Wed. May 2
Excerpts from DVD “Cool It”, which consider how to address current global changes
Don’t forget on-line course evaluation, available until midnight Thursday May 3 at https://tce.oirps.arizona.edu/TCEOnline (it could earn you 15 more points on the sum of your top 5 GAs)
Current grades will be posted on D2L- please review them to make sure we have them correct.
Our Final Exam is Friday (May 4), 3:30am-5:30pm (room 308 Kuiper Space Sciences), and it will be all M/C (about 100 questions, roughly half from first part of course before mid-term exam)
NASA video about the formation of Antarctic Ozone Hole
Stratospheric ozone: Consequences- increased UV-B reaching surface (because less ozone is present in stratosphere to absorb it) is of greatest concern for our health (skin cancer, cataracts, premature aging, vitamin D), ability of decomposers to operate and release nutrients as they break down organic matter, and health of plants whose photosynthesis and growth may be reduced and damage to DNA increased.
Some reduction of stratospheric ozone in the northern Hemisphere polar regions, but much more so over Antarctic
Review of GA6 results from the 15 groups and 1 make-up group.
Are the high global temperatures of the last decade the warmest temperatures ever on Earth????? (NO! estimated to be 10 degrees higher in Cretaceous)
Types of renewable energy and relationship to solar source
Approaches to Addressing Global Environmental Change:
Mitigation
Adaptation
YOU SHOULD NOT PASS THIS CLASS IF YOU DO
NOT KNOW:
1. Greenhouse Effect vs. “Enhanced” Greenhouse Effect
2. The Ozone Hole is not related to the Enhanced
Greenhouse Effect (largely independent, with very minor overlaps, i.e., THE
OZONE HOLE IS NOT A SIGNIFICANT ELEMENT OF CURRENT GLOBAL WARMING!)
3. The tropospheric ozone
problem (photochemical smog) vs. the Stratospheric
ozone problem (Ozone Hole)
4. EM Radiation characteristics of Solar and
terrestrial radiation (as in GH Effect)
5. Photosynthesis/PRODUCTIVITY can be impacted or
affected by predicted enhanced GHG effects,
increased CO2, ozone, acid rain, and ozone hole (increased UV) problems
(ozone and acid rain breakdown chlorophyll)- Protect the base of the food
chain!!
6. Past global changes have occurred throughout Earth
history, unrelated to human activities. (the speed of
current changes may be much faster, however)
Study Suggestions:
Review your quizzes, sample quizzes, and mid-term exam
Review your lecture notes in conjunction with the
slides and highlights of topics covered in the lectures (the “classnotes” link available at D2L content and the course
web site)
Review Study Guide
Review Mackenzie and Mann/Kump
readings
Mon. Apr. 30
Q6 returned and answers given (+3 pt quiz adjustment will be added to your raw score to a max of 26.5)
The lowest of the six (6) GA scores will be dropped prior to calculation of final course grade IF more than 50% of class does on-line course evaluation https://tce.oirps.arizona.edu/TCEOnline
SO2 “cap and trade” program of 1995/2000 (establishing a “cap” or allowance for emission from each source, then allowing the selling or trading of allowances when a specific source is above or below its allowance), and its influence on reducing SO2 emissions from utilities in the US. In 2003 a NOx Cap and Trade system was implemented by EPA
Stratospheric ozone- the “good” ozone (O3) is very effective in absorbing incoming UV; it is destroyed in reactions with Cl (freons, CFC)
A strong decrease in stratospheric ozone concentration above Antarctica has occurred since the late 1970s; large increase in extent of ozone depletion above Antarctica- this is “ozone hole” (unrelated to global warming); increased UV-B reaching surface (because less ozone is available in stratosphere to absorb it)
Montreal Protocol in 1987 to stop manufacture and trade of CFCs and other chlorine-containing compounds; we hope to soon see the ozone hole area start to decline in the very near future (but unfortunately some of the largest areas of the ozone hole have been in the first decade of the 21st Century). The projection is that by 2070, ozone levels above Antarctica will recover to their 1980 levels.
NASA video about the formation of Antarctic Ozone Hole
Stratospheric ozone: Consequences- increased UV-B reaching surface (because less ozone is present in stratosphere to absorb it) is of greatest concern for our health (skin cancer, cataracts, premature aging, vitamin D), ability of decomposers to operate and release nutrients as they break down organic matter, and health of plants whose photosynthesis and growth may be reduced and damage to DNA increased.
Loss of stratospheric ozone decreases atmospheric temperature, it does NOT
contribute in any large way to global warming
Fri. Apr. 27
Quiz 6 and GA6 (“What would you do?/What do you think?”)
Wed. Apr. 25
Course Evaluations are on-line at https://tce.oirps.arizona.edu/TCEOnline; they are available through
May 3
“Point sources” vs. “non-point sources of pollution” [Mackenzie Fig. 11.17]
Radiative forcing from anthropogenic sources is about 1.5 W/m2, on top of the 340 W/m2 from the sun.
Is CO2 a
pollutant? The Supreme
Court ruling in 2007 gave EPA the authorization to regulate CO2, and EPA announced
an emissions monitoring program in mid-March 2009). Now just last month the EPA proposed to regulate
construction of power plants. The Clean Air Act's defines "air
pollutant" as emissions (1) that cause or contribute to air pollution,
which may reasonably be anticipated to endanger public health or welfare; and
(2) that are emitted from numerous or diverse mobile or stationary
sources.
