...

[bluewave]

......

[Absolute Humidity]

Interesting coincidence here for me today. My company held a climate change seminar today with special guest speaker Heidi Cullen of Princeton, Climate Central (formally with TWC, Forecast Earth). She mentioned all the above in pretty good detail and presented these findings in an understandable way for an audience with little or no scientific background. She gave special detail to the PDO and the increase of deep sea water temps since 2000. I did have an opportuitity to ask her questions relating to the NAO and high altitude blocking and how the melting Greenland ice might be responsible for an increase in the severe episodes of high latitude blocking weve seen this past decade. The big question we agreed as unresolved is whether these will lead to a continued era of KU events along the eastern third of North America. I guess we'll see.

[SVT450R]

Thanks for the links bluewave this shows we need more research done on the multidecadal oscillations to understand whats going on in the climate to make more accurate predictions down the line. 

[The_Global_Warmer]

A new study just out addresses how the PDO can impact global temperatures on a decadal timescale.

The full paper isn't available free of charge online yet.

 

http://www.climatecentral.org/news/why-the-globe-hasnt-warmed-much-for-the-past-decade-15788

 

 

The natural variation in this case appears to be changes in wind patterns associated with the Pacific Decadal Oscillation, or PDO, a gradual see-sawing of ocean surface temperatures and wind patterns that goes through warm and cold phases lasting several decades. (The more familiar El Nino/La Nina oscillation, by contrast, see-saws every few years).

According to Trenberth and his colleagues, deep ocean temperatures began to rise significantly starting in about 2000, at about the same time as trade winds in the Pacific were changing in strength, in turn affecting ocean currents, all very plausibly as a result of a shift in the PDO. 

 

http://www.skepticalscience.com/new-research-confirms-global-warming-has-accelerated.html

 

 

This study builds on another paper published in 2011.

 

 

http://www.cgd.ucar.edu/cas/Staff/Fasullo/my_pubs/Meehl2011etalNCC.pdf

 

 

There have been decades, such as 2000–2009, when the observed globally averaged surface-temperature time series shows little positive or even slightly negative trend1 (a hiatus  period). However, the observed energy imbalance at the top-of-atmosphere for this recent decade indicates that a net energy flux into the climate system of about 1 W m−2 7 (refs 2,3) should be producing warming somewhere in the  system4,5 . Here we analyse twenty-first-century climate-model simulations that maintain a consistent radiative imbalance at

the top-of-atmosphere of about 1 W m−2 as observed for the 11 past decade. Eight decades with a slightly negative global mean surface-temperature trend show that the ocean above 300 m  takes up significantly less heat whereas the ocean below 300 m  takes up significantly more compared with non-hiatus decades.  The model provides a plausible depiction of processes in the  climate system causing the hiatus periods, and indicates that a  hiatus period is a relatively common climate phenomenon and

may be linked to La Niña-like conditions.

 

 

The time series of globally averaged surface temperature from  all five climate-model simulations show some decades with little or no positive trend (Fig. 1a), as has occurred in observations  (Supplementary Fig. S1 top). Running ten year linear trends of globally averaged surface temperature from the five model ensemble  members reveal hiatus periods (Fig. 1a) comparable to observations  (Supplementary Fig. S1 middle). Using the first ensemble member as an example, the overall warming averaged over the century is about +0.15 ◦ C per decade. However, the decades centred around  2020, 2054, 2065, 2070, and several decades late in the century  show either near zero or slightly negative trends in that ensemble  member. We choose two ten year periods in this ensemble member when the globally averaged surface temperature is negative, that is, less than −0.10 ◦ C over the decade (Fig. 1a), and six similar  periods that meet the same criterion from the other four ensemble  members, to form an eight-member composite of hiatus periods.

 

http://www.sciencedaily.com/releases/2011/09/110918144941.htm

 

 

To track where the heat was going, Meehl and colleagues used a powerful software tool known as the Community Climate System Model, which was developed by scientists at NCAR and the Department of Energy with colleagues at other organizations. Using the model's ability to portray complex interactions between the atmosphere, land, oceans, and sea ice, they performed five simulations of global temperatures.

The simulations, which were based on projections of future greenhouse gas emissions from human activities, indicated that temperatures would rise by several degrees during this century. But each simulation also showed periods in which temperatures would stabilize for about a decade before climbing again. For example, one simulation showed the global average rising by about 2.5 degrees Fahrenheit (1.4 degrees Celsius) between 2000 and 2100, but with two decade-long hiatus periods during the century.

