Tag Archives: measuring

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.

hockeystickThis 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.

Thoughts about blog posts

So we are more than halfway through the first blog assessment period.  The TAs and I have read through everything that you all have posted.  There are a lot of interesting ideas out there, ideas that, with a bit of thought, could be developed into excellent posts.  (And remember, you can go back and edit your post, until the end of the blogging period, if you want to improve it; the final grade will be based on the final version of your post.) But fewer of the posts are excellent right now.  Here are some suggestions for the future.

  1. You cannot get points for posting if you don’t post.  As of right now, 8 class members have not made any posts at all, and a further 16 have not posted anything beyond the introduction that was required in week 1.  Yes, I know that according to the grading rules, you can in theory make things up in the second or the third blogging period, but it will take practice – practice which might as well start now.
  2. Posts should contain numbers, but should also set those numbers in context.  Too many posts suffer from the “gee whiz” use of numbers (this is a problem with a lot of environmental writing generally, I find): “if we all did this simple thing we could save 3000 barrels of oil a year”.  All well and good, but how does 3000 barrels a year compare to the total amount of oil that “we” are responsible for consuming?  Is it huge in relation to our total consumption, or insignificant? If insignificant, is it worth the time to do the simple thing (whatever it is)? What are the costs of doing the “simple thing”? etc.
  3. Posts should also contain calculations: it’s not a math post just because you quote a lot of numbers from some web site or other. This post for instance tries to do that by expressing energy consumption of different countries in terms of the number of people who consume one MToe/year.
  4. I’d like to see a clearer awareness of the distinction between environmental benefits (accruing to society at large) and financial benefits (maybe to the individual consumer) – I’m thinking of some of the posts about hybrid cars here, for example.  Related, though not the same point, is to make some effort to quantify trade-offs: if putting solar panels on my roof costs me x dollars right now, and saves me y dollars per year using net metering, how many years will it take to pay back my investment?  (This particular example requires some financial math, about the present value of an annuity, that we will cover in the next chapter.)

Okay, that’s enough suggestions for one post!   Remember that I or the TAs are happy to talk about your blogging during office hours or at any other time by appointment…

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?


Scales and Scientific Notation

On Friday’s class, we talked about how large astronomical bodies can get, but we did not look at the numbers. We also did not talk about the small objects scientists study like DNA, molecules, atoms, high-energy waves like gamma rays and subatomic particles like electrons.

To find the numbers for particular scales you can check out this list here: http://www.falstad.com/scale/

These numbers can provide a point of reference when you are trying to estimate values.

A fun interactive that helps you develop a sense of these scales can be found here: Scale of the Universe 2. To navigate the scales, use the sliding bar at the bottom. I’ve posted a screenshot of the software below, which shows how a white blood cell, a red blood cell, e-coli, a clay particle, an x-chromosome, a y-chromosome, red light and violet light compare.

Screen Shot 2015-01-19 at 11.09.54 AM

How Much Water Does it Take to Make a Pair of Jeans?

Water rights and accessibility is no doubt a global issue. Despite it being in the news, day to day when we wash our face or dishes we rarely think about how much we are wasting. However even if you are water conscious at home its more likely that you do not think about how much water is being wasted when you buy products.

Indirectly we can waste water, whether its buying agriculture from fields which do not have a efficient irrigation systems, or from buying a pair of jeans.  ” It takes around 1,800 gallons of water to grow enough cotton to produce just one pair of regular ol’ blue jeans.” That’s more water than it takes to make a ton of cement or a barrel of beer (although I’m sure some of you do not consume this yet).  And that’s just in terms of growing cotton, when you take into account the dye process as well as the machine wash almost 9,982 gallons of water are used.

How can we fix this?

1. stop purchasing so many jeans

2.  Buy levis, they are built to last, and its strongly recommended to not machine wash them. They suggest freezing them instead, it kills all the germs. however, if  there is a grass stain that you would like to get off all it takes is a sponge and a cup of water opposed to 40 gallons ( a typical machine wash).


sources: http://www.treehugger.com/clean-technology/how-many-gallons-of-water-does-it-take-to-make.html

Is Urinating in the Shower the Next Big Green Idea?

Yes, you read that right.  From Inside Higher Education:

Students at the University of East Anglia are encouraging their fellow students to skip their first trip to the toilet in the morning and to, instead, urinate in the shower, the BBC reported. The idea is to save water by avoiding the first flush of the day, and student materials (see below) suggest significant water savings could be achieved. Students are being encouraged to pledge their participation with the #gowiththeflow hashtag on Twitter.

See https://www.insidehighered.com/quicktakes/2014/10/10/urinating-shower-next-big-green-idea for more.

Apart from the gross-out factor, how does the math work here?  You could for instance compare the water amounts involved in one flush versus one extra minute of shower time.  How do these compare with one person’s total daily water use?


Carbon Dioxide and World Climate

This is the title of an article published in Scientific American by Roger Revelle, a science professor at UCSD who was one of the first to carry out research on global warming.  This article is one of the earliest to bring the problem to wide public attention.   You can download the full text from the Penn State Library.

Journal reference:  Revelle, Roger. 1982. “Carbon Dioxide and World Climate.” Scientific American 247 (2): 35.

PSU Library Link: here, or link to library search page here