From Hockey Stick to Ski Jump

March 8, 2013


In an enormous leap forward, new analyses of temperature records for the last 11000 years have now been published.

Don’t look for the climate denial blogosphere to learn anything from new science. Expect instead a newly focused attack on the facts, – trolls will have to bone up – and a new buzzword.

The older temperature graphs took in only the past 1000 or 2000 years, and were recognizable for the pronounced upward swing at the end. The new, longer graphs include a hump that peaked 9500 years ago, when the planet’s axial tilt was most extreme toward the sun, and have declined slowy until the past century, where we see a dramatic spike.

Less like a Hockey stick, said one scientist. More like a Ski Jump. With a brick wall at the end.

Associated Press:

A new study looking at 11,000 years of climate temperatures shows the world in the middle of a dramatic U-turn, lurching from near-record cooling to a heat spike.

Research released Thursday in the journal Science uses fossils of tiny marine organisms to reconstruct global temperatures back to the end of the last ice age. It shows how the globe for several thousands of years was cooling until an unprecedented reversal in the 20th century.

Scientists say it is further evidence that modern-day global warming isn’t natural, but the result of rising carbon dioxide emissions that have rapidly grown since the Industrial Revolution began roughly 250 years ago.

The decade of 1900 to 1910 was one of the coolest in the past 11,300 years — cooler than 95 percent of the other years, the marine fossil data suggest. Yet 100 years later, the decade of 2000 to 2010 was one of the warmest, said study lead author Shaun Marcott of Oregon State University. Global thermometer records only go back to 1880, and those show the last decade was the hottest for this more recent time period.

“In 100 years, we’ve gone from the cold end of the spectrum to the warm end of the spectrum,” Marcott said. “We’ve never seen something this rapid. Even in the ice age the global temperature never changed this quickly.”

LA Times:

“By the year 2100, we will be beyond anything human society has ever experienced,” said study leader Shaun Marcott, a postdoctoral researcher at Oregon State University‘s College of Earth, Ocean and Atmospheric Sciences.

According to NASA, the average global temperature for 2012 was 58.3 degrees Fahrenheit, making it the ninth-hottest year in recorded history. However, there is no single, agreed-upon method of calculating these temperatures, so scientists tend to discuss climate change by highlighting deviations from a specific reference point.

While a 1-degree Fahrenheit increase sounds small, it represents an enormous amount of heat energy. For instance, a 10-degree drop would plunge the world into another period of major glaciation, while every 1.8-degree increase would gradually amount to a roughly 65-foot rise in sea level due to melting polar ice, according to NASA climatologist James Hansen.

Previous efforts to measure past climate conditions have relied heavily on measurements of tree ring thickness. At high latitudes, tree growth is controlled mostly by temperature, so thick rings suggest warm years. But trees don’t live longer than several thousand years, so those efforts have focused on shorter periods of time — just 1,500 to 2,000 years.

New Scientist:

Marcott’s graph shows temperatures rising slowly after the ice age, until they peaked 9500 years ago. The total rise over that period was about 0.6 °C. They then held steady until around 5500 years ago, when they began slowly falling again until around 1850. The drop was 0.7 °C, roughly reversing the previous rise.

Then, in the late 19th century, the graph shows temperatures shooting up, driven by humanity’s greenhouse gas emissions.

Unprecedented warming

The rate of warming in the last 150 years is unlike anything that happened in at least 11,000 years, says Michael Mann of the Pennsylvania State University in University Park, who was not involved in Marcott’s study. It was Mann who created the original hockey stick graph, which showed the change in global temperatures over the last 1000 years.


The Hockey stick confirmed – again – and expanded

Over the Holocene, temperatures rose and fell less than 1 °C, and they did so over thousands of years, says Marcott. “It took 8000 years to go from warm to cold.” Agriculture, communal life and forms of government all arose during this relatively stable period, he adds. Then in 100 years, global temperatures suddenly shot up again to very close to the previous maximum.

How fast temperatures change is the real issue of climate change, says Mann. “That’s what challenges our adaptive capacity.” Rapid change means farming practices must alter quickly, and preparations for extreme weather events must also be rapidly put in place.

Wobbly planet

The gradual changes through the Holocene were driven by changes in Earth’s rotation, says Marcott. The planet is tilted about 23° relative to the plane of its orbit, and this tilt increased early in the Holocene before decreasing again. “It sort of wobbles,” Marcott says. A greater tilt increases the amount of sunlight at the poles during summer, and this keeps the planet warmer.

If humans had not begun warming the planet by releasing greenhouse gases, Earth would eventually return to an ice age. “If we were following the orbital trend we’d still be cooling,” Marcott says.

