Orbital Forcing on Climate Finish Climates of Geologic Time Introduction to Orbital Factors Axial Tilt Axial Precession Changes in Earth’s eccentric orbit.

Slides:



Advertisements
Similar presentations
Orbital Theory of Ice Ages
Advertisements

It all begins with the sun……
GEOS 112 Lecture Topics 4/28/03 Read Chapter 12 (Glaciers) Final Exam – Monday, May 5 1:00pm 1.Types of Glaciers; 2.Glacier Formation, Mass Balance, and.
Global Air temperature from 1850 The time series shows the combined global land and marine surface temperature record from 1850 to The year 2007.
Climate Variability on Millennial Time Scales Introduction Dansgaard-Oeschger events Heinrich events Younger Dryas event Deglacial meltwater Meridional.
Deglaciation Timing of Millennial-Scale Climate Change in Antarctica and Greenland During the Last Glacial Period Thomas Blunier and Edward Brook, 2001.
1 Last Glacial Maximum (~20K yrs ago) and afterwards What was climate like during LGM? What happened to end LGM? How has climate varied since LGM? What.
Seasonal & Diurnal Temp Variations ATS351 Lecture 3.
14.3 Climatic Changes.
Lecture 34: Orbital (Milankovitch) Theory of the Ice Ages
Abrupt Climate Change Evidence of climate changes that are too abrupt to be explained orbitally.
Lecture 34: Orbital (Milankovitch) Theory of the Ice Ages
Lecture 7 Paleoclimate and the Ice Ages. Ruth Valley Glacier Alaska--The glacier occupying Yosemite Valley probably looked similar.
Myr ago Puzzle: Ice Ages! Occur with a period of ~ 250 million yr Cycles of glaciation within the ice age occur with a period of 40,000 yr Most recent.
Fossils, Paleoclimate and Global Climate Change. Global Warming CO 2 levels in the atmosphere rising Average global temperature is rising Polar ice caps.
Natural and Human Influences on Climate Change
Determining Past Climates Sediment cores Ice cores Oxygen isotope ratios Dendrochronology (tree rings )
Gyroscope.
The dominant periodicities are the same as those from astronomical calculations of changes in the Earth’s orbital parameters.
Earth Sun Geometry.
Climates of Geologic Time Current Weather Finish Ice Core Research Overview and Historical Perspective The Pleistocene and Holocene For Next Class: Read.
Causes of Climate Change anthropogenicand natural causes Physical Fundamentals of Global Change WS 2006/2007 Ina Sahlmann.
Paleoclimatology Why is it important? Angela Colbert Climate Modeling Group October 24, 2011.
Natural Climate Variability Spring 2012, Lecture 10 1.
Climate & Climate Change Objectives: 1. What factors affect climate? 2. What is El Nino & how does it work? 3. What causes ice ages? 4. How can scientists.
CE 401 Climate Change Science and Engineering orbital variations and climate, aerosols, carbon cycle 25 January 2011.
What is an Ice Age ? Ice ages are times when large areas of the earths surface are covered with ice sheets The term is used to describe time periods when.
NATS 101 Section 13: Lecture 32 Paleoclimate. Natural changes in the Earth’s climate also occur at much longer timescales The study of prehistoric climates.
Ch : Climate & Climate Change Objectives: 1
OC 450: Orbital Controls on Climate (Chaps 8 and 10) Main Points: Small cyclic variations in the earth’s orbital characteristics affect the distribution.
History of Climate Change  During earth’s history, climate has generally been warmer than it is today, but is periodically interrupted by short cooler.
Lecture 8 The Holocene and Recent Climate Change.
Quaternary Environments Climate and Climatic Variation.
MORE ON CLIMATE. WEATHER IS NATURE’S MECHANISM TO BLANCE TEMPORARY DIFFERENCES IN PRESSURE WITHIN OVERALL ATMOSPHERIC CIRCULATION. WHEN THE DIFFERENCES.
Insolation and the Seasons
The Climate System Lecture 1 Ecological Climatology.
Chapter 8 Astronomical Control of Solar Radiation 1.Changes in Earth’s axial tilt through time 2.Changes in Earth’s Eccentric Orbit through time 3.Precession.
DAISY WORLD, LIGHT/DARK DASIES EFFECT OF DASIES ON GLOBAL CLIMATE.
Module 4 Changes in Climate. Global Warming? Climate change –The pattern(s) of variation in climate (temperature, precipitation) over various periods.
CLIMATE CHANGE THE GREAT DEBATE Session 5.
MILANK OVITCH cycles. What are the Milankovitch Cycles They are a series of theoretical cycles presented by Yugoslav Astronomer Milutin Milankovitch that.
Dr Mark Cresswell FOLLOWED BY: Solar Practical Solar and Milankovitch Forcing 69EG5513 – Climate & Climate Change.
SC.912.E.7.2: Analyze the causes of the various kinds of surface and deep water motion within the oceans and their impacts on the transfer of energy between.
Climate Change Monday, November 5th. Anthropogenic Climate Change Thomas Jefferson, 1781 Notes on the State of Virginia –Springs are warmer –Less winter.
Class #39: Friday, April 171 Mechanisms of Climate Change Natural and Anthropogenic.
Factor Influencing Climate Change Tectonics Ocean Circulation Patterns and the Thermohaline Cycle Orbital Forcing Mechanisms Atmospheric Variations.
Discuss the relationship between climate and biomes.
History of Climate Change  During earth’s history, climate has generally been warmer than it is today, but is periodically interrupted by short cooler.
An Orbital Theory For Glacial Periods
Climate Change Ch. 12 Study Guide. 1. Identify 2 physical features and explain how they influence the climate. Latitude Elevation.
 On a climograph, what data are represented with bars? ◦ What data are represented with a line graph?  How can you determine the climate classification.
Weather, Climate and Society ATMO 336 Seasons Orbital Variations and Ice Ages.
Ice Age Ice Age, a time when ice sheets and alpine glaciers were EXTENSIVE, and advanced and receded repeatedly over LONG PERIODS of time.
Climate. Weather vs. Climate Weather – the condition of Earth’s atmosphere at a particular time and place. – Short-term: Hours and days – Localized: Town,
Climate and the Seasons
1 MET 112 Global Climate Change MET 112 Global Climate Change - Lecture 6 Natural Climate Forcing Dr. Eugene Cordero San Jose State University Outline.
Orbital Hypothesis of Climate Change & Pleistocene Ice Ages.
Milankovitch, 1937 Orbital Theory of Ice Ages
Lecture 20: Orbital Variations in Ice Sheets (Milankovitch Cycles)
Climates of Geologic Time
Milankovitch cycles/ Chaotic obliquity variations
Long and Short Term Changes in Climate
Long-term climate change & Short-term climate variability
Climate and the Seasons
“The Science Behind Media Reports”
Lecture 18: Orbital Variations
Do Now Please take out your Milankovitch Cycles Packet.
Earth Sun Geometry.
Climate Surprises Current Weather and News Abrupt Climate Changes
Historical Climate Change
Presentation transcript:

