adjusted - and whaddya know, now it better fits the confirmation bias.

Someone asked me if the world is getting warmer, I said no, but the past is certainly getting colder.

[nflwxman]

Yes, but the thing is that those datasets were missing the Arctic data long before 1997-98. Long before the big melts of the past 5-10 years. How would that affect past trends?

Good question.  I think it's in the paper though until about 1979.  There's no reason not to improve our datasets due to past uncertainty though.

[tacoman25]

Good question.  I think it's in the paper though until about 1979.  There's no reason not to improve our datasets due to past uncertainty though.

 

As long as we're comparing apples to apples, I'm fine with it. But if we're picking and choosing what data to use when, that's when it become awfully easy to shape a trend to our preference.

[donsutherland1]

JC thinks the methodology is questionable.

 

http://judithcurry.com/2013/11/13/uncertainty-in-sst-measurements-and-data-sets/#more-13685

 

 

JC assessment

Let’s take a look at the 3 methods they use to fill in missing data, primarily in Africa, Arctic, and Antarctic.

1. 1.  Kriging
2. 2.  UAH satellite analyses of surface air temperature
3. 3.  NCAR NCEP reanalysis

The state that most of the difference in their reconstructed global average comes from the Arctic, so I focus on the Arctic (which is where I have special expertise in any event).

First, Kriging.  Kriging across land/ocean/sea ice boundaries makes no physical sense.  

 

The new paper mentions that kriging performed better with respect to sea surface temperatures and a hybrid reconstruction method performed better with respect to land temperatures. So, I'm not sure where JC is getting the idea that the authors of the new paper used kriging "across land/ocean/sea ice" boundaries. In fact, the authors of the new paper wrote:

 

These results indicate that reconstruction of the regions of the globe where coverage is poor is best achieved with the hybrid method, using a scale for the satellite data in the region of 1.0. This is in contrast with the result for the globe in gneral, where optimal results are achieved by a combination of the kriging and hybrid methods to cover land and ocean, or failing that a hybrid calculation with the satellite data down-weighted. (p.5 of the paper)

 

In other words, it appears that the authors of the new paper were not relying on kriging to deal with sparse Arctic data. They tested that approach and found that it was inferior to the hybrid method.

 

The hybrid method also was the authors' preferred approach for dealing with air temperatures over sea ice, but also note that more research will be required, as sea ice melts creating "an unknown temperature bias." 

[The_Global_Warmer]

I am on team warmth.

 

 

After dropping below .20C for one update.  CFS has jumped back above .20C on the dailies.  Which is now about 5 days almost in a row of it.  Monthlies are up to .119C.  This is now a .67C GISS equivelant.

 

ENSO is priming for a NINO or a big heat dump into the atmosphere. 

 

 

[bluewave]

I'm really starting to lose respect for her.  Shes become more of a hack and less of climate scientist.  She pointedly shows the issue of using UAH and other LT measurements in temperature analysis, but then constantly uses UAH and RSS in her blog posts almost daily to play up the pause and reduce the long term trend. 

 

 

NCEP/NCAR renalaysis also shows warming in Antarctica and surrounding southern ocean while satellite data, and O'Donnell et al (in the Steig rebuttal paper) showed cooling. A recent paper by Thompson et al tried to link the recent cooling to the ozone hole.

 

So clearly there are discrepancies within the peer reviewed literature versus NCEP/NCAR reanalysis over that part of the globe...which is pretty significant when filling in missing data over the southern hemisphere.

 

 

 

The new paper mentions that kriging performed better with respect to sea surface temperatures and a hybrid reconstruction method performed better with respect to land temperatures. So, I'm not sure where JC is getting the idea that the authors of the new paper used kriging "across land/ocean/sea ice" boundaries. In fact, the authors of the new paper wrote:

 

These results indicate that reconstruction of the regions of the globe where coverage is poor is best achieved with the hybrid method, using a scale for the satellite data in the region of 1.0. This is in contrast with the result for the globe in gneral, where optimal results are achieved by a combination of the kriging and hybrid methods to cover land and ocean, or failing that a hybrid calculation with the satellite data down-weighted. (p.5 of the paper)

 

In other words, it appears that the authors of the new paper were not relying on kriging to deal with sparse Arctic data. They tested that approach and found that it was inferior to the hybrid method.

 

The hybrid method also was the authors' preferred approach for dealing with air temperatures over sea ice, but also note that more research will be required, as sea ice melts creating "an unknown temperature bias." 

 

The important point is that the model forecasts were based on areas where observations existed at the time. So this

does not change the fact that the models still overestimated the warming for those areas. Maybe the model forecasts 

would have been higher had they included the areas outside the data range so the current temperatures would be

below the forecasts by the same magnitude. We all know that GISS is superior to Hadcrut for Arctic temperatures.

