Dr Zoe Robinson, Keele University, [email protected] C-Change in GEES: Introduction to the Causes of Climate Change – Earth Surface Causes

Dr Zoe Robinson, Keele University, [email protected]

C-Change in GEES: Introduction to the Causes of Climate Change – Earth Surface Causes

C-Change in GEES

Introduction to the Causes of Climate Change

Session 2Session 2:

Earth Surface Causes



How to use these teaching slides These slides are not intended to form a complete lecture

on the session topic. These resources are designed to suggest a framework to

help tutors develop their own lecture material The resource slides comprise where appropriate; key

points, case studies, images, references and further resources.

These resources may be used for educational purposes only, for other uses please contact the author

These slides were last updated in January 2010



DisclaimerLinks within this presentation may lead to other sites. These are provided for convenience only. We do not sponsor, endorse or otherwise approve of any information or statements appearing in those sites. The author is not responsible for the availability of, or the content located on or through, any such external site. While every effort and care has been taken in preparing the content of this presentation, the author disclaims all warranties, expressed or implied, as to the accuracy of the information in any of the content. The author also (to the extent permitted by law) shall not be liable for any losses or damages arising from the use of, or reliance on, the information. The author is also not liable for any losses or damages arising from the use of, or reliance on sites linked to this site, or the internet generally.Pictures, photographs and diagrams within this presentation have been produced by the author unless otherwise stipulatedNo content within this resource is knowingly an infringement of copyright. Any infringement can be immediately rectified on notification of the author of the resource



Session Outline

• Plate tectonic controls on climate

• Chemical weathering and climate

• Land use change and climate

Changes in the distribution of land mass can affect climate

Tectonic PlatesSource: USGS



Earth Surface Change

• Plate tectonics:– Continent latitude– Continent size– Ocean gateways– Mountain building

• Land cover

Affects: - ocean circulation

- atmospheric circulation - atmospheric composition - radiation balance

Source: Faisal.Saeed (Flickr.com)



Changing position and amalgamation of landmasses affects climate due to changes to:

– Latitude (ice sheet generation)

– Atmospheric circulation and meteorological effects

– Continentality

Distribution of energy received at the Earth’s surface – units in W/m2 (Smithson et

al., 2002, p43)

Glaciation in the Permo-Carboniferous maybe related to the presence of a

sizeable continental landmass at polar latitudes

Continent Size and Latitude



Continental Pressure Systems

Continent geometry affects seasonal shift in atmospheric patterns

Strong high pressure systems dominate continental areas in winter, low pressures in summer

Formation of pressure systems over continents. High pressure over continents in winter

Exaggerated effect with super-continents

NOAA 2002

Need to ask permission



Super-continents and Climate Change

Pangaea ~250 Ma

Temperature of continent determined by size and latitude Continental temperature variation increases with size and latitude

Glacial deposits in South America, Africa, India and Australia.

Postulate a single continental glacier flowing over the South-Polar regions of Gondwanaland in Permian times

Increased seasonal variation in temperature

Pangaea - summer monsoons either side of Tethys ocean, extensive aridity in continental interior



Tectonic factors affect ocean circulation and heat transport

At a global scale differences in salt concentration between the Atlantic and Pacific oceans drives a ‘global conveyor’

A 3D circulation pattern.

Land Masses and Ocean Circulation

North Atlantic Deep Water (NADW)– critical component of circulation - sinking of cold, saline water north of Iceland which then flows south.

Draws surface waters up from the Gulf of Mexico (Gulf Stream)Image: NASA



The Isthmus of Panama and northern hemisphere glaciation

• Postulated cause of northern hemisphere glaciation.

• Closure of ‘gateway’ 13-1.9 Ma and changes to ocean circulation 4.6Ma

• Intensified Gulf Stream – increased quantity of warm and saline masses to high latitudes

• Evaporation leads to increased moisture supply

• Moisture supply a precondition for ice sheet growth triggered by incremental changes in

Earth’s obliquity

Or closure of Indonesian seaway? (Cane and Molnar, 2001)

See: Haug, G.H. and Tiedemann, R. 1998.

