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Climate in perspectiveClimate in perspective––

EarthEarth’’s Climate History and s Climate History and

Climate ChangeClimate Change

Pat PringlePat PringleCentralia CollegeCentralia College

Selected slides courtesy of Selected slides courtesy of Peter U. Clark, OSU, and Peter U. Clark, OSU, and Christina Christina HulbeHulbe, PSU, PSU

EarthEarth’’s Climate Historys Climate History

•• What is the IPCC assessment?What is the IPCC assessment?

•• How does EarthHow does Earth’’s weather work?s weather work?……

•• What is EarthWhat is Earth’’s paleoclimate & how do we s paleoclimate & how do we know about it?...know about it?...

•• What can we learn about global warming What can we learn about global warming from studying Earthfrom studying Earth’’s weather and s weather and paleoclimate?paleoclimate?

Ahrens Fig. 10-1, p.246

Keeling curve

Post-1700 dramatic rise of CO2. Pre-1960 values from

air samples trapped in Antarctic ice. Post ~1960 values

directly measured at the top of Mauna Kea, Hawaii.

Collins et al, 2007:

CO2 35%

CH4 250%

O3 20%

Compared to

preindustrial levels

Web search: Vulcan project PurdueWeb search: Vulcan project PurdueCarbon Cycle, IPCC, 2007Carbon Cycle, IPCC, 2007

Black = natural Black = natural fluxesfluxes

Red = anthropogenic contributionsRed = anthropogenic contributions

CO2 over the past 650,000 yrBirch Museum UC San Diego

Figure SPM.3Figure SPM.3

Observed changes in (a) global avr. surface temp., (b)global avr. sea level from tide gauge (blue) and satellite (red) data and (c)Northern Hemisphere snow cover for March-April.All changes are relative to corresponding averages for the period 1961–1990.

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Most of the observed warming in the past 50 Most of the observed warming in the past 50 years is attributable to human activitiesyears is attributable to human activities

http://www.learner.org/channel/courses/envsci/unit/text.php?unithttp://www.learner.org/channel/courses/envsci/unit/text.php?unit=12&secNum=6=12&secNum=6Annenberg Habitable Planet online textbookAnnenberg Habitable Planet online textbook

EG6_Figure_07_27-L

IPCC 07 IPCC 07 Figure Figure SPM.2SPM.2

•• Global average Global average radiativeradiative forcing (RF) estimates and forcing (RF) estimates and ranges in 2005 for anthropogenic carbon dioxide (COranges in 2005 for anthropogenic carbon dioxide (CO22), ), methane (CHmethane (CH44), nitrous oxide (N), nitrous oxide (N22O) and other O) and other important agents and mechanismsimportant agents and mechanisms…… EG6_UNN_07_01-L

IPCC 07 IPCC 07 Figure Figure SPM.5SPM.5

Solid lines are multi-model global averages of surface warming (relative to 1980–1999) for scenarios A2, A1B and B1, shown as continuations of 20th century simulations.

IPCC 2007 conclusions includeIPCC 2007 conclusions include……•Warming of the climate system is unequivocal…

• Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG concentrations.

http://www.skepticalscience.com/http://www.skepticalscience.com/ Many skeptics existMany skeptics exist

http://www.ipcc.ch/pdf/assessmenthttp://www.ipcc.ch/pdf/assessment--report/ar4/syr/ar4_syr_spm.pdfreport/ar4/syr/ar4_syr_spm.pdf Summary for policymakersSummary for policymakers

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“Global conveyor belt” ~1,000 yr cycleWhat is paleoclimate?What is paleoclimate?Where do we get the record?Where do we get the record?

•• FossilsFossils……

•• Geologic timeGeologic time……

•• Geologic environmentsGeologic environments……hot/cold and/or hot/cold and/or dry/wetdry/wet……paleomagnetic recordspaleomagnetic records

•• Isotopes preserved in lakes, glacial iceIsotopes preserved in lakes, glacial ice……

•• Tree rings, carbonate deposits of corals Tree rings, carbonate deposits of corals or in cavesor in caves……

•• Marine, lake, and bog depositsMarine, lake, and bog deposits

http://www.scotese.

com/legend.htm

Lithologic Lithologic Indicators Indicators of Climateof Climate

banded iron deposits

black shalesblack shales

red beds

Stromatolites, 3.5 Billion

Years ago

Co2 O2

http://www.washington.edu/burkemuseum/geo_history_wa/

Atmosphere <1% O2

& no O3

http://eesc.columbia.edu/cours

es/ees/slides/life/oxygen2.gif

•• ~ 3.5 ~ 3.5 GaGa photosynthesis by photosynthesis by cyanobacteriacyanobacteria

•• ~2.4~2.4--2.3 2.3 GaGa, algae; Oxygen revolution, banded iron , algae; Oxygen revolution, banded iron

•• ~450 Ma, vascular plants, Ozone?~450 Ma, vascular plants, Ozone?