Population and Waste: Cascading effects of
gas emissions
American Lung Associations 2012 “State of the Air” report released today; ozone in Los Angeles is the lowest levels since the reports were done; but other cities have issues with ozone and particulates.
Waste may have ecological and health costs, but historically dirty air is sometimes viewed as evidence of “success”
Primary pollutants (directly out of the smokestack or tailpipe): such as VOCs (volatile organic compounds), nitrogen oxides, sulfur oxides, carbon monoxide (CO) and particulates; Sources dominated by transportation, power generation, industry [all primary pollutants derive from the fuel (for example coal can contain lots of sulfur), except for nitrogen oxides whose nitrogen derives primarily from air N2]
Secondary pollutants like sulfuric acid, nitric acid, ozone are produced by transformations of primary pollutants SO2, NOx, and NOx+HC, respectively.
Photochemical smog: formed naturally during lightning discharges; formed largely artificially in presence of nitrogen oxides, VOCs and sunlight; more likely to be formed in winter in large northern cities, but plenty of sunlight in cities such as LA, Phoenix and Mexico City to form ozone throughout the year; reduction of urban ozone possible by reducing concentrations of reactants, especially VOCs and nitrogen oxides many fuel pumps now designed to reduce loss of fuel vapors
Auto emissions usually check for particulates, unburned hydrocarbons (“HC” or VOCs), and CO; catalytic converters on automobiles are designed to convert CO to CO2, VOCs to H2O and CO2, and NOx to N2; strong oxidizing capacity of ozone can affect respiratory system, degrade chlorophyll in plants, break down rubber products (tires, seals, belts, electrical cords)
Despite the best intent of “The solution to pollution is dilution”, a build-up of air pollutants is favored by very stable atmospheric conditions (reducing vertical movement) associated with temperature inversions
Natural sources exist for emission of nitrogen oxide, sulfur oxide, VOCs (such as terpenes/isoprenes from plants) and even ozone itself (lightning).
Trees and pollution
Acid rain (more properly “acid precipitation” or “acid deposition”)
pH scale; acid rain often defined when pH<5-5.2. The pH when background atmospheric CO2 dissolves to form weak carbonic acid is about 5.6 (much more acid than neutral pH of 7), and sometimes other natural acids including organic acids can make the pH a little lower; thus rain from “clean” areas is slightly acidic)
The eastern U.S. has the lowest pH of precipitation (highest acidity) because of numerous sources of NOx and particularly SO2 gases to the atmosphere.
Acid rain can often effect “cultural heritage”, materials such as metals/marble, aquatic ecosystems, terrestrial systems.
Neutralization (“buffering") of acid rain in carbonate terrain, whereas greatest negative impacts in granitic terrain such as the Northeast and Canada.
Even if SO2
emissions were reduced, NOx would still be
emitted in large quantities across the
Mon. Apr. 23
Population and water
Central Arizona Project (CAP) delivers water largely contributed from the mountains in Wyoming, Colorado and Utah to Phoenix and Tucson, by means of a canal beginning at Lake Havasu.
Tree-ring reconstructions of Colorado River flow indicate the period from about 1905 to 1925 was the wettest in the last 500 years. This is a problem, because water allocation to adjacent states was based on this large flow, so extended dry periods may result in insufficient water to provide the allotments.
Eutrophication- addition of excess nutrients to the aquatic system causes plants (especially algae) to flourish, dieback of the plants/algae results in large demand on oxygen to decompose them, thereby reducing oxygen concentration in water, which is particularly critical for higher organisms in food chain. “Point sources” vs. “non-point sources of pollution” [Mackenzie Fig. 11.17]. Algae could become important biofuel, however.
Population and waste: GHGs
Sanitary landfill (garbage dump) image with methane collection system
Radiative forcing- our understanding is “very high” that contributions to global warming by greenhouse gases have been important (about 2.5 W/m2, versus average total insolation of 340 W/m2), with the order of importance= CO2 > CH4 > N2O and halocarbons (such as Freon).
Radiative forcing by greenhouse gases- our understanding is “very high” that contributions to global warming by greenhouse gases have been important associated with inputs of CO2, CH4, and N2O. The “Global Warming Potential” (GWP) of methane (CH4) is about 20 times that of CO2 and the GWP of N2O is about 300 times that of CO2.
Anthropogenic sources of
CO2: industry, autos, land-use change/deforestation, wildfires and biomass burning
N2O: industry, autos, feedlots, fertilizers, wildfires and biomass burning
CH4: rice paddies, cattle, natural gas from wells and distribution system, natural gas from coal mines and landfills, wildfires and biomass burning.
Greenhouse gas emissions from livestock about 18% of greenhouse gas emissions, and it is related to Land-use change, Water, Feed, Ruminant digestion, Solid & liquid waste, Transportation (HSUS full report). Agriculture-related greenhouse emissions would be related to some of these processes as well.
Considered outcome of GA3 with respect to beef and non-beef meat consumption with summary table of all groups (15 regular and 3 make-up).
Fri. Apr. 20
Quiz 5 handed back and discussed
Earth Day celebrations Friday at UA, Saturday at Biosphere 2, and Sunday.
