Climate has changed

CLIMATE has changed significantly

in the PAST

and has definitely changed in

RECENT DECADES

Vostok ice core record (Temp, CH4, CO2)

Adapted from: Petit et al., NATURE, 399: 429-436 (1999)

(For this diagram, please see:

Mann, Michael E. “The Value of Multiple Proxies.” Science 297 (30 August 2002): 1481-2. NH temperature histories.

http://www.sciencemag.org/cgi/reprint/297/5586/1481.pdf)

(For this diagram, please see:

Intergovernmental Panel on Climate Change. “Summary for

Policymakers: A Report of Working Group I of the

Intergovernmental Panel on Climate Change.” Figure 1(a), p. 3.

“Climate Change 2001: Synthesis Report.”

http://www.ipcc.ch/pub/un/syreng/wg1spm.pdf)

WHAT IS THE NATURE

OF THE SYSTEM THAT

DETERMINES CLIMATE?

The Earth is a Dynamic System

…That Changes on all Time Scales

Courtesy of the Intergovernmental Panel on Climate Change. Used with permission.

ENERGY BALANCE IN THE CLIMATE SYSTEM

WHAT ARE THE VERTICAL FLOWS OF ENERGY

THAT DETERMINE GLOBAL TEMPERATURES?

THE FUNDAMENTAL UNITS WE WILL USE TO MEASURE FLOWS ARE WATTS/(METER)2

IPCC_TAR_Working Group 1_1.2. Courtesy of the Intergovernmental Panel on Climate Change. Used with permission.

HUMAN & OTHER INFLUENCES ON CLIMATE

HOW IS THE COMPOSITION OF THE

ATMOSPHERE CHANGING?

HOW HAVE THE ENERGY FLOWS CHANGED

SINCE PRE-INDUSTRIAL TIMES?

RADIATIVE FORCING (watt/m2) IS THE CHANGE IN THE VERTICAL ENERGY FLOW (at the tropopause) INDUCED BY CHANGES IN

GREENHOUSE GASES, AEROSOLS, & OTHER CLIMATE FORCING

PROCESSES

i .FIGURE 2: Long records of past changes in atmospheric composition provide the context for the influence of anthropogen c emissions

Courtesy of the Intergovernmental Panel on Climate Change. Used with permission.

AEROSOL EFFECTS

sunlight

smaller cloud droplets which (1) increases reflection, and (2) suppresses rainfall

(C) Semi-direct effect: absorbing aerosols heat air and cool surface suppressing convection and condensation

(A) Direct Effect: aerosols reflect or absorb

(B) Indirect Effects: aerosols create more and

MASSAC

HUSETTS

INSTITUTE OF TECH

NOLO

GY

ALE/GAGE/AGAGE CCl3F monthly mean mole fractions and standard deviations.

EFFECTS OF MONTREAL PROTOCOL

Climate Forcings 1850 to 2000

F ( W

/ m

2 )

Courtesy of the Intergovernmental Panel on Climate Change. Used with permission.

Hansen, J., R. Ruedy, M. Sato, and R. Reynolds. "Global surface air temperature in 1995: Return to pre-Pinatubo level." Geophys. Res. Lett. 23, no. 13(1996): 1665-1668. Copyright [1996] American Geophysical Union. Reproduced/modified by permission of American Geophysical Union.

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