Demystifying Climate Change Session 5 Boneyard Creek, Champaign Ca

Demystifying Climate Change Session 5 Boneyard Creek, Champaign ca. 20,000 B.C.E. ? Natural Variability of the Climate

OLLI at Illinois Spring 2021

• OLLI Course Download site has – Each slide set (with annotations) posted a day after session – Syllabus – Reference List

3/2/2021 Climate Change 5 2 416.67 ppm Feb 28, 2021

3/2/2021 Climate Change 5 3 Course Outline

1. Building Blocks: Some important concepts 2. Our Goldilocks Earth: a Radiative Balancing Act 3. The Role of the Atmosphere: Greenhouse Gases & Clouds 4. Global Circulation and Dynamics of the Earth System: Oceans, Atmosphere, Biosphere, Cryosphere, People, Lithosphere 5. Natural Variability of the Climate, short and long term. Ice Ages 6. Carbon Dioxide and other Greenhouse Gases: where do they come from, where do they go, how are they regulated? 7. Impacts and Future Projections for Global Warming -- Uncertainties 8. Adaptation and Amelioration Strategies. The Climate debate. Policy options.

3/2/2021 Climate Change 5 4 Theory vs. Empiricism

According to my Balderdash! calculations…. Show me the actual data…

3/2/2021 Climate Change 5 5 Reconstructing Past Climates

• Recent Past: Instrumental Records

• More Distant Past: Inference from Proxies

– Paleoclimatology

3/2/2021 Climate Change 5 6 Oldest Continuous Instrumental Temperature Record

30 stations currently

• Anomalies relative to a baseline period: • 1961-1990 10 Year Moving Average • Small Region

3/2/2021 Climate Change 5 7 4 Global Instrumental Surface Temperature Records

3/2/2021 Climate Change 5 8 Historic Temperature Anomalies 0.3

LVTM* 0.2

0.1

-0.1 Temperature Anomaly (C)Anomaly Temperature

-0.2

* Late Victorian Thermal Maximum -0.3 1800 1820 1840 1860 1880 1900 1920 1940 1960 1980 2000

3/2/2021 Climate Change 5 J. Unrepro. Rslts (2019) 9 Historic Temperature Anomalies 0.3

LVTM* ? 0.2

0.1

-0.1

Temperature Anomaly (C)Anomaly Temperature Normally distributed -0.2 random numbers * Late Victorian Thermal Maximum -0.3 1800 1820 1840 1860 1880 1900 1920 1940 1960 1980 2000

3/2/2021 Climate Change 5 J. Unrepro. Rslts (2019) 10 Modes of Weather Observation

WMO.int 3/2/2021 Climate Change 5 11 World Meteorological Organization Weather Station Networks

• 3000 in Regional Basic Climatological Networks

• 4000 in Regional Basic Synoptic Networks

• also Antarctic Observing Network

•  4000 additional stations not shown

3/2/2021 WMO.int Climate Change 5 12 Global Ocean Observing System administered by Intergovernmental Oceanographic Commission

• 1400 Surface Drift Buoys • 700+ Moored Buoys • 4000 Profiling Floats • 400+ Voluntary Observing Ships • Many other platforms

3/2/2021 Climate Change 5 13 When Did Weather Stations Come Online?

Global Historical Climatology Network Stations

Kevan Hashemi (2009)

3/2/2021 Climate Change 5 14 NOAA Weather Stations in CU

• mostly rain gauges only

• 3 provide Temperature, Wind etc.

