2012 Global Temperatures

[tacoman25]

I believe that most of us accept that the global temperature record over the past century or more has both a component of natural variability and a component of anthropogenic warming. The relative magnitudes of the various processes involved make it possible for natural variability to offset and mask the steady AGW warming trend for periods that may be short (such as we've seen with volcanic eruptions) or a period of years (as with ENSO in recent years). Since the temperature record is a mix of the various components, the only way to accurately assess the AGW trend is to extract known natural variability and then look at what remains. Do you agree?

Foster & Rahmstorf 2011 is a peer-reviewed study that does just that. What they found is that there has not been any break or reduction in the AGW warming. Here's figure 1 from their paper:

Figure 1: Annual averages of the adjusted data - the global warming signal

If warming due to AGW was diminishing we would expect to see a leveling off on that plot. What some people took for a slowing of the warming was a combination of several years of La Nina and the solar minimum temporarily offsetting the AGW warming.

As TSI heads towards a solar maximum in 2013, the Earth enters an El Nino phase, and AGW forcing continues to increase we are almost certain to see record global temps in coming years. Unless, of course, we see a major volcanic eruption instead.

Well, one thing to keep in mind is that many "AGW experts" did NOT previously expect any leveling off of global temperatures due to natural factors, until recent years when it had already become apparent it was happening. Good luck finding any papers from Hansen, etc from the 1990s or 1980s projecting decades-long periods of stalled temperature rise due to the PDO/solar/whatever else. Many scientists believed only volcanic activity would cause a significant effect.

These graphs we now have removing the natural factors are products of the actual global temperature trend and the influence of natural factors we have seen.

[ORH_wxman]

No one wants to remove the natural variability. But You can't say that the earth temperature started rising

any faster in 1998 just because we had a super Nino that year with the temperature spike. The same is true

with the last 4 out of 5 years being Ninas doesn't represent a slowing of the temperature rise. The underlying

steady warming signal is there, but there is an ebb and flow of the ENSO phases riding on top of it.

This would agree with some of us that said the 1975-2000 warming wasn't really indicative of the "new normal" for temperature rise...that it may have been aided by natural variation.

[tacoman25]

No one wants to remove the natural variability. But You can't say that the earth temperature started rising

any faster in 1998 just because we had a super Nino that year with the temperature spike. The same is true

with the last 4 out of 5 years being Ninas doesn't represent a slowing of the temperature rise. The underlying

steady warming signal is there, but there is an ebb and flow of the ENSO phases riding on top of it.

But at the same time, those looking for the AGW signal in the late 1970s to early 2000s trend have to admit that the +PDO phase enhanced the warming during that period. It's a two-way street. Natural factors are not just negative feedbacks on AGW.

The fact that you reference a steady warming signal shows that when natural factors are accounted for, there has been little if any real increase in the AGW warming rate over the past few decades...slow, steady, non-acceleration.

[SVT450R]

No one wants to remove the natural variability. But You can't say that the earth temperature started rising

any faster in 1998 just because we had a super Nino that year with the temperature spike. The same is true

with the last 4 out of 5 years being Ninas doesn't represent a slowing of the temperature rise. The underlying

steady warming signal is there, but there is an ebb and flow of the ENSO phases riding on top of it.

Tho long as natural variability plays a role if we continue to see a slow down/possible cooling then future temperature projections will need to be adjusted and would further push alarmist projections down the road which in time we will be seeing more renewable energy etc.

[donsutherland1]

The only problem is that in the real world natural variability can't be removed.

That's true. But one can reasonably estimate the impact of natural variability (though there will be a margin of uncertainty/error in doing so).

The Rahmsdorf graph is important, because it helps address the issue as to whether the recent, short-term slowing of the rise in global temperatures means that AGW either does not exist/has only a negligible impact or has less impact than thought. The graph shows steady warming due to AGW. Hence, the recent short-term slowing of the rise in global temperatures can only be explained by natural variability's masking the extent of AGW-induced warming.

My very simple representation also had a consistent result with that outcome. If one considered the decline and then flip in the PDO, the slowing of the warming makes sense. Moreover, the 2011-20 period will likely see continued slow warming. However, given the continuing increase in atmospheric CO2 (which means that the CO2 forcing will grow relative to other factors), the warming would accelerate during the following decade, even if one assumes a significantly colder PDO than what occurred during the last PDO- cycle. In other words, the balance of influence would shift even more toward the CO2 forcing and natural variability would have a decreased ability to mask the strengthening AGW forcing.

Finally, the literature, robust climate models, and even very simple representation all strongly argue that the idea that global temperatures would fall to levels seen during the 1970s during the 2020s or 2030s is very unlikely, barring perhaps the kind of volcanic eruption that the world has not witnessed for centuries or longer.