 

 

Metoffice decadal forecast using a similar theme:

 

http://www.metoffice.gov.uk/news/releases/archive/2013/decadal-forecasts

 

http://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/long-range/decadal-fc

 

http://www.metoffice.gov.uk/research/news/decadal-forecasting

[donsutherland1]

 

A new study just out addresses how the PDO can impact global temperatures on a decadal timescale.

The full paper isn't available free of charge online yet.

 

http://www.climatecentral.org/news/why-the-globe-hasnt-warmed-much-for-the-past-decade-15788

 

 

The natural variation in this case appears to be changes in wind patterns associated with the Pacific Decadal Oscillation, or PDO, a gradual see-sawing of ocean surface temperatures and wind patterns that goes through warm and cold phases lasting several decades. (The more familiar El Nino/La Nina oscillation, by contrast, see-saws every few years).

According to Trenberth and his colleagues, deep ocean temperatures began to rise significantly starting in about 2000, at about the same time as trade winds in the Pacific were changing in strength, in turn affecting ocean currents, all very plausibly as a result of a shift in the PDO. 

 

http://www.skepticalscience.com/new-research-confirms-global-warming-has-accelerated.html

 

 

This study builds on another paper published in 2011.

 

 

http://www.cgd.ucar.edu/cas/Staff/Fasullo/my_pubs/Meehl2011etalNCC.pdf

 

 

There have been decades, such as 2000–2009, when the observed globally averaged surface-temperature time series shows little positive or even slightly negative trend1 (a hiatus  period). However, the observed energy imbalance at the top-of-atmosphere for this recent decade indicates that a net energy flux into the climate system of about 1 W m−2 7 (refs 2,3) should be producing warming somewhere in the  system4,5 . Here we analyse twenty-first-century climate-model simulations that maintain a consistent radiative imbalance at

the top-of-atmosphere of about 1 W m−2 as observed for the 11 past decade. Eight decades with a slightly negative global mean surface-temperature trend show that the ocean above 300 m  takes up significantly less heat whereas the ocean below 300 m  takes up significantly more compared with non-hiatus decades.  The model provides a plausible depiction of processes in the  climate system causing the hiatus periods, and indicates that a  hiatus period is a relatively common climate phenomenon and

may be linked to La Niña-like conditions.

 

 

The time series of globally averaged surface temperature from  all five climate-model simulations show some decades with little or no positive trend (Fig. 1a), as has occurred in observations  (Supplementary Fig. S1 top). Running ten year linear trends of globally averaged surface temperature from the five model ensemble  members reveal hiatus periods (Fig. 1a) comparable to observations  (Supplementary Fig. S1 middle). Using the first ensemble member as an example, the overall warming averaged over the century is about +0.15 ◦ C per decade. However, the decades centred around  2020, 2054, 2065, 2070, and several decades late in the century  show either near zero or slightly negative trends in that ensemble  member. We choose two ten year periods in this ensemble member when the globally averaged surface temperature is negative, that is, less than −0.10 ◦ C over the decade (Fig. 1a), and six similar  periods that meet the same criterion from the other four ensemble  members, to form an eight-member composite of hiatus periods.

 

http://www.sciencedaily.com/releases/2011/09/110918144941.htm

 

 

To track where the heat was going, Meehl and colleagues used a powerful software tool known as the Community Climate System Model, which was developed by scientists at NCAR and the Department of Energy with colleagues at other organizations. Using the model's ability to portray complex interactions between the atmosphere, land, oceans, and sea ice, they performed five simulations of global temperatures.

The simulations, which were based on projections of future greenhouse gas emissions from human activities, indicated that temperatures would rise by several degrees during this century. But each simulation also showed periods in which temperatures would stabilize for about a decade before climbing again. For example, one simulation showed the global average rising by about 2.5 degrees Fahrenheit (1.4 degrees Celsius) between 2000 and 2100, but with two decade-long hiatus periods during the century.

 

 

Metoffice decadal forecast using a similar theme:

 

http://www.metoffice.gov.uk/news/releases/archive/2013/decadal-forecasts

 

http://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/long-range/decadal-fc

 

http://www.metoffice.gov.uk/research/news/decadal-forecasting

 

I believe the enlarged, colored text is important. Indeed, it's what I found from constructing just a simple linear model (CO2 and PDO), which suggested that the descent of the PDO can dampen the warming.

