# Blogging Theme for Week 14

As a theme for this week, I would suggest “Policy proposals for limiting carbon emissions”.   We discussed some of these in class on Friday, but in a quite abstract, mathematical way – how they could work in an “ideal world”.   But how about in the real world? What ideas are being tried, how might they work in practice, how successful are they?

Here are some possible readings and references on this issue

Remember that, as always, the theme above is only a suggestion.  You are welcome to post on any relevant topic, including one of the earlier suggested themes.  Here is a list of those:

# The precautionary principle

A good topic for blog posts in our general theme area of “probability” for this week might be the precautionary principle.  This idea, which has legal force in some countries, has several forms: one of them is that “if a proposed action is suspected of causing a risk to the environment, then  those proposing the action need to demonstrate that it does not propose a risk; those opposing the action do not need to demonstrate that it does pose a risk.”

Here is a basic scientific paper on the principle

Precautionary

and a link to an important early consensus statement

The precautionary principle is appealing, but there are some obvious problems with it, for instance: What counts as “demonstrated” absence of harm?  What if our choice is not between “risk” and “safety” but between two courses of action both of which are “risky” in different ways?

You could post about the application of these ideas, and its relation to more probabilistic methods of risk assessment, in any one of several contexts: GMO foods, vaccines, cell phones and brain cancer, climate change…

# The “Hockey Stick” graph

There is an interesting article on Penn State’s sustainability site today about the “hockey stick” graph and the controversy surrounding it.

This graph, devised by Penn State scientist Michael Mann and his collaborators, shows a reconstructed temperature record for the Northern Hemisphere going back a thousand years. As the Penn State news post explains, this graph became an “icon” of climate change and thrust Mann into an unexpected (and probably unwelcome) public spotlight.

Mann has also written a book-length account of the whole affair, in The Hockey Stick and the Climate Wars.

# Earth: The Operator’s Manual

This seems like a good opportunity to give a shout-out to Richard Alley’s book Earth: The Operator’s Manual.  This book is written in a very accessible style – it was designed to accompany the PBS series of the same name.   It explains the basic physics of climate change, how we know about the climate of the past, and some of the things we can do to reduce the risks that climate change may pose in the future.

Bibliographic information:  Alley, Richard B. 2011. Earth: The Operators’ Manual. New York: W. W. Norton & Company.

# Blogging Theme Week 4

The suggested blogging theme for this week is Climate.   A brief reminder about blogging requirements: you may post on anything related to the course (the “theme” for the week is only a suggestion), and your postings will be graded according to the rubric that appears in the syllabus,  The rubric involves five grading elements: frequency of posting, mathematical content, thematic content, organization and presentation, references and connections.

This is the week of Richard Alley’s visit so it is a good one to start some threads on climate and climate change.   There are (of course!) numerous web sites and online materials dealing with this topic. Not all of them are reliable – if you link to an outside site you might want to explain how you assessed its likely reliability and accuracy.  Here are some example topics: again, many more are possible.

• How many tonnes of carbon dioxide does the average person on earth generate per year?   How many tonnes do you generate? (Use one of the many carbon footprint calculators available online to estimate this.)
• (A Richard Alley classic) Have you ever lived or worked in a place where horse-drawn transportation was common? (I have.) If so, you’ll know that they produce a lot of poop, which someone has to clean up.   A car also produces “poop” in the form of carbon dioxide, but as that is an invisible gas we tend not to notice it. Suppose for a moment though that a car’s CO2 poop sat around on the road in solid form, like horse poop does. Does a car or a horse produce more poop per hour (by weight)?   How about poop per mile traveled?
• You probably measure a car’s gas consumption in miles per gallon. A mile is a unit of length and a gallon is a unit of volume, so “miles per gallon” has the dimensions of length over volume, that is, the inverse of an area. What does this area represent?
• Find out and explain how we are able to estimate the Earth’s temperature during the most recent ice age (which ended some 13,000 years ago).
• Imagine that you are speaking to an intelligent 11-year-old.   In 400 words or less, explain the role that carbon dioxide plays in regulating the Earth’s temperature.
• Write about the work of Svante Arrhenius, first scientist to attempt to make quantitative predictions of the greenhouse effect.
• While getting treatment last summer, I regularly made the round trip from State College to Johns Hopkins Hospital in Baltimore, a one-way distance of about 150 miles.  My Prius gets about 50 mpg on this trip, and measures fuel consumption to the nearest 0.1 mpg.  Now State College is 1000 feet above sea level, and Baltimore is at sea level, so that the trip to Baltimore is “downhill” and the return journey is “uphill”.  Should I expect to see a significant difference between the fuel consumption on the outbound and on the return journeys?