Effect of the formation of the Isthmus of Panama on

Atlantic Ocean thermohaline circulation.

Nature 393: 673-676

Source: US CIA World Factbook



The Thermohaline Circulation (THC)

• Transfer of heat and salt around oceans

• Gulf Stream and North Atlantic Deep Water formation an important part of the global thermohaline circulation

• As much as 50% of Europe’s winter energy budget from the Gulf Stream

• Change in thermohaline circulation possible climate triggering/amplification mechanism

• Explanation of large and abrupt change (Broecker, 1997)

Oceans play a major role in triggering/amplifying change in the climate record

Image: NASA



Slow thermohalinecirculation

Decrease NADW formation

Increase freshwater fluxto ocean

Cooling at higher latitudes

Increase warming

Decrease albedo

The result:A New Ice Age??

Decrease in cryosphere

Positive feedback loop

Some models shut THC down in 100-1000 years if 3.4 to 7.4°C

warming reached



Orogenesis and Climate Change

Mountain building affects climate by:• Raising land

(greater/longer snow cover at higher elevation – albedo effects)

• Change to atmospheric circulation

• Increasing chemical weathering leading to decreasing atmosphericCO2

Turquoise colour identifies regions of orogenic uplift

Source: USGS



Late Cenozoic Uplift

Theory of widespread Late Cenozoic uplift associated with climatic deterioration of the Neogene (Raymo and Ruddiman, 1992)

Geological evidence is ambiguous:

Different estimates based on fossil floras, eroded sediments…

Has climate change simulated uplift?

Areas described as having undergone uplift in the Late

Neogene

Hay et al. (2002)

Hay, W.H. et al. (2002) The Late Cenozoic uplift–climate change paradox. International Journal of Earth Sciences, 91, 746-774



Atmospheric CirculationTibetan plateau

Formed by the collision of Indian and Asia plate ~50 Ma ago

Led to the development of stronger wetter monsoons in S Asia

Increasing aridity in areas – led to increased dust in the atmosphere (feedbacks?)

Digital Elevation Model of Tibetan plateau Source: Jide (GTOPO)

Reorganization of atmospheric circulation patterns - see Dettman et al. (2003)



Modelling Plate Tectonic Effects

• Modelling of palaeogeography and circulation models to determine how changes affect climate

• Compare modelled climate with palaeoclimate records

• e.g. Ramstein et al., 1997

Retreat of Paratethys - an epicontinental sea

Shift in Asian climate from temperate to continental conditions

http://en.wikipedia.org/wiki/File:World_map.png

Tectonic changes in the late NeogeneDavid Monniaux



Weathering and Climate

Amount of CO2 in the atmosphere affects global temperature - the greenhouse effect

Atmospheric CO2 removed by chemical weathering

CaCO3 + CO2 + H2O Ca2+ + 2HCO3-

CaSiO3 + 2CO2 + H2O Ca2+ + 2HCO3- + SiO2

Dissolution of carbonates

Dissolution of silicates



However…

…on geological timescales only weathering of silicates affects atmospheric CO2

Precipitation of CaCO3

The precipitation of CaCO3 drives an increase in oceanic CO2 and therefore an increase in atmospheric CO2

CO2 drawdown from weathering depends on the hydrological cycle, temperature, exposure of material

(mechanical weathering), rock type

Ca + 2HCO3 CaCO3 + CO2 + H2O



Long-term Controls on Atmospheric CO2

BLAG hypothesis (Berner, Lasaga and Garrels) – Over long timescales -

atmospheric CO2 levels are controlled by the balance between volcanic input and output from chemical weathering

60-52 Ma CO2 >2000 ppmSince 24 Ma CO2 < 500 ppm

(Pearson and Palmer, 2000)

Volcanic outgassing

Chemical weathering

Atmospheric CO2

Berner, R.A. and Barron, E.J. (1984) Comment on the BLAG model: factors

affecting atmospheric CO2 and temperature over the past 100 million years. American

Journal of Science, 284, 1183-1192



Enhanced Weathering and Uplift

One theory is that uplift of the Tibetan plateau caused Cenozoic global cooling:

• Tectonically driven increases in chemical weathering

Raymo, M.E. and Ruddiman, W.F. (1992) Tectonic forcing of late Cenozoic climate. Nature, 359, 117-122.