 

http://www.americanwx.com/bb/index.php/topic/31853-2012-global-temperatures/page-24#entry1698274

 

I'll re-run the results later this year once last year's data is less preliminary and see if there are any meaningful changes. Needless to say factors other than the PDO and CO2 are also contributing to the recent slowing of the rise in global temperatures. The warming signal associated with the rising CO2 is still present once one accounts for the other major variables.

[LocoAko]

http://www.americanwx.com/bb/index.php/topic/39873-distinctive-climate-signals-in-reanalysis-of-global-ocean-heat-content/

 

Can the two threads be merged? Interesting discussion to be had. 

[donsutherland1]

As noted last year, I ran the numbers again using the same simple linear model (#817) with the updated data through 2012. I used the same scenarios concerning CO2 and the PDO as I did last year.

 

For context:
2001-10: +0.546°C Actual outcome for reference
Warmest year: +0.663°C, 2010

 

2011-20 to date: +0.553°C (through 2012)

Here are the numbers I came up with:

Historic PDO Decline:
Scenario 1: 30-Year Moving Average for CO2 rises by 14 PPM/decade:
2011-2020: +0.588°C
2021-2030: +0.716°C

Scenario 2: 30-Year Moving Average for CO2 rises by 16 PPM/decade:
2011-2020: +0.626°C
2021-2030: +0.771°C

Aggressive PDO Decline:
If one were more aggressive with the PDO, and assumed figures of -0.15 and -0.75 (deeper than the last PDO-), the data would be a little cooler, but the 2021-2030 period would be notably warmer than the 2001-10 timeframe:

Scenario 1: 30-Year Moving Average for CO2 rises by 14 PPM/decade:
2011-2020: +0.574°C
2021-2030: +0.705°C

Scenario 2: 30-Year Moving Average for CO2 rises by 16 PPM/decade:
2011-2020: +0.613°C
2021-2030: +0.760°C

The big change is that the averages are between 0.04°C and 0.05°C warmer than last year's figures. In part, the lesser response to 2011's and 2012's PDO figures (annual averages < -1) may have led to a lesser response to the continuing evolution of the longer-term PDO- cycle that remains underway.

 

There continues to be a suggestion that the existing record anomaly of 2010 could be eclipsed at some point during the second half of this decade (somewhere in the 2016-20 period) and then on multiple occasions during the 2021-30 period. The 2021-30 period also has a decadal average above the 2010 record anomaly.

 

While the figures might be somewhat aggressive, especially farther out in time, the consistency in the idea that the 2011-20 period's slowdown in the rate of warming will give way to faster warming for the 2021-30 period is a more important theme.

 

[CoastalWx]

Good article, although not sure we needed an article to tell us this.

[Cory]

Shots fired. The heavily-denied "pause" has been acknowledged in a prominent journal. 

[nflwxman]

Shots fired. The heavily-denied "pause" has been acknowledged in a prominent journal.

This is such a simplistic way to look at this. 8 years of pause means very little to nothing in the grand scheme. We've had a total of 58 out of 78 months( or 74%) of months being ENSO negative since 2007, so of course natural factors play a part in short term climate. This is not new, not unexpected, and nearly impossible to model due to the fact PDO unpredictability. I recommend everyone look at the temperature record in the 1940s when the PDO last switched negative. The 5 year average temperature almost immediately dropped .2 degrees. What should be telling is we have NOT had that drop this time around- indicating a strong forcing from stopping it from occurring, even in the short term.

[Cory]

This is such a simplistic way to look at this. 8 years of pause means very little to nothing in the grand scheme. We've had a total of 58 out of 78 months( or 74%) of months being ENSO negative since 2007, so of course natural factors play a part in short term climate. This is not new, not unexpected, and nearly impossible to model due to the fact PDO unpredictability. I recommend everyone look at the temperature record in the 1940s when the PDO last switched negative. The 5 year average temperature almost immediately dropped .2 degrees. What should be telling is we have NOT had that drop this time around- indicating a strong forcing from stopping it from occurring, even in the short term.

 

I wasn't looking at anything--I simply commented that a hiatus was acknowledged in a prominent journal. There are climate scientists and activists who will disembowel people for mentioning a pause or slow down in warming. 

[ORH_wxman]

Good article, although not sure we needed an article to tell us this.