[Jonger]

Anyone have CRN data since launch?

[Snow_Miser]

Channel 5 temperatures plummeted from yesterday. They are now in 6th place when one considers the fact that the 1998 anomaly for August was warmer than 2010, which is warmer than 2012.

[Jonger]

Tho long as natural variability plays a role if we continue to see a slow down/possible cooling then future temperature projections will need to be adjusted and would further push alarmist projections down the road which in time we will be seeing more renewable energy etc.

Its in everyone's best interest to push renewable energy hard now and that's the one positive thing the AGW community does. I'm not on-board with much of their data origination and BIAS, but pushing for renewables is smart from even an economic perspective.

[Jonger]

Channel 5 temperatures plummeted from yesterday. They are now in 6th place when one considers the fact that the 1998 anomaly for August was warmer than 2010, which is warmer than 2012.

Could it have anything to do with landmass cooling over north america recently? I admittedly know little about channel 5 temps.

[Snow_Miser]

Its in everyone's best interest to push renewable energy hard now and that's the one positive thing the AGW community does. I'm not on-board with much of their data origination and BIAS, but pushing for renewables is smart from even an economic perspective.

Agreed Jonger. The ignoring of evidence for a large solar contribution over the 20th Century is one example of such a bias. Renewables are definitely the choice we should be making going forward.

[tacoman25]

That's true. But one can reasonably estimate the impact of natural variability (though there will be a margin of uncertainty/error in doing so).

The Rahmsdorf graph is important, because it helps address the issue as to whether the recent, short-term slowing of the rise in global temperatures means that AGW either does not exist/has only a negligible impact or has less impact than thought. The graph shows steady warming due to AGW. Hence, the recent short-term slowing of the rise in global temperatures can only be explained by natural variability's masking the extent of AGW-induced warming.

My very simple representation also had a consistent result with that outcome. If one considered the decline and then flip in the PDO, the slowing of the warming makes sense. Moreover, the 2011-20 period will likely see continued slow warming. However, given the continuing increase in atmospheric CO2 (which means that the CO2 forcing will grow relative to other factors), the warming would accelerate during the following decade, even if one assumes a significantly colder PDO than what occurred during the last PDO- cycle. In other words, the balance of influence would shift even more toward the CO2 forcing and natural variability would have a decreased ability to mask the strengthening AGW forcing.

Finally, the literature, robust climate models, and even very simple representation all strongly argue that the idea that global temperatures would fall to levels seen during the 1970s during the 2020s or 2030s is very unlikely, barring perhaps the kind of volcanic eruption that the world has not witnessed for centuries or longer.

It's interesting though, I recall back in 2008-09 a graph that supposedly accounted for natural factors (in other words, removed them) over at a very pro-AGW awareness website showing a definite slowing of the warming rate since the early 2000s. And they were using GISS/HadCRU data. I'm sure others that have been following this for awhile know which website (*cough* Gavin Schmidt *cough*) and graph I'm talking about.

The Rahmsdorf graph certainly shows a different trend, and that certainly is important to supporting the underlying premise. But why such changes from previous graphs from like-minded people?

[bluewave]

Tho long as natural variability plays a role if we continue to see a slow down/possible cooling then future temperature projections will need to be adjusted and would further push alarmist projections down the road which in time we will be seeing more renewable energy etc.

I would probably take any specific projections beyond say 10-30 years with a degree of caution, as we really can't

even know for certain what world events would add to more or less CO2 contribution. The slow steady rise

looks like the best way to go for now.

[donsutherland1]

The Rahmsdorf graph certainly shows a different trend, and that certainly is important to supporting the underlying premise. But why such changes from previous graphs from like-minded people?

I don't know, but perhaps most of the difference is explained by differences in methodology. Hopefully, the newer work is more accurate, under the assumption that statistical methodology for accounting for natural variability has improved.

[bluewave]

This would agree with some of us that said the 1975-2000 warming wasn't really indicative of the "new normal" for temperature rise...that it may have been aided by natural variation.

Sometimes I guess it's better to look at longer running means than even the say 5 year or less increments

as a better representation.

[Snow_Miser]

Could it have anything to do with landmass cooling over north america recently? I admittedly know little about channel 5 temps.

I think it has more to do with Climo than anything else, although the cooling over North America definitely doesn't hurt the decline in Channel 5 temperatures.

[SVT450R]

Its in everyone's best interest to push renewable energy hard now and that's the one positive thing the AGW community does. I'm not on-board with much of their data origination and BIAS, but pushing for renewables is smart from even an economic perspective.

