This month, RSS beat Roy Spencer out of the gate with a temperature for the lower troposphere. RSS reports
- The September monthly anomaly for the lower troposphere of 0.525C
- This is lower than the August anomaly of 0.583C.
- It is higher than the September 2009 anomaly of 0.476C.
- It is the all time high anomaly for any September in the record.
- It is the 18th all time highest anomaly in the full RSS record (likely owing to the fact that AGW really is happening.)
- It is the coolest anomaly this year (likely owing to the transition to La Nina.)
The RSS monthly anomalies rebaselined to 1980-1999 are shown below:
Or as Robert, seeming to write in defense of the 10:10 video, puts it in his always impartial, never partisan prose:
In other news, RSS reports September 2010 to be the warmest on record, despite the burgeoning La Nina.
Status of the “skeptics†efforts to alter the laws of physics through partisan point-scoring: prospects still doubtful.
It’s not quite clear whose argument Robert is “rebutting”, I’ve never made efforts “to alter the laws of physics”, and I have no idea precisely who Roberts considers an in quotation marks “skeptic”. But, no, no matter how bad the 10:10 video was, (and it truly was a horror) neither horrifying PR stunts or inflamed rhetoric can change the laws of physics. Everyone agrees with that.
Returning to watching the horse race of monthly temperature records, many of us have also wondering how measurement groups would report anomalies that will result in 2010 would break the all time record for 12month average temperature. Here is a graph of the 12 month average for RSS:
(Note: A1B projections for surface temperature are shown for reference only. )
The current 12 month average is well below the all time record value. Moreover, the record 12 month average exceeds the current monthly temperature. Unless temperatures rise over the next three months, RSS will not set a record this year.
Hat tip: to Robert for letting me know RSS was out on Sunday.
I am wondering what the particular meaning of RSS feeds are, compared to other global temperature datasets. Rather than just ask, I googled a bit. Wikipedia seemed to have the best capsule, including this description:
In case anybody else needed a basic primer, too.
Lucia,
“… I’ve never made no efforts …”
Double negative. I don’t think that is what you meant.
Given the magnitude of the satellite response during the ’98 ENSO, this year has a pretty high bar to beat. Even GISTemp looks less likely to see a new record (though it will be close), as La Nina kicks in.
Zeke– Absolutely. ’98 really hit the ceiling.
Bob– Nope. Thanks.
Zeke–I should note that one of the reasons for my interest in whether or not we hit a record is Joe Romm’s early post entitled NASA: “It is nearly certain that a new record 12-month global temperature will be set in 2010″
http://climateprogress.org/2010/03/19/nasa-giss-james-hansen-global-warming-record-hottest-year/ and later this
http://climateprogress.org/2010/05/16/nasa-easily-the-hottest-january-and-hottest-jan-april-in-temperature-record/
Presumably Hansen was only predicting for GISS, which didn’t show 1998 as warm as many other groups. But the reporting focusing on GISS only triggered my interest in watching all of them.
I wouldn’t expect a guy who starts discourse on a subject by first calling people who disagree with him “idiots” (blog name!) to be particularly reasonable, but the “alter the laws of physics” statement is way over the top. Jeez, somebody needs to mellow out a little and actually understand those he disagrees with. Unless of course he really does not want to have meaningful discussion, that is.
As to the topic at hand: RSS has been trending cooler than UAH in recent years associated with the AQUA satellite in UAH so my guess is that UAH should be closer to 98’s record than RSS is. Still looks unlikely that we will see a record setting year.
(And here is something I’ve noticed before but find “curious” and decided to mention it just now, there is a strange change in the behavior of the multi-model average that after 2000, the curve exhibits more variability that is not obviously associated with any forcing, while before then the curve is smooth and the internal “noise” of the various models cancels out. Any idea why “weather” of the models isn’t canceling so well after 2000?)
Andrew_FL– There are 22 models. A few models have very, very wild weather with violent “El Nino” (if one could call them that.) It is so wild I sometimes wonder how farmers could plan on those planets– but then I’ve never looked on a local level. Maybe all the wildness is at the poles. Other models have very mild “weather”.
The oscillations in the wild-weather planets contribute overwhelmingly to the “noise” in the average.
Lucia,
You say there are 22 models, but Gavin himself admitted several years ago that all the models used many of the same parameters and so you could’nt really say that the models were different.