Bondville Environmental and Atmospheric Research Site (BEARS) “Urbana 4.2 ESE”

Champaign 3 S GHCND:USC00118740

Bondville Willard BEARS site Illinois State Water Survey CMI

3/2/2021 Climate Change 5 15 Historical Observing Metadata Repository (HOMR) NOAA.gov | NationalHistorical Centers Observing for Metadata Repository Environmental Information (noaa.gov) 3/2/2021 Climate Change 5 16 Global Temperature Anomaly (relative to 1850-1900)

3/2/2021 Climate Change 5 BerkeleyEarth.org 17 IPCC Breakdown of Components of Recent Global Forcings

IPCC AR5 WG1 Fig. FAQ 5.1-1

3/2/2021 Climate Change 5 18 Global Temperature Anomaly (relative toThe 1850 “Hiatus”-1900)

3/2/2021 Climate Change 5 BerkeleyEarth.org 19 3/2/2021 Climate Change 5 20 2

3/2/2021 Climate Change 5 21 Global Temperature Anomalies vs. 1951-1980 Baseline

Baseline: NASA Scientific 1951-19803/2/2021 Climate Change 5 22 Visualization Studio Baseline: NASA Scientific 1951-19803/2/2021 Climate Change 5 23 Visualization Studio Questions about the Recent Instrumental Global ? Temperature Record

Climate Change 5 3/2/2021 24 3/2/2021 Climate Change 5 25 National Climatic Data Center (NOAA) 60 ton trunk of Kauri tree found in a bog in New Zealand. 42,000 years old, lived 1700 years

3/2/2021 Climate Change 5 Science Feb 19, 2021 26 3/2/2021 Climate Change 5 27 National Climatic Data Center (NOAA) Fall 2003: High Sunspot Activity

During active sunspot years, overall Irradiance is HIGHER, but it DROPS briefly when a sunspot drifts across

SORCE Solar Radiation & Climate Experiment

Laboratory for Atmospheric and Space Physics G Kopp, LASP U Colorado (Boulder) 2019

3/2/2021 Climate Change 5 28 Fall 2003: High Sunspot Activity

During active sunspot years, overall Irradiance is HIGHER, but it DROPS briefly when a sunspot drifts across

SORCE Solar Radiation & Climate Experiment

Laboratory for Atmospheric and Space Physics G Kopp, LASP U Colorado (Boulder) 2019

3/2/2021 Climate Change 5 29 Meet the Maunders

1890’s Dallmeyer Photo-Heliograph at Royal Observatory Annie and Walter Maunder in India Greenwich 1898 for Solar Eclipse expedition

3/2/2021 Climate Change 5 30 Sunspot Number Prediction

3/2/2021 Climate Change 5 31 Satellite Solar Irradiance Measurements 1979-2019

3/2/2021 Climate Change 5 32 Corrected solar irradiance data, together with observed sunspot counts

Satellite Solar Solar Radiative Forcing Varies Irradiance with 11 year Sunspot Cycle Maunder Measurements Minimum To right: Best estimates of historical Solar Irradiance based on recorded sunspot activity. Total variation is less than3/2/2021 2 W/m2 out of 1360 W/m2. Climate Change 5 33 3/2/2021 Climate Change 5 34 National Climatic Data Center (NOAA) Global Temperature Anomaly Estimated from Proxy Data Large numbers (thousands) of Proxy data series are archived internationally, such as the PAGES2K database. From this data estimates of past global temperatures can be derived, with large uncertainties.

2021

Ed Hawkins (2020) PAGES2K dataset Base 1850-1900

3/2/2021 Climate Change 5 35 12,000 Year Global Temperature Reconstructions based on ~800 Proxy Records

Kaufman et al, “Holocene Global Mean Temperature, a Multi-Method Reconstruction Approach”, Nature: Scientific Data (2020) At 1200 years before present (BP), we are coming out of the last ice age. Temperature peaks at ~ 6000 years BP. then slowly falls, until industrial era. 3/2/2021 Climate Change 5 36 Various Proxy Reconstructions of Global Temperature for Last 2000 Years

Instrumental Record Moberg et. al. Nature (2005) 11 Proxy Datasets Early reconstructions were based on regionally biased datasets (European e.g.) which show more variability, Robert Rohde, Wikipedia including the infamous “Medieval Warm Period” and “Little Ice Age” 3/2/2021 Climate Change 5 Year 37 12,000 Year Global Temperature Reconstructions based on ~800 Proxy Records

Kaufman et al, “Holocene Global Mean Temperature, a Multi-Method Reconstruction Approach”, Nature: Scientific Data (2020)

