1 / 23

Historical Perspectives on Climate Change Research

Historical Perspectives on Climate Change Research. Primary Source: IPCC WG-I Chapter 1 - Historical Overview of Climate Change Science. The Scientific Basis. 1. Hypothesis testing - Should be subject to peer analysis & review - Can it be shown, in principle, to be false?

wirt
Télécharger la présentation

Historical Perspectives on Climate Change Research

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Historical Perspectives onClimate Change Research Primary Source: IPCC WG-I Chapter 1 - Historical Overview of Climate Change Science

  2. The Scientific Basis 1. Hypothesis testing - Should be subject to peer analysis & review - Can it be shown, in principle, to be false? - Can it provide predictions (tests)? Basis for scientific progress - builds on previous work - self-correcting • For IPCC: Key questions • Has it been rigorously tested? • Did it appear in the peer-reviewed literature? • Did it build on the existing research record where appropriate? • What are the uncertainties?

  3. How Do Climate Scientists Conduct Experiments? • There is only one planet. • How can one test hypotheses? Observed behavior (e.g., short-term climate perturbations, like volcanic emissions) Simulation models Fundamental theory

  4. Rigorous Review is Essential! Growth in the Peer-Reviewed Literature

  5. Rigorous Review is Essential! Growth in the Peer-Reviewed Literature

  6. What Determines Earth’s Climate? Earth’s Orbit

  7. Earth’s Orbital Parameters Vernal Equinox (~ March 21) Aphelion (~ July 5) Perihelion (~ Jan 3) Why is Iowa colder in January?

  8. Earth’s Orbital Parameters b a Eccentricity = SQRT(a2 - b2)/a ; for circle, = 0 Longitude of perihelion (one choice: angle from NH vernal equinox) Tilt of rotation axis (obliquity)

  9. What Determines Earth’s Climate? Earth’s Albedo Earth’s Orbit Earth’s Emissions

  10. The Greenhouse Effect

  11. The Greenhouse Effect: Early Discoveries Edme Marriotte (1620-1684): Sun’s heat passes through glass, other heat does not (1681). (www.nndb.com) Horace Bénédict de Saussure (1740-1799): Air in mountains does not trap heat as much as air in low-lying regions (www.eoearth.org)

  12. The Greenhouse Effect: Atmospheric Properties & Climate Change John Tyndall (1820-1893): Measured infrared radiation absorption properties of atmospheric molecules Changing H2O or CO2 could cause “all the mutations of climate which the researches of geologists reveal” (en.wikipedia.org) Svante August Arrhenius (1859 -1927): 40%  or  in CO2 could explain advance & retreat of glaciers. (2xCO2 T ~ 4˚C.) Human CO2emissions could prevent another ice age. Nobel Prize - Chemistry (1903) (en.wikipedia.org)

  13. The Greenhouse Effect: Impact of Humans? Guy Stuart Callendar (1897-1964) 2xCO2 T ~ 2˚C Must treat atmosphere as set of interacting layers, not a single slab. Speculated, with others, that T over first part of 20th Century was anthropogenic. (www.aip.org) Criticisms: Overlap of H2O and CO2 absorption bands  saturation  no impact of increasing CO2. Earth regulates CO2 amounts, esp. via ocean. Humans have negligible impact.

  14. Other Atmospheric Constituents Other Greenhouse Gases: - Methane (CH4) - Nitrous Oxide (N2O) - CFCs Anthropogenic Aerosols (particles): • Scatter sunlight back to space • Cause more, smaller cloud particles (increase albedo) (oea.larc.nasa.gov)

  15. The Climate System How do we simulate this?

  16. Development of Global Climate Models (GCMs)    What is this? Computing demand increases inversely with cube of horizontal resolution. Increased computing power has allowed increased resolution …

  17. Development of Global Climate Models (GCMs) … and increasing complexity. Which should be favored?

  18. Complements to GCMs Global stretched-grid models Regional (limited-area) models

  19. Example Regional Model Domain

  20. Contrast the Hadley Centre GCM … 2.5˚ (lat) x 3.75˚ (lon) (Mt/Ag/EnSc/EnSt 404/504 - Global Change) History (from IPCC WG-I, Chapter 1)

  21. … with a regional model ~ 0.5˚ (lat) x ~ 0.5˚ (lon) (Mt/Ag/EnSc/EnSt 404/504 - Global Change) History (from IPCC WG-I, Chapter 1)

  22. How Well Have GCMs performed? One test: Projected changes in global temperature T [˚C] Much more detail later (AR4, Chapter 8)

  23. END Historical Perspectives onClimate Change Research

More Related