On-line course evaluation, available until Friday May 3 at https://tce.oirps.arizona.edu/TCEOnline
The “Green Revolution” began mainly around the mid-1900s, and has greatly increased agricultural production in the face of rising population (and even diminishing cropland) by: mechanization, pesticides, herbicides, irrigation, new crop strains (breeding and now genetic engineering), and fertilizers. The billion dollar question is whether it can be sustained and adopted by poorer and developing countries (because of cost of fertilizers and pesticides, soil degradation, continued loss of farmland, loss of water for irrigation, and loss of genetic variability/variety). Also, has not worked as well with tropical agriculture as with temperate agriculture in Europe and N. America
Population and Resources: Water
The demise of Lake Chad illustrates how climate change (regional drying) can be important in the face of the demands of a large, growing population (“Lake Chad has been the source of water for massive irrigation projects. In addition, the region has suffered from an increasingly dry climate, experiencing a significant decline in rainfall since the early 1960's.”- NOAA)
The catastrophic effects of water diversion in the Aral Sea, west-central Asia
Massive water
collection and distribution network in
Wed. Apr. 18
Quiz 5 has been graded, and along with GA4 has been entered into the on-line grades students can view and review at D2L. We will go over it on Friday.
Population and Resources: Soils
Historical and ancient historical observations of water/soil perturbations- Attica (Greece) deforestation and grazing 2000 years ago; salinity impacts on agriculture in Mesopotamia and Upper Nile civilizations thousands of years ago; Aswan Dam in 1900s; salinity problems in 1900s in Iraq, Iran, Pakistan, Peru, Argentina; dust from Sahel and Mongolia transported thousands of miles
Soil Degradation [Worldwide Mackenzie Fig. 11.17]
Soil Erosion (57% by water, 29% by wind, Mackenzie Fig. 11.3) in US this erosion averages about 10 tons per hectare
On-site and off-site costs of erosion in US might be $44B annually ($400B for whole world)
Natural events impacting soils= floods, landslides, glaciers, wind, subsidence, drought, waves
Anthropogenic activities impacting soils= mining, agriculture, logging, dams, transportation, subsidence,wells
Soils are composed of layers known as "horizons" [Mackenzie Fig. 11.1]: A horizon tends to be organic-rich and materials tend to be leached from this horizon downward; B horizon tends to accumulate materials leached downward, including clays and iron oxide, and in western US carbonate ("caliche") accumulates in this horizon; C horizon is partially weathered horizon below B; western soils have low acidity (they are alkaline) and permit accumulation of carbonates related to evaporation exceeding rainfall, but eastern soils tend to be acidic with no carbonates related to rainfall exceeding evaporation.
Soil characteristics: [a] soil grain size important to working soils, water and nutrients; “loam”-type soils with a mixture of clays, sand, and silt tend to be a better quality soils for crops; [b] type of clays present and cation-exchange capacity (hold cations such as K+ and Ca++ important to nutrition)
Soil Degradation
Consequences: A- loss of fertile soil (reduced production; more runoff; less water storage in soils; soil harder to till; loss of soil carbon B- impacts on surface water (higher flood levels; reservoirs can fill in with sediments; turbidity (muddiness) can impact aquatic life) Wind erosion can abrade leaves and expose roots
Changes in erosion related to land-use change (example the Washington DC area, forest to agriculture to abandoned field to construction/urbanization)
Other Soil Degradation (besides water and wind erosion [Mackenzie Fig. 11.3])
1. Physical (2-3%) excessive compaction, waterlogging)
2. Chemical (12%) salt build-up; stripping of nutrients; excess fertilizers; pesticides/herbicides; wet/dry deposition (acid); industrial wastes/spills
Anthropogenic causes of soil degradation- overgrazing, deforestation, agricultural practices, fuelwood gathering, industrial & waste pollutants (on a global basis, overgrazing, deforestation and agricultural practices dominate soil degradation [Mackenzie Fig. 11.7], affecting about 17% of arable land [Mackenzie Fig. 11.2])
Epic trailer of sizzling, terrifying new movie starring Sir Biff Wellington about soil erosion catastrophe- Coming soon! I smell Academy Awards and dozens of questions about it on the next quiz.
Mon. Apr. 16
Quiz 5 first 20 minutes
GA5 Make-up= Tuesday April 17, 12:30 pm, room 330 Space Sciences
Review of important beneficial characteristics of tropic forests from last time (4/11)
Tropical forest deforestation carbon inputs to atmosphere compared to fossil fuels and to non-tropical deforestation over the past 150 years, and projections for future (Mackenzie Fig. 10.17)
Deforestation in
Deforestation in
U.S.- Great Lakes forest fires of Oct. 8-11,
1871. Forest was considered
inexhaustible resource by settlers and commercial interests moving eastward
from East Coast from early 1800s to
Deforestation was associated with European settlement. After land was logged, slash was left behind. When drought came to the area, what was left behind caught fire and burned what trees were left, and degraded the soil. Both forest, soil, and human resources were lost. To a large extent, the areas that were logged and burned are now forested. This occurred though both afforestation and reforestation. These vigorous, young trees took a lot of carbon out of the atmosphere, and stored the carbon in wood, contributing to the net carbon uptake of US forests since about 1940 in the figure showing history of net carbon uptake from atmosphere or net carbon release to atmosphere from forested areas around the world (Mann/Kump p. 175). This forest regrowth appears to be a major contributor to a sink for some of the excess carbon (i.e., it is part of the missing carbon sink).
