Section 1 Background December 2002

What’s Happening, and What Can We Expect 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 thunderstorm troposphere The air we breath (21% oxygen) Suitable, stable climate and weather

Reflected Energy ~31% Incoming Solar Energy Outgoing Heat Energy Energy Trapped By Greenhouse Gases CO20.028% CH % N2O0.0003% The atmosphere’s energy budget is determined by net heat flow

Estimating the Magnitude of the Natural Greenhouse Effect Net Incoming Solar Energy Outgoing Heat Energy = (S 0 (1-A)  R 2 )(4  R 2 kT e 4 ) S 0 is the solar constant A is average albedo, or reflectivity R is the radius of the earth k is Boltzmann’s constant T e is earth’s apparent temperature (seen from space )  TeTe equals -19  C However, average global surface T is + 14  C Natural greenhouse effect warms the surface by 33  C  where

Primary Contributors to the Natural Greenhouse Effect ~65% ~25% ~10%

Mars Atmosphere: mass <1% earth’s GH Gases: >80% CO 2 Sfc. Temp.: -47  C GH Effect: 10  C FAR TOO COLD! Other planets also have Greenhouse Effects, but these are unsuitable for life Earth GH Gases: ~0.04% CO 2 ~ 1% H2O Sfc. Temp.: 15  C GH Effect: 33  C NOT BAD! Venus Atmosphere: mass 90x earth’s GH Gases: >90% CO 2 Sfc. Temp.: 477  C GH Effect: 523  C 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 unintended, uncontrolled, globally pervasive experiment whose ultimate consequences could be second only to a global nuclear war.” World Conference on The Changing Atmosphere: Toronto, June 1988

Greenhouse Effect Disaster Junk Science! Kyoto Framework Convention on Climate Change IPCC I Love Global Warming I Love Global Warming! Everyone seems to be talking about climate change - but confusion reigns!

Cautious Increasing Confidence The IPCC is the principal source of sound advice on climate change science First Report Second Report Third 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: “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 NAS Wall 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, PEngG&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 climatologist Bull. 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.”