3/2/2021 Climate Change 5 38 Ice Core Summer Melt Examples of Proxy (Ellesmere Island) Data Used in Climate Diatom Composition Reconstruction Ice Borehole Temps (Greenland) (Lake Tsuolbmajavri)

Pollen from Sediments

18 Tree Ring Data  O Cave Stalagmite Cave Stalagmite Layer Thickness Mg/Ca Fossil Shells

18O Foraminifera 9 Proxy Composite

Marine Sediment 18O Foraminifera Foraminifera Abundance

A lot of these data series are horribly noisy and uncorrelated. It’s a wonder that anything useful can be recovered, and we should be a bit skeptical. 3/2/2021 Climate Change 5 39 Attempts to Model Recent Northern Hemisphere Climate

“Medieval Climate Anomaly” “Little Ice Age”

Northern Hemisphere temperatures estimated from Proxies (gray) are compared with several General Circulation Climate models, using inputs Year such as known CO2 concentrations and volcanic eruptions. Decent agreement is IPCC AR5 WG1 3/2/2021 obtained. Climate Change 5 Fig 5.08a 40 CO2 in Atmosphere over the Last Millenium

Antarctic Ice Cores Data from Mauna Loa

Until recently, for the last 1000 years,

3/2/2021 Climate Change 5 CO2 hovered around 280 ppm. 41 Questions about Sunspots and ? the Last Millenium?

Solar Irradiance Estimate

Climate Change 5 3/2/2021 42 Preview: Proxy Estimates of Earth Surface Temperature C F

Glen Furgus “All Palaeotemps.svg” Wikipedia “Paleoclimatology”. Composite from various source data. 3/2/2021 Climate Change 5 43 The Most Important Temperature Proxy

18O “Delta Oh Eighteen”

3/2/2021 Climate Change 5 44 Isotopologues of Water

Oxygen Isotopes Hydrogen Isotopes Boiling Points:

16O 16 99.75% 1H 1 99.985% 16 100.0 C Regular 17O 17 0.04% 2H 2 0.015% Water

(Deuterium) 16 18 O 18 0.20% 16

100.15 C 9 Water Isotopologues

Heavier 18 1 in 500 18O Water 3/2/2021 Climate Change 5 45 Isotopologues of Water Since Boiling Points are different, regular Oxygen Isotopeswater and 18OHydrogen water can be separatedIsotopes by multiple distillation…. Boiling Points:

16O 16 99.75% 1H 1 99.985% 16 100.0 C 17O 17 0.04% 2H 2 0.015%

(Deuterium) 16 18 O 18 0.20% 16

100.15 C 9 Water Isotopologues 18 1 in 500

3/2/2021 Climate Change 5 46 You can buy it…

Sigma-Aldrich: $272,000 per liter

3/2/2021 Climate Change 5 47 Fractionation by Distillation

18 More H2 O 16 16 More H2 O Less H2 O 18 Less H2 O

3/2/2021 Climate Change 5 49 Fractionation by Distillation

18 More H2 O 16 16 More H2 O Less H2 O 18 Less H2 O

3/2/2021 Climate Change 5 50 Fractionation by Distillation

18 More H2 O 16 16 More H2 O Less H2 O Less H 18O As we go toward poles, multiple 2 distillations result in lower 18O in precipitation and in surface water.

3/2/2021 Climate Change 5 51 Global Map of 18O in Surface Seawater

3/2/2021 Climate Change 5 52 NASA Goddard ISS Global Map of 18O in Surface Seawater

3/2/2021 Climate Change 5 53 NASA Goddard ISS Global Map of 18O in Surface Seawater

18  O Water samples are compared with a “standard ocean water” sample (VSMOW) to determine a Difference in 18O value in “parts per thousand” Parts per Thousand from VSMOW ( Vienna Standard Mean Ocean Water)

Wikimedia

3/2/2021 Climate Change 5 54 NASA Goddard ISS Comparison of 0 18O in Precipitation Tropics and -20 Mean Annual Temperature 18O at various sites -40