But more studies will need to be done to see if this is a better method for measuring Arctic temperatures than

GISS has. 

 

“No difficult scientific problem is ever solved in a single paper. I don’t expect our paper to be the last word on this, but I hope we have advanced the discussion.

 

The bottom line remains Ed Hawkins’ figure that compares climate model simulations for regions where the surface observations exist.  This is the appropriate way to compare climate models to surface observations, and the outstanding issue is that the climate models and observations disagree.

[The_Global_Warmer]

What is going on down South.  the Indian ocean is torching something fierce.  As well as the SW Pacific.  The Bermuda High is causing the Atlantic to be well above normal as well. 

 

CFS is now closing in on a week at or above .20C.  As of the 00z 11-15-13 update the dailies are at .24C.  Up a bit from yesterday.  And the month so far is at .123C.  That would be a .67(.62-.72) on GISS.  So we are starting the second half of November at .24C on weatherbell.  .24C would be a .79(.74-.84) on giss.  Gives us an idea of where we are in the near term. 

 

Essentially we are at a very warm level.  So far one region of the ocean seemingly warms up when another cools off to prevent us from going under .20C on the SSTA. 

 

[The_Global_Warmer]

Here is a great post on Dr. Roy Spencers blog.

 

Davey:

That +0.27 in December 1987 was the highest figure for any month in the 1980s. In the 1990s, it was exceeded 11 times, almost all of them in the super El Nino year of 1998. In the 2000s, it was exceeded 18 times. In the 2010s, it has been exceeded in 20 out of a total of 46 months so far. So nowadays, nearly half of all months are warmer than the hottest of all months in the 1980s. Such a difference, and in only a quarter of a century!

 

 

 

 

 

That pretty much sums it up for me.  We have been in a negative ENSO state for most of the 2010s.  But we have already passed .27C+ more times in a few years than all of the 2000s. 

 

It's all going to be about timing for when the walls will fall.

 

 

[chubbs]

 

The bottom line remains Ed Hawkins’ figure that compares climate model simulations for regions where the surface observations exist.  This is the appropriate way to compare climate models to surface observations, and the outstanding issue is that the climate models and observations disagree

 

Agree models are not tracking this hiatus period but 10-15 years is too short a period for a meaningful evaluation. .Much more appropriate to look at climate model performance over 50-60 year period so that natural variability becomes less important relative to man-made forcing. On that basis models are overestimating warming by roughly 20% just eyeballing the Hawkins chart. That level of performance is not perfect but not horrible either. . 

[bluewave]

Agree models are not tracking this hiatus period but 10-15 years is too short a period for a meaningful evaluation. .Much more appropriate to look at climate model performance over 50-60 year period so that natural variability becomes less important relative to man-made forcing. On that basis models are overestimating warming by roughly 20% just eyeballing the Hawkins chart. That level of performance is not perfect but not horrible either. . 

 

We all know that the Arctic has been the fastest warming part of the globe over the last decade. GISS has been

behind NCEP/NCAR. So am am not sure that this study is really news. Even GISS and NCAR show a slower rate

of global temperature rise over the last 15 years relative to the previous 15 years. But once we eventually

flip back to a +PDO by 2025-2030, it will be off to the races. I could see a 2030-2060 temperature rise of

around .8C before we enter the next slower warming period 2060-2090.

 

[ORH_wxman]

We all know that the Arctic has been the fastest warming part of the globe over the last decade. GISS has been

behind NCEP/NCAR. So am am not sure that this study is really news. Even GISS and NCAR show a slower rate

of global temperature rise over the last 15 years relative to the previous 15 years. But once we eventually

flip back to a +PDO by 2025-2030, it will be off to the races. I could see a 2030-2060 temperature rise of

around .8C before we enter the next slower warming period 2060-2090.

 

8667658109_95100353ba_o.jpg

 

 

For the study to gain more credibility from a numbers standpoint (specifically that we've seen over a 0.10C per decade trend since 1997), I think they'll have to show that GISS has a cold bias from the SST parameter that they vaguely alluded to in the press release but that their study didn't focus on.

 

Especially since NCEP/NCAR reanalysis already is at odds with some of the other methods of temperature analysis in polar regions...specifically the southern polar regions where they are very different. But even the graph you show there has a divergence in the arctic region with GISS starting around 1996 after being in good agreement before that.

[bluewave]

For the study to gain more credibility from a numbers standpoint (specifically that we've seen over a 0.10C per decade trend since 1997), I think they'll have to show that GISS has a cold bias from the SST parameter that they vaguely alluded to in the press release but that their study didn't focus on.

