Transcript THE WESTON OBSERVATORY Department of

UEI Teacher Summer Institute 2009
URBAN ECOLOGY AND CLIMATE CHANGE
A space-filling model of carbon dioxide (CO2). This simplest of organic
molecules is the chemical basis for the food web and is the critical
anabolic fuel for plants. Life would be impossible without it…
however, too much of it in the atmosphere puts our species and the
biosphere at risk.
Global Climate Change Summary
Climate change of the past 35 years is
not consistent with natural variations
over the last 400,000 years
Evidence clearly shows that radiative
forcing due to anthropogenic
greenhouse gases has contributed half
of the warming of the last 35 years
Mitigation efforts, urgently needed,
will have little effect on global
warming until the end of the century
Adaptation strategies should be
developed for the next 50 years
Polar Ice melt, from Scientific American
Radiative Forcing - a tool for understanding climate change
The Term, Radiative
Forcing as used by the
IPCC has a specific
meaning:
In the context of climate
change, the term forcing
is restricted to changes in
the radiation balance of
the surface-troposphere
system imposed by
external factors, with no
changes in stratospheric
dynamics.
Cloud trails such as these created by jet exhaust
exert both a negative forcing (blocking sunlight)
and a positive forcing (trapping longwave
radiation). The net result is a positive forcing
Integrated Science for Society and the Environment
Net anthropogenic
Change in radiative forcing
1750-2005 from UNIPCC
Greenhouse effect of the atmosphere Simple
Greenhouse Gasses:
Water vapor
Carbon Dioxide
Methane
Nitrous oxide
Ozone
The gases in the
atmosphere that act
like glass in a
greenhouse are called
greenhouse gases.
• Light from the sun includes the
entire visible region and smaller
portions of the adjacent UV and
infrared regions.
• Sunlight penetrates the atmosphere
and warms the earth’s surface.
• Longer wavelength infrared
radiation is radiated from the earth’s
surface.
• A considerable amount of the
outgoing IR radiation is absorbed by
gases in the atmosphere - these
molecules reradiate energy to earth.
From the Standpoint of Radiative Forcing on Earth We can think of it as a system of gains & losses
Energy from the sun in the form of photons reaches the earth and propels both biotic
& abiotic systems. Earth temperature is a dynamic balance of absorbtion & radiation
The carbon cycle - with anthropogenic (human) “enhancement”
Increased energy consumption from
fossil fuels burdens the earth system
Global mean surface temperatures have increased
Have Humans changed the climate?
Climate models capture
the last 100 year's
warming only if we
include the human
effects
Natural Climate Influence
All Climate Influences
Energy Consumption is directly
linked to Carbon Emissions
World production of
carbon dioxide from
anthropogenic sources
in 2001 (in Gigatons)
Greenhouse Gas Emissions Have Rising
The industrial revolution of the mid nineteenth century
initiated the surge in combusted gases… these impacts
are anthropogenic in origin and are linked to urbanization
Petroleum Era Begins
Industrial Revolution
We face significant threats from greenhouse gases - most of which
are anthropogenic in origin and related to industrialization. These
gases act as a thermal blanket in the earth’s atmosphere, causing the
earth to heat up. The chart below shows the various greenhouse gases
that are produced , their anthropogenic source and their relative
contribution to the overall effects of global warming.
Methane Production from Cattle and Other Sources
The 100 million cattle in the
United States account for 20%
of our nation’s methane
production! There are 1.3
billion cows worldwide.
Every cow “pie”
contains enough
energy (3 kwh)
through the
combustion of
nitrogen to power
a 100 watt light
bulb for over 24
hours. Cows
produce 100 lbs
of “poop” per day
While passenger cars, trucks and busses are an appropriate target for regulation
with respect to air pollution, other internal combustion machines remain “dirty” especially those using “two-cycle” technology. The frontier for air pollution
abatement lies in the control of emissions from these machines. The problem is
especially challenging in cities where the population density is so high.
The chart below reveals the pollution impacts of other combustion engines and
measures them in relation to the pollution produced by cars in “miles traveled”.
The greenhouse effect
SUN
Some sola r radiation is
reflected by the ea rth’s
surface and the at mosphere
Some of the infrared
radiation is absorbed
and re-em itted by the
gre enhous e gases .
The effe ct of this is to
warm the surface
and the lower
atm osphere
ATMOSPHERE
Solar radiation
passes through the
clear a tmosphere
Mos t solar radiation is absorbed
by t he surf ace, which wa rm s
EARTH
Hadley Centre for Climate Prediction and Research
Infrared radia tion
is e mit ted from the
Earth’s surface
GJJ99
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Ecology of the Ozone Layer
The ozone layer resides
in the stratosphere and
surrounds the entire
Earth. UV-B radiation
(280- to 315- nanometer
(nm) wavelength) from
the Sun is partially
absorbed in this layer. As
a result, the amount of
UV-B reaching Earth’s
surface is greatly
reduced. UV-A (315- to
400-nm wavelength) and
other solar radiation are
not strongly absorbed by
the ozone layer.
Data Gathered from the Total Ozone Mapping
Spectrometer (TOMS) satellite system
The Ozone Hole over the Antarctic
The natural ozone layer at the earth’s poles
provide a layer of protection for the earth. That
layer has been shrinking dramatically over the
past fifty years as a result of pollutants.
This graph tracks the thickness of
the ozone layer over Antarctica
over a recent 35 year stretch of
time. The most probable cause is
the anthropogenic release of CFC’s
from refrigerants.
Distribution of acid
precipitation in North
America and Europe
Above: Areas of
highest acid rain
precipitation in
Europe and North
America in 1999.
Right: Averaged
yearly rainfall
across the United
States in 1999.
