All Tucson Area Physics Teachers and Friends,
The
Physics Department's TAPT Annual Breakfast is scheduled
for Saturday, September 8th, at 8:30 AM, in the PAS Building,
Room 218. Only the West doors will be open. Breakfast will be supplied
by the University of Arizona Physics Department. It's always great.
To
note: we will start at 8:30 am.
J.D.
has, as usual, gotten a great speaker for the morning. Dr. Warren Beck is a
faculty member in the Physics and Geosciences Departments. He will talk about
Global Warming. Here is an abstract:
Global
Warming: Many Questions and Fewer Answers
Since the start of the Industrial
Revolution (Circa 1800 AD), atmospheric CO2 concentrations have risen from 280
ppm (parts per million) to 411 ppm, and this increase is due almost entirely to
increased fossil fuel burning and land use changes associated with human
activities.
CO2 is a greenhouse gas, thus, higher atmospheric
concentrations should lead to a warmer Earth. This is an inescapable
conclusion reached when using simple Energy Balance models of climate. But the
climate system has a large dynamic component which is not revealed by Energy
Balance models alone. Changes in dynamics could potentially lead to more
efficient heat radiation processes—or make them less efficient.
This leads us to the obvious question: Is the recent global warming trend caused
by these increased (Anthropogenic) greenhouse gasses? If so, what will
happen if we continue to add CO2 to the atmosphere by burning additional fossil
fuels?
These two questions are surprisingly difficult to answer. Finding an
answer requires not only energy balance models of climate, but rather the use
of general circulation models (GCM’s) that show how climate responds to changes
in greenhouse gasses. GCM’s use finite-element methods and thermodynamics to
predict how the worlds oceans and atmosphere will respond dynamically to this
greenhouse gas perturbation. Such dynamics control the pattern of major wind
belts, which couple to ocean currents. These dynamics control where the
rain falls and where it doesn’t, and where ice accumulates and where it melts.
They control the patterns of where deserts or jungles develop, and
in so doing influence Earths energy balance via feedback involving albedo
(reflectivity). Such dynamics even influences how fast ocean water circulates
into the oceans deep interior, and whether they carry with them large amounts
of dissolved anthropogenic CO2 captured from the atmosphere—or not. This
so-called Thermohaline Circulation may ultimately control how extreme climate
change from human influences may become. The ocean interior can be a potent
buffer on atmospheric CO2 concentrations, which dissolve into cold descending
waters near the poles, but are also released from upwelling waters in the
tropics. The ocean interor has a large CO2 storage capacity, but changing ocean
stratification can affect how efficiently it can remove CO2 from the
atmosphere, and for how long. Thus the carbon cycle is coupled in
fundamental ways to the climate system, and how the atmosphere couples
dynamically to the ocean.
Please join us at 8:30 Saturday PAS 218. If you know of anyone
interested in this topic, or in joining TAPT, please be sure to pass along this
invitation.
Best,
Karie