Reading of portions of Father Pernin’s first-hand account of the fire catastrophe at Peshtigo
Fri. Apr. 13
GA5 Ecologist and Economist gambling on the future (Make-up= Tuesday April 17, 12:30 pm, room 330 Space Sciences)
Wed. Apr. 11
Examples of writing without using “there is”, “there are”, “there were”, etc.
Tier 2 class next Fall (Prof. Leavitt will teach): GEOS 220 – Section 002, Environmental History of the Southwest, Class Number 62633, MonWedFri 12:00PM - 12:50PM Kuiper Space Sci, Rm 308.
Population and Resources: Forests
Mann/Kump figure of 21st Century deforestation (p. 175)
Modern forests- 4-5 billion hectares world-wide, estimates vary depending on definitions of forests and woodlands
Land-use changes (urbanization; conversion of land to grazing, agriculture; dedication of land to transportation [roads] or energy-flooding-resource concerns [dams/reservoirs])
Major mechanism of land-use change is deforestation
Reasons for deforestation: debt repayment (some woods are a very valuable commodity); resettlement (the only land available to poor may be forested areas that they must work by hand to own); conversion of forest to pasture; international logging; hydropower (impounding water behind dam can inundate forests); fuelwood (cooking and heating)
Dramatic change in global forest cover over the last 8,000 years, with removal of tropical forests especially notable in the old world (paleotropics)
40-50% of tropical forests (S. America, Asia, Africa) have been cut in last 200 years, ie, very rapid deforestation using “slash and burn” methods (India, Indonesia, Brazil have greatest deforestation); tropical forests may have distinct wet/dry seasons related to the position of the ITCZ
Tropical forests (India, Indonesia, Brazil have greatest deforestation, i.e., they are greatest “producers” of tropical wood; Japan, USA and Singapore and now China are biggest importers of tropical wood); tropical forest characterized by great biodiversity, including diversity with height; a genetic “storehouse” possibly containing many new compounds that could become cures and treatments for our illnesses and ailments (“Tropical Pharmacy”); about 30% of all terrestrial NPP; contains 1/3 of all carbon in terrestrial biomass, but soils only contain a small fraction (4%) of all carbon in soils world-wide; [from MacKenzie text: very tight nutrient cycling and retention promoted by mutualistic fungi, dense canopy that inhibits erosion, leguminous (N-fixing) trees]
Mon. Apr. 9
Population (LM)
Thomas Malthus hypothesis of world population growth dating back to the early 1800s - world population will increase disastrously unless checked by war, famine and disease, or “moral restraint”.
“Compounding”= building up of something on the basis of its rate of growth; for example, in a bank account money can earn interest at some annual rate by compounding.
“Rule of 70”= you can determine how long it will take to double by dividing the annual rate of increase into 70. For example, a city whose population is increasing 7% per year will double its population in 10 years (70/7 = 10 years)
Hypothetical population growth curve stages=> 1. lag, 2. exponential, 3. stationary, 4. death- we are in exponential phase transitioning to stationary over the 21st Century. World population may eventually top out around 8-10 billion people.
“Carrying capacity”= optimum population that can be sustained in a system/area, and depends on 1-natural resources (incl. food), 2-energy, 3-waste, 4-interactions)
Population density (number of people per unit area; map) is greatest in Japan, Asia and Europe; lowest in Australia.
Population (highest in Asia; world population map) and rates of growth on different continents (highest in S. America Asia and Africa).
Characteristics of populations (these can influence the trajectory of population change): 1-birth rate, 2-death rate, 3-sex ratio, 4-age distribution of populations (age distribution or “population pyramids”-[tutorial]), 5-dispersal (emigration, immigration)
(World Population Prospects, see the 2010 Revision and highlights)
Current world population: slightly over 7 billion (census.gov)
Population and Resources: Forests
Mann/Kump figure of 21st Century deforestation (p. 175)
First forests in Devonian (about 400 my ago), but perhaps largest past forests were 300-350 my ago [Carboniferous], 40-100 my ago [Cretaceous], evidence of which is found in coal beds (eastern US coal is mainly carboniferous in age and high sulfur). Although many of the tree species in the Earth’s early forests no longer exist, some descendants persist, many of which are diminutive in size.
Climate can
affect type and distribution of forests, (for example “in the last 150,000 years
there has been about 10°C change in temperature from interglacial periods
135,000 years ago [and now] versus conditions during the cold glacial “maximum”
at 20,000 years ago). The ice age glacial maximum 20,000 years ago resulted in
shifting of forest southward in N. America and
Saguaro cactus moved into the Tucson area approximately 8,000 years ago as the climate warmed in the current interglacial period
Modern forests- 4-5 billion hectares world-wide, estimates vary depending on definitions of forests and woodlands
Fri. Apr. 6
Current CO2 concentration is the highest it has been in the last million years, but is 393 ppm CO2 today the highest ever?
Past CO2 from carbon cycle models and analysis of leaf fossils and soil minerals
Last 600 million years=> evidence that much of the period had CO2 concentrations from about 5 to as many as 18 times the current CO2 concentration (corresponding “ice house” and “hot house periods”).