 

 

Its interesting that their model shows about a 0.2C temp rise between 1975-2005 when they remove anthropogenic forcings and only account for the Pacific variability.

 

That actually agrees with some other studies that found a significant portion of the 1975-2005 warming was in response to ENSO/PDO...and of course it disagrees with some of the studies that said ENSO had very little to do with the positive temperature trend from 1975-2005.

 

I'm sure more studies will be coming out soon about trying to quantify the role of ENSO and related ocean cycles more accurately than has been done to this point.

[Cory]

Its interesting that their model shows about a 0.2C temp rise between 1975-2005 when they remove anthropogenic forcings and only account for the Pacific variability.

 

That actually agrees with some other studies that found a significant portion of the 1975-2005 warming was in response to ENSO/PDO...and of course it disagrees with some of the studies that said ENSO had very little to do with the positive temperature trend from 1975-2005.

 

I'm sure more studies will be coming out soon about trying to quantify the role of ENSO and related ocean cycles more accurately than has been done to this point.

 

Yeah it might be slightly helpful to get that all worked out. 

[nflwxman]

Its interesting that their model shows about a 0.2C temp rise between 1975-2005 when they remove anthropogenic forcings and only account for the Pacific variability.

That actually agrees with some other studies that found a significant portion of the 1975-2005 warming was in response to ENSO/PDO...and of course it disagrees with some of the studies that said ENSO had very little to do with the positive temperature trend from 1975-2005.

I'm sure more studies will be coming out soon about trying to quantify the role of ENSO and related ocean cycles more accurately than has been done to this point.

If you look at the PDO between 1975-2005, you'll notice it starts out very strong and fizzles out a bit towards the end of the period. The warming continues abated and even increases in the 1990s. I wonder if the anthropogenic forcing increasing kept the trend up in the 1990s bee positive even though the PDO trend was negative.

[ORH_wxman]

If you look at the PDO between 1975-2005, you'll notice it starts out very strong and fizzles out a bit towards the end of the period. The warming continues abated and even increases in the 1990s. I wonder if the anthropogenic forcing increasing kept the trend up in the 1990s bee positive even though the PDO trend was negative.

 

 

We did have a massive volcano eruption in 1991 (Pinatubo) that kept the early 1990s temperatures depressed. A chunk of the 1990s warming is a rebound from that along with the Super El Nino at the end of the decade.

[GaWx]

We did have a massive volcano eruption in 1991 (Pinatubo) that kept the early 1990s temperatures depressed. A chunk of the 1990s warming is a rebound from that along with the Super El Nino at the end of the decade.

 

I also wonder about the sun's role in the warming of the late 20th century. 1951-2000 is the 50 year period that has had the most sunspots on record by a good margin in, at the very least, 350 years.

 

 Anyway, the bottom line for me is to keep an open mind and observe what actually occurs especially between now and 2030, especially with a grand solar minimum likely/imminent, because nobody really knows what will happen regardless of how convinced they may seem.

[nflwxman]

I also wonder about the sun's role in the warming of the late 20th century. 1951-2000 has the most sunspots on record by a good margin in, at the very least, 350 years.

Anyway, the bottom line for me is to keep an open mind and observe what occurs especially between now and 2030.

Wouldn't we be rapidly cooling now if the sun was a strong factor? We are in the lowest sunspot activity in the last 100 years.

[ORH_wxman]

Wouldn't we be rapidly cooling now if the sun was a strong factor? We are in the lowest sunspot activity in the last 100 years.

 

 

There's speculation that there is more of a lag when it comes to multi-decadal sunspot activity versus just the single 11-year cycle response to TSI which typically has a 1-3 year lag. But there's been only a few marginal papers that try to address this (some on GCR) and it remains a difficult link to prove or quantify. I think that is why some are keeping an open mind of the subject until the 2020-2030 timeframe...in which if we still don't see much temperature response, those theories will have been incorrect.

[CoastalWx]

Its interesting that their model shows about a 0.2C temp rise between 1975-2005 when they remove anthropogenic forcings and only account for the Pacific variability.

 

That actually agrees with some other studies that found a significant portion of the 1975-2005 warming was in response to ENSO/PDO...and of course it disagrees with some of the studies that said ENSO had very little to do with the positive temperature trend from 1975-2005.

 

I'm sure more studies will be coming out soon about trying to quantify the role of ENSO and related ocean cycles more accurately than has been done to this point.

