Section 1 Background December 2002. What’s Happening, and What Can We Expect GLOBAL CLIMATE...
Transcript of Section 1 Background December 2002. What’s Happening, and What Can We Expect GLOBAL CLIMATE...
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
…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
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.”