Analysis of the statement “fossil-fuel emissions of CO2 are actually quite small compared to Nature’s inputs of CO2 to the atmosphere, and therefore we need not be concerned with them” in light of the carbon cycle. It does not tell the important part of the cycle, ie, carbon formed slowly and stored for tens of millions of years is being rapidly being added to atmosphere; we see large atmospheric concentration increase, because the normal carbon sinks are not sufficiently fast to capture it all.
These emissions have increased since the beginning of the “Industrial Revolution” around 1800, but only 55-60% of the emissions are represented in the atmospheric CO2 concentration. So where is the rest of the carbon going????
The “missing sink” problem (maybe better called the “unidentified sink(s)” problem) as of early 1990s=> about 6-6.5 GtC are going into atmosphere from fossil fuels per year + another 1.5-2 GtC from land-use change (largely Amazon deforestation) =7.5-8 GtC total; HOWEVER, we can only account for sinks for this excess carbon of about 3.5 GtC in the atmosphere (about 50-60% of the fossil-fuel carbon release) + 2.2 GtC in oceans by inorganic dissolution=5.7GtC. So where is the rest of the carbon (1.3-2.3 GtC) going, ie, what is the "missing sink"? Answer- probably temperate ecosystems (mid-latitude forests including soils) and tropical ecosystems (forests), with re-growth being a major component of these sinks.
Volcanic inputs of C to atmosphere are large (about 1/10th of a billion tons), but quite small compared to human (fossil fuel and land-use change) inputs.
Combustion of fossil fuels also affects other element cycles (not just the carbon cycle). An imbalance in the N cycle from anthropogenic activities related to fossil-fuel burning (N2 burned to NOx) and manufacture of fertilizers from atmospheric Nitrogen. Furthermore, the release of NOx and SO2 gases from fossil-fuel combustion contributes to other world-wide problems such as acid rain (maybe the SO2 emissions from fossil-fuel combustion have also been counteracting the enhanced greenhouse effect, at least up until now)
Coal-oil-natural gas geographic landscape (Mackenzie), N. America has lots of coal and natural gas, but limited petroleum compared to other global regions. The Middle East has relatively little natural gas and coal, but it has most of the oil.
Reserves (Fig. 3 of TecEco web home) of coal, oil and natural gas are enough to sustain us well into future, but their distribution is variable, for example US has large reserves of coal and natural gas, but not oil. Reserves of coal and oil would last about 150 years at current rate of usage [but would potentially triple atmospheric CO2 concentration]. Additional potential fossil-fuel resources as tar sands (Keystone pipeline), oil shales, and methane hydrates could more than double the energy the potential energy compared to coal, but they would also cumulatively increase atmospheric CO2 concentration 4 or 5 times]
Heavy U.S. dependence in 2008 on fossil fuels for energy (about 90%), with only about 10% for alternative fuels (nuclear and renewable); by 2010 it looks like the nuclear and renewable account for about 16%.
US oil imports exceeded domestic production in the early 1990s and now imported oil dominates.
“Peak Oil 1” [part 2], M. King Hubbert and the possibility that global oil production has/will peaked/peak sometime between 2005 and 2030, and possible consequences.
“Peak Coal”
Wed. Apr. 4
Quiz 4 was handed back, and answers discussed.
Student Conservation Association and opportunities for internships in summer or other parts of the year.
Phenology used with European grape harvests to estimate growing season temperature over the last 500 years. It has a “hockey stick” shape, with the harvest date getting gradually later and later over most of the period, and then getting earlier on average in the last hundred years.
Climate change and human health- WHO estimates 150,000 excess deaths worldwide related to climate change (from cardiovascular mortality and respiratory illnesses during heatwaves, to altered transmission of infectious diseases and malnutrition from crop failures, to flooding events). Disease spread may be accelerated by warming (like malaria northward), but diseases might sometimes be reduced (like malaria tropical areas that experience reduced precipitation/drying)
Carbon cycle box model diagram and primary forms of carbon [atmosphere= CO2, CO, CH4; ocean= HCO3-, CO3-, dissolved CO2; biosphere= CH2O; lithosphere= limestone (CaCO3) and kerogen (oil, coal, and finely dispersed organic matter)]
Imbalance of Carbon cycle related to energy production (for transportation, heating, agriculture and other needs of modern society) and consequent rapid transfer of carbon from the lithosphere (where it has been isolated millions of years) to the atmosphere
Fossil-fuel CO2 release has exponentially increased from less than 0.1 gigatons C (0.1 gigaton [Gt]= 0.1 billion tons = 1015 g carbon) 150-200 years ago to approaching 8 gigatons C per year of carbon today [8 Gt C= 8 billion tons C= 8 x 109 tons C)]. This CO2 comes from oil, coal, natural gas, “flaring” and cement manufacture.
CO2 emissions by country- U.S. was number one, but China is now number one.
Atmospheric CO2. The rate of increase has been variable over the time period of direct measurement since 1958, related to sources and sinks. Analysis of gas in ice cores tells us the pre-Industrial Revolution concentration of CO2 was about 270-280 ppm.
Over last eight-hundred thousand years there is a cyclic rise and fall of CO2 concentrations from about 190ppm at the peak of the glacial periods to about 275 ppm during “interglacial” periods. Current concentration is the highest it has been in the last million years.