Has this situation changed or do the models still continue to produce similar outcomes because they are all fed with very similar inputs?
Dave–
Some people suggest the models are “independent”. Others say otherwise. Obviously, in some sense they can’t be “independent”, since they must rely on some shared understanding of phenomemology.
What is certainly true is the multi-model mean projection I am showing is based on models used in the AR4, published in 2007. So, whatever was true of them in 2007 is still true today.
Lucia,
It’s not true that the RSS has to reach your orange level to set a calendar year record, which is what most people think of. That line seems to be the peak attained by the 12-month running average at any time. What it needs to do is to reach, in December, the max level attained by that blue curve in a previous December, which seems to be about the level it is currently at.
The statement you’ve quoted from Romm is not entirely clear, but does not seem to refer to calendar year record. It is true that the 12-month smoothed GISS average reached a record level in April.
Nick–
I’m double checking my spreadsheet– but as far as I can tell, to set a record the RSS average does have to hit that orange line. The all time high 12 month running average for RSS is for the 12 months from Jan 1998-Dec 1998. I assumed you down loaded the data from http://www.remss.com/data/msu/monthly_time_series/RSS_Monthly_MSU_AMSU_Channel_TLT_Anomalies_Land_and_Ocean_v03_2.txt and found a different set of 12 months for the maximum 12 month average. Which 12 month period do you get for the maximum 12 month average.
I think what Romm wrote is entirely clear. He is absolutely not referring to the calendar year. He wrote:
(My graph was set up to match the things Romm is watching– not calendar years. Romm and watching all time high 12 month records and that’s what I show in my graph. But, the all time 12-month record happens to correspond to the record for a calendar year in the case of RSS.
In Dec. we can discuss calendar years more specifically. Admittedly, we often speculate about what might happen. But we know the 12 month average ending in September now, so I compare non-dec ending 12 month averages to all time record averages. You seemed to realize that, and I think the rest of my readers do too. )
I’ll admit Hansen may very well have only meant NASA GISS records, not all time high records. If Romm misinterpreted what Hansen meant and Hansen was predicting an all time high record for the calendar year, Hansen’s prediction could still turn out to be wrong for GISS. It’s going to be close.
Is that what you meant? That Romm misinterpreted Hansen and Hansen’s prediction may still turn out to be wrong? I agree. If Hansen meant calender year, there’s a chance his prediction may turn out wrong.
Here is what Romm said in his October 1st post:
Second, you may recall that NASA predicted in January 2009 that 2010 would likely set a record. In this paper, he explains “It is likely that the 2005 and 2010 calendar year means will turn out to be sufficiently close that it will be difficult to say which year was warmer, and results of our analysis may differ from those of other groups. What is clear, though, is that the warmest 12-month period in the GISS analysis was reached in mid-2010, as shown in the Rev. Geophys. preprint.â€
.
Again, this is impressive because we are just coming out of the deepest solar minimum in a century. Hansen provides this figure:
.
.
Now Hansen explains why 2012 is likely to set a new record. He notes “Projections of trends over the next few years are possible based on the following considerationsâ€:
.
1. the planet is out of energy balance by at least several tenths of one W/m2 due to the rapid increase of greenhouse gases during the past few decades, as confirmed by measurements of changing ocean heat content
2. inertia of energy systems that assures continuing growth of atmospheric CO2 by about 2 ppm per year for the next few years
3. expectation that the solar irradiance will climb out of the recent long-lasting solar minimum, as shown in Figure 5
4. model projections suggesting that the current La Nina may bottom out near the end of 2010.
.
He then concludes:
Given the dominant effect of El Nino-La Nina on short-term temperature change and the usual lag of a few months between the Nino index and its effect on global temperature, it is unlikely that 2011 will reach a new global record temperature.
In contrast, it is likely that 2012 will reach a record high global temperature. The principal caveat is that the duration of the current La Nina could stretch an extra year, as some prior La Ninas have (see Nino 3.4 index at the bottom of Figure 3). Given the association of extreme weather and climate events with rising global temperature, the expectation of new record high temperatures in 2012 also suggests that the frequency and magnitude of extreme events could reach a high level in 2012. Extreme events include not only high temperatures, but also indirect effects of a warming atmosphere including the impact of higher temperature on extreme rainfall and droughts. The greater water vapor content of a warmer atmosphere allows larger rainfall anomalies and provides the fuel for stronger storms driven by latent heat.