Marcott’s data suggests that the planet is now nearly – but not quite – as warm as at its warmest point in the last 11,000 years. Some climatologists have suggested that it is already hotter, but it is difficult to say for sure due to uncertainties in the data.

Mann says it should be possible to find out. He points out that, according to Marcott’s data, the tropics are currently hotter than at any point during the Holocene. The poles, on the other hand, appear to have been unusually warm in the past. But Marcott’s data set contains a lot of data from the far north, and Mann thinks it might be slightly exaggerating past warmth.

“It’s possible, given the potential bias, that there is in fact no precedent over the past 11,000 years,” says Mann says.

Even if we are not yet hotter than the entire Holocene, we will soon be. Marcott examined the latest climate models’ temperature predictions for this century, and found that by 2100 they were all outside the Holocene range. “The projections for 2100 will be very clearly outside the entire distribution of the data,” Marcott says.

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34 Responses to “From Hockey Stick to Ski Jump”

  1. FYI in the graph, Before Present (BP) is a year numbering system, used for the far past times, relating dates to the year 1950. in other words it is now -63 BP(years).

  2. omnologos Says:

    You’re late on this. Main issue is resolution in time I believe. It’s several decades at best and will make this paper as inconclusive as every other one. Try it again, Climate Sam!

    • MorinMoss Says:

      We look forward to an omnological interpretation of the data for the last 11 millennia.

      • omnologos Says:

        Revkin on FB: “An important reader concern about the new Holocene temperature study (seeking scientists’ replies on the blog): “[T]hey take these proxies that go back thousands of years and are smoothed to show an average and then tack on our recent temperatures. This is akin to showing our average temperature graphs for the year and then adding our daily temperatures for the last month to show the volatility of our recent climate.”

        Why don’t people ever get tired of this.

        • Not a good question or a comparison. If it was volatility then we would see it in the instrumentation record which we don’t. Notice that the last few decades don’t drop to the1880s and back do we.

          Also to, if “an important reader concern” would actually read the full article and could have comprehension; he would have read in the first paragraph.

          “Placing present climate into a historical perspective beyond the instrumental record is important for distinguishing anthropogenic influences on climate from natural variability (1). Proxy-based temperature reconstructions of the past 1500 years suggest that the warming of the past few decades is unusual relative to pre-anthropogenic variations (2, 3), but whether recent warming is anomalous relative to variability over the entirety of the Holocene interglaciation (the past 11,500 years) (4) has yet to be established.”

          It is just his lame excuse for thinking and not reading then thinking!

    • ontspan Says:

      Thanks omno for showing again your ‘true’ skeptism, so I guess the current misinformation meme argues that these coarse proxies by sheer bad luck all missed the previous sharp 1-degree global warming events that otherwise would prove the current sharp global warming event to be nothing special? Do I get the gist of this meme correctly?

      Ok, so now comes the post by omnologos that shows:
      A) how it’s possible that 73 independent proxies with a coarse 100 year resolution all missed the supposed previous rapid 1-degree global warming event(s) that have come and gone in such a short timespan that it didn’t leave a trace in these proxies…

      B) what could have caused such previous large and rapid global warming (and subsequent cooling) event(s)…


      • omnologos Says:

        ontspan – how do you know if any of those proxies would register any rapid warming?

        Anyway…I am tired of repeating the same points over and over. IMNSHO this paper is the n-th attempt to demonstrate the as-yet-impossible to demonstrate. It would take decades to collect enough more data from the same proxy to get anything meaningful, as the graph looks completely different in a tiny slice on the extreme right.

        And what for?

        “>a href=””>speaking to the BBC recently, Prof Mann, a climatologist at Pennsylvania State University, said he had always made clear there were “uncertainties” in his work.

        “I always thought it was somewhat misplaced to make it a central icon of the climate change debate,” he said.”


        • omnologos Says:

          Apologies for messing up the hyperlink

        • “Anyway…I am tired of repeating the same points over and over. IMNSHO this paper is the n-th attempt to demonstrate the as-yet-impossible to demonstrate.”

          Yep! it demonstrate that you have no clue about the topic or a born again liar .

          Let see “an important reader concern” see this fabrication:

          “Placing present climate into a historical perspective beyond the instrumental record is important for distinguishing anthropogenic influences on climate from natural variability . Proxy-based temperature reconstructions of the past 1500 years (changed) shows that the warming of the past few decades is (changed) very unusual (deleted) to pre-anthropogenic variations , (deleted) recent warming is anomalous relative to variability over the entirety of the Holocene interglaciation (the past 11,500 years) (changed) which has now been established without any doubts . UN- AGW- underground”

          I’m guessing he is “concern” whether recent warming is anomalous relative to variability over the entirety of the Holocene interglaciation (the past 11,500 years) HAS YET to be established.