Orbital Forcing on Climate Finish Climates of Geologic Time Introduction to Orbital Factors Axial Tilt Axial Precession Changes in Earth’s eccentric orbit Precession of the Ellipse For Next Class: Read Ruddiman Ch. 9 (AsUlearn) Exam 2 on October 8 th !

© AMS6 Climates of the Pleistocene Ice Age  Chronology and Temperature Trends Last major glacial climatic episode began about 27,000 years ago and reached its peak about 20,000 to 18,000 years ago Last major glacial climatic episode began about 27,000 years ago and reached its peak about 20,000 to 18,000 years ago

© AMS7 Climates of the Pleistocene Ice Age

© AMS8 Climates of the Holocene  The Holocene Epoch is the present interglacial Glacial ice withdrew from North American Great Lakes region about 10,500 years ago Glacial ice withdrew from North American Great Lakes region about 10,500 years ago Civilization and agriculture developedCivilization and agriculture developed Holocene has had spatially and temporally variable temperature and precipitation Holocene has had spatially and temporally variable temperature and precipitation

Global climate transitioned from a cold glacial (Pleistocene) to a warmer interglacial (Holocene) approximately 15,000 years ago primarily as a result of orbital forcing. However, two prominent periods of abrupt cooling are evident at the end of the Pleistocene and beginning of Holocene.

Abrupt Climate Changes Theory, models, and paleoclimatic reconstructions have shown that changes in the climate system can be abrupt and widespread. Abrupt climate change: “... occurs when the climate system is forced to cross some threshold, triggering a transition to a new state...” (Alley et al. 2002) “Climate surprises” often used to refer to these abrupt transitions

Responses of a Climate Variable to Forcing

Younger Dryas About 14,500 years ago, the global climate began to transition to a warmer interglacial. Around 13,000 years ago, the climate suddenly or abruptly returned to glacial conditions, cooling 3- 8 °C (even colder across portions of Europe). This period is called the Younger Dryas, named after an Arctic flower that became common across Europe.

NOAA 2011

8.2 ka Cooling Event Another period of abrupt climate change occurred approximately 8,200 years ago and is hence termed the 8.2 ka cooling event. Temperatures were lower and much of the world was much drier. Climate returned to warmer conditions characteristic of the present interglacial after about 150 years.

8.2 ka Event in Paleoarchives NOAA 2011, from Morrill and Jacobson (2005)

Possible Causes of 8.2 ka Event

Day After Tomorrow uCE

Causal Mechanisms Significant influx of freshwater into the North Atlantic appears to have caused both the Younger Dryas cooling and the 8.2 ka cooling event. Freshwater influx changed the density structure associated with meridional overturning circulation (or thermohaline circulation) and caused a slowing or stopping of Gulf Stream circulation.

Orbital Influences on Insolation Variations in axial tilt (41,000 year cycle) Axial precession (25,700 year cycle) Changes in Earth’s eccentric orbit (100,000 year cycle) Precession of the ellipse (23,000 year cycle)

Earth’s Tilt Actually Varies Varies between 22 and 24°, on a 41,000 year cycle

No Tilt vs. 90° Tilt How does the annual pattern of solar radiation vary at the Equator and at the Poles in the two examples on the right? Which scenario would be most favorable for polar ice sheet growth? Tropical glacier advance?

Axial Precession A rotating body like the Earth is subject to a slow wobble.

Changes in Eccentric Orbit Eccentricity, or the shape of Earth’s path around the sun, changes on a 100,000 year cycle Causes changes to the distance away from the sun during the perihelion and aphelion, resulting in subtle differences in insolation.

Precession of the Ellipse The entire ellipse is also subject to slow rotation.

Precession of the Equinoxes Axial precession and precession of the ellipse results in the precession of the equinoxes. A strong cycle is evident on a 23,000 year cycle.

Influences on Solar Radiation

Departure from Modern Insolation