Geochemical Weathering

Uplift

Increased chemical weathering

Increase rockfragmentation

Glaciation

Increase flushing of weathered products

Increase orographicprecipitation

Decrease atmospheric CO2

Global cooling

Uplift

Increased chemical weathering

Increase rockfragmentation

Glaciation

Increase flushing of weathered products

Increase orographicprecipitation

Decrease atmospheric CO2

Global cooling



Factors Affecting Chemical Weathering

• Uplift• Sea level• Glaciation• Continental latitude• Continent size• Carbonate vs silicate

lithologies• Climatic variables



Snowball Earth: ‘Encapsulating Climatic Catastrophe’

• Global glaciation during Neoproterozoic (1000 to 543 Ma) - end of Precambrian

• Glaciation within 10o of equator

• Stratigraphic correlation of Neoproterozoic glacial deposits

• Sharp stratigraphic definition, with ‘cap carbonates.’www.celestiamotherlode.net

Collapse in biological productivityGeologically sudden lowering of surface mean T to around –50°C

Reduction in energy forcing to critical level to become completely frozen planet



The Theory….

Shutdown of hydrological cycle and heat exchange

Gradual (3-30Ma) accumulation of volcanically-derived greenhouse gases

Warming and intensification of hydrological cycle

Deglaciation – positive feedback – rapid

Intense terrestrial weathering and transfer of CO2 to oceans –cap carbonate formation (see Hoffman et al. 1998)

Temperature drops – albedo increases

Cessation of continental weathering



Other Earth Surface Changes

• Land cover/vegetational cover affects:– Albedo– Evapotranspiration– Frictional drag– Atmospheric composition

• Volcanism– mountain building– lithology– atmospheric composition

Volcanic eruptionSource: NASA



Land Surface Changes• Terrestrial changes in summer

albedo contribute to high latitude warming

• Correlation between summer warming in Arctic Alaska and lengthening snow-free period

• Increased atmospheric heating by 3 W/m2/decade (similar to heating expected from doubling CO2)

• Could be amplified by change in vegetation

• See Chapin III et al. (2005)

Temporal air temperature anomaly from long-term mean in Alaska

Changes in land use may have a direct effect on temperature

(Kalnay and Cai, 2003)

From: Chapin III, F.S. et al (2005) ‘Role of land-surface changes in Arctic summer warming’. Science, 310, 657-660 Reprinted with permission from AAAS. This figure may be used for non-commercial, classroom purposes only. Any other uses require the prior written permission of AAAS



Modelled Natural and Anthropogenic Change to Land Cover

Figure source: Fig 2.15 IPCC (2007) Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA,



Key Points – Earth’s Surface

• Earth surface changes (e.g. continent size, location, uplift, changes to ocean gateways etc.) affect climate change through changes to the atmospheric and oceanic circulation.

• Earth surface changes may also affect climate through controls on atmospheric composition and radiation balance.

• Feedbacks add complexity to the Earth surface-climate system

• Many changes to the Earth’s surface affect atmospheric composition and hence climate

• Earth surface conditions are a prerequisite for orbital forcing to have climatic impact (requires land at high latitudes)



Internal Factors of Climate Change

Atmospheric composition

Earth Surface Changes

ClimateChange

+ orbital factors



ReferencesBerner, R.A. and Barron, E.J. (1984) Comment on the BLAG model: factors affecting atmospheric CO2 and temperature over the past 100 million years. American Journal of Science, 284, 1183-1192

Broecker, W.S. (1997) ‘Thermohaline circulation, the Achilles heel of our climate system: Will man-made CO2 upset the current balance?’ Science, 278, 1582-1588.

