Homework 2 (I need
your written answers for questions 2-4, due at the next class)
1. Review all the slides: concepts and facts
- The Climate System
- Components of the climate system: atmosphere, land, ocean,
lithosphere, and the biological, biogeochemical, and human aspects
embedded in these physical components
- Climate science is highly interdisciplinary: atmospheric
oceanography, geochemistry, hydrology, biology, physics, chemistry, and
the human dimension (economics, political sciences, ...).
- Climate changes not just because of human activities: it has
varied from warm periods when dinosaurs and crocodiles roamed the polar
regions to the Snowball (or Slushball) Earth when much of the Earth was
covered by ice and snow.
- Instrumental record (thermometers) of climate change are only
about 150 years old, but proxy record allows scientists to reconstruct
the past climate history, including tree rings, ice cores, sediments,
2. Ask questions
3. Guesstimate on human impact, carbon footprint, and ecological
- What's the difference between weather and climate?
- What are the key variables of the 'traditional' definition
of climate: temperature, precipitation, wind, humidity, etc..
- Think a few other 'novel' subject areas beyond sciences that are
related or impacted by climate change
- What are the main forcings of climate variability and change in
the past, at present, and in the future?
- Natural climate variability vs. anthropogenic climate change
- Earth's mean surface temperature has warmed by how much since
- How much more warming we will get according the IPCC climate
projections if we conduct 'business-as-usual' (continue to emit carbon
without climate policy)?
4. William Ruddiman proposed the 'early Anthropocene' hypothesis in
which he claims that at the dawn of civilization, deforestation by
early humans for agriculture released a large amount of carbon into the
atmosphere, and the resulting greenhouse effect prevented the onset of
an ice age that would have already taken place by now.
- If we cram all the world's people together, how big an area will
it take? At the end, express it as approximately the size of something
more tangible than a number, for example, the size of University of
Maryland campus, the size of Washington DC, the size of Maryland, the
- How much carbon is stored in the bodies of all the people in the
world? How does it compare (percentage) to the amount of carbon in the
- How much carbon is stored in the bodies of all the large animals
on land? All the livestocks in the United States? The world? How do
these compare to the carbon in live vegetation? (Note: this question is
- How much carbon do you respire each year?
Do you think this hypothesis is plausible? Discuss
your reasons briefly. We will discuss/debate this in-depth in a later
Review of course material and questions to ponder on
Please finish before the next class. You don't need to
anything, but I will ask about Question 4 in class later
1. Please review all slides we covered in class
2. Review carefully some basic numbers/units/concepts that will
be very useful for the remainder of the class (Slide 'Some basic stuff')
ppmv: parts per million by volume
What's the atmospheric CO2 concentration now, in ppmv and percentage?
What's the atmospheric CO2 concentration before the industrial time?
What is the greenhouse effect?
What is the so-called climate sensitivity?
CO2 concentration vs. total mass of carbon in the atmosphere?
1 ppmv of atmospheric CO2 concentration corresponds to about 2 PgC of
carbon in the whole Earth's atmosphere
1 tC (tonne of carbon) is contained in 44/12 (=3.7 or about 4;
molecular weight ratio of CO2:C) tonne of CO2 (you can remember it
simply as: 1 tC = 3.7 tCO2)
1 PgC (Peta gram or 10^15 gram) = 1 GtC (Giga-tonne of carbon)
3. Study carefully the slide "The disturbed carbon cycle' by
1) Compare the magnitude of the carbon
2) Compare the magnitude of the carbon fluxes
3) Try to remember these numbers, at least the relative magnitude of
these pools and fluxes
Things to discover
4. Carbon footprint (answers to the questions below were Not clearly
stated in class; tell me how you got the numbers):
How much carbon an average American emits every year? An
average person in the world?
5. Read the book 'CO2 Rising' in the next two weeks