-60 -60 -40 -20 0 20 Mean Annual Temperature (C) Alley & Cuffey 2001 3/2/2021 Climate Change 5 56 Comparison of 0 18O in Precipitation Tropics and -20 Mean Annual Temperature 18O at various sites 18O is a PROXY for: -40 • Mean Temperature for Ice Deposition (Ice Cores) • Ice Cap Volume 18 (Using CaC O3 in Sediments)

-60 -60 -40 -20 0 20 Mean Annual Temperature (C) Alley & Cuffey 2001 3/2/2021 Climate Change 5 57 Temperature effect on the 18O of precipitation

holds for both … and yet another data set showing how spatial T variability 18O at one location (Vienna) correlates with temperature over 30 years. and temporal variability

Another data set showing how 18O correlates with mean annual temperature. Rozanski, 1993 3/2/2021 Climate Change 5 58 Lonnie Thompson Byrd Polar Research Ctr OSU (NOAA)

Eric Wolff, British Antarctic survey. GRIP core being sawed

Ice Core Drilling

3/2/2021 Climate Change 5 59 Lonnie Thompson Byrd Polar Research Ctr OSU (NOAA)

What can we get from Ice Cores?

Eric Wolff, British AntarcticAt each layer: survey. GRIP core being sawed

1. Precipitation Temperatures from 18O

2. Atmospheric Gases from Bubbles (e.g. CO2) 3. Dust

Ice Core Drilling

3/2/2021 Climate Change 5 60 Annual Layers Visible in Vostok Core Depth = 1855 m (6085 feet)

Summer Layers

 8 inches

3/2/2021 Climate Change 5 61 Finely Spaced Ice Core 18O Measurements Can Sometimes Trace Out Annual Deposition Layers

Kobenhavns University Niels Bohr Institute Centre for Ice and Climate

Final piece of core at North Greenland NEEM drill site. 3/2/2021 Climate Change 5 62 This data covers 4 Ice Ages Vostok Ice Core Data T Past 420,000 years 18O From Drilling 1970’s through 1996

CO2

Dust

Vostok Station

Wikimedia Wikimedia Note that CO2 correlates well Present 3/2/2021 with temperature (from 18O) Climate Change 5 63 Vostok Gas Data: CO2 vs. Methane

NOAA Vostok Data, plotted by Age (years) E. Mearns

3/2/2021 Climate Change 5 64 Ice Ages Dansgaard-Oeschger not so Events in Greenland during last Ice Age: Simple: Short Warm Spells

D-O and Heinrich Heinrich Events in Events during North Atlantic during last Ice Age last Ice Age: Rafted Stones Dumped in Ocean during Cold Spells

NCDC NOAA Grootes et al 1993, Bond & Lotti 1995 3/2/2021 Climate Change 5 65 Dansgaard-Oeschger Events only show up in Greenland

D-O Events: Rapid climate fluctuations during last glacial period.

25, in Arctic Only

Leland McInnes Wikimedia

3/2/2021 Climate Change 5 66 Last Big Cooling Event as we emerged from 10C in Greenland a decade the last Ice Age 13K years ago: The Younger

Dryas Venezuela

Antarctica

Dryas octopetala

NCDC.NOAA 3/2/2021 Climate Change 5 67 Last Big Cooling Event as we emerged from 10C in Greenland a decade the last Ice Age 13K years ago: The Younger

Dryas Venezuela

Antarctica

Dryas octopetala

NCDC.NOAA 3/2/2021 Climate Change 5 68 Deep Sea Drilling

Sediment Layers

Drill ship JOIDES Resolution Integrated Ocean Drilling Program

Oregon State Univ. Ocean Sediment Core Collection (2017) 35 km

NOAA map of ocean coring sites

3/2/2021 Climate Change 5 69 Deep Sea Drilling

ForaminiferaSediment Layers (forams)

Drill ship JOIDES Resolution Integrated Ocean Drilling Program

Typically .05-0.5mm Planktonic or Benthic Oregon State Univ. Ocean Sediment Core Collection (2017) 35 km

