Section 1Section 1

BackgroundBackground

December 2002

What’s Happening, and What’s Happening, and What Can We ExpectWhat Can We Expect

GLOBAL CLIMATE CHANGE:GLOBAL CLIMATE CHANGE:

What is ‘climate’?

•Climate is ‘average weather’- and its variability- for a particular region- over a period of time

•Includes many different elements

What is ‘climate change’?•Climate change is a shift in ‘climate’ relative to a given reference time period

•It is caused by:

Natural factors-Solar variability

-Volcanic dust levels-Internal variability -Geological change

- Greenhouse gases - Aerosols -Ozone depletion

-Land use change

Human factors

The earth’s atmosphere consists of multiple layers

     

                       

 

 

…and provides several important life supporting services

Protection from solar uv-b(stratospheric ozone)

surface

stratosphere

thunderstormtroposphere

The air we breath (21% oxygen)

Suitable, stable climate

and weather

     

                       

 

 

Reflected Energy~31%

Incoming Solar Energy

Outgoing Heat Energy

Energy TrappedBy Greenhouse Gases

•CO2 0.028%

•CH4 0.0007%

•N2O 0.0003%

The atmosphere’s energy budget is determined by net heat flow

     

                       

 

 

Estimating the Magnitude Estimating the Magnitude of the Natural Greenhouse Effectof the Natural Greenhouse Effect

Net Incoming Solar Energy

Outgoing Heat Energy=

(S0 (1-A) R2) (4R2kTe4)

S0 is the solar constantA is average albedo, or reflectivityR is the radius of the earthk is Boltzmann’s constant

Te is earth’s apparent temperature (seen from space)

Te equals -19C

However, average global surface T is + 14C

Natural greenhouse effect warms the surface by 33C

where

Primary Contributors to the Natural Greenhouse Effect

Water Vapour

OtherCarbon Dioxide

~65%

~25% ~10%

MarsAtmosphere: mass <1% earth’sGH Gases: >80% CO2

Sfc. Temp.: -47C GH Effect: 10C

FAR TOO COLD!

Other planets also have Greenhouse Effects, but these are unsuitable for life

EarthGH Gases: ~0.04% CO2

~ 1% H2OSfc. Temp.: 15C GH Effect: 33C

NOT BAD!

VenusAtmosphere: mass 90x earth’sGH Gases: >90% CO2

Sfc. Temp.: 477C GH Effect: 523C

FAR TOO HOT!

Sun

Latitudinal differences in net energy balance cause atmosphere and ocean circulation

However, the climate system is also influenced by many other complex interactions and feedbacks

Denser waters in high latitude oceans create a thermohaline circulation system that has a major impact on regional climates

Highlights of historical research into the natural greenhouse effect

• 1827: Fourier – theorized that greenhouse gases warm the planet

• 1896: Arrhenius - proposed that changes in atmospheric CO2 concentrations due to volcanic eruptions can cause climate change

• 1938: Callendar – first noted that human emissions of CO2 may add significantly to natural concentrations in the atmosphere

• 1957: Revelle et al. – first warned that human emissions have started a global scale geophysical experiment and initiated an atmospheric CO2 concentration monitoring program

An Early Warning About Climate Change

“Many important economic and social decisions are being made today on long-term projects…based on the assumption that past climate data…are a reliable guide to the future. This is no longer a good assumption…”

UNEP/WMO/ICSU Conference

Villach, Austria 1985

““Humanity is conducting an Humanity is conducting an unintended, uncontrolled, unintended, uncontrolled,

globally pervasive experiment globally pervasive experiment whose ultimate consequences whose ultimate consequences

could be second only to a global could be second only to a global nuclear war.”nuclear war.”

World Conference on World Conference on The Changing The Changing

Atmosphere: Atmosphere: Toronto, June 1988Toronto, June 1988

Greenhouse Effect

Disaster

Junk Science!

KyotoFramework Convention

on Climate Change

IPCC

I Love Global Warming

I Love Global Warming!

Everyone seems to be talking about climate change - but confusion reigns!

"Our belief in any particular natural law cannot have a safer

basis than our unsucessful attempts to refute it"

Sir Karl Raimund Popper,philosopher of science

Cautious

Increasing Confidence

The IPCC is the principal source of sound advice on climate change science

1990

1992

1995

1997

2001

First ReportFirst Report

Second ReportSecond Report

Third ReportThird Report

The IPCC process for providing science advice• Selection of lead authors

– based on internationally recognized expertise

• Assessment based on published literature

– invited contributions from other experts

• Contents peer reviewed twice

– Second draft also reviewed by governments

• Final contents are responsibility of lead authors

– accepted (not approved) by IPCC

• SPM developed and approved collaboratively by IPCC and lead authors• 2001 WGI report involved 1078 experts

The IPCC progression in confidence

FAR: "Our judgement is that the size of [global] warming is broadly consistent with predictions of climate models but it is also of the same magnitude as natural climate variability“

SAR: "The balance of evidence suggests a discernible human influence on global climate.“

TAR: "There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities."

Some Contrarian Viewpoints:Some Contrarian Viewpoints:

“I have never witnessed a more disturbing corruption of the peer-review process than the events that led to this IPCC report.”

Dr. Fred Sietz, Former president, US NASWall Street Journal 12/6/96

“When it to comes to climate change, humans aren't the culprits.”Dr. Sally Baliunas, Harvard-Smithsonian astrophysicist;Dr. Tim Patterson, Carleton geologist; Allan McCrae, PEng G&M 19/11/02

“By failing to convey a balanced presentation of the science presented in the detailed reports, the SPMS, along with the IPCC press releases, have become a tool to drive public hysteria.”

Chris De Freitas, U of Auckland climatologistBull. Can. Petroleum Geologists, June 2002

U.S. NRC Committee advised President Bush that IPCC reports were well done

It noted that:• Full IPCC TAR WGI report is “an

admirable summary of research activities in climate science”

• The full report is adequately summarized in the Technical Summary

• The SPM puts stronger emphasis on concerns, less emphasis on uncertainties than full report– all changes were made with consent of

convening lead authors– most changes had little impact on contents

Joint statement by Academies of Science from 17 other countries – May 2001

“The work of the…IPCC represents the consensus of the international science community on climate change science. We recognize IPCC as the world’s most reliable source of information…and endorse its method of achieving this consensus.”