The highly integrated nature of trophic dynamics intensifies the
impacts of lead in ecosystems for all organisms
Lead poisoning is
an epidemic in
animal populations
as well… 1.5-2.0
million waterfowl
(ducks and geese)
die annually from
ingesting
anthropogenic lead.
Certain types of air pollution can cause Acid Rain
When combustion leads to the production of sulfur and nitrogen,
these chemicals can be converted to a highly toxic acid in the upper
atmosphere. These compounds return to the earth during rainstorms
in the form of liquid acids (acid rain) and cause tremendous damage
to ecosystems - especially lakes and ponds.
Tipping Points: Ice Ages vs. Interglacial Periods
Last 150yrs:
greenhouse
gases driving
temperature
change
greenhouse
gases change
in response
to climate
change
Warm periods
(warm, wet, calm)
Ice Ages
(cold, dry, windy)
Understanding Pollution & Biomagnification
involves thinking about where pollutants are found
• In an ecological context, pollutants can be
thought of as found in “compartments”
• These pollutants are produced at a source,
where they move from the air to water and
soil - plus into the biota (living organisms)
• The chart on the next slide helps us to
envision this relationship. Different
pollutants can be found in the different
compartments and remain there for various
amounts of time.
The Fates and Movements of Chemicals in the Environment
The bold text
represents physical
compartments for
various chemicals;
the processes and
drivers that move
and sequester the
chemicals are
depicted in
parentheses
The Physical environment and thermodynamics determine magnification
Inherent inefficiencies of
energy transfer within an
ecosystem exaggerate
the impacts of toxic
substances - especially
for long-lived, high
metabolic rate
organisms.
Pioneering author, scientist and environmental activist,
Rachel Carson and her watershed book Silent Spring
which day-lighted the adverse impacts of agricultural
pesticide use in the United States (first published in 1962)
Periodic Table of the Elements. The toxic elements are
highlighted and tend to clumped by virtue of their similar properties.
Lead (Pb) is a heavy metal, along with mercury (Hg), Thallium (Tl)
and Bismuth (Bi).
Lead is highly toxic, even in small doses and enters the
human environment in a variety of chemical pathways.
• Most widely distributed of the toxic elements
• Enters environment through smelting of ores
• Also enters through batteries, pipes, conduit, pewter,
solder and tetraethyl lead in gasoline
• Lead tetroxide is a corrosion resistant additive to paint
• Lead monoxide is an additive in leaded crystal
• Lead arsenate is an additive in many pesticides.
• Most damaging by far is lead tetraethyl
Lead tetraehtyl molecule featuring a very useful weak bond.
Much happens to this bond in the violent world of
Inside the high compression world of internal combustion.
Major Sources of lead exposure
According to the Centers for Disease Control
Occupational
• Plumbers, pipe fitters, Lead miners, Auto repairers, Glass manufacturers,
Shipbuilders, Printers, Plastic manufacturers, Lead smelters and refiners,
Police officers, Steel welders or cutters, Construction workers, Rubber
product manufacturers, Gas station attendants, Battery manufacturers,
Bridge reconstruction workers, Firing range instructors
Environmental
• Lead-containing paint, Soil/dust near lead industries, roadways, leadpainted homes, Plumbing leachate, Ceramicware, Hobbies and Related
Activities, Glazed pottery making, Target shooting at firing ranges, Lead
soldering (e.g., electronics), Painting, Preparing lead shot, fishing sinkers,
Stained-glass making, Car or boat repair, Home remodeling, Folk
remedies, Cosmetics (kajal), Moonshine whiskey, Gasoline "huffing"
Lead has many toxic affiliations with the
human body with various negative outcomes.
• Lead has many chemical forms which make it both water
(lead chloride), and fat soluble (lead acetate) - thus
entering the body in many ways.
• Lead blocks pathways to heme biosynthesis - disrupting
the transport of oxygen (ferrochelatase).
• Lead can replace calcium in bone and disrupt osteoclast
(stem bone cells) activity.
• Lead disrupts the process of the formation of Acetyl-CoA,
a critical intermediate in in metabolism.
• Lead disrupts calcium function in nerve cells, disrupting
CNS function, leading to lead encephalopathy. Possible
relationship with Protein Kinase C (PKC)
• Lesser effects include hyperactivity, decreased attention
span, reduced I.Q.; linked to criminal behavior.
Lead Blocks Several Steps in the Synthesis of Heme Pigments
Heme pigments are
the critical oxygen
carrying parts of a
hemoglobin
molecule, found in
red blood cells.
Critical enzymes,
ALA dehydratase
and ferrochelatase,
are inhibited by
lead. This prevents
the porphyrin ring
from being built,
which is the key
functional part of
the heme unit.
Above: Stippling in
red blood cells as a
function of the
disruption of heme
formation by lead
Environmental Lead is Ubiquitous, Especially in Urban Landscapes
Blood Levels of Lead as a Function of Demographics in Children
Children suffer an increased risk of lead poisoning as a the degree
to which the urban character of their community increases.
Children living in industrial areas where heavy industry such as
coke smeltering takes place are at the highest risk.
Recent Data indicate that tiny
particles do indeed have toxic effects
From: Nell (2005) Science 308: 04-806
Photomicrographs from
tiny particles captured in
Los Angeles. Top photo
shows soot from diesel
emissions. Bottom photos
reveal impacts of soot on
mitochondrial anatomy.
Healthy control
mitochondria are shown
at left. These particle
residues can cause
cellular pathologies.
Human Behavior can Alter the Environment in Positive Ways.
The combined
affects of new
laws, high
technology and
increased
awareness have
improved some
critical
elements of air
quality especially with
respect to lead.