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Causes of Climate Change. anthropogenic and natural causes Physical Fundamentals of Global Change WS 2006/2007 Ina Sahlmann. Introduction Natural Causes Anthropogenic Causes Conclusion. Table of Contents. Introduction. processes, altering the globe continously: Natural Geology

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Causes of Climate Change

anthropogenic

and

natural causes

Physical Fundamentals of Global Change

WS 2006/2007

Ina Sahlmann


Introduction natural causes anthropogenic causes conclusion

Introduction

Natural Causes

Anthropogenic Causes

Conclusion

Table of Contents


Introduction
Introduction

processes, altering the globe continously:

  • Natural Geology

  • Hydrology

  • Atmosphere

  • Biotic Factors


Introduction1
Introduction

processes devided into two types:

internal processesexternal processes

- motion of plate tectonics - solar energy


Introduction2
Introduction

Def. Climate: sub-system of the earth

long term changes of climatologic patterns

subsystems of climate:

atmosphere

hydrosphere

lithosphere

biosphere

Climate change occurred throughout earth's history. Changes may affect the basic environment necessary for our existence.


Natural causes
Natural Causes

Table of Contents:

Plate Tectonics

Configuration of the Continents

Surface Albedo

High-Latitude Land Area

Transfer of Latent Heat

Restrictions to Ocean Currents

Thermal Inertia

Elevation of Continents

Changing Elevation

General Circulation

Regional Climate

Atmospheric Concentration of Carbon Dioxide


Natural causes1
Natural Causes

Table of Contents:

Milankovitch Cycles

Eccentricity

Obliquity

Precession

Volcanoes

Solar Activity


Natural causes plate tectonics
Natural Causes – Plate Tectonics

= motion in earth's astenosphere which causes global scale dynamics of the rigid lithosperic plates

affects climate through 3 major mechanisms:

  • altering the distribution of land masses

  • changing continental elevation

  • variability in atmospheric concentration of carbon dioxide


Natural causes plate tectonics configuration of the continents
Natural Causes – Plate TectonicsConfiguration of the Continents

1. Surface Albedo

= amount of energy reflected by surface

average albedo – tropical forest: 7 %

average albedo – desert: 25 %

lower latitudes receive greater amount of solar radiation

poleward latitudes – less

amount of ocean versus land surface at low latitudes:

great affect of absorbed solar energy or reflection


Natural causes plate tectonics configuration of the continents1
Natural Causes – Plate TectonicsConfiguration of the Continents

2. High-Latitude Land Area

albedo of ice/snow: 65-80 %

the higher the albedo, the more ice/snow can accumulate


Natural causes plate tectonics configuration of the continents2
Natural Causes – Plate TectonicsConfiguration of the Continents

3. Transfer of Latent Heat

= the energy needed for a substance to change states

e.g. water evaporation from ocean and the following precipitation

heat loss over oceanic regions higher than over land


Natural causes plate tectonics configuration of the continents3
Natural Causes – Plate TectonicsConfiguration of the Continents

4. Restrictions to Ocean Currents

oceanic circulation is primary mechanism by which heat is redistributed from equatorial to polar latitudes

transport is blocked by continental barriers

distribution of moisture is affected


Natural causes plate tectonics configuration of the continents4
Natural Causes – Plate TectonicsConfiguration of the Continents

5. Thermal Inertia

oceans have a higher thermal heat capacity than land

summer: solar energy stored

winter: solar energy released


Natural causes plate tectonics elevation of continents
Natural Causes – Plate TectonicsElevation of Continents

1. Changing Elevation

atmospheric temperatures decrease with hight (6,5°C per km)

cold temperatures lead to snow coverage and high albedo


Natural causes plate tectonics elevation of continents1
Natural Causes – Plate TectonicsElevation of Continents

2. General Circulation

oceanic circulation driven by excess heat energy at the equator and a deficit at the poles

wind belts of the earth are influenced by pressure differences across mountain chains

a change in topography may alter the distribution of cold air masses

glaciation

warming of high-latitude regions


Natural causes plate tectonics elevation of continents2
Natural Causes – Plate TectonicsElevation of Continents

3. Regional Climate

different climates on different mountain sides:

luf: wet

lee: rain-shadow effect


Natural causes plate tectonics atmospheric concentration of carbon dioxide
Natural Causes – Plate TectonicsAtmospheric Concentration of Carbon Dioxide

atmospheric carbon dioxide is fixed in the process of weathering of silicates and transported to inner parts of the earth

carbon dioxide is released through:

drifting of the continents (formation of mountains)

volcanic activity

weathering of silicates is accelerated by:

higher temperatures

collision of continents


Natural causes milankovitch cycles
Natural Causes – Milankovitch Cycles

earth's orbital cycle alters:

amount and distribution of heat

periodic glacial & interglacial cycles

3 components:

Eccentricity

Obliquity

Precession


Natural causes milankovitch cycles eccentricity
Natural Causes – Milankovitch CyclesEccentricity

orbit of earth changes shape from circular to elliptical

yearly maximum & mini- mum distance between earth & sun varies

enhanced seasonality


Decreased tilt less sunlight on polar regions increased tilt enhanced seasonality

decreased tilt: less sunlight on polar regions

increased tilt: enhanced seasonality

Natural Causes – Milankovitch CyclesObliquity


Natural causes milankovitch cycles precession

slight wobble in the earth's spin

equinoxes: length of night & day are equal

solistice: max. distance from sun to equator

local distribution and timing of insolation affected

Natural Causes – Milankovitch CyclesPrecession



Anthropogenic causes green house effect
Anthropogenic CausesGreen-House Effect


Anthropogenic causes green house effect1
Anthropogenic CausesGreen-House Effect


Anthropogenic causes green house effect2
Anthropogenic CausesGreen-House Effect


Anthropogenic causes green house effect3
Anthropogenic CausesGreen-House Effect


Conclusion
Conclusion

  • climate system is very complex, changes occur over a wide range of temporal and spatial scales

  • climate parameters change simultaneously

  • the system is continuously responding to each push and pull

  • climate change and their forcing factors are not easily linked


Conclusion1

the main factors influencing the climate are:

Variations in the Earth's orbital characteristics

Computer models and historical evidence suggest that the Milankovitch cycles exert their greatest cooling and warming influence when the troughs and peaks of all three cycles coincide with each other

Atmospheric carbon dioxide variations

Volcanic eruptions

Variations in solar output

Human activities

Conclusion


Literature
Literature

Introduction to the atmosphere. Causes of climate change.http://www.physicalgeography.net/fundamentals/7y.html

What causes global climate change? http://ccir.ciesin.columbia.edu/nyc/ccir-ny_q1a.html

Rahmstorf, S. Schellnhuber, H.J.(2006): Der Klimawandel. München. S. 15ff.

Impacts on the climate system. http://www.geo.umn.edu/courses/1001/climate.html


Comments for ina sahlmann from manfred stock
Comments for Ina Sahlmann from Manfred Stock

  • To be finished .....


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