.
So 2012 may top 2010 as the hottest year on record with more extreme events.
Nothing really new here. The 4 month delay time for ENSO effect seems to be playing itself out. But the El Nino should not effect October, so we should see some drop there. November and December should show substaintial La Nina effects. Let’s wait till this La Nina plays itself out to see if anything has changed. I’m guessing that if we run the ENSO corrected numbers for 97 through to the end of 2010, we’ll still be fairly flat.
Please note that the graph of TSI was omitted in the quote I just posted.
My interpretation: That Hansen is saying there isn’t any meaningful statistical difference between 2005 and 2010 in terms of the hottest global surface temperature anomaly. So when Hansen forecasts that 2012 is likely to set yet another new annual record for highest global temperature, Romm is correctly interpreting Hansen as forecasting that 2012 may top 2010 (tied with 2005 etc.) as the hottest year on record.
I don’t understand Lucia’s confusion on this… the source of all this information is Hansen, and Romm seems to have quoted him correctly.
i am looking forward to UAH data.
.
her is what i was told some time ago:
.
Layman Lurker (Comment#52377) September 15th, 2010 at 11:05 am
Even though the release of 5.3 has removed much of the seasonal discrepencies between RSS and UAH, according to the monthly means of RSS and UAH5.3 there still remains some seasonal tendancies (for both data sets). These tendancies favour +RSS from the end of May to the end of August, then swing to +UAH from Sept to the end of Dec. Sod, I’ll bet you some quatloos that UAH (LT) is higher then RSS for September.
Lucia,
I think Hansen was quite explicitly talking about he 12-month running average, and so was Romm – the brief excerpt that you quoted in #53375 did not quite settle that. Your post also was fairly clear in talking about the running mean, But then you said
“Unless temperatures rise over the next three months, RSS will not set a record this year. ”
which does sound like you’re talking about the 2010 average, which is what most people focus on.
My point was that exceeding the 1998 average is less formidable than exceeding the 1998 peak value of 12-mtm average. 1998 cooled towards the end.
I don’t think calendar year distinctions are a big scientific issue, but I’ve been tracking the 2010 prospects here with this horse-race plot. If 2010 does not cool at the end as 1998 did (big if), then 2010 may still set a RSS record.
I only wish we had some global climate here instead of local weather. Our central heating runs since the beginning of September and I wear my lighter winter coat for 2 weeks already.
Well… actually I meant it won’t set either kind. Unless it rises over the next three months, it’s neither going to set a record for the 12 month running mean nor a record for the calendar year because the current temperature lies below the mean.
But I will admit what I meant was not entirely clear.
All I meant in my comment to Zeke was that Romm was reporting 12 month running averages ending in arbitrary months– like for example March. That triggered my interest, so began tracking 12 month running averages during mid year. Like Romm, I am reporting 12-month running averages ending in a current month.
I do happen to compare my 12-month running averages ending in month-“not december” to absolute maximum, not the one based on calendar year only. I think everyone understood I was doing that. In my brief comment, didn’t mean to imply I was doing everything exactly to check Hansen’s prediction or to match Romm. Only that looking for records is motivated by that.
I guess I misunderstood Romm. His later post read to me like he is telling us Hansen predicted a record would be set in 2010– which evidently is not quite so. But, what I do mean is: I have been watching partly because this is something people are expecting to be close. I’ve been watching all the records– which differs form Romm. (Not a criticism of Romm, just saying I’m watching all of them.) That’s all I mean.
With respect to the other part of my answer to Nick: The absolute record for 12-month mean happened to be set with a period that spans Jan-Dec. So, the orange line is both the calendar year end record and for this particular data set, the ambiguity “doesn’t matter” because the orange line represents both.
Oddly, when the orange line doesn’t represent both, my posts have sometimes been clearer on this because I discuss both directly. I thought about doing that in this post… but thought… nah. Doesn’t matter. Guess that was wrong!
Hey Sod how about it? Are you taking the bet? 20 quatloos? Cmon Sod, we might as well have some fun with this eh? I will even go even odds with you – thats the kind of guy I am. If you want to throw this in my face later you better ante up. 🙂
Cmon Sod, you already know that RSS is a record for Sept. Huge advantage for you. I think you should actually give me odds.