Agreed and as we seen the article i posted in renewable energy thread last year globally $257billion was invested in renewables making it the highest year to date.

[SVT450R]

I would probably take any specific projections beyond say 10-30 years with a degree of caution, as we really can't

even know for certain what world events would add to more or less CO2 contribution. The slow steady rise

looks like the best way to go for now.

+1

[PhillipS]

But at the same time, those looking for the AGW signal in the late 1970s to early 2000s trend have to admit that the +PDO phase enhanced the warming during that period. It's a two-way street. Natural factors are not just negative feedbacks on AGW.

The fact that you reference a steady warming signal shows that when natural factors are accounted for, there has been little if any real increase in the AGW warming rate over the past few decades.

I think that you are completely correct in saying that natural factors can be both positive and negative - and I don't think that there are many posters on this forum who would argue otherwise. But over the past decade natural variability has been a net negative and we can't expect that to continue.

And I agree that the AGW warming rate has been pretty steady over recent decades - both ORH's plot and the F & R plot give an AGW warming rate of around 0.15 - 0.17 C/decade.

That's not good news - a warming rate of 0.15 C/decade will move the Earth's climate into regimes not seen for thousands of years. Climate regimes that much research projects will be more severe than anything we're used to.

That warming rate also indicates that the Earth's energy balance is far from equilibrium because the AGW component will drop towards zero as the Earth approaches equilibrium.

[tacoman25]

It's interesting though, I recall back in 2008-09 a graph that supposedly accounted for natural factors (in other words, removed them) over at a very pro-AGW awareness website showing a definite slowing of the warming rate since the early 2000s. And they were using GISS/HadCRU data. I'm sure others that have been following this for awhile know which website (*cough* Gavin Schmidt *cough*) and graph I'm talking about.

The Rahmsdorf graph certainly shows a different trend, and that certainly is important to supporting the underlying premise. But why such changes from previous graphs from like-minded people?

Here is the graph I was referring to. It only accounts for ENSO, not solar or volcanoes (you can clearly see the drop from Pinatubo). As you can see, both GISS and HadCRU showed an ENSO-corrected slowing of the warming trend after 2000 through 2008. I have to wonder, is the main difference in the newer graph due entirely to solar (there certainly hasn't been any meaningful influence from volcanic activity)? That would seem to be an awfully big difference.

[Snow_Miser]

The Foster and Rahmstorf study oversimplifies the climate system in my opinion, as it only removes ENSO, TSI, and Volcanism. It does not take out other factors that are known to impact surface and atmospheric temperatures like Land Use changes, Ozone changes, Multidecadal Oceanic Oscillations, and most importantly, the indirect solar impacts. I would have been more interested if they used the ACRIM TSI dataset, instead of the PMOD TSI dataset, or even an average of all three of the TSI datasets (ACRIM, IRMB, and PMOD) and see how their results would have differed from just using the PMOD dataset. It has also been observed that there is an amplifying indirect solar mechanism that amplifies the TSI Forcing by a factor of 7 or 8.

So therefore, there could be large sources of natural factors/variability in the "adjusted" dataset that allegedly shows the anthropogenic greenhouse gas trend, and still have not been taken out.

[Snow_Miser]

Here is the graph I was referring to. It only accounts for ENSO, not solar or volcanoes (though you can clearly see the drop from Pinatubo). As you can see, both GISS and HadCRU showed an ENSO-corrected slowing of the warming trend after 2000. I have to wonder, is the main difference in the newer graph due entirely to solar? That would seem to be an awfully big difference.

Shows pretty much zero warming from about 1998/1999 onward.

[tacoman25]

I think that you are completely correct in saying that natural factors can be both positive and negative - and I don't think that there are many posters on this forum who would argue otherwise. But over the past decade natural variability has been a net negative and we can't expect that to continue.

And I agree that the AGW warming rate has been pretty steady over recent decades - both ORH's plot and the F & R plot give an AGW warming rate of around 0.15 - 0.17 C/decade.

That's not good news - a warming rate of 0.15 C/decade will move the Earth's climate into regimes not seen for thousands of years. Climate regimes that much research projects will be more severe than anything we're used to.

That warming rate also indicates that the Earth's energy balance is far from equilibrium because the AGW component will drop towards zero as the Earth approaches equilibrium.

My main point is that people need to keep in mind that future temperature projections may be more accurate than past ones, but they also may be failing to account for some factors we are not full aware of currently. Scientists in previous years didn't have it all figured out, let's not be fooled into assuming current ones do.

Regardless, if you look at the context of the discussion over the last couple days, there was a lot of talk about how the PDO has effected temperature trends. So that was the point of the graph Will posted and you asked about. Because of natural variability, the observed rate of warming has slowed over the past decade as his graph showed...and as you and others pointed out, of course this doesn't mean AGW went away.

