What’s the hottest Earth has been “lately”?
Difference from historic average temperature since last ice age. NOAA Climate.gov cartoon by Emily Greenhalgh. Inspired by Figure 1(b) in Marcott et al., 2014.
This article is the second of two articles describing the hottest time periods in Earth’s history.
Throughout its 4.54-billion-year history, Earth has experienced multiple periods of temperatures hotter than today’s. But as far as the “recent” past, a study published in March 2013 concluded that global average temperature is now higher than it has been for most of the last 11,300 years.
The scientists assembled dozens of temperature records from multiple studies, including data from sediment cores drilled in lake bottoms and sea floors, and from ice cores. Assembling data from 73 records that overlap in time, the scientists pieced together global average temperatures since the end of the last ice age.
A researcher examines an ice core extracted from the West Antarctic Ice Sheet. Photo courtesy Thomas Bauska, Oregon State University, National Science Foundation.
The 11,000-year temperature reconstruction shows global average temperature increasing after the end of the last ice age and leveling off about 7550 and 3550 BC. After that time, global temperatures dropped until the “Little Ice Age,” bottoming out somewhere between AD 1450 and 1850. Afterwards temperatures rose again, first slowly then very rapidly. (The estimated temperatures for the past 1,500 years correlated with previous research that covered the same time period.)
Global temperature anomalies over the past 11,300 years compared to historic average (1961-1990). The purple line shows the annual anomaly, and the light blue band shows the statistical uncertainty (one standard deviation). The gray line shows temperature from a separate analysis spanning the past 1,500 years. Image adapted from Figure 1(b) in Marcott et al.
Natural variability can explain much of the temperature variation since the end of the last ice age, resulting from factors such as changes in the tilt of the Earth’s axis. Over the past century, though, global average temperatures have “risen from near the coldest to the warmest levels” in the past 11,300 years, the 2013 study authors explain. Over this same period, emissions of heat-trapping gases from human activities have increased.
Given the uncertainty inherent in estimating ancient temperatures, the scientists conservatively concluded that the last decade has brought global average temperatures higher than they have been for at least 75 percent of the last 11,300 years. The recent increase in global average temperature is so abrupt compared to the rest of the time period that when the scientists make a graph of the data, the end of the line is nearly vertical.
What about the future? To project future temperatures, the research team used greenhouse gas emission scenarios outlined in the Intergovernmental Panel on Climate Change (IPCC) Climate Change 2007: The Physical Science Basis report, and the authors expect the steep increase to continue through the year 2100 regardless of which one of the emission scenarios from the 2007 report is considered.
Most of what we consider modern civilization fits within the last 11,000 years—a period of remarkable climatic stability in which people have been able to continuously inhabit in the same regions for millennia. The United Nations Educational, Scientific, and Cultural Organization describes Tell es-Sultan (ancient Jericho) as “the oldest town on earth.” Photo courtesy Seetheholyland.net (some rights reserved).
For most of the past 10,000 years, global average temperature has remained relatively stable and low compared to earlier hothouse conditions in our planet’s history. Now, temperature is among the highest experienced not only in the “recent” past—the past 11,000 years or so, during which modern human civilization developed—but also probably for a much longer period.
Carrie Morrill of the National Climatic Data Center explains, “You’d have to go back to the last interglacial [warm period between ice ages] about 125,000 years ago to find temperatures significantly higher than temperatures of today.”
References
Mann, M.E., Zhang, Z., Hughes, M.K., Bradley, R.S., Miller, S.K., Rutherford, S., Ni, F. (2008). Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia. Proceedings of the National Academy of Sciences. 105(36), 13252-13257.
Marcott, S.A., Shakun, J.D., Clark, P.U., Mix, A.C. (2013). A reconstruction of regional and global temperature for the past 11,300 years. 339(6124), 1198-1201.
Otto-Bliesner, B. L., Rosenbloom, N., Stone, E. J., McKay, N.P., Lunt, D.J., Brady, E.C., Overpeck, J.T. (2013). How warm was the last Interglacial? New model-data comparisons. Philosophical Transactions of the Royal Society, Series A, 371(2001), 20130097.
Perkins, S. (2013, March 7). Global temperatures are close to 11,000-year peak. Nature News. Accessed February 4, 2014.
Revkin, A. (2013, April 1). Fresh thoughts from authors of a paper on 11,300 years of global temperature changes. The New York Times. Accessed June 13, 2014.
“Global temperature anomalies over the past 11,300 years compared to historic average (1961-1990). The purple line shows the annual anomaly, and the light blue band shows the statistical uncertainty (one standard deviation).”
One standard deviation is NOT the “statistical uncertainty”! One SD only covers 68% of possible values. They could be justified in using 2 SDs since it’s roughly 95%. But you need 3 SDs to get to 99.7%, or what might be considered true statistical uncertainty. But of course the narrower the “light blue band” the more accurate the graph looks and the more horrifying the “unprecedented recent warming”.