•• ~350 Ma, Carboniferous begins~350 Ma, Carboniferous begins

Oxygen milestones

XX

MajorMajor

““Ice AgesIce Ages””

in Earth Historyin Earth History

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2

3

4

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http://www.scotese.

com/climate.htm

““Snowball EarthSnowball Earth””TilliteTillite of late of late prepre--Cambrian Cambrian Windermere: Windermere: Toby Formation Toby Formation of ne WA & IDof ne WA & ID

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Climate Change, Plate Tectonics, Climate Change, Plate Tectonics, MountainMountain--Building, volcanismBuilding, volcanism

Figure 6.1

(Top) Atmospheric CO2 and continental glaciation 400 Ma to present. Vertical blue bars mark timing and palaeolatitudinal extent of ice sheets (Crowley, 1998). Plotted CO2 records = five-point running averages from each of four major proxies (see Royer, 2006).

(Bottom) Detailed record of CO2 for the last 65 Myr.Individual records of CO2 and associated errors color-coded by proxy method; when possible, records based on replicate samples (see Royer, 2006 for details and data references).

IPCCIPCC

global tectonics

Ron Blakey, Northern Arizona University

Dynamic processes, driven by heat within Earth’s interior, that

cause the geometry of the continents and ocean basins to change over millions of years.

Mississippian, 340 Ma

Early Cretaceous, 130 Ma

plate tectonics

Ron BlakeyStefan Rahmsdorf

Late Cretaceous, 80 Ma

Miocene, 20 Ma

modern

Opening of Drake Opening of Drake Passage ~41 Ma;Passage ~41 Ma;ScherScher & Martin, 2006,& Martin, 2006,

ScienceScience, Vol. 312. no. 5772, , Vol. 312. no. 5772, pp. 428 pp. 428 -- 430430

long-term global cooling

• Earth has been cooling for ~ 60 Ma

• changes in – continent positions

– ocean circulation

• ice in Antarctica by ~ 30 Ma– “big white reflector”

helps cool Earth

from Ruddiman, Earth’s Climate

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recent events: Ice Age Earth

From Ruddiman, Earth’s Climate

• repeated cycles of gradual cooling and rapid warming

• global glaciation and deglaciation

• cyclic changes in Earth’s orbit around the Sun

• feedbacks within Earth’s climate system

Ice Age Earth

Earth’s orbit & climate

• gravitational interactions among planets & sun

• cyclic changes in Earth’s orbit

• cycles in the amount of solar energy arriving at Earth’s surface

• intensity of seasons

UCAR graphic

Records from ice coresRecords from ice cores

AntarcticaAntarctica

GreenlandGreenland

Courtesy of Peter U. ClarkCourtesy of Peter U. Clark annual layers

photographs by Steve Price

backlit face of a snow pit, Siple Dome, Antarctica

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Morrison (1991) marine oxygen isotope stagesMorrison (1991) marine oxygen isotope stages

Stage numbers = even-numbered peaks (at top) are

glacial maxima, and odd-numbered troughs (at

bottom) are interglacial minima. Red areas =

interglacial episodes.

coldcold

warmwarm

Vostok temperature & CO2

• 4 glacial-to-interglacial cycles

• temperature and CO2 vary together

• slow cooling & rapid warming

data from Petit et al. 1999

http://cdiac.ornl.gov/trends/temp/vostok/jouz_tem.htm

BarnoskyBarnosky QR, QR, 1981, Davis Lake 1981, Davis Lake QuatQuat. Veg.. Veg.

14C14C

1601 1601 light light ringring

Pat Pringle, photo: Douglas fir Pat Pringle, photo: Douglas fir Cougar Rock, Mount Rainier Cougar Rock, Mount Rainier elevelev~3200 ft~3200 ft

BriffaBriffa et al, et al, QuatQuat. Sci. Rev., 2000, v. 19. Sci. Rev., 2000, v. 19

EG6_Figure_07_28a-L

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N. Hemisphere changes in average temperature for

1000 to 2000 (from tree rings and glacial ice). Note

distinct increase in temperature since 1900.

The so called “hockey stick” of Mann et al, 1998, 1999; Briffa

Mann et al, 2003, On past temperatures and anomalous late-20th century

warmth: EOS, v. 84, no. 27, p. 256-257.

(response to Soon and Baliunas, 2003

published in Climate Research)

• Fig. 1. (a) The relationship between increased radiativeforcing, cooling of the eastern Pacific Ocean, and evidence for widespread drought in western North America during the twelfth century.

