Distant Past

     Dr. Fry’s analysis is based most of all on the Vostok ice cores over the past 430,000 years.  And on other researchers’ findings on conditions some 4 and 14 million years ago.  See above, but below notably Tripati 1209, Csank 0311, Pagani 1209, and Shevenell 0208.

How Earth Got Its Ice Caps, Rare in Its History 0225

Beholding the Arctic’s Wonders, and Its Melting Future 1224

The Surprising Place We Stand Now, vs Earth’s 485 Million Years of Climate 0924

Prehistoric Earth Was Very Hot. That Offers Clues About Future Earth. 0924

CO2 Puts Heavier Stamp on Temperature than Previously Thought 0624 - from Abstract:  “.... From 15.0-0.3 Myr ago, our reconstructed pCO2 values steadily decline from 650 ± 150 to 280 ± 75 ppmv, mirroring global temperature decline. Using our new range of pCO2 values, we calculate average Earth system sensitivity and equilibrium climate sensitivity, resulting in 13.9°C and 7.2°C per doubling of pCO2, respectively. These values are significantly higher than IPCC global warming estimations, consistent [with] or higher than some recent state-of-the-art climate models, and consistent with other proxy-based estimates.”

Chemical Analysis of CO2 Rise over 50,000 Years Shows Rate Now is 10X Faster 0524 than any other in the period

Long-Lost Greenland Ice Core Suggests Potential Disastrous Sea Level Rise 0723 - Much of Greenland was ice-free around 416,000 years ago.  Thus, Greenland has not been frozen for a million years.  As the scientists started to sieve it to separate out the sediment, they were surprised to see twigs, mosses, leaves and seeds.  “We have a fossilized frozen ecosystem here,” said Bierman, “And what that meant, of course, is the ice sheet had gone away, because you can’t grow plants under a mile of ice.”  The potential implications for sea level rise are enormous, said a co-author, probably 10s of meters.

‘We are damned fools’ - Scientist Who Sounded Climate Alarm in 1980s Warns of Worse to Come 0723 -

Dr. James Hansen and others interviewed.

     The world is moving towards a “new climate frontier”, with temperatures higher than at any point over the past million years....  This is due to what Hansen said was an “unprecedented” imbalance in the amount of energy coming into the planet from the sun, versus the energy reflected away from Earth....  As heat waves strafe populations unacustomed to extreme temperatures, forests burn, and marine life struggles to cope with soaring ocean heat, the current upward spike is occurring at a pace not seen since the extinction of the dinosaurs 65 million years ago....  It's the rate of change that's the issue.
    We have been staring this in the face as scientists for decades, but now the world is going through that same process, which is like the 5 stages of grief, another scientist said.  “It’s painful to watch people go through it.  “But we can’t simply give up because the situation is dire,” Huber added.  “We need to say ‘Here is where we need to invest and make changes and innovate’ and not give up.  We can’t just write off billions of people.”

Paleoclimate Implications for Human-Made Climate Change - Hansen: Springer 1212 - PDF

Making Sense of Palaeoclimate Sensitivity - Hansen 1112 - PDF - see Water page for sea level graphs

Extreme Global Warming Caused Largest Extinction Ever 1012

Antarctic Trees 16 MY Ago, Interglacial 0912

Palm Trees Grew in Antarctica 0812

Reconstruction of a continuous high-resolution CO2 record over the past 20 million years - van de Wal 1211 - PDF

1st Land Plants Plunged Earth into Ice Age 0212

Effects of 390 ppm CO2 Million Years Ago - Csank 0311 - PDF

Climate More Sensitive to CO2 0110

CO2 & Temps to 5M Yrs Ago - Pagani 1209 - PDF

15 MY Record Finds High Warming Sensitivity to Doubled CO2 - Tripati 1009

Tropic Warm Pool Expanded Greatly ~4 Mya, +4°C Global - Brierly 0309 - PDF

Graph of CO2 Levels over 500 M Yrs - UCSD 1208 - PDF - see top graph on Home page