You completely skipped doing a GISS post for August.
So they predicted a new record would be set in either 2009 or 2010, and when that fails, they then predict in 2012?
I wish people ( Hansen) would stop talking about records. no good comes of it.
AHHHHHHHHHHHH! September 2010 is the warmest September….since 1979. Well that does it for me, I am going to move into a fallout shelter and stack up on food and condensed water. Condensed water because obviously by this point dirty coal fracked water has infested all of our waterways and those who are drinking water from the tap are undoubtedly getting aids and cancer. Robert, please move to Spain. You would find many friends there.
Shoosh– Yes. That’s the full record for satellites.
If the satellites went back further in time, it would probably the the warmest in… oh… at least 200 years.
Lucia, yes. And 200 years out of billions is still less than 1%. Somebody could do a study, starting when there was no ice at the poles, and show that we have had massive ice increases. Then, they could make a graph and say “oh boy oh boy look at the trend, we’re all doomed, the planet will be covered in ice.” Also, how about my ice prediction? I told you the ice was gonna come back with a vengeance. Also, when I’m wrong, feel free to hold my feet to the fire. I’m not a wuss like Sod and go into hiding when I’m wrong. Did you get that guy’s email, I want to ask him about that enormous peach…
Dr. Shooshman, phd,
Perhaps you should ask why we are seeing such a dramatic increase in global temperatures, as measured in the troposphere and at the surface, over such a short time range. Why is the slope so steep? We are at a 100-year solar minumum. What is driving this change? Plus, a thermal energy imbalance as measured at TOA is driving a measurable phase change in both land ice and sea ice. Not to mention a rise in sea level. What has changed in these few short years? Natural variability you say? That simply means you don’t know the answer. What is driving it??????
Owen, we are at the top of the Milankovitch cycles.
Why do you think it is not supposed to be a warmer world now?
Energy balance? There is no such thing. Sheesh.
“Perhaps you should ask why we are seeing such a dramatic increase in global temperatures, as measured in the troposphere and at the surface, over such a short time range.”
You are looking at tenths of a degree on a graph. I could find that “dramatic” stuff in one minute walking from one room to another in my house. Oh No!
“That simply means you don’t know the answer.”
“global temperatures” (which is a statistical constructed number anyway) could move up or down by one degree or more “over such a short time range” all the time; throughout an interglacial period when the ice is supposed to be melting on Earth. Warm periods could last hundreds and hundreds of years; so could cool periods even if it s an interglacial; and you are fixating on a teeny tiny snap shot of time and fractions of one degree on a chart. Please stop scaring my children (and dreaming of blowing them up) and go work on new forms of energy or something until you know for sure.
“Not to mention a rise in sea level.
Sea level has been rising steadily since the last ice age ended. The Pacific ocean gets one inch smaller every year too. Did you know this? Huge land masses in the Northern Hemisphere-like on the East Coast of the USA are still popping up from the retreat of ice; ice that was miles high thick; ice that covered that land in the last glacial period. The land is rising. Did you know this? “Sea level” rise is very hard to measure…bunch of numbers all smooched together on a graph, same as global “ave temp”. Did you know this?
There are also subduction zones where land is sinking all over the world too. Do you know that? They cause tsunamis; that just recently killed hundreds of thousands of people in Indonesia. (Oops there goes the “balance”)
What about all that ice melting from the last ice age? Just saw a paper online (I’ll try to find it) that suggested that the groundwater we extract and pump up into our systems, then into our gutters, then eventually into the sea adds to sea level rise. You should be worried about this too. Get over to Las Vegas, or Dubai, or Houston, or, or… and turn off all that water!
Every time you look at a year from the past on the graph; that “Earth” is gone. Yet you still compare it to “now” as if it were exactly the same; forget we are in interglacial period; and you then you only blame C02 for “warm”? Natural variability you say can’t be the reason. You need to tell me (and everyone else does too) why it CAN NOT BE the reason.
BTW Mt St. Helens erupted in 1980. (Oops there went that balance.)
Here is the paper:
September 28, 2010: A collaboration between IGRAC and the Utrecht University lead to a joint article which is presently in press in Geophysical Research Letters.