• The evidence for positive radiative forcing and decreased volcanic negative forcing is from

• Crowley [2000]. The modeled cooling in the Niño-3 region of the eastern equatorial Pacific during

• the twelfth century is from Mann et al. [2005]. Niño-3 is the region of the equatorial Pacific

• from 90ºW to 150ºW. The tree-ring-based reconstruction of a prolonged negative state of the

• Pacific Decadal Oscillation (PDO) is from MacDonald and Case [2005]. The reconstruction

• of increased drought severity (Palmer Drought Severity Index, orPDSI) for the core area of the

• twelfth-century drought from the southwestern interior of Canada to northwestern Mexico is from

• tree rings (data from Cook et al. [2004] and World Data Center for Paleoclimatology). Negative

• PDSI values indicate arid conditions, and values of –3 or less represent severe drought. Evidence

• for decreases in river flow during the twelfth century comes from tree-ring-based reconstructions

• of annual discharge of the North Saskatchewan River [Case and MacDonald, 2003], the

• Colorado River [Meko et al., 2007; MacDonald et al., 2007], and the Sacramento River [Meko

• et al., 2001; MacDonald et al., 2007]. All series are smoothed with an 11-year moving average.

• (b) PDSI map of the twelfth-century drought and (c) the early 21st-century drought (data in

• Figure 1b are from Cook et al. [2004] and World Data Center for Paleoclimatology, and data

• in Figure 1c are from National Climatic Data Center).

McDonald et al, 2008, Eos. McDonald et al, 2008, Eos. 89:989:9

Jamestown; the Lost ColonyJamestown; the Lost Colony•• StahleStahle, D.W., M.K. , D.W., M.K. CleavelandCleaveland, D.B. Blanton, , D.B. Blanton,

M.D. M.D. TherrellTherrell, and D.A. Gay, 1998. The Lost , and D.A. Gay, 1998. The Lost

Colony and Jamestown Droughts. Colony and Jamestown Droughts. ScienceScience 280, 280,

564564--567.567.

Tree ringsTree rings

Reconstructed Palmer Drought Severity Index for Columbia

River Basin (gray), and the reconstructed Columbia River

Flow for The Dalles, Oregon (black)--five-year running

average filter. From Gedalov, Peterson, & Mantua, 2004.

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Time series of tree rings over 3000 Time series of tree rings over 3000 yrs in Pacific NW, including yrs in Pacific NW, including individual subfossil treesindividual subfossil trees (unfiltered (unfiltered

data)data). . Compiled by Pat PringleCompiled by Pat Pringle

landslide deposit

Spider Lake, SE Olympic Mountains -- 1992 drought

Subfossil trees Subfossil trees ~ 1000 ybp~ 1000 ybp

Land areas will warm more than oceans Land areas will warm more than oceans ------greatest warming at high latitudesgreatest warming at high latitudes

Annual mean temperature change, 2071 to 2100 relative to 1990: Global Average in 2085 = 3.1oC

Increasing Melt Area on Greenland

• 2002 all-time record melt area• Melting up to elev. of 2000 m• 16% increase from 1979 to 2002

Satellite-era record melt of 2002 was exceeded in 2005.Source: Waleed Abdalati, Goddard Space Flight Center

70 meters thinning in 5 years

West Antarctic Ice Sheet= 5 m global sea level

IPCC fig. SPM.1IPCC fig. SPM.1

Atmospheric concentrations of carbon dioxide, methane and nitrous oxide over the last 10,000 years (large panels) and since 1750 (insets). Data from ice cores (different colors - different studies) and atmospheric samples (red). Corresponding radiative forcings are on right hand axes of the large panels. {Figure 6.4}

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External Causes of Climate External Causes of Climate ChangeChange

•• changes in incoming solar radiation (sun, changes in incoming solar radiation (sun, volcanism)volcanism)

•• changes in the composition of the changes in the composition of the atmosphere (GH gases)atmosphere (GH gases)

•• changes in the Earthchanges in the Earth’’s surface (albedo, s surface (albedo, tectonics, foreststectonics, forests……))

•• Emissions of COEmissions of CO22 and other greenhouse gases areand other greenhouse gases are

by no means the only way to change the climateby no means the only way to change the climate..

Climate Change and Feedback Climate Change and Feedback MechanismsMechanisms

•• positive feedback mechanismspositive feedback mechanisms

•• negative feedback mechanismsnegative feedback mechanisms

•• Ex: water vaporEx: water vapor--greenhouse feedbackgreenhouse feedback

•• Ex: snowEx: snow--albedo feedbackalbedo feedback

•• Feedbacks cause climate changes to be either Feedbacks cause climate changes to be either

amplified or reduced.amplified or reduced.