wk 3 1-27-10

wk 3 1-27-10 - EE 571/471 Sustainable Energy Systems David...

Info iconThis preview shows pages 1–12. Sign up to view the full content.

View Full Document Right Arrow Icon
EE 571/471 Sustainable Energy Systems David Shaw EE 1/27/10
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 2
Is the climate changing? And if so, are we causing it?
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
How to deal with a complex problem on human influence on climate? Based on “How to Think About Human Influence on Climate, by Chris E. Forest, Peter H. Stone and Henry D. Jacoby, Report No. 68, October 2000, MIT Joint Program on Science and Policy of Global Change
Background image of page 4
Simulated global-mean annual-mean surface air temperature (thick line) from a climate model simulation with no applied (human) forcings superimposed on the record of observed temperature change for 1860-1999 (thin line, after Parker et al., 1994). The variations of annual-mean, global-mean surface air temperature are generated by the climate model’s internal feedbacks as determined by the dynamics of the various components of the climate system.
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
With anthropogenic forcing
Background image of page 6
Is this causal association enough? Is there still some significant chance that the association is coincidental? Critical thinking!
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 8
Prediction of future climate change is complex! It is because of these complexities that scientists who try to summarize available knowledge often use such words as “the preponderance of the evidence indicates that …,” or “it is likely that a significant (or major, or substantial) portion of the observed warming is attributable to human influence.” The words “preponderance” or “significant” or “substantial” can take on implicit probabilistic significance among scientists (for example, in the IPCC drafting groups) who spend many hours debating them. Discussions today is designed to help avoid the too frequent leap to one of two extreme positions: that because of the uncertainty we know nothing, or that scientists have “proven” that we are responsible for temperature changes of the recent past.
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
In order to be confident that the change is real, and to attribute it to human influence, we need to consider several issues. (Issue I) Is the estimated global temperature record accurate? Urban heat island effect: Urban areas tend to have higher temperatures than in rural areas (~ 1- 2 0 C) Changes in instrumentation and coverage over a century: How accurate were the measurements in 1870? The temperature record is more sparse back in the 19 th century. Uneven distribution of temperature sensors: Less data over oceans and Siberia. There is some disagreement between the surface record shown in the figure and satellite measurements (which are only available for the last couple of decades in any case) Climate scientists generally agree, however, that there has been a warming of 0.6 C over the past 150 years (National Research Council 2000), with some uncertainty (10%) as to the precise Physics for future Presidents, by Richard Muller Physics for future Presidents, by Richard Muller
Background image of page 10
(Issue II) Which natural processes are important and are they properly formulated in the models? The climate varies as
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 12
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 73

wk 3 1-27-10 - EE 571/471 Sustainable Energy Systems David...

This preview shows document pages 1 - 12. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online