“Large-scale abstraction of groundwater for irrigation of crops leads to a sea level rise of 0.8 mm per year, which is about one fourth of the current rate of sea level rise of 3.3 mm per year.”
http://www.igrac.net/publications/422
Oafwhen I don’t even accept your premise. A dramatic rise in temperature to you is half a degree. A dramatic rise in temperature to me is 4 degrees. Also, there is no basis to claim we are having a dramatic rise in temperature, I look at past events and see much more rapid temperature rises and falls.
Stalagmite data from blue holes:
In the blue hole where they cut the stalagmite, Brian and Kenny noticed something that might help solve the mystery. In the cave wall, they found a layer of red sediment. The color is the key here: the red in the dust means it’s loaded with iron. And that means that thousands of years ago, a thick layer of iron-rich red dust covered the island’s surface.
Repeated rains washed it through the rock, leaving a bright red band.
So how did the red dust get here? One theory suggests it came from the Sahara Desert, some 4,000 miles away.
During times of extreme drought, towering dust storms gather in the Sahara, pushing dust high into the atmosphere, where it’s carried across the Atlantic.
When Swart analyzes the iron in the stalagmite, he confirms that it’s made of Sahara dust, though its red color has been washed out after thousands of years.
And in the dark band, he isn’t finding traces of iron, but significant concentrations.
PETER SWART: Now, the iron was very low concentrations, with the exception of this boundary here.
NARRATOR: The areas with the highest concentration of iron correspond almost exactly to the places on the stalagmite where the chemical composition indicates a period of major climate change.
That probably means a major Sahara dust event came right before each change, when temperatures and sea levels rose.
The fact that Saharan dust storms happen with greater frequency today is raising concerns that history could be repeating itself.
PETER SWART: Now, we know, for the last 40, 50 years, there’s been a major drought in Africa. And that has seen an input in the amount of dust which is coming from the Sahara region to the Bahamas.
NARRATOR: It’s estimated that over the past five decades, the Sahara has seen a ten-fold increase in large-scale dust storms. If we are witnessing the beginning of a major climate change, it could happen fast, just as it happened in the past, maybe in as little as a lifetime.
PETER SWART: We don’t worry too much about climate change, because it’s something that’s going to happen “after I’m dead.” But, in actual fact, some of the records that we’ve been looking at, we see tremendous changes in a matter of decades. And so, when climate changes that fast, obviously it would have tremendous implications for the present-day society.
NARRATOR: Swart’s findings are preliminary, but they do suggest that climate change in the past happened faster than anyone imagined. If such change occurred today, immediate concern would be for the millions of people in areas most affected by sea level rise—island nations and coastal regions throughout the world.
http://www.pbs.org/wgbh/nova/transcripts/3705_cavedive.html
See here!
” But, in actual fact, some of the records that we’ve been looking at, we see tremendous changes in a matter of decades. ”
” just as it happened in the past, maybe in as little as a lifetime.”
“but they do suggest that climate change in the past happened faster than anyone imagined. “
Re: Owen (Oct 5 17:14),
> We are at a 100-year solar minumum.
That’s interesting. Could you add a link to a trustworthy source, if one is to hand?
Here’s a current article on glacial rebound:
http://www.ouramazingplanet.com/glacier-ice-loss-less-than-thought-study-suggests-0576/
“New estimates of ice melt from Earth’s glaciers, made during a study tracking how water is transported across Earth’s surface, find that the amount of ice lost to the seas is smaller than scientists previously thought. The new study also finds that Earth’s center of mass is actually shifting.”
AMac (Comment#53519) October 6th, 2010 at 7:40 am
Re: Owen (Oct 5 17:14),
> We are at a 100-year solar minumum.
That’s interesting. Could you add a link to a trustworthy source, if one is to hand?
AMac – see http://blog.ametsoc.org/media-tips/a-minimum-of-maximum-concern/ or http://science.nasa.gov/science-news/science-at-nasa/2009/01apr_deepsolarminimum/
Both total solar irradiance and sunspot number have reached lows not seen since ca. 1911-14.
AMac,
see http://blog.ametsoc.org/media-tips/a-minimum-of-maximum-concern/
or just google deep solar minumum – the levels of total solar irradiance and sunspot number are the lowest we’ve seen since 1911 – 1914.