Yet another example of how the climate obsessed do not care about science, accuracy, honesty or integrity. Not to mention accountability for there use of tax payer money.
You begin to lose faith in the idea that climate propaganda mistakes are just that, mistakes, but the revival of the Marcott up tick is either grossly negligent or a deliberate intent to deceive.
I that you deniers would give up on this finally when sea levels rose enough that the Maldives were made uninhabitable, and they had to evacuate the population to New Orleans and Venice. Oh well, I guess you’ll NEVER learn.
[Reply: You are new here, so you get a warning instead of having your comment deleted: labeling others as “deniers” violates site Policy. Please refrain. ~mod.]
@Brock Way:
Sea level rise is not accelerating, despite numerous alarmist predictions that it would. Those predictions were wrong. All of them.
Therefore, the Maldives inhabitants have nothing to worry about, and New Orleans and Venice will not have to ‘evacuate’ their populations.
Where do you get your misinformation? More importantly: why would you believe such nonsense?
Umm, Brock,
Did I miss a major news item or did you forget your /sarc tag ?
or, to put it another way … What the heck are you talking about ?
I think he forgot the /sarc tag … otherwise why would he have the Maldives evacuating to New Orleans and Venice.
Does badgering us by calling us names make your point.
But then I just think it your way.
Do not put down to stupidity, that which is ignorance.
Brock Way,
I guess you never read this:
Welcome Brock. Stick around. (You need not tell anyone.) Your eyes will be opened.
1. Making mistakes is human.
2. Being mis-informed is not a virtue.
3. Making wild predictions about the future is for tabloid magazine fortune tellers.
4. Calling names does not increase ones knowledge, though granted can feel good at times. See #1 above.
Brock, the Maldives are a group of atolls. Atolls are caused by rising and falling sea levels. The slower than snails change in sea levels are easily adjusted to by coral changes responding to sea level changes, regardless of the cause. You can find lots of information about atolls on the internet and in high school geography books. Nonetheless, living on an atoll is living on high risk coral rubble. One single strong hurricane can wipe out entire communities in a single Maldive atoll in the chain, maybe more, even when sea level is falling. So the real and present threat to the Maldives are ocean storms, not rising or falling sea levels. As for ocean storms, solid data indicates no increasing threat. So sleep well tonight friend and get up refreshed ready to go to school. No worries.
Could you say when the Maldives will become uninhabitable?
Let’s hope the new airports are finished before then, so people can be resettled before it is too late.
( Mod, I think this is sarcasm, and that Brock is probably a “denier” himself. )
My friends, we live in a time where it is claimed that grant-eaters with a computer can tell us what the temperature was in the distant past far better than the records recorded in those days. They can use “proxies” or “adjustments” or “homogenization” to “correct” the data of the past.
If there are farms or trees under the ice and we discover it; they will tells us that we are deluded — it was cold then and hot now.
These people are like the biblical description of Satan: “and the truth was not in him”.
This bible verse was not about Satan but about ourselves – if we claim to be without sin.
1 John 1 8: If we claim to be without sin, we deceive ourselves and the truth is not in us.
Not so biblical, but what bugs me the most is that every regular Joe, say pizza delivery guy, is also referred to as scientist as soon as he happens to be in a same scene with equipment/materials of any scientific significance 😆
About Marcott’s hockey stick, (1) the “present” is 1950 — that’s the zero BP on the horizontal axis. (2) Marcott used a smoothing method which smoothed by hundreds of years over most of the chart, but decreased the smoothing near 1950, and at 1950 (zero BP) there was no smoothing at all. The blade is the unsmoothed dust bowl decades 1930-1950. Cherry pick much?
They have gone from at least “trying” to be scientific, to just plain making stuff up.
Someone go wake up Leif Svengaard. He needs to fire off one of his “nonsense” rants at these folks.
As other commenters the whole premise is invalid since no rational person or scientist could expect tenth of degree accuracy estimating temperatures over 12,000 years ago. We are still trying to figure out what the global temperatures was from 50 years ago.
But let’s assume the graph is 100% correct, not by science of course, but by miracle, that the temperature steadily declined from 6,000 years ago to about 100 years ago. According to GW theory that indicates there must have been a parallel steady drop in CO2 over that period. Queue the people now who just make stuff up, to provide an explanation as to how that steady CO2 drop occurred.
Queue another set of people to explain why we would want that increasingly colder trend to continue indefinitely.
Does anyone have a link to a list of peer reviewed papers that do NOT show a hockey stick in a reconstruction going back at least 1000 years? As in they show a MWP and LIA? I know there are many, Mann claims 12 Hockey Stick papers. I think someone should compile an anti-hockey stick list if it does not exist.
Mann’s gang of 12 are most likely papers using the same proxies and bogus statistics, slightly re-arranged, and with “independent” authors.
No proxy reconstruction is going to be definitive. The error bars will always be as large as the signal they purport to isolate.