Mon. Apr. 2
Quiz 4 at beginning of period- IPCC and our knowledge of radiative forcing, as relevant to GA4, which concerns GHGs CO2, CH4 and N2O (and whether the ozone hole contributes to global warming or cooling)
Biosphere and carbon cycle
Atmospheric CO2. Direct CO2 measurements (“the most important graph of the 20th Century”), beginning with Keeling’s measurement site established in Mauna Loa, Hawaii, and providing continuous measurements since 1958; now a world-wide network. Current CO2 concentration is almost 389 ppm (part per million)- about 33% increase since 1958 resulting largely from fossil-fuel inputs.
Increase in atmospheric CO2 concentration has not occurred as a smooth line, but like the teeth of a saw blade, with a maximum and minimum concentration each year. Varying dominance of photosynthesis vs. respiration causes it. This annual “amplitude” (maximum CO2 to minimum CO2) change is greatest at high latitudes in N. Hemisphere (large presence of “seasonal biosphere”). Why is the amplitude low at the Equator and in most of the S. Hemisphere? (lots of terrestrial biosphere at Equator, but it is not seasonal; little terrestrial biosphere at higher latitudes of S. Hemisphere)
Al Gore clip on the causes of seasonal high and low CO2 (the “zig-zag” ups-and-downs in the Keeling Mauna Loa CO2 curve)
Change of Seasons- seasons may be shifting and expanding as a result of global warming.
Phenology is the study of timing of recurring biologic phases such as budbreak, flowering, first leaf unfolding, leaf fall, migration, hibernation, emergence, and breeding.
Phenology can be linked to carbon and water cycling and energy of biosystems.
Lilacs in US appear to be flowering about 3-4 days earlier now than the first half of the 20th Century.
A US Phenology network is coordinating and tabulating this information for several species, and other networks exist outside the US.
Fri. Mar. 30
GA4 plan for reducing greenhouse gas emissions
Wed. Mar. 28
Read EPA GHG pamphlet by time of GA4 on Friday and come up with 3-5 sentences describing your idea for reducing GHG emissions
Extinctions
Modern systems have the greatest abundance of species (especially insects) ever, but extinction rates seem to be high. Massive extinctions have occurred in the past, unrelated to human activity. Permian-Triassic extinction event (225 million years ago) the largest of the 6 major extinction in the Phanerozoic (last 600 million years), plus extinction of megafauna about 12,000 years ago, and possible major extinction event in progress over the last 500 years (and growing).
Extinction of dinosaurs (65 million years ago) might have been caused by meteorite impact, evidenced by iridium “anomalies” occurring in sedimentary rocks around the world of that age.
At the Permian-Triassic boundary, evidence from geological record suggests the possibility the extinction was driven by large volcanic eruptions (Siberian traps) or meteorite/comet impact. Evidence suggests loss of land plants and lots of sediments, and many "Bucky Balls" (fullerenes) containing inert gases whose isotopic composition suggests extraterrestrial origin.
Invasive species come from different locations, in many cases different continents, moving via a worldwide network of air and especially sea transportation. Invasive species in US may be responsible for over $100 billion in losses each year. Examples:
Buffelgrass (from Africa, introduced to US in the 1940s; it is a C4 grass meaning it is better adapted to warm summer conditions) and cheatgrass (from Eurasia about 100 years ago; a C3 grass meaning it is better adapted to cool season conditions) a big problem in western states because they capture water and nutrients that would otherwise be used by the native plants. Both grasses also promote wildfire, the consequence of which may be the death of native trees and bushes, and the continued expansion of these grasses. Warming may help buffelgrass to expand because it is better adapted to warm temperatures, and rising atmospheric CO2 may provide cheatgrass a further competitive advantage.
Zebra mussel were introduced into the Great Lakes from ship ballast in the 1980s, and are now spread throughout the Great Lakes and other nearby river systems including the Mississippi River. ZM’s are prolific filter feeders and filter fine organisms and particles out of the water, which removes the food for some fish species. Also, they encrust pipe taking up water and boats. Climate warming is expected to help them extend their range northward.
Invasive species are a 2-way street, with many Great Lakes species getting into European lakes/seas, and many from outside Africa now causing problems for systems throughout Africa
Biosphere and carbon cycle (clip from Al Gore AIT about rising atmospheric CO2 where we see “zig-zag” pattern as CO2 rises)
Mon. Mar. 26
For Friday’s GA4 preparation, read EPA pamphlet available in D2L content for week of March 26. Friday, you will also bring in your written scheme for reducing GHG emissions (see GA4 preparation instructions in D2L) and particularly note in the table of the EPA pamphlet the various activities responsible for large inputs of CO2, N2O and CH4
Term paper- see D2L content for March 26 for instructions on how to avoid misusing ‘due to’, ‘while’, ‘since’, ‘that’/’which’
Section 02 starts their 4th virtual discussion today (1st part due April 6, and 2nd part due April 16).
Global maps (same password as other password-protected readings) of (1) sunlight, water and temperature as influencing growth and productivity, (2) changes in productivity from 1982-1999, and (3) IPCC model projections of vegetation change by 2100.