NOAA map of ocean coring sites

3/2/2021 Climate Change 5 70 Deep Ocean 18 Deep Sea  O Tracks Ice Sediment Cap Volume Cores Reveal 18 Total Ice Cap Sea Low O Volume Bottom Dwelling Forams Level 0.5 mm dropped 120 m (400 ft) 18O in Oceans is High

Ammonia beccarii Shells made of (Wikimedia) CaCO3

3/2/2021 Climate Change 5 71 SEM micrographs of four benthic foraminiferans (ventral view) from the USGS. Clockwise from top left: Ammonia beccarii, Elphidium excavatum clavatum, Buccella frigida, and Eggerella advena.

3/2/2021 Climate Change 5 72 5.3 Million Year Record of 18O in Deep Sea Benthic Forams

• “Stacked” Record • 57 cores

• Proxy for Ice Cap Volume Thus indirectly • Climate • Sea Level

Lisiecki & Rayme (2005) 3/2/2021 Climate Change 5 73 Another Plot of the Same Foram 18O Data

This Part Matches with Ice Core Data

3/2/2021 Climate Change 5 74 Climate

Estimates 6 18  C) from O in  Larger Fossil 4

Shells: 2 back 500 million 0 years -2

-4 Estimated Temperature Change ( Change Temperature Estimated

Wikimedia, Veizer 1999 3/2/2021 Climate Change 5 75 Questions about 18O, ? Ice Cores, Ocean Sediments

Sea Low 18O Level dropped 120 m (400 ft) 18O in Oceans is High

Climate Change 5 3/2/2021 76 Milanković Cycles

Basic Idea: • Changes in Solar Insolation due to Earth’s Orbit Changes

Milutin Milanković over time can drive climate (1879-1958) Serbian Civil Engineer – Solar Radiation Forcing and Climatologist • Orbital Changes Include Magnum Opus: “Canon of Insolation of the – Axial Tilt and Precession Earth and its Application to the Problem of the Ice Ages” – Elliptical Orbit Eccentricity (1941, in German) [English Translation 1969] – Orbital Precession

3/2/2021 Climate Change 5 77 Earth’s Orbit Nearly Elliptical

Wikimedia Wikimedia Johannes Isaac Kepler Newton …but not nearly (1571-1630) (1643-1727) this eccentric Sun

Plane of Orbit called the “Ecliptic Plane”

Wikimedia

3/2/2021 Climate Change 5 78 Orbital Eccentricity Varies Slowly

Eccentricity: • varies from 0.0034 to 0.058 r r P rAr • Now 0.0167 (almost circular) • Complex variation • Roughly 100,000 year cycle

푟 − 푟 푒 = 퐴 푃 푟퐴 + 푟푃

3/2/2021 Climate Change 5 79 No climate effect, however

3/2/2021 Climate Change 5 81 Inclination to the Invariable Plane: Procession of the Ecliptic

1.57

Again, No climate effect

3/2/2021 Climate Change 5 82 Axial Obliquity (Tilt)

Axial Tilt appears to vary on a 40,000 year cycle… Angle referenced to Ecliptic Plane At present, Tilt  23.4

Sizable climate effect

3/2/2021 Climate Change 5 83 Axial Precession Caused by Tidal Torques from Moon & Sun

25,770 Year Period

3/2/2021 Climate Change 5 84 Now Axial Precession Polaris

25,770 Year Period 3/2/2021 Climate Change 5 85 Now Axial Precession Polaris

Hipparchus of Nicaea (190-120 BC) Greek Astronomer

Discovery and Measurement of the “Precession of the Equinoxes” 25,770 Year Period 3/2/2021 Climate Change 5 86 Current Orbit Spring Equinox (Mar 20) Summer Solstice (Jun 20)

Winter Solstice (Dec 21)

Fall Equinox (Sept 22)

3/2/2021 Climate Change 5 87 Due to axial 13,000 Years Ago Fall precession, North Equinox pole now pointed (Sept 22) toward sun Winter Solstice (Dec 21)

Winter Solstice?