 

And other signals also tell the story regarding the PDO such as ACE. It will be interesting to see what happens in 20 or so years when then PDO flips again, but at least it documents the oceans having a say in either accelerating or decelerating the background warming...just kind of funny some needed this document to believe it. 

[GaWx]

Wouldn't we be rapidly cooling now if the sun was a strong factor? We are in the lowest sunspot activity in the last 100 years.

 

 This is a valid point. However, I don't have the answer due to our very complicated atmosphere. The possibility of a 5-10 year lag is still there in my mind based on what happened ~1875-1880. Then, cooling started ~5 years after sunspots first took a multidecadal long plunge overall. IF that cooling was largely sun related, then it tells me that at least a 5 year lag is a realistic possibility. Perhaps there is some sort of global warming inertia that prevents the globe from actually turning cooler on a dime?? Does anyone really know for sure that that couldn't be realistic?

 

 Could reduced solar flux really cause higher GCR (galactic cosmic rays) which may generate more cloud cover which may reduce global temp.'s?  If so, maybe that could contribute to a lag??

 

 Anyway, I've been saying that I'm giving it til ~2018 to see if the globe finally starts cooling before largely abandoning the possibility in my mind that the sun will have a significant cooling impact over the next 20 years or so.

[f2tornado]

I wasn't looking at anything--I simply commented that a hiatus was acknowledged in a prominent journal. There are climate scientists and activists who will disembowel people for mentioning a pause or slow down in warming. 

 

I agree. It is refreshing too see some scientists attempt to scientifically tackle reasonable points brought up by skeptics out there rather than draw the sword. This paper ironically reasserts skeptics' views as Judith Curry is more pumped than I've ever seen. http://judithcurry.com/2013/08/28/pause-tied-to-equatorial-pacific-surface-cooling/

[Cory]

  Anyway, I've been saying that I'm giving it til ~2018 to see if the globe finally starts cooling before largely abandoning the possibility in my mind that the sun will have a significant cooling impact over the next 20 years or so.

 

Same here. If some of the rumblings of a "grand solar minimum" end up correct, we'll have a real-life experiment play out in front of us. Hopefully nature will be answering a bunch of questions in the next decade. 

[nflwxman]

This is a valid point. However, I don't have the answer due to our very complicated atmosphere. The possibility of a 5-10 year lag is still there in my mind based on what happened ~1875-1880. Then, cooling started ~5 years after sunspots first took a multidecadal long plunge overall. IF that cooling was largely sun related, then it tells me that at least a 5 year lag is a realistic possibility. Perhaps there is some sort of global warming inertia that prevents the globe from actually turning cooler on a dime?? Does anyone really know for sure that that couldn't be realistic?

Could reduced solar flux really cause higher GCR (galactic cosmic rays) which may generate more cloud cover which may reduce global temp.'s? If so, maybe that could contribute to a lag??

Anyway, I've been saying that I'm giving it til ~2018 to see if the globe finally starts cooling before largely abandoning the possibility in my mind that the sun will have a significant cooling impact over the next 20 years or so.

Fair enough. It's refreshing that you have an open mind on the issue.

[nflwxman]

I agree. It is refreshing too see some scientists attempt to scientifically tackle reasonable points brought up by skeptics out there rather than draw the sword. This paper ironically reasserts skeptics' views as Judith Curry is more pumped than I've ever seen. http://judithcurry.com/2013/08/28/pause-tied-to-equatorial-pacific-surface-cooling/

Just one issue that I need to point out. The term "global warming" includes all portions of the biosphere, not just the 2m above our planets surface. The media really butchered that point. Using the correct definition, it appears that global warming has not slowed at all as the imbalance is as high as ever according to satellite measurements and OHC.

[ORH_wxman]

Just one issue that I need to point out. The term "global warming" includes all portions of the biosphere, not just the 2m above our planets surface. The media really butchered that point. Using the correct definition, it appears that global warming has not slowed at all as the imbalance is as high as ever according to satellite measurements and OHC.

 

 

Many climate scientists also butchered that point too since they pretty much scoffed at the idea that PDO/ENSO could be responsible for a significant portion of the warming from the 1970s-2000s.

 

If surface/atmospheric warming is significantly diluted/regulated by the oceans, then the science (and in particular the IPCC) has to reassess the long term impacts in a major fashion.

[nflwxman]

Many climate scientists also butchered that point too since they pretty much scoffed at the idea that PDO/ENSO could be responsible for a significant portion of the warming from the 1970s-2000s.