          Please do tell of the REAL “concern”.

          Doctor: “you should not drink alcohol with this medication.”

          Skeptic: “I’m concern with drinking alcohol while taking this medication; no one will answer my concern.”

          • omnologos Says:

            Yada yada yada. I would at least wait until we stop dealing with “unprecedented” reconstructions.

          • Jason Says:

            Climate “Skepticism” is kinda like God of the Gaps.

            Omno’s point isn’t entirely wrong. The resolution on these distant reconstructions of global climate isn’t the same as what the modern instrumental record gives us.

            But that conveniently ignores other records like ice cores which do give us high resolution. True, those are regional, not global – so if you’re especially imaginative you could suppose that temperatures in glacial regions one and all are uniquely stable historically (but not today) except for when they’re not – while the non-glacial bits of the world were fluctuating wildly etc etc.

            Knowlege is imperfect. True story. If you’re desperate enough to hide there’ll always be wiggle room. Question is whether it’s rational to do so.

          • omnologos Says:

            And I do not disagree entirely with you either, Jason. In fact, knowledge is imperfect. If you’re desperate enough to find something like a hockey stick, it’ll always be there for you. Question is whether it’s rational to do so.

          • Jason Says:

            When multiple lines of independent evidence build up such that it’s reasonable to present such a case then yeah – that’s traditionally how it’s been done.

  3. Jason Says:

    I’m noticing that they’re reconstructing global temperatures, not just Northern Hemisphere – bold stuff.

  4. [...] dear Dr. Markott, dice il primo commento. Infatti da Climatecrocks il portavoce di Forza Gn-Uk sparge il meme [...]

  5. joffan7 Says:

    I think it’s pretty clear, but for the avoidance of doubt, the start of the grpah there does not represent full-on ice age conditions as the New Scientist quote almost implies. That’s the end of the slope up from ice-age conditions, and the temperature was significantly lower during the glacial period; about 8C.

  6. adelady Says:

    MWP can’t be seen?

    Remember this is a global reconstruction, not just Northern Hemisphere. The MWP is a regional detail rather than an overall feature when working at this scale.

  7. [...] From Hockey Stick to Ski Jump ( [...]

  8. Rob de Vos Says:

    Only 7 of the 73 proxy datasets reach 0 BP (=1950). most of these 7 do not show any hockeystick elevation after 1850…..

    • greenman3610 Says:

      but of course, after 1880, we don’t need proxies, because we have reliable, global instrumental and, more recently, satellite data.

      • Rob de Vos Says:

        So you say that proxies are not reliable?

        • No, it is that you don’t know anything about the topic nor the source you quote.

          Love your source

          “Alarmists are high-fiving themselves because the Marcott study purports to have found the same blade of the hockey stick in the 73 proxies used in the study, lending further proof that anthropogenic CO2 has warmed the earth in an unprecedented way in the past 150 years.”

          If ever major academy of science and every scientific organization (non- think tank) are” Alarmists” than you should do something about it because you only have the nuts and profiteers that are not Alarmists

          “…same blade of the hockey stick in the 73 proxies used in the study”
          It is like” wile e coyote” hitting Anthropocene – Holocene wall on the graph. I WILL SPELL IT OUT the blade is the instrumental temperature record. The proxies are used for period of non-instrumental records.

          If you really would like a basic understanding of proxies there calibration and temperature reconstruction the go here

          This is the American National Academy of Science you know Alarmists :_0

          • greenman3610 Says:

            Rob, you are reaching.
            I’m saying you don’t need proxies when you have thermometers.

          • omnologos Says:

            Shouldn’t you have an overlapping period if only to verify your proxies are actually indicating temperatures one way or another?

  9. Jason Says:

    Jason notes 3 things.

    1. Hey, we’re having a discussion about why data from a handful of individual locations (never mind the differences in smoothing) don’t all match data for the global average of many many locations. For real. With analysis that sharp, I’m wondering why I don’t give up on science all together and just read “skeptic” blogs instead.

    2. Checking the veracity of proxies against instrument & other data with robust statistical testing is standard practice for all multi-proxy climate studies, including this one.

    3. I think the graph looks most of all like a very excellent woolly scarf. And I want one.

    • Jason Says:

      Oh, I was hoping that would be tacked on to the conversation above. Never mind.

      “Shouldn’t you have an overlapping period if only to verify your proxies are actually indicating temperatures one way or another?” ~ Omnologos

      Indeed you should. But at no point would you compare proxy data from individual locations to instrument data for the global average. You’d compare proxy data for a location with instrument data for the same location. Else you’d get in a muddle. Or at least, you wouldn’t unless you had a very strong feeling that individual locations really should match global averages.

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