CO2 Control Knob? A 15-22°C Warmer Arctic With Sea Levels 25 m Higher When CO2 Ranged From 300-400 ppm

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CO2 concentrations have risen from 310 ppm to 410 ppm since the 1930s. However, there has been no net change in Arctic or Greenland temperatures during these last 90 years. During the Pliocene, CO2 also ranged between about 300-400 ppm, but the Arctic was 15-22°C warmer and sea levels 25 meters higher than today. Is CO2 really Earth’s “control knob”?

Nearly ten years ago, the imagery of a CO2 “control knob” for climate was canonized in the journal Science.

Image Source: Lacis et al., 2010

The CO2 concentration was said to determine – or control – Earth’s temperature.

However, the scientific literature’s paleoclimate record does not provide fundamental support for this paradigm of a CO2-controlled climate.

During the Ordovician, for example, CO2 concentrations reached 4,200 ppm – more than 10 times today’s levels. And yet the Earth returned to a glaciated “Snowball Earth” state during this period (Shuang et al., 2019).

Image Source: Shuang et al., 2019

Arctic/Greenland warming?

The Arctic is a region where a significant percentage of the Earth’s recent warming has arisen, and consequently this warming has been linked to the rise in CO2 concentrations from about 310 ppm in the 1930s to 410 ppm today.

And yet scientists continue to publish papers indicating the 1930s warmth was similar to or greater than that of today (Araźny et al., 2019, Hanhijarvi et al., 2013) despite the sharp contrast in CO2 levels.

Image Source: Araźny et al., 2019

Image Source: Hanhijarvi et al., 2013

There has been no significant net warming in Greenland during the last 90 years according to newly published papers (Holme et al., 2019Ruan et al., 2019,  Vermassen et al., 2019,  Khazendar et al., 2019) as well as other recent papers (Hanna et al., 2011, Kobashi et al., 2017, Mikkelsen et al., 2018).

Image Sources: Holme et al., 2019Ruan et al., 2019,  Vermassen et al., 2019,  Khazendar et al., 2019

Image Source: Hanna et al., 2011

Image Source: Kobashi et al., 2017

Image Source: Mikkelsen et al., 2018

Is modern Greenland ice sheet melt significant?

During the Holocene Thermal Maximum (about ~9000 to ~7000 years ago), the Greenland ice sheet had about 500 meters less thickness than it has had in recent millennia, and its margins had retreated up to ~100 km behind their present-day position (Nielsen et al., 2018).

Image Source: Nielsen et al., 2018

The modern Greenland ice melt has amounted to an insignificant 15 mm since 1900 (Fettweis et al., 2017, Fettweis et al., 2008). That’s just 1.5 cm added to sea levels since the 20th century began – and no net contribution for the 60 years between the 1940s and 2000s.

Image Source: Fettweis et al., 2017

Image Source: Fettweis et al., 2008

The Pliocene Arctic was 15-22°C warmer than today despite similar CO2 levels 

Cronin and Cronin ( 2015) reported that the Arctic Ocean was sea-ice-free and had temperatures reach a balmy 8-10°C three interglacials ago (MIS 11), when CO2 values peaked at 280 ppm. Polar bears somehow survived this much-warmer-than-today interval.

The same paper indicates the Arctic’s mean annual temperatures were 18.3°C warmer than today during the Pliocene, even though the Pliocene had CO2 concentrations similar to modern.

Image Source: Cronin and Cronin, 2015

A new paper indicates CO2 concentrations ranged between about 300 and 400 ppm during the Pliocene, but that Arctic mean annual temperatures were 15-22°C warmer than now (Fletcher et al., 2019) during this period.

Furthermore, all this polar warmth meant Earth’s sea levels were as much as 25 meters higher than present-day during the Pliocene.

Image Source: Fletcher et al., 2019

If CO2 was the Earth’s control knob, this is inconsistent with a “Snowball Earth” glaciation at 4,200 ppm, a sea-ice-free, 10°C to 22°C warmer Arctic at 280 ppm to 400 ppm, and no significant net change in Arctic/Greenland temperature as CO2 rose from 310 ppm to 410 ppm.

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8 responses to “CO2 Control Knob? A 15-22°C Warmer Arctic With Sea Levels 25 m Higher When CO2 Ranged From 300-400 ppm”

  1. Lasse

    So much facts-it is tiresome.
    My little daughter has no chans to understand this and is in a hurry to her demonstration for the climate. 😉

    It will be interesting to follow MOSAIC but I guess they have bias in their science, just see their ice chart compared to the Russian site:
    https://follow.mosaic-expedition.org/
    http://www.aari.ru/odata/_d0015.php?lang=1&mod=0

    1. Kurt in Switzerland

      Hey Lasse,

      Where do you see the MOSAIC ice chart?
      The Russian one is plain to see.

  2. Bob's in NC

    …and human activity only contributes 3.4% to the total CO2 atmosphere. Amazing…

  3. Is CO2 really Earth’s “control knob”? – Searching for Balance

    […] CO2 Control Knob? A 15-22°C Warmer Arctic With Sea Levels 25 m Higher When CO2 Ranged From 300-400 … […]

  4. Christopher Hanley

    Similarly, both UAH satellite data since 1979 and HadCRUT4 surface data since 1958 show no net warming at the Antarctic.
    As climate4you points out the poles are supposed to show enhanced warming due to increasing CO2 :
    > “… atmospheric carbon dioxide (CO2) has its greatest absorption of infrared radiation (IR) at sub-zero temperatures …”.
    > “… the air is dry due to prevailing low temperatures, allowing CO2 to exert a much greater influence than would be possible in warmer and moister air masses at lower latitudes …”.

  5. Yonason

    This graph is particularly frightening.
    https://notrickszone.com/wp-content/uploads/2019/09/Arctic-temps-20-C-warmer-Pliocene-Fletcher-2019.jpg

    From it we see that [CO2] was at times just about 150ppm, at which point all plant die, the main consequence of which is that all animals die.
    https://youtu.be/sXxktLAsBPo

    We are still in an ice age and have barely enough CO2 to keep everyone alive, and (expletive almost not deleted) greenie activist fools want us to remain precariously balanced on the edge of extinction. THAT is the real “climate crisis” that needs to be told, and few other than Patrick Moore are telling it.

  6. Yonason

    It’s not about the climate. It’s about imposing a fictitious socialist utopia on the world.
    https://youtu.be/GIgH0bnWSnc

    It will not end well for them, because they WILL destroy themselves.

  7. Kenan Meyer

    Go and google “pliocene, climate” and you’ll find plenty of alarmists/media taking exactly this as a showcase of how bad things will become in our future!

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