Global Warming: The science behind the news

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Global Warming The science behind the news
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POP QUIZ!
As required by the No Teachers Behind Left Act
Please select the single best answer from the
choices given
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What is Global Warming?
1. A tree-huggers plot to prevent Americans from
buying SUVs.
2. A vast international conspiracy of radical
secular liberal academics.
3. ... the greatest hoax ever perpetrated on the
American people. (James Inhoffe R-OK)
4. A well-documented, biosphere-wide phenomenon,
involving increases in average global
temperatures that profoundly affects all life on
Earth.
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As science educators, we must ask ourselves why
most Americans would choose one of the first
three answers given, rather than the correct one.
In addition to widespread scientific illiteracy,
we have powerful vested interests determined to
prevent the worldwide scientific consensus on
global warming form reaching the public.
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This determination, at the highest levels of
government in the worlds most technologically
advanced and powerful democracy, is producing
dangerous results at several government agencies.
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This is particularly disturbing, because NASA,
NOAA, and other government agencies have long
been the best sources for scientific information
and materials for public education. For example
Satellite data used in this presentation are
available from NASA.terra.gov
and svs.gsfc.nasa.gov (NB NO www in either of
these URLs)
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Because of todays partisan approach to science,
we must distinguish in our teaching between
ecology and environmentalism
Environmentalist (objective definition) someone
concerned about the environment
Environmentalist (cynical definition) a
tree-hugger more interested in whales than people
Ecologist a scientist studying interactions
among organisms and between organisms and
environments in a rigorous scientific manner
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How can we encourage students to wrap their
heads around a topic that is completely removed
from their daily experience?
Intentionally take them out of the familiar here
and now to a global perspective.
Tell students that even from way out here, alien
scientists could detect something odd and
different about this planet.
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This perspective frames two concepts vital to
understanding global warming and its importance
1. Earth is very large ... yet also finite.
2. Earth really is a BIOsphere - which means that
activities of living organisms have global
effects.
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We can now use an interdisciplinary combination
of physics, earth science, and biology to build
an important conceptual framework for teaching
Earths climate system, which governs the
distribution of life on Earth, is composed of
global winds and ocean currents powered by solar
energy.
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To start from the beginning solar energy is not
evenly distributed between the equator and the
poles.
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But the atmosphere is not a stable blanket it
responds to the differential heat distribution
between equator and poles by responding in the
way we learned in basic physics
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These thermally-powered, rising and falling air
masses, combined with earths rotation, generate
global wind patterns.
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Satellite data on movement of air masses in the
lower atmosphere, tagged by CO concentration
NASA Earth Observatory Website terra.NASA.gov
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These winds, together with similar patterns of
heating and cooling in oceans, generate currents
that transport water and heat.
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In addition, of course, the tilt of earths axis
creates changes in the amount of solar energy
received by northern and southern hemispheres
over the seasons.
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This tilt means that the maximum input of solar
energy moves north and south of the equator over
the course of a year.
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Global winds and ocean currents, by transporting
heat and water, determine regional and local
climate patterns.
On land, winds interact with mountain ranges and
other physical features to control patterns of
precipitation.
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Now we can put heat, winds, currents, and
mountains together for an eye-opening look at
global weather patterns
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Summary of Key ideas Differential solar heating
of the globe creates and drives winds and ocean
currents. Winds and currents shape local
patterns of temperature and precipitation.
Climate has profound effects on the distribution
of life.
This system is driven by the amount of heat
retained within the biosphere and the global
distribution of that heat..
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Now, how do we relate all this earth science
to organisms and ecosystems?
Begin by pointing out that all organisms have
preferences and tolerances for environmental
conditions such as temperature, humidity, and
rainfall.
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Key concept Local climate conditions,
established by interactions of winds and currents
with geography, shape biological communities.
Now you can discuss biomes within a coherent
conceptual context that supports understanding,
rather than just memorization.
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Climate diagrams can also show that temperature,
rather than precipitation patterns, is the main
driving force in many temperate ecosystems,
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Seasonal chlorophyll-based primary productivity
in terrestrial and marine environments
NASA Earth Observatory Web site terra.NASA.gov
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Those same data show that seasonal ocean currents
have equally profound effects on aquatic
ecosystems.
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This is the perfect context in which to emphasize
that activities of living organisms play a
significant and visible role in the global carbon
cycle - including the concentration of C02 in the
atmosphere.
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Now we can explore the scientific consensus on
global warming.
AS ALWAYS IN SCIENCE, we state our
hypothesis clearly, and look for data to test
that hypothesis and either support or
refute it.
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What IS the hypothesis were testing?
Actually, there are two interlocking hypotheses,
which are often confused.
Hypothesis 1 Earth is getting warmer (In other
words, global warming is occurring.)
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Hypothesis 2 Current global warming is caused,
in part, by rising levels of carbon dioxide (and
other greenhouse gases), produced by human
activity. (In other words, human activity is
increasing the efficiency of the global
greenhouse.)
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Now, the data Do scientific observations offer
evidence to support the hypothesis that the
biosphere is warming?
Some data are in the form of physical evidence,
such as temperature recordings, along with
changes in arctic and mountain glaciers, and
arctic and antarctic sea ice.
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Other physical data relevant to the global
warming hypothesis come from observations of
glaciers and permafrost.
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Effect of sea level rise on Shanghai, China
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Evaluating the second hypothesis involves
cutting-edge efforts to unravel the mysteries of
ancient climate.
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Theres another way for biologists to examine the
hypothesis that Earth is getting warmer ...
... and to try to evaluate what warming might
mean to organisms and ecosystems
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We can examine changes in the biology of
organisms which may (or may not) suggest that
living components of the biosphere are responding
to rising temperatures.
These case studies cover a wide range of animals
and plants in habitats around the world, and two
different types of responses.
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First, consider possible effects of climate
change on an organisms range
Assume that the extent of an organisms range is
dependent, to some degree, on temperature.
Question What would happen to that organisms
range if temperatures across that range increase?
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Hypothesis If temperatures rise, organisms
ranges should
1 expand away from the equator, and also retreat
from the equator,
2 expand into higher elevations and retreat from
lower elevations.
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We know from studies in paleontology and
paleoclimate that ranges of many plant and animal
species have responded way since the last ice age.
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Why should this be the case?
Remember organisms tolerance for a range of
environmental conditions
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Research is also turning up many biological
indicators all of which suggest that average
temperatures, in many habitats around the world,
are rising.
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Not only are more and more range shifts being
documented, but other temperature-related changes
are being reported in the literature.
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Thus far weve been looking at global issues. So
what does global warming mean to your students in
Georgia?
Where can you find out about them? (Again, being
careful to separate science from hype.)
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Teach about climate change as if all our lives
depend on it because they do!
So let your enthusiasm and imagination take wing!