Here’s one of the latest from TheHockeySchtick: http://hockeyschtick.blogspot.com/2014/09/new-paper-another-non-hockey-stick-in.html
Search that blog for ‘non-hockey-stick-reconstructions’ and you’ll get many many more.
Based on their trend line it appears we may have nipped the impending ice age in the bud. Hurray for global warming.
Um, didn’t Marcott admit that the “blade” section is not at all robust? How are they still getting away with claiming it is when they have openly conceded:
“20th century portion of our paleotemperature stack is not statistically robust, cannot be considered representative of global temperature changes, and therefore is not the basis of any of our conclusions.”
http://climateaudit.org/2013/03/31/the-marcott-filibuster/
That’s what I thought too. I’m sure I read where he rejected Mann’s claim that it confirmed his (Mann’s) hockey stick. Perhaps we are being too harsh on Marcott – on this point at least..
Reblogged this on Centinel2012 and commented:
These guys and gals got their PhD’s from DreamWorks LLC!
“Global temperature anomalies over the past 11,300 years compared to historic average (1961-1990).”
Gee, too bad we don’t have any data since 1990.
Oh, wait:
“To project future temperatures, the research team used greenhouse gas emission scenarios outlined in the Intergovernmental Panel on Climate Change (IPCC) Climate Change 2007: The Physical Science Basis report, and the authors expect the steep increase to continue through the year 2100 regardless of which one of the emission scenarios from the 2007 report is considered.”
We don’t need that data, or any other in the future. We’ve got model “scenarios” that tell us what we need to know.
Too bad none of those scenarios got the period from 1990 to today right – don’t they all overestimate the warming?
Carrie Morrill of the National Climatic Data Center explains, “You’d have to go back to the last interglacial [warm period between ice ages] about 125,000 years ago to find temperatures significantly higher than temperatures of today.”
Yes Joel O’Bryan, I do wish people would think before they opened their mouths & just let drivel out! As Monty Pythoners’ would say, “It’s statin the bleedin obvious!”! Did she not realise we are in an inter-glacial? Four of the last inter-glacials dating back 500,000 yrs were warmer than today by as much! Sheesh!
Anyone else notice that their “references” include two that are purely reviews (one is a newspaper article…) of their second reference? So out of 5, only 3 are original… pretty sad science if you ask me.
When the present is not turning out well for you, then it is time to rewrite climate history – climate history revisionism – it is simply an act of desperation.
No mention of the temporal resolution of Marcott et al? I believe their resolution is larger than the whole of the instrumental record. Which means any changes less than 200 years won’t be seen.
“a period of remarkable climatic stability in which people have been able to continuously inhabit in the same regions for millennia”
Except for the civilizations whose fall is blamed on climate change, which we’re reminded about when we’re being warned of the dangers of climate change.
That entire stock-market-downturn would have been a whole lot easier to ride through if I had just waited a couple of years and looked back over smoothed data. I would have been none-the-wiser, and would have slept better.
This is what they are spending our tax dollars on?
It never really struck me before, but after looking at that figure from Marcott et al., the thing that is really anomalous is where they draw the average temperature line. They cherry-pick the 30-year period from 1961-1990 and set that as the “average” temperature for a graph showing 11,500 years of temperature estimates and data. Approximately 80% of the temperatures in the graph are greater than that average line; so how does that “average” constitute an average? The periods that are below the “average” line include both about 500 years of coming out of the ice age and the Little Ice Age Period. It looks to me that the average temperature line should be about 0.2 degrees higher.
As Steve McIntyre discovered, there was no obscure statistical black box that created the entirely spurious Marcott 2013 blade as a pure artifact, an artifact of intentional and somewhat bizarre proxy re-dating compared to the original Ph.D. thesis data, creating quite simple sudden data drop off in the present day, of evidently low lying series when those dropped out, the average shot up. There simply is no significant blade in *any* of the input data to even cherry pick from, just some variation well within the noise level:
http://oi60.tinypic.com/2lwtawk.jpg
This is the most epic exposure of corruption so far in climate “science” for it so clearly reveals their cheating hand as being of Enron level, indeed criminal, deceit, not just paradigm fueled bias. I’m utterly delighted Marcott 2013 is now official, for it’s so much easier now to debunk the entire paradigm, based on their knowing and willing promotion of such an undeniable fraud that once and for all proves that they are fully aware of being liars, not so much the flawed paper itself but the way the admitted to flaw is being now used to promote alarm, for power and profit, Mann included in this.
Ah yes.. The Mike Mann use of 100 year plots and then a whole bunch of ten year plots on the end.. I wonder if the cartoonist and Mann attended the same school? (together or who was teaching whom.)
Just a thought….
Ironically, when the NSIDC publishes the September Antarctic Sea Ice Extent figures here, it’ll look remarkably like a hockey stick.
http://nsidc.org/data/seaice_index/
(Click on the Antarctic tab at the top and see the monthly graph on the right.)
The parody article almost writes itself. Anyone want to estimate how much this will increase albedo?