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ATMOS 397GATMOS 397GBiogeochemical Cycles and Global ChangeBiogeochemical Cycles and Global Change

Lecture 1: An IntroductionLecture 1: An Introduction

Don WuebblesDon Wuebbles

Department of Atmospheric SciencesDepartment of Atmospheric Sciences

University of Illinois, Urbana, ILUniversity of Illinois, Urbana, IL

January 21, 2003January 21, 2003

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Course Syllabus HighlightsCourse Syllabus Highlights

Will use 2 texts plus handouts Biogeochemistry: An Analysis of Global Change, by W.

H. Schlesinger, Academic Press, 1997 (required). Earth System Science, by M. C. Jacobson, R. J.

Charlson, H. Rodhe, and G. H. Orians, Academic Press, 2000 (recommended).

Grading Midterm exam 25% Final exam 25% Homework 10% Class participation 20% Special project 20%

Special Project: A research project where you together act as a research team

Course schedule

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Why Study Biogeochemical Cycles?Why Study Biogeochemical Cycles?

Number 1 of the Grand Challenges in Environmental Sciences National Academy of Sciences, 2001

“ The challenge is to further our understanding of the Earth’s major biogeochemical cycles, evaluate how they are being perturbed by human activities, and determine how they might better be stabilized.”

Major research areas: Quantifying the sources and sinks of the nutrient elements and

gaining a better understanding of the biological, chemical and physical factors regulating them.

Improve understanding of the interactions among the various biogeochemical cycles.

Assessing anthropogenic perturbations of biogeochemical cycles and their impacts on ecosystem functioning, atmospheric chemistry, and human activities.

Developing a scientific basis for societal decisions about managing these cycles.

Exploring technical and institutional approaches to managing anthropogenic perturbations.

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The Carbon CycleThe Carbon Cycle

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Why study biogeochemical cycles (cont.)Why study biogeochemical cycles (cont.)

NSF Geosciences Beyond 2000 includes as Primary Challenges

Determining how the biogeochemical cycles of carbon, nitrogen, oxygen, phosphorous, and sulfur are coupled.

Environmental Science and Engineering for the 21st Century: The Role of the National Science Foundation February 2000

Lists biogeochemical cycles and carbon cycle terrestrial-atmospheric-oceanic connections as key areas for enhanced research.

U.S. Global Change Research Program, which includes DOE, NASA, NOAA, NSF has as a major emphasis to better understand the carbon cycle -- $220M in FY2002

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Biogeochemical CyclesBiogeochemical Cycles

Six nutrient elements make up 95% of the biomass mass on earth and form the biochemical foundation for life.

Carbon (CO2, CH4, CO)

Nitrogen (N2O, NO, NO2, NH3)

Sulfur (SO2, COS, H2S, H2SO4)

Phosphorous

Hydrogen

Oxygen

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COCO22 Concentration Growth since 1958 Concentration Growth since 1958

310

320

330

340

350

360

370

380p

pmv

1960

1964

1968

1972

1976

1980

1984

1988

1992

1996

2000

Year

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300

250

200

450 300 150 0150

450

400

350

600

550

500

700

650

Age of Entrapped Air (kyr BP)

Vostok Record

IPCC IS92a Scenario

Current (2001)

Projected (2100)

Contemporary Record

• • Atmospheric COAtmospheric CO22has has increased by 31% since increased by 31% since 1750.1750.

• • TheThepresent amount of present amount of COCO22has likely not been has likely not been exceeded during the exceeded during the past 20 million yearspast 20 million years

••The current rate of The current rate of increase of COincrease of CO22is is unprecedented in the unprecedented in the past 20,000 years.past 20,000 years.

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Increasing Carbon DioxideIncreasing Carbon Dioxide

The Natural Carbon Cycle

(Pg-C = Gton-C, Pg-C/yr)

The Human Perturbation

(for 1980s)

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Mann et al. (1999)

1000 year reconstruction

~ 0.7 oC (~ 1.3 oF) increase in global surface temperature during last 140 years

(IPCC, 2001)

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Radiative Forcing on ClimateRadiative Forcing on Climate

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Projected Global Surface Temperature Response:Projected Global Surface Temperature Response: ~ 2.5 to 10.4 °F by 2100 ~ 2.5 to 10.4 °F by 2100

Relative to 1990

Projected changes in emissions and concentrations of greenhouse gases could lead to large changes in climate over the century

With recent advances in climate model’s ability to represent the earth-atmosphere system, there is now a wider range in potential global and hemispheric-level change due to the range in possible emission scenarios than the range in model results

With recent advances in climate model’s ability to represent the earth-atmosphere system, there is now a wider range in potential global and hemispheric-level change due to the range in possible emission scenarios than the range in model results

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Length of growing season projected to continue to increase

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From Randy Kawa

From Terry Root

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Methane trend

From NOAA CMDL

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CH 4CH 4

CH 4

CH 4

Atmosphere

floodwater

ebullitiondiffusion

CH 4

Anaerobic Soil(CH production)4

rice plant

The Soil-Water-Plant ecosystememitting methane to the atmosphere

aerobic-anaerobicinterface

(CH oxidation)4

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From Jon Foley

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