The Current Interglacial (Holocene)

AOS 528, 11/29/07

Approximately 11,600 years ago to the present

Increasingly modified by human activities• Land use causes local climate effects• Altered atmospheric composition causes global

climate effects

Records of long and short-term climate change:• Alpine glaciers• Monsoons• El Niño-Southern Oscillation

The Holocene

Orbital Variations

Volcanic eruptions• Changes in amplitude and occurrence

Solar luminosity variations• Much study (Particularly at NASA. Why?),• Minimal effects

Greenhouse gas concentrations

Waning Ice Sheets• Effects on albedo and atmospheric circulation

Holocene Climate Forcings

Orbital Variations

Volcanic eruptions• Changes in amplitude and occurrence

Solar luminosity variations• Much study (Particularly at NASA. Why?),• Minimal effects

Greenhouse gas concentrations

Waning Ice SheetsEffects on albedo and atmospheric circulation

Holocene Climate Forcings

The Holocene and Orbital Variations

N. HEM. SUMMER INSOLATION

Incident Shortwave Radiation over Land, Ocean and GloballyIncident Shortwave Radiation at 10Kyr, 6Kyr, and 0Kyr BPSpecified SSTPredicted SST

NW African Climate

INSOLATION and PRECIP EFFECTS

deMenocal et al., Science, 2000

Summer Radiation

(W/m2)

SimulatedPrecipitation Change incentimeters

www.cgd.ucar.edu/asr/asr03/ccr/index.html

INSOLATION and PRECIP EFFECTS

Source: PMIP (Paleoclimate Model Intercomparison Project) and theGlobal Lake Status Database, (GLSDB: Kohfeld and Harrison, 2000, Harrison et al., 2003)

Effect of Insolation on the African Monsoon

Holocene Greenhouse Gases

Known from ice cores

Carbon Dioxide (CO2)• 10-8kyr: decreases 7ppm• 8kyr-preindustrial: increases 20ppm

Methane (CH4)• 10-6kyr: decreases 150ppb• 6-preindustrial: increases 150ppb

Nitrous Oxide (N2O)10-8kyr: decreases 10ppb8-2kyr: increases 10ppb

Holocene Greenhouse Gas Forcing

Total combined Holocene greenhouse gas forcing was about 0.5 W/m2

•CO2 = 0.4 W/m2

•N2O+CH4 = 0.1 W/m2

Flueckiger et al., 2002

N2O

CH4

CO2

T

The Anthropocene?

Why were GHG concentrations varying before the industrial age?

Ruddiman, 2005http://www.realclimate.org/index.php/archives/2005/12/early-anthropocene-hyppothesis/

Term Paper Instructions

3. Required sections:

a) Introductionb)Model Descriptionc) Experiment Descriptiond)Resultse)Discussion

(interpret and contextualize results)

f) Conclusions(and Future Work)

Term Paper Instructions

1. Due dates: December 8th and 13th (midnight)

2. Term Paper Instructionsa)10-15 pages, single-spaced

including:- Title page- Figures- References (at least 5)

b)1 inch margins, 12pt fontc) All figures must have captionsd)Each person must contribute some

material

Term Papers Due Dec. 13th

Presentations: Thursday, December 6th (during class)

Group 2: Phillips, SchiferlThe Effectiveness of the Kyoto Protocol

Group 7: Schmidt, Bruskewitz, Serwe:Title?

Group 8: Schuh, Moore, OlsonEffects of Global Warming on Agriculture Production in the Midwest

Group 9: Kirchner, Shewczyk, WelhouseGlobal Climate Change's Effects On Agriculture

Group 10: Franklin, Obbink, OrlandThe Effects of Orbital Forcings During Mid-Pliocene Global Warming

Presentations: Thursday, December 20th (10:05am)

Group 1: Lubcaynka, Moua, PropheterUS and China's Affect on Global Warming

Group 3: Caruso, Maloney, SchmelzerTitle?

Group 4: Schreiber, Brown"Peak Oil" Predictions and Their Effect on Future Warming

Group 5: Asuma, Caves, KochA Comparison of Global Climate Effects Due to Varying Rates of Methane Introduction

Group 6: Marsicek, Ronnei, McCarvilleUsing Drought Index to Analyze Potential Impacts on the Tropical Rainforest By Increasing CO2 and Solar Luminosity

Group 11: Hladish, KampaA Potential Glacial Maximum in the Future?

Term Papers Due Dec. 8th