Liza,
The rate of temperature change in the past 40 years is quite high, so is the rate of ice loss. You can argue against that point, but I think most scientists would agree that we are seeing a rapid change in the climate system. The measurements will continue and become even more refined and accurate – climate science is becoming more sophisticated every year.
What is the downside of weaning ourselves from burning sequestered carbon? It took nature millions of years to move all that carbon underground. You want to release it in a couple hundred years? We will eventually have to move off of sequestered carbon as an energy source as only a finite amount exists. Why wait?
But before you jump into the job-killing, economy-destroying alarmism of the American right, consider Germany with its high energy taxes, strict environmental laws, and strong export economy. Germany was only within the last year displaced by China as the number one goods-exporting country in the world. It has a strong economy in spite of its many solar panels and high gasoline prices. Do you own a Jetta Diesel?
Dr. Shooshman, phd, Doctor of Philosophy, etc.,
You need to quit living in the past. Here we have a rapid change in temperature, the slope of which is dramatic by any standards, and all you can see is ancient 4 degree changes linking temperate times and ice ages. Come back to the present. Most of the past changes that you keep looking back at were due to fairly-well understood orbital and precessional changes of Earth. Focus now on the present. What is driving the current rise in global temps? I want to hear you say it – I know you can.
Owen,
You didn’t answer my questions.
“The rate of temperature change in the past 40 years is quite high, so is the rate of ice loss.”
Oh so now it’s forty years? Okaayyy.
http://maps.grida.no/go/graphic/overview-on-glacier-changes-since-the-end-of-the-little-ice-age
“but I think most scientists would agree that we are seeing a rapid change in the climate system.”
So what? What you think is what you think. I am married to a scientist. A published environmental Earth scientist and he thinks that that sort of talk doesn’t mean anything. As for releasing “all that carbon”…tiny amounts compared to the geologic record. And no where in the geologic record does C02 “matter” as much as you insist it does to the climate. What about that groundwater??
I am not against finding alternative energy. What I am against is the religious fever..the sin and damnation; the alarmism; the hype. Where’s those 6 million new “green jobs” we were supposed to see? Tell me exactly what “green job” there is that doesn’t already exist. Scientists also say we can’t stop GW anyway.
“But before you jump into the job-killing, economy-destroying alarmism of the American right,”
A economic study by a California LIBERAL school, requested by the LIBERAL folks in Sacramento legislation; suggests that California will lose one million jobs because of the carbon regulation laws they want to pass. The results of the study were HIDDEN from the public until a reporter poked around for it. California, and the entire USA can not be compared to Germany fairly or equally. Not even close.
Just in the other topic folks are talking about Netflicks. Netflicks puts people out of work-they forgot to mention that part.
“fairly-well understood orbital and precessional changes of Earth. Focus now on the present. What is driving the current rise in global temps?”
The Earth is not orbiting any more? Wow.
“Here we have a rapid change in temperature”
If I may… we have what some believe is a rapid change in temperature.
Andrew
In the absence of any known driving force (other than the unmentioned elephant in the room), the change in temperature (ca. 1 degree in the past 100 years and ca. 0.7 degrees in the past 40 years – from GISS) is both rapid and dramatic. Nicht wahr?
“the change in temperature (ca. 1 degree in the past 100 years and ca. 0.7 degrees in the past 40 years – from GISS) is both rapid and dramatic.”
Owen,
Again, we like be exact here. You believe … etc etc etc.
Andrew
>My point was that exceeding the 1998 average is less formidable than exceeding the 1998 peak value of 12-mtm average. 1998 cooled towards the end.
1998 cooled even more after the end. The original GISTEMP level for 1998 was .64. Their 2001 summary shows it(1998 temps) to be ~ .59, By 2002 it had dropped some more to ~.55. Now it is at ~.57, so it has warmed a little bit since then.
Owen:
Prior to 1975, the temperature change can be explained almost entirely from natural forcings (according to the models, prior to circa 1975 anthropogenic CO2 driving was masked by increases in atmospheric aerosols such as sulfates). This point is made in Figure 4 of IPCC AR4.
So now let’s look at what Hadcrut is giving:
A 0.5°C increase from 1910 to 1940 (0.17°C/decade)…al naturale.
A 0.6°C increase from 1960 to 2010 (0.12°C/decade) or if you prefer a 0.5°C increase from 1970 to 2010 (0.13°C/decade). This is thought to be primarily anthropogenically driven. (If you are allowed the heresy to say 2000-2010 temperatures have been stable, that gives a similar slope for the late-20th century warming as for the early 20th century warming).