Cane, M. A., and Molnar, P. (2001) Closing of the Indonesian seaway as a precursor to east African aridification around 3–4 million years ago, Nature, 411, 157-162.

Chapin III, F.S. et al (2005) ‘Role of land-surface changes in Arctic summer warming’. Science, 310, 657-660.

Dettman, D. et al (2003) ‘Uplift-driven climate change at 12 Ma: a long δ18O record from the NE margin of the Tibetan plateau’ Earth and Planetary Science Letters 214(1-2): 267-277

Haug, G.H. and Tiedemann, R. (1998) Effect of the formation of the Isthmus of Panama on Atlantic Ocean thermohaline circulation. Nature 393: 673-676

Hay, W.H. et al. (2002) The Late Cenozoic uplift–climate change paradox. International Journal of Earth Sciences, 91, 746-774

Hoffman, P.F., Kaufman, A.J., Halverson, G.P. and Schrag, D.P. (1998) ‘A Neoproterozoic Snowball Earth’ Science 281(5381): 1342-1346

Kalnay, E and Cai, M. (2003) ‘Impact of urbanization and land-use change on climate’. Nature, 423, 528-531.



Pearson, P.N. and Palmer, M.R. (2000) ‘Atmospheric carbon dioxide concentrations over the past 60 million years’ Nature 406: 695-699

Ramstein, G. et al. (1997) ‘Effect of orogeny, plate motion and land-sea distribution on Eurasian climate change over the past 30 million years’ Nature 386: 788-795

Raymo, M.E. and Ruddiman, W.F. (1992) Tectonic forcing of late Cenozoic climate. Nature, 359, 117-122.

Smithson, P., Addison, K. and Atkinson, K. (2002) ‘Fundamentals of the Physical Environment’ (3rd edition). Routledge.

Strahler, A. and Strahler, A. (2003) ‘Introducing Physical Geography’ (2nd Ed.) Wiley

References (cont)



This resource was created by the University of Keele and released as an open educational resource through the 'C-change in GEES' project exploring the open licensing of climate change and sustainability resources in the Geography, Earth and

Environmental Sciences. The C-change in GEES project was funded by HEFCE as part of the JISC/HE Academy UKOER programme and coordinated by the GEES Subject Centre.

This resource is licensed under the terms of the Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales license (http://creativecommons.org/licenses/by-nc-sa/2.0/uk/).

However the resource, where specified below, contains other 3rd party materials under their own licenses. The licenses and attributions are outlined below:

1. Slide 25: Graph is from Chapin III, F.S. et al (2005) ‘Role of land-surface changes in Arctic summer warming’. Science, 310, 657-660 Reprinted with permission from AAAS. This figure may be used for non-commercial, classroom purposes only. Any other uses require the prior written permission of AAAS

2. The name of the University of Keele and its logos are unregistered trade marks of the University. The University reserves all rights to these items beyond their inclusion in these CC resources.

3. The JISC logo, the C-change logo and the logo of the Higher Education Academy Subject Centre for the Geography, Earth and Environmental Sciences are licensed under the terms of the Creative Commons Attribution -non-commercial-No Derivative Works 2.0 UK England & Wales license. All reproductions must comply with the terms of that license



Author Dr Zoe Robinson

Stephen Whitfield

Institute – Owner Keele University, School of Physical and Geographical Sciences

Title Earth Surface Causes of Climate Change Powerpoint Presentation

Date Created January 2010

Description Earth Surface Causes of Climate Change – Powerpoint Presentation – Part Two of Introduction to the Causes of Climate Change

Educational Level 2

Keywords (Primary keywords – UKOER & GEESOER)

UKOER, GEESOER, plate tectonics, continent, ocean gateways

Creative Commons License Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales

Item Metadata

Documents

Dr Zoe Robinson, Keele University, [email protected] C-Change in GEES: Introduction to the Causes of Climate Change – Earth Surface Causes