Spring Equinox (Mar 20)

3/2/2021 Climate Change 5 88 …so it’s now 13,000 Years Ago Fall actually a Summer Equinox Solstice… but a (Sept 22) much hotter summer since Winter we’re close to sun Solstice (Dec 21)

Winter Closer- extra Solstice? hot summer (N)

Spring Equinox (Mar 20)

3/2/2021 Climate Change 5 89 13,000 Years Ago Fall Equinox (Sept 22)

Farther- extra Closer- extra cold winter (N) hot summer (N)

Winter Solstice (Dec 21)

Spring Equinox (Mar 20)

3/2/2021 Climate Change 5 90 ??? Years Ago: Max Fall Axial Tilt Equinox (Sept 22) Winter Solstice (Dec 21)

Summer Even Colder Even Hotter Solstice Winter (N) Summer (N) (Jun 20)

When max axial tilt coincides with maximum eccentricity and summer Spring solstice is closest to Equinox sun… super hot summer (Mar 20)

3/2/2021 Climate Change 5 92 0 Thousands of years ago Milkanovic Precession (19,22,24 kYear) Cycles and Obliquity Ice Ages (41 kYear cycle) Eccentricity (95, 125, 400 kYear) Solar Forcings are sizable, but not enough Solar Forcing alone to explain huge 65N Summer temperature swings. Warm Probably act as triggers -- Glaciation Amplified by CO2 Wikimedia from Ocean and by Milkanovich Ice Dynamics Cold Variations 3/2/2021 Climate Change 5 94 0 Thousands of years ago Milkanovic Precession It turns out that the most (19,22,24 kYear) Cycles and critical Solar Forcing (for the last few million years) is Obliquity that in Summer at northern Ice Ages (41 kYear cycle) latitudes – causes ice cap melting. Eccentricity (95, 125, 400 kYear) Solar Forcings are sizable, but not enough Solar Forcing alone to explain huge 65N Summer temperature swings. Warm Probably act as triggers -- Glaciation Amplified by CO2 Wikimedia from Ocean and by Milkanovich Ice Dynamics Cold Variations 3/2/2021 Climate Change 5 95 Back to the Foram 18O Data Milankovic Mid-Pleistocene Eccentricity? Transition (MPT)

Milankovic Obliquity?

This Part Matches with Ice Core Data

3/2/2021 Climate Change 5 96 Explaining the Mid-Pleistocene Transition 1 Million Years Ago

Hasenfratz et. al. Science, March 2019 (from 41 ky to 100 ky Glacial Cycles) Ocean Cores at 53S : 18O, Mg/Ca in both Benthic & Stratification of the Southern Ocean Floating Forams used to estimate southern ocean Temperature and Salinity profiles. CO2 CO2

More ice →

Later: Earlier: Slower ocean Faster ocean circulation, circulation, enhanced stronger CO 2 Slowed CO2 transfer transfer Relatively Fast from Circulation from deep Circulation atmosphere ocean to to deep ocean atmosphere. lowers air

CO2.

V. Altounian/Science

3/2/2021 Climate Change 5 97 Proxy Estimates of Earth Surface Temperature C F

Subtropical Microscopic Marine Ice Core Polar Data and Tropical Organism Shells 18O (18O & 2H) Multi-Proxy Marine Shell [Adjusted for Global] Data Fossils 18O Glen Furgus “All Palaeotemps.svg” Wikipedia “Paleoclimatology”. Composite from various source data. 3/2/2021 Climate Change 5 99 Proxy Estimates of Earth Surface Temperature C F

PETM: Paleocene-Eocene Thermal Maximum

Massive CO2 event lasting thousands of years. Amounts very roughly comparable to our current injection, but over much longer time span. Subtropical Microscopic Marine Ice Core Polar Data and Tropical 5-8C warming,Organism mammals Shells appear, 18O mass extinctions, etc.(18O & 2H) Multi-Proxy Marine Shell [Adjusted for Global] Data Fossils 18O Glen Furgus “All Palaeotemps.svg” Wikipedia “Paleoclimatology”. Composite from various source data. 3/2/2021 Climate Change 5 100 Proxy Estimates of Earth Surface Temperature C F