Further complication: 1850-1950 appears to be a natural climate shift associated from leaving the Little Ice Age, so “arctic amplification” was a major driver of that rapid temperature swing (loss of ice). That is still playing some role in the rapid increase in temperature in the arctic right now. At some point, that effect is expected to saturate.
Statistically the warming periods for 1910-1940 and 1970-2010 are indistinguishable.
A substantial amount of the warming we’ve seen from 1850-now is unrelated to anthropogenic CO2 increases (directly at least).
That doesn’t address what happens to temperature in the future if we for example double the CO2 from 1850 levels. We can’t learn from the past in this case, so we have to rely on radiative and atmospheric physics to guide us here, and that would provide for an additional 1.5°C or more warming in the next century.
So what you said was true, but misleading.
Carrick,
“Prior to 1975, the temperature change can be explained almost entirely from natural forcings (according to the models, prior to circa 1975 anthropogenic CO2 driving was masked by increases in atmospheric aerosols such as sulfates).”
The aerosol effect was a cooling effect. CO2 was increasing prior to 1975. I don’t know if I buy your assertion that the temp change prior to 75 can be explained by natural forcings.
“A substantial amount of the warming we’ve seen from 1850-now is unrelated to anthropogenic CO2 increases (directly at least).”
Again, I can’t really buy this statement. If not CO2, then what?
Re: Owen (Oct 6 11:24),
Thanks for the link that points out that we’re at a solar minimum–helpful.
> Again, I can’t really buy this statement. If not CO2, then what?
Climate is affected by lots of things, many known and some unknown. Some influences are straightforward to calculate, others are at or beyond the limits of current-generation models. “If not CO2, then what?” brings the board game Clue to mind, with its limited number of suspects (“Colonel Mustard in the Drawing Room”). The extent to which the correlation of rising CO2 (1910-1940) and rising temperature (1910-1940) is because rising CO2 caused rising temperature can’t be assumed. Estimates have to be supported by logic and calculations.
Owen:
Well, it’s what the models say (check the IPCC figure in my previous post).
You can choose to invent your own science, but what the best science says is CO2 was balanced by sulfates… Otherwise you get too much warming for the period 1910-1940.
Look at the model forcings. They provide an explanation of the warming from 1850 to now.
My point isn’t that the science is necessarily right, but if we accept what the science says, then my summary is correct. And if the science is wrong, we have bigger issues.
Owen, here’s a recent article on ice-loss and arctic amplification. I’m providing it to you caveat emptor…but it may help fuel your thinking.
Carrick,
I like the graph that you referenced of model forcings. But is seems to say that CO2 is the only likely forcing agent. Am I reading it wrong?
Owen,
Well, CO2, Methane, Nitrous Oxide, and various halocarbons.
Bear in mind that there is some uncertainty surrounding both past forcing estimates and individual forcing magnitudes (especially sulfate aerosols).
Owen, if you look at the forcings prior to 1975, greenhouse gases and sulfates nearly cancel, leaving mainly natural forcings.
Post 1975, it’s CO2 that’s driving temperature change, according to the models.
Carrick,
I looked again at the forcings graph – CO2 is by far the largest forcing agent for warming. Solar forcing since 2008 is back to the level of approximately 1910 or so. Ozone forcing is quite low, and is increasing only slightly as we continue to reduce the use of certain chlorofluorocarbon. Sulfate aerosols and volcanic activity produce negative forcings with respect to warming. Given no unexpected changes in the Earth’s orbit, CO2 seems to be the overwhelming choice as the primary forcing agent. What else could it be?
Carrick,
I’ll buy the pre-1975 cancellation (or partial cancellation) of CO2 and aerosols. And thanks for the forcing graph. I expect that methane will soon appear on that graph.
Owen:
It’s included on the chart under “Greenhouse gases”, which includes water vapor feedback too. If I remember right, it accounts for maybe 5-10% of the total greenhouse gas effect. And unlike CO2 it doesn’t typically increase in proportion to economic activity (if I had to guess without really looking, I’d say it tracks with global population instead). And it’s lifetime is much shorter, maybe a 10-year lifetime instead of say 1000 years (while noting that CO2 has a very long tail).