How to Talk to a Climate Skeptic: Responses to the most common skeptical arguments on global warming A Grist Special Series

‘It was warmer during the Holocene Climatic Optimum’—This period was not global and not like today 4

(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: It was warmer during the Holocene Climatic Optimum than it is today -- without any human influence.

 

Answer: Though some temperatures during that period were in the same range as today, they were confined to the northern hemisphere and the summer months.

What's more, the cause is understood (orbital forcing similar to what controlled the Ice Ages), just as today's cause is understood (CO2 emissions), and these causes are very different. NOAA has a page on this that contains the following quote:

In summary, the mid-Holocene, roughly 6,000 years ago, was generally warmer than today, but only in summer and only in the northern hemisphere. More over, we clearly know the cause of this natural warming, and know without doubt that this proven "astronomical" climate forcing mechanism cannot be responsible for the warming over the last 100 years.

As an aside, it's worth noting that even if the Holocene had been as warm as or warmer than today, it would do nothing to undermine the theories and data that indicate today's warming is rapid and anthropogenic.

Former musician, turned tree planter, turned software engineer. Same old story…

I have been blogging about climate change since 2006 at A Few Things Ill Considered.

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  1. WWAGD?!'s avatar

    WWAGD?! Posted 7:42 am
    05 Mar 2007

    Holocene? Gimme Pleistocene!

    "If we drill back in time, we can get a record of how [the Ross Ice Shelf] behaved, during times, certainly in the last million years, when we know the temperatures from the ice cores suggest that the planet was two to three degrees warmer," the Andrill project member explained.

    Andrill article

    The Texeme Construct offers international text memetics construction and textcasting services.

    Permalink

  2. GreyFlcn Posted 3:19 pm
    07 Apr 2007

    Uhm

    If you go back any earlier than the last iceage isn't that kinda silly?

    Permalink

  3. Meowse Posted 3:59 pm
    03 Jun 2007

    Why did you quote from that article?

    Mr. Bailo, did you even read the article you just quoted there?

    Of course the Earth has been warmer in the past--as the article you cited states,

    Previous drilling has showed that ice sheets were quite dynamic, collapsing and reforming in line with the Earth's Milankovitch cycles. These are small "wobbles" in the Earth's orbit that are known to happen roughly every 20,000, 40,000 and 100,000 years.

    It goes on to comment,

    But said Dr Naish, "during all those natural cycles, carbon dioxide never got above 300 parts per million. So in the last 200 years, we've had this geologically unprecedented increase in CO2 - it's 30% higher than it has been over the last several million years and it's occurred at a rate we've never seen geologically."
    ...
    Dr Naish muses: "If they collapsed in the past without the present level of CO2 and the Earth was two to three degrees warmer, what's going to happen with the doubling of CO2 and potentially much higher temperatures?"

    Permalink

  4. perchecreek Posted 9:40 am
    19 Apr 2008

    CO2 levels "never seen..." is incorrect

    Meowse,

    It may be that the context of the remark by Dr. Naish would qualify the meaning implied by his statement that you've quoted, but to simply imply categorically that contemporary atmospheric CO2 levels are at a level that have never "occurred at a rate we've seen geologically" (emphasis is mine) is incorrect; for, in fact, atmospheric C02 levels have been much, much higher (above 2000ppm).  Of course, it's probably not very reassuring that those levels were associated with a mass extinction.  It would be more correct to say that current C02 levels were not exceeded during the Pleistocene, which seems to be what Dr. Naish meant.

    It is also important to emphasize, I believe, that asserting that climate has varied greatly without anthropogenic forcing should in no way be taken to obfuscate the likely significant consequence of such change now.  