If surface/atmospheric warming is significantly diluted/regulated by the oceans, then the science (and in particular the IPCC) has to reassess the long term impacts in a major fashion.

Ill take your word for this, but I don't remember climate scientists talking about ENSO not impacting global temperatures in the short term. In fact, I remember many climate scientists claiming surface warming pauses were quite likely as early as 2005. In the long term (30+ years) is usually what they refer to, no? Undoubtedly, climate science has not communicated well with the public. That, I think we can all agree on.

[ORH_wxman]

Ill take your word for this, but I don't remember climate scientists talking about ENSO not impacting global temperatures in the short term. In fact, I remember many climate scientists claiming surface warming pauses were quite likely as early as 2005. In the long term (30+ years) is usually what they refer to, no? Undoubtedly, climate science has not communicated well with the public. That, I think we can all agree on.

 

 

Correct. But this is what is being debated. 1970s-2000s is 30 years. If there was a significant component of ENSO in that 30 years of surface/atmospheric warming, then studies that were based on the assumption that it was almost all anthropogenic warming are flawed. I.E. they over-estimated the anthropogenic trend.

 

There definitely is an anthropogenic component to it, but its pretty important to determine just what it is. The study that just came out implied that the anthro trend was roughly +0.10C per decade if you believe their model...even though the focus of their paper was not the warming period, but rather the lack of warming (2000-2012). A couple of other recent studies have come up with similar numbers. In contrast, others have put the numbers closer to about +0.2C per decade.

[LakeEffectKing]

Many climate scientists also butchered that point too since they pretty much scoffed at the idea that PDO/ENSO could be responsible for a significant portion of the warming from the 1970s-2000s.

 

If surface/atmospheric warming is significantly diluted/regulated by the oceans, then the science (and in particular the IPCC) has to reassess the long term impacts in a major fashion.

It wasn't just PDO/ENSO...(ie changes in heat flux of oceans).... that was scoffed at, but also the solar cycle and it's potential impacts...but now, we are seeing those exact same reasons being brought out to explain the global temp. stall/slow down.  Many expected the AGW component of CO2 to "overwhelm" the other potential forcings, no matter what state those forcings were in...at least on a decadal timeframe....well, here we are, some decade and a half, and even some of the warmistas are STILL proposing a stall for quite a bit longer DUE TO THE FACTORS THAT US SKEPTICS HAVE DISCUSSED FOR THE LAST DECADE!

 

And not to mention, if the factors that they are claiming, now, are influencing the global temps, when they poo-poo'd them before, we have to call into question what weight those same people ascribed to said factors in determining the amount of observed warming that had occurred in the historical record when proposing the AGW hypothesis.

[nflwxman]

It wasn't just PDO/ENSO...(ie changes in heat flux of oceans).... that was scoffed at, but also the solar cycle and it's potential impacts...but now, we are seeing those exact same reasons being brought out to explain the global temp. stall/slow down. Many expected the AGW component of CO2 to "overwhelm" the other potential forcings, no matter what state those forcings were in...at least on a decadal timeframe....well, here we are, some decade and a half, and even some of the warmistas are STILL proposing a stall for quite a bit longer DUE TO THE FACTORS THAT US SKEPTICS HAVE DISCUSSED FOR THE LAST DECADE!

And not to mention, if the factors that they are claiming, now, are influencing the global temps, when they poo-poo'd them before, we have to call into question what weight those same people ascribed to said factors in determining the amount of observed warming that had occurred in the historical record when proposing the AGW hypothesis.

I hate to do this, but warming hasn't stopped for 15 years, it's been 8-10 at most.

[LakeEffectKing]

Correct. But this is what is being debated. 1970s-2000s is 30 years. If there was a significant component of ENSO in that 30 years of surface/atmospheric warming, then studies that were based on the assumption that it was almost all anthropogenic warming are flawed. I.E. they over-estimated the anthropogenic trend.

 

There definitely is an anthropogenic component to it, but its pretty important to determine just what it is. The study that just came out implied that the anthro trend was roughly +0.10C per decade if you believe their model...even though the focus of their paper was not the warming period, but rather the lack of warming (2000-2012). A couple of other recent studies have come up with similar numbers. In contrast, others have put the numbers closer to about +0.2C per decade.

Kind of mimics my above post that crossed yours!  The result of this study isn't a minor blip for the warmistas....it's a bit bigger.....