Climate and CO2 Over 500 M Yrs - UCSD 1208 - PDF: includes graph above & on Home page

LT CO2 Doubling Yields Twice the Warming We Thought - Paleoclimate 0908

Deep Sea Temps + c. 15 Mya - Shevenell 0208 - PDF

CO2 Levels and Configuration of Continents 1206 - PDF - includes graph at top of entire Heat section

What's the Hottest Earth Has Ever Been? 0620 - 3,700°F in Hadean era, not long after formation of Earth, in the aftermath of the Moon's formation.  Since Snowball Earth about 800 million years ago (Mya), Earth's surface temperatures reached around 90°F repeatedly, as recently as 92 Mya.  73°F during PETM, 55 Mya.  Earth's surface is currently near 60°, during an interglacial, but with much ice still at both poles.  Earth has rarely been as cold as the ice ages of the past 2-3 million years.  Not since long ice ages about 270 Mya.

Climate Is Warming Much Faster than It Has in the Last 2,000 Years 0719

Coupling CO2 to Ice & Sea Level Over 20 Million Years - Tripati 1209 - PDF - See figure below (part of Fig. 1 in article.)

Geologic Record & Climate Change 0105.pdf

     Patterson re-makes the case (from 1991 and 1997 by Friis-Christensen and Svensmark) that warming (and cloudiness) in the past century has been tied to variations in solar output.
    However, at least 38% of annual sunspot numbers in Patterson's graph 1 (after 1934) appear too low (none shown as over 85, but 17 were actually over 100, including 4 over 149, and 1 over 200).
    The high correlation between solar irradiance and cosmic rays measured on Earth is to be expected, as the sun’s magnetosphere waxes and wanes, coincident with the sunspot cycle.
      Low clouds generally cool Earth; they correlate reasonably well with solar irradiance and cosmic rays.  However, not shown are high clouds, which generally warm Earth; they too vary with solar irradinace and cosmic rays, probably more strongly than low clouds do.
    This tends to [more than?] offset the cooling effect of more low clouds when cosmic rays increase.  That is, the cloud elevation difference explains why surface temperatures correlate poorly with cosmic ray flux variations.  But the correlation is much better before the human emissions component overwhelmed the solar the solar variation component of surface tempoerature change, that is before 1990 or 2000.

     For perspective, see "∆T, CO2, SO4, Sun" under Temperature Analysis on the Data page.  Three files go thru 2004, 2009, and 2012.  Statistical ties to the sun grow weaker from the 2004 edition to the 2012 edition.  "Sun" there was sunspot number, not sunspot cycle length.

Paleotemperatures and ice volume of the past 27 Myr revisited with paired Mg:Ca and 18O:16O measurements on benthic foraminifera - Billups 0202.pdf  - Temperatures related to ice volumes.

Fig. 1 - Records of key climate variables over the last 20 Myr.
    Forcing of the model are changes in the stacked benthic 6180 record with respect to preindustrial times (a, dark blue, Zachos et al., 2008).
    Output is a consistent record for the Northern Hemisphere temperature change with respect to pre-industrial conditions (b, green) and sea level (c, light blue).  The reconstructed CO2 record (d, orange) is obtained by inverting the relation between NH tem- peratures and CO2 data.  The ∂18O curve is smoothed in order to clarify the gradual decrease over time.  Atl data are available every 0.1kyr.  The thick lines represent 400-kyr running mean. Grey error bars indicate the standard deviation of model input and output. For CO2 the error bar is calculated as 400-kyr running mean, for the other records it is the standard deviation on the 0.1 kyr value as used in the model.

     Regarding solar output changes, in contrast to Tim Patterson's graph above for North America until 1990, Earth's total land surface temperature diverged strongly from solar output after 2001, except for 2013-15 and 2020-21.

     Still, sunspot numbers during the satellite era, particularly their square root, correlate well with solar output.

6 Centuries of Temps - Hockey Stick - Mann 0498.pdf

Section Map: Heat