Biomass is mass of living organisms (= phytomass + zoomass, which is approximately equal to phytomass alone) (mass/volume; mass/area)
Primary productivity is amount of plant matter produced [by photosynthesis] (per area per time)
Gross Primary Productivity (GPP) is total production
Net Primary Production (NPP) = GPP-respiration losses
Respiration loss is about ½ GPP
Aquatic: open ocean biome has LOW productivity; algal beds and reefs have HIGH productivity
Terrestrial: desert- LOW to tropical rain forests-HIGH (and tropical wetlands-HIGH)
Coral reefs are like the “rain forests of the ocean” in terms of productivity. They are damaged or threatened by:
1) Hurricanes
2) Humans (excess nutrients, dynamite fishing, aquarium tropical fish trade, overfishing of starfish predators and algae and seaweed eating fish)
3) Change in environment (salinity, clarity, pH, temperature)
The pH change could be toward increasing acidity as more CO2 dissolves in the water (rising atmospheric CO2 concentrations)
The current dieback observed in coral reefs may be a result of several factors, often hard to isolate. Coral reefs may be reduced/killed by future warming of the ocean, but coral species are not equally susceptible to the conditions forcing coral bleaching, so the relative abundance of coral species may change and reefs may persist
Aquatic biomes exist in lakes, streams and the ocean. In the ocean, biomes are related to whether they are on the ocean bottom (benthic) or in the water column (pelagic). High biological productivity in upwelling areas and in “estuaries” where fresh water streams encounter coastlines in embayments with highly variable environments of salinity (higher salinity toward bottom and lower salinity at top) and organism associated with tidal mixing and rates of stream flow. Extremely important to commercial fishing. (examples, Chesapeake Bay and San Francisco Bay)
Extinctions
Modern systems have the greatest abundance of species (especially insects) ever, but extinction rates seem to be very high. Massive extinctions have occurred in the past, unrelated to human (or zombie) activity.
Fri. Mar. 23
According to Mackenzie text, biosystems (ecosystems) are composed of both abiotic and biotic components
These biosystems can be altered by global climate change or other influences/events. For example:
Change in species (abundance or composition; pioneering, invasion and extinction)
Change timing of species development or activity; loss of breeding habitat
Contribute to emigration or adaptive response
Contribute to catastrophic change- wildfire and frequency
Example of fish called “threadfin bream” in India, which may be shifting time of spawning to counteract effects of warming waters.
Food chains and food webs (“Energy Pyramid” “trophic level pyramid”= “biomass pyramid”= “ecological pyramid”)
90% loss of energy going from one trophic level to the next level above it
Energy consequences of "eating low" on the food chain for Western & Asian diets
Biosphere "abiotic components"- climate, nutrients (eg, C,O,H,N,S,etc), sunlight, water
A closer look at abiotic factors of nutrients (eg, major nutrients C,O,H,N,S,P and minor nutrients K, Ca, Fe, Mg- Table from MacKenzie) and climate
Abiotic and biotic components comprise biosystems (ecosystems)
Large, easily identified community units are known as "biomes"; interaction of biota and climate (Fig. 1.9) on a regional scale. Biomes around the world, such as grasslands (Fig. 4.8; table 4.3). These biomes generally conform well to climate regions, where climate is similar (map)
Distribution of organic matter (O.M.) in biomes between the living organisms (mainly plants) and the dead organic matter of soils and litter (Figure from lecture- same password as other password-protected readings) expressed as “dry organic material”. Biomes are typically different in terms of either total organic matter or distribution of organic matter between living and dead O.M.
Biomass in oceans is a miniscule 0.5% of the biomass on continents, but some estimates suggest NPP in oceans is almost 1/2 of NPP on continents. Biomass is needed on continents to provide support to reach light, and therefore the continental biomass is dominated by structural components (CHO- carbohydrates). Marine biomass does not need the structural components, tends to have a higher ratio of proteins to carbohydrates, and have much shorter life spans than terrestrial organisms
Wed. Mar. 21
First stage of term writing project is due today
Section 02 students have (short) 3rd virtual discussion beginning today (Discussion tab on their D2L site)
Sea-Level Rise (cont’d)
Consequences of sea-level rise
Increased coastal flooding
Increased coastal erosion
Loss of coastal wetlands
Salt water intrusion
Loss of “developed” land
Displacement of people (e.g., Tuvalu islands in SW Pacific now or Beijing/Shanghai/New York in future)
A 1990’s estimate of the cost of a 1 meter sea-level rise in the U.S. was about $400 billion.
The recent and expected rise in sea level is believed to be a consequence primarily of melting of ice on land (glaciers/ice sheets) and expansion of (warming) ocean water (because it decreases density at higher temperature)
Besides global sea level change being dominantly influenced by warming of ocean and melting of permanent ice on land (glaciers/ice sheets) for the neat past and future, other effects on sea level are related to impoundment of rivers behind dams (like Three Gorges Dam, China), or local effects that may be permanent such as subsidence (like Venice) and tectonic changes (faults/earthquakes), or temporary such as hurricanes.
IPCC modeled prediction of global temperature changes of about 1.5 to 6°C by 2100 (2-4°C is most likely), and the mean estimate of global sea level rise is expected to be about 40-50 cm. These predictions represent modeling different scenarios related to fossil fuel usage, economy, population, alternate fuels, etc. Mann/Kump show an estimate of sea level rise of 80-90 cm (or about twice that of IPCC 2007), because models are now better taking into account effects of ice dynamics, such as “calving” of ice sheets into the ocean.