 

Especially since NCEP/NCAR reanalysis already is at odds with some of the other methods of temperature analysis in polar regions...specifically the southern polar regions where they are very different. But even the graph you show there has a divergence in the arctic region with GISS starting around 1996 after being in good agreement before that.

 

The other question is if we can expect the rate of Arctic temperature rise over the last decade to continue, or if we

see a plateau or slower rate of increase for the next 10? 

 

Chris Reynolds had a great Arctic temperature post last spring.

 

http://dosbat.blogspot.co.uk/2013/04/giss-loti-and-ncepncar-reanalysis.html

[Jesse]

I am on team warmth.

 

 

After dropping below .20C for one update.  CFS has jumped back above .20C on the dailies.  Which is now about 5 days almost in a row of it.  Monthlies are up to .119C.  This is now a .67C GISS equivelant.

 

ENSO is priming for a NINO or a big heat dump into the atmosphere. 

 

 

 

 

 

 

Don't think anyone every doubted that, buddy.

[nflwxman]

For the study to gain more credibility from a numbers standpoint (specifically that we've seen over a 0.10C per decade trend since 1997), I think they'll have to show that GISS has a cold bias from the SST parameter that they vaguely alluded to in the press release but that their study didn't focus on.

 

Especially since NCEP/NCAR reanalysis already is at odds with some of the other methods of temperature analysis in polar regions...specifically the southern polar regions where they are very different. But even the graph you show there has a divergence in the arctic region with GISS starting around 1996 after being in good agreement before that.

 

I'm not sure this paper is lacking credibility at all.  It does need to undergo scrutiny in the public arena, but I assume it's been thoroughly reviewed.  People are going to be quick to jump on it obviously since it basically dispels a lot of the skeptic arguments of the past 5 years.  While it's not news per say, it does show that 16% of the world can alter the global temperature profile (in the short term at least). What it also shows to me is that the ENSO impact on many of the linear regression techniques that attempted to filter out natural variability may have been overestimated.  It also shows that the impact of the PDO may have been overestimated globally, which has been a hot topic recently.  From a purely circumstantial view- the study does back up some recent observation of ice loss in the area. Arctic amplification is certainly an aspect of this- we have no idea if methane is also playing a part in this as well.  Didn't the authors use primarily a "kriging" technique using UAH and not reanalysis? Or a little of both?

[ORH_wxman]

I'm not sure this paper is lacking credibility at all.  It does need to undergo scrutiny in the public arena, but I assume it's been thoroughly reviewed.  People are going to be quick to jump on it obviously since it basically dispels a lot of the skeptic arguments of the past 5 years.  While it's not news per say, it does show that 16% of the world can alter the global temperature profile (in the short term at least). What it also shows to me is that the ENSO impact on many of the linear regression techniques that attempted to filter out natural variability may have been overestimated.  From a purely circumstantial view- the study does back up some recent observation of ice loss in the area. Arctic amplification is certainly an aspect of this- we have no idea if methane is also playing a part in this as well.  Didn't the authors use primarily a "kriging" technique using UAH and not reanalysis? Or a little of both?

 

 

The paper is fine in itself given the caveats they mentioned. But what it does is modify a specific temperature dataset (Hadcrut4) so that it is a warm outlier versus other full coverage datasets. GISS is full coverage, but they only make a vague reference to SSTs on the GISS dataset in their press release as to why GISS is also cold biased. I didn't see any reference to satellites as to why they are cold biased. UAH has virtually full coverage and RSS is only really missing the southern polar region which is not warming anyway...it has most of the arctic.

[nflwxman]

The paper is fine in itself given the caveats they mentioned. But what it does is modify a specific temperature dataset (Hadcrut4) so that it is a warm outlier versus other full coverage datasets. GISS is full coverage, but they only make a vague reference to SSTs on the GISS dataset in their press release as to why GISS is also cold biased. I didn't see any reference to satellites as to why they are cold biased. UAH has virtually full coverage and RSS is only really missing the southern polar region which is not warming anyway...it has most of the arctic.

 

RSS is missing some of the arctic and has coarser spatial resolution.  Secondly, the met office did make some improvements to their SST methodology in 2011.  I believe NASA has even suggested that they feel like they need to do a similar correction in the 2012 global temperature review.  I have not read the full paper so I'm not sure what the correction is, but they said if they applied it to GISS data it increases the trend from 0.08 C/decade to 0.10 C/decade (which not really a huge difference over such a short period of time).

 

But I agree, they obviously need to continue to defend their method as they do suggest the highest trend in the last 15 years.