Subtropical Microscopic Marine Ice Core Polar Data and Tropical Organism Shells 18O (18O & 2H) Multi-Proxy Marine Shell [Adjusted for Global] Data Fossils 18O Glen Furgus “All Palaeotemps.svg” Wikipedia “Paleoclimatology”. Composite from various source data. 3/2/2021 Climate Change 5 101 Estimates of IPCC Past CO2 Levels Scenarios and Global

Temperatures CO2

Jessica Tierney et. al., “Past Climates Inform -- 250 our Future” Science (Nov 2020) Now 3/2/2021 Climate Change 5 102 possible future CO2 paths, depending on what we do… Estimates of IPCC Past CO2 Levels Scenarios and Global

Temperatures CO2

Jessica Tierney et. al., “Past Climates Inform our Future” Science (Nov 2020) Now 3/2/2021 Climate Change 5 103 Estimates of IPCC Past CO2 Levels Scenarios and Global

Temperatures CO2

Showing roughly how possible futures line up with climates 10’s of millions of years ago…. Jessica Tierney et. al., “Past Climates Inform our Future” Science (Nov 2020) Now 3/2/2021 Climate Change 5 104 0 Thousandsyears ago of Years Ago Milkanovic Precession (19,22,24 kYear) Cycles and Obliquity Ice Ages (41 kYear cycle) Eccentricity (95, 125, 400 kYear) Solar Forcings are sizable, but not enough Solar Forcing alone to explain huge 65N Summer temperature swings. Warm Probably act as triggers -- Glaciation Amplified by CO2 Wikimedia from Ocean and by Milkanovich Ice Dynamics Cold Variations 3/2/2021 Climate Change 5 105 Example of Recent Ice Milankovic Maximum Age Modeling: Summer Insolation 65N Ganopolski & Brovkin 2017 Actual GH Gas Forcing from Ice Core Data Were able to model last 4 Ice [Not used in Model] Ages using only Milankovic …Models can Orbital Forcing together with be tweaked Dust Deposition reasonable feedbacks from (with from Ice Core Data • Ice sheet models reasonable [Not used in Model] • AMOC models parameters) to • CO2 automatic feedbacks produce ice Sea Level Deduced • Ocean dynamics ages that look from Ice Core Data • Plankton blooms due pretty close to Modeled Sea Level to dust what actually happened. • Peat and Permafrost

dynamics Atmospheric CO2 • Land biota Level Deduced • Volcanic Activity from Ice Core Data Modeled CO2

G & B (2017) Fig.2 3/2/2021 Climate Change 5 106 Jessica Tierney et. al., What Might Past Climates Inform our Future (Review) the Future Science Nov 6, 2020

Hold for CO2?

IPCC AR5 Scenarios

3/2/2021 Climate Change 5 107 Figuring Out Where a Glaciated Rock Was… Way Back Then 225 Ma

Nizam & Abdullah 2006

NASA Modeled Magnetic Field During a Reversal

Now Now 170 Ma Wikimedia (from USGS) Hundreds of Random Flips

3/9/21 Climate Change 6 108 Rough Timeline of Past Glaciations

Baykonurian Gaskiers Mirinoan Andean-Saharan (Quaternary) Pongola Huronian Antarctic Sturtian Karoo* 0.73

0.53 Hadean 0.33 0.13

-0.08 60 50 40 30 20 10 0 4.5 4 3 2 1 400 100 25 5 0 Billions of Years Ago Millions of Years Ago Snowball

Data source: Wikipedia “Late Paleozoic Icehouse” Table Earth? * AKA Late Paleozoic Icehouse

3/9/21 Climate Change 6 109 Questions about Milanković Cycles ? and the Long Term Proxy Record?

0 years ago Precession (19,22,24 kYear)

Obliquity (41 kYear cycle) Eccentricity (95, 125, 400 kYear) Solar Forcing 65N Summer

Warm

Glaciation Climate Change 5 3/2/2021 110 Cold Course Outline

3/2/2021 Climate Change 5 111