One of the robust findings is that sea level will continue to rise for many centuries, even if GH gas emissions and GH gas concentrations are stabilized.
One of the IPCC robust findings is that sea level will continue to rise for many centuries, even if GH gas emissions and GH gas concentrations are stabilized. Uncertainty as to how long Greenland will take to melt; during last interglacial 125,000 years ago more of Greenland melted and consequently sea level was over 3 m higher than today. Greenland ice sheet may melt to size of ice sheet 125,000 years ago in several thousand years, although it may be substantially sooner depending on ice dynamics.
Biosphere (also called “Ecosphere” in our Mackenzie text)
Contains "abiotic components"- climate, nutrients (eg, C,O,H,N,S), sunlight, water
Contains "biotic components"- trophic (nourishment) levels from bottom to top: (1)-primary producers=autotrophs; (2)-primary consumers=herbivores (=heterotrophs); (3)-secondary consumers=carnivores (also =heterotrophs) and additionally a group (4)-decomposers. “Omnivores” may eat at more than one trophic level.
Mon. Mar. 19
Mid-term
exam was handed back and we
went over 2-3 M/C questions per exam page.
All answers are at D2L content for week of March 19.
First stage of writing project due Wednesday at beginning of class period. See D2L content week of Feb. 27 for instructions and D2L content week of Mar. 19 for grading information
Spring Equinox tomorrow (March 20), day of year when sunlight comes in vertically over the equator at noon and we (and everybody) have 12 hours of day and 12 hours of night
Kilimanjaro - iconic symbol, and representative of global environmental change and our (humankind’s) badness to the planet, but maybe these stories aren’t as they seem
.
Sea-level rise over the last 20 years is about 3 mm per year
Quiz 3 handed back, correct answers were given by Laura who lectured in today’s class.
Summary of Consequences of Arctic warming
Ice/snow Melting: reduces albedo, enhances warming (this is positive feedback)
Melting of permafrost with consequences to
Northwest Passage and commerce
Shifting vegetation, tundra => forest (forest has lower albedo than tundra); longer growing seasons
Warming, drying and possible forest fire increase; shrub encroachment
Review of group activity main points:
Ocean circulation, surface ocean
El Niño and currents in S. Pacific
El Niño tends to recur in irregularly from 2-7 years, and strength varies among events.
Group Activity 3- beef consumption, resources and fun?#!@
Deep-ocean currents (and the “Ocean Conveyor Belt”) require dense water to start cycle by sinking
Dense water achieved by (1) cooling or (2) increase in salinity [by (a) evaporation or (b) freezing]
Properties of water (also this link)
Groundwater, aquifers and subsurface flow of water in the water cycle
Properties of water (also this link)
“Polar” water molecule (which has a “positive” side and “negative” side)
Humidity in atmosphere, and current weather maps/forecast precipitation
Group Activity 2, water resources and problems around the world
Begin Group Activity 2 preparation for Friday’s group activity on world water resources.
We discussed answers to Homework 3 exercise involving different temperature scales
Electromagnetic radiation is mechanism by which energy is gained and lost by the Earth.
Reverse reaction of photosynthesis is respiration/combustion/decomposition
Water vapor (H2O) and carbon dioxide (CO2) are the 2 most important greenhouse gases on our planet.
Demonstration of 4 atmospheric gases (N2, H2O, CO2 and O2), some in unusual (cold) forms.
Experiment to determine if the liquid in the test tube sitting in liquid nitrogen was N2 or O2.
Extra Credit opportunity began over weekend that is related to Tucson Gem, Mineral, Fossil Shows.
Oil crash video (possible finite fossil-fuel energy resources)
Video of innovative Nepal fuel (biomass fuel that has some health and environmental benefits)
Smith’s “In Praise of Petroleum” essay
Origin of Solar System (cont’d)
3rd- Every action has an equal and opposite reaction (conservation of momentum)
Structure of the Earth (heterogeneous distribution of chemicals with depth=layers)
Differences in chemistry among layers (for example low SiO2 in mantle and higher in
First Quiz next Wed. Jan. 25; I’ll put up a sample quiz on D2L this weekend
First Group Activity next Fri. Jan. 27; preparation instructions to follow in a few days
Grading Rubric will be posted shortly for the first writing assignment
More Grand story of epic proportions:
First Quiz next Wednesday (Jan. 25)
Grand story of epic proportions:
Short Writing Exercise 1 (essay style) announced, due by class time Wednesday, Feb. 8:
What is the best course for the country (p. 144-5)
Keeping the power turned on (p. 160-1)
Your essay will contain 2 elements
1. Summary; boil it down; explain what is being said.
2. What do you think should be done? Why? You can express personal, US, world viewpoint(s)
(in-text citations and references not necessary, but all words should be your own).
All matter is made of small particles (atoms and their constituents)
Atoms of the same element have similar chemical properties
Atoms are not divided by chemical reactions
Chemical reactions involve electrons; nuclear reactions involve protons/neutrons
(in a column of period table different elements may behave similarly in chemical rxns)
Elements arranged according to increasing Atomic Number (number of protons).
(This arrangement is also related to filling of electrons in discrete electron “shells”)
Each element has name and 1- or 2-letter shorthand notation.
When an atom is “neutral”, it will have an equal number of protons (+) in nucleus and
electrons (-) orbiting nucleus. Neutrons (no charge) also can reside in nucleus at the