    Permalink

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Series Intro
'There is no evidence' -- Yes, there is 59
'Mauna Loa is a volcano' -- CO2 rise is measured on top of a volcano! 8
'Warming is due to the Urban Heat Island effect' -- No, it isn't 25
'One hundred years is not enough'--Yes it is 18
'The scientists aren't even sure' -- No scientist ever is 33
'One record year is not global warming'--Luckily, there are plenty more years to consider 19
'Glaciers have always grown and receded'--A few glaciers melting does not mean global warming 14
'The temperature record is unreliable'--But temperature trends are clear and widely corroborated 8
'It's cold today in Wagga Wagga'--Weather and climate are different 2
'The satellites show cooling'--No, they don't 15
'What about mid-century cooling?'--No one said CO2 is the only climate influence 11
'Antarctic ice is growing'--Well, probably not, but even if it were, we are not off the hook 8
'Global warming stopped in 1998'--Only if you flagrantly cherry pick 170
'But the glaciers are not melting'--Except ... they are! 3
'Antarctic sea ice is increasing'--Yes, but ... 14
'Sea level in the Arctic is falling'--Sea level is a surprisingly complicated thing 11
'Climate sensitivity is not very high'--Thermal inertia of the oceans means the jury is still out 2
'Some sites show cooling'--But you can't draw global conclusions from individual sites 0
'Global warming is a hoax'--I wish James Inhofe were just a hoax ... 12
'There is no consensus'--If this is not consensus, what would consensus look like? 109
'Position statements hide debate'--True enough, but that is not the whole picture 5
'Consensus is collusion'--Is climate science maturing, or should we reach for our tinfoil hats? 8
'Peiser refuted Oreskes'--In a poor piece of work that has been retracted by its author 4
'Models don't account for clouds'--Clouds are complex and uncertain, but unlikely to stop warming 6
'Climate models are unproven'--Actually, GCM's have many confirmed successes under their belts 13
'Aerosols should mean more warming in the south'--More North. Hemisphere warming is well-understood 1
'We can't even predict the weather next week'--But weather is not climate 11
'Chaotic systems are not predictable'--Sure, but who says climate is chaotic? 13
Understanding what is happening right under our noses does not require paleoclimate perfection 1
'They predicted global cooling in the 70s'--But that didn't even remotely resemble today's consensus 29
'Hansen has been wrong before'--Maybe, but not about the climate! 13
'It was warmer during the Holocene Climatic Optimum'--This period was not global and not like today 4
'The Medieval Warm Period was just as warm as today'--Repeating this point does not make it true 216
'Greenland used to be green'--Don't judge a book by its cover, much less a land by its name 23
Yes, the last ice age started thawing over 20,000 years ago, but that stopped a long time ago 5
'The hockey stick is broken'--Well, no ... but who's playing hockey anyway? 6
'Vineland was full of grapes'--Or was it an early advertising campaign? 4
'Global warming is part of a natural cycle'--This idea is one short step above appealing to magic 39
'Mars and Pluto are warming too'--No they aren't -- and what if they were? 24
'Volcanoes emit more CO2 than humans'--Not even close ... 31
'The null hypothesis says warming is natural'--An inappropriate test, and one that would fail anyway 4
'Climate is always changing'--That doesn't mean it isn't different today 5
'Natural emissions dwarf human emissions'--But emissions are only one side of the equation 5
'The CO2 rise is natural'--No skeptical argument has been more definitively disproven 12
'We are just recovering from the LIA'--Why should we expect this to happen? 4
'Climate scientists dodge the subject of water vapor'--No, they really don't 4
Water vapor is indeed a powerful greenhouse gas, but there is plenty of room for CO2 to play a role 29
There is no proof in science, but there are mountains of evidence 78
'CO2 doesn't lead, it lags'--Turns out CO2 rise is both a cause and an effect of warming 43
'Geological history does not support CO2's importance'--Just not true 0
'Historically, CO2 never caused temperature change'--Not so 19
'It's the sun, stupid'--Very bright, yes, but not getting brighter 18
The problem is not how high the temperature may go, but how fast it is changing 14
'Kyoto is a big effort for almost nothing'--Kyoto is only in its first phase 16
China and India have joined Kyoto, they just have different obligations, as is morally appropriate 3
'Climate change mitigation would lead to disaster'--Not really, but this may be lesser of two evils 6
Only if you ignore fossil fuel emissions 10
In 2008, did temperatures drop as much as they rose over the whole 20th century? 71
Is the IPCC so wrong their theories contradict a basic laws of physics? 23
Is the American Physical Society a crack in the climate change consensus? 3
Summer ice in the Arctic has recovered--Was the Arctic ice retreat a climate anomaly? 7
'Global warming comes from within'--Is heat at the Earth's core the real cause of global warming? 10
Was there another breathless announcement of another phony record, and another quiet retraction? 1
Hansen wants the skeptics thrown in jail--Did James Hansen really want to try the climate skeptics? 6
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