[tacoman25]

Also an interesting graph posted by Gavin Schmidt in May 2008:

The idea is that based on underlying AGW forcing, regardless of natural variability, here are the odds of seeing an unambiguous new global temperature record for a given year after one has occurred. The last unambiguous (meaning all temperature data sources agreed) record year was 1998. So it has currently been 14 years. According to this graph, the odds that we would have seen a new unambiguous temperature record by this point is about 90%. So natural variability or not, we are really defying the odds to this point.

[bluewave]

The Foster and Rahmstorf study oversimplifies the climate system in my opinion, as it only removes ENSO, TSI, and Volcanism. It does not take out other factors that are known to impact surface and atmospheric temperatures like Land Use changes, Ozone changes, Multidecadal Oceanic Oscillations, and most importantly, the indirect solar impacts. I would have been more interested if they used the ACRIM TSI dataset, instead of the PMOD TSI dataset, or even an average of all three of the TSI datasets (ACRIM, IRMB, and PMOD) and see how their results would have differed from just using the PMOD dataset. It has also been observed that there is an amplifying indirect solar mechanism that amplifies the TSI Forcing by a factor of 7 or 8.

So therefore, there could be large sources of natural factors/variability in the "adjusted" dataset that allegedly shows the anthropogenic greenhouse gas trend, and still have not been taken out.

It does a great job of accounting for the temperature rise that we saw since 1979. You can pretty much get a rough

estimate of what the ENSO state was each year by looking at thie annual t's which matches their findings. Notice how

the record warmest years have been El Nino years. 2010 still set a new high despite being sandwiched between Ninas.

[tacoman25]

It does a great job of accounting for the temperature rise that we saw since 1979. You can pretty much get a rough

estimate of what the ENSO state was each year by looking at thie annual t's which matches their findings. Notice how

the record warmest years have been El Nino years. 2010 still set a new high despite being sandwiched between Ninas.

It's definitely intriguing that the current/latest period has by far the greatest difference between NH and SH temps.

[WeatherRusty]

Tho long as natural variability plays a role if we continue to see a slow down/possible cooling then future temperature projections will need to be adjusted and would further push alarmist projections down the road which in time we will be seeing more renewable energy etc.

In the long run the natural variability will average out to near zero, unless something significant in the system permanently changes such as a slowing of the thermohaline circulation. What remains is the background, man made forced warming. It is because this forcing is what is altering the TOA balance longer term, that climate sensitivity is relative to the total anthropogenic forcing. So if we consider only CO2 and we double it, we get a radiative forcing equaling 3.7W/m^2 and a temperature response equal to the equilibrium sensitivity value. We can ignore internal variation because in the long run it carries little consequence.

So if ECS is 2.7C then we get 2.7C of warming just from a doubling of CO2 + feedback. Along the path to equibibrium the temperature rise will proceed at varying rates, and even when the theoretical 2.7C is reached it will represent a mean value with natural variability superimposed upon the trend.

[Snow_Miser]

It does a great job of accounting for the temperature rise that we saw since 1979. You can pretty much get a rough

estimate of what the ENSO state was each year by looking at thie annual t's which matches their findings. Notice how

the record warmest years have been El Nino years. 2010 still set a new high despite being sandwiched between Ninas.

You can not deny that there are forcings that the Foster and Rahmstorf study did not take out that are important, and non-greenhouse gas related. One of the most important are the indirect solar impacts on climate.

[Snow_Miser]

Also an interesting graph posted by Gavin Schmidt in May 2008:

The idea is that based on underlying AGW forcing, regardless of natural variability, here are the odds of seeing an unambiguous new global temperature record for a given year after one has occurred. The last unambiguous (meaning all temperature data sources agreed) record year was 1998. So it has currently been 14 years. According to this graph, the odds that we would have seen a new unambiguous temperature record by this point is about 90%. So natural variability or not, we are really defying the odds to this point.

Perhaps the sensitivity has been overestimated, which is the reason for defying such odds?

[bluewave]

It's definitely intriguing that the current/latest period has by far the greatest difference between NH and SH temps.

Yeah, when you isolate the Arctic the amplification is even more pronounced.

[bluewave]

You can not deny that there are forcings that the Foster and Rahmstorf study did not take out that are important, and non-greenhouse gas related. One of the most important are the indirect solar impacts on climate.

They account for solar in their paper. In another paper, they discuss the impact that a quieter sun would have on

future warming projections.

http://www.pik-potsdam.de/news/press-releases/archive/2010/weakening-sun-would-hardly-slow-global-warming