Physics 12: Homework 8
This assignment mainly relates to climate change, treated in section 10.3
of the book, and Lecture 18 in class.
- This course has conveyed the enormous scale of our energy demand, and
we have now worked through all the alternatives to fossil
fuels—whether at a viable scale or not. Are you optimistic or
pessimistic about our ability to adopt a new regime quickly enough
to avoid a painful transition? Such a change will not happen by itself.
What, in your opinion, do we need to do to make such a transition work
well?
- Each person in the U.S. on average demands 10,000 W for all goods and
services. About 80% of this is from fossil fuels, so 8,000 J/s from
CO2-emitting fossil fuels. Considering our current
mix of oil, coal, and gas, we get about 40 kJ of energy for each gram of
fossil fuel used. Each gram of fuel contributes about 3 grams of
CO2. So how much CO2 is a typical American
responsible for emitting into the atmosphere each year (in kg)?
- If each of the 300 million people in our country essentially emit 20
metric tons (1 metric ton is 1000 kg) of CO2 each year, and the
U.S. uses about a fifth of the world's fossil fuels, how many tons of
CO2 do we emit globally each year by burning fossil fuels. The
answer should be convenient to express in billions (109) of tons.
- The earth's atmosphere has a mass of approximately 5 quadrillion
(5×1015) metric tons. So a part per million (ppm) would
have a mass of 5 billion tons. If the Keeling curve showing CO2
concentration within the atmosphere is rising by about 3 ppm per year by
mass (2 ppm per year by volume), and half of all CO2 emitted
quickly gets absorbed in the ocean rather than staying in the air, how much
CO2 must be emitted to account for the observed atmospheric rise? The
answer should be comparable to the one in the last problem—thus
offering additional validation that it's our fossil fuel burning that
causes the rise in CO2.
- List three pieces of evidence we have indicating that global warming is
happening.
- Go to the
UCS Global Warming FAQ website and read through the various questions
and answers. Actually spend time doing this! It will take 15 to 30
minutes, but this is part of your assignment. Comment on the
most striking or surprising thing you learn from this exercise.
- What, briefly, in your opinion should our country do about global
warming (keeping in mind that we generate 20% of the CO2 in the
world)? Should we deny the problem; acknowledge but ignore the problem;
lead (or at least follow) international efforts or protocols to
remedy the situation; begin to phase out fossil fuels; aggressively phase
out fossil fuels in favor of clean, renewable sources; offer assistance to
sea-flooded countries? The issue is complex, and your answer may be
likewise.
- Go to the site: http://www.contactingthecongress.org/
and enter your address/zip-code (just your zip + 4 works) so that you find
out who your representatives are in our federal government. Write down
their names (two senators and one house representative), and two phone
numbers for each (local and Washington D.C.; may have to do some searching). This is how you contact your
reps. Don't be bashful about doing this: their offices are set up to
accept loads of phone calls. Let them know what concerns you and how they
can represent you better. It actually matters.
- Enter your CAPE ratings for this course (online). Check your UCSD
e-mail for reminders, with student-specific access codes. These must be
done by Sunday, 6/09 at the latest. Consider it part of your homework
(ungraded, of course). CAPEs are important for the future development of
this course, and are taken seriously in the job evaluation of professors.
For the homework, just indicate that you've done it. To check our progress
as a class, check out: the daily-updated
statistics on how many have been filled in. Somewhat
counter-intuitively, PHYS 12 is wedged between PHYS 100C and PHYS 120 A.