Ecology - Mod 19 (Ch 25): Global Ecology

global ecology

global ecology

the study of the interactions among earth’s terrestrial and aquatic ecosystems and the atmosphere, how these interactions affect global ecological processes and the distribution and abundance of living organisms across the planet (biosphere), and how human activities influence these interactions and ultimately the diversity of life on earth both presently and in the future

interaction of earth’s biogeochemistry, climate, and biodiversity

all intertwined

earth’s ecosystems interact with one another and with the atmosphere via movement of biologically important elements (e.g. H, C, O, N, P, S, etc)

determines climate, sea level, globally important ecological processes (e.g. nutrient availability and rates of primary production, decomposition, soil formation and erosion, disease spread, speciation, extinction)

Earth’s 4 major compartments

each compartment stores elements (e.g. H, C, O, N, S) and molecules (e.g. CO2, O2, H2O, CH4)

geosphere, hydrosphere, atmosphere, biosphere

geosphere

crust, mantle, core

lithosphere: outermost part = crust and outermost upper mantle

crust: hardest rocks + pedosphere (soil)

asthenosphere: just beneath lithosphere = soft rocks of upper mantle

hydrosphere

water

liquid gas H2O in oceans, lakes, rivers, clouds

solid H2O (cryosphere) in ice and glaciers

H2O also occurs within other compartments

e.g. large amounts of water may exist 300 miles below Earth’s surface (wet mantle)

atmosphere

gases surrounding earth

and particulate matter (dust, smoke, pollutants, etc)

layers: troposphere, stratosphere, mesosphere, thermosphere, exosphere

biosphere

all living organisms

occurs within other compartments

e.g. bacteria have been found in the atmosphere, 5-10 miles above Earth’s surface, diatom frustule fragment from lower stratosphere

biogeochemical cycles

physical and biological processes that move elements, molecules, and particulate matter within and between earth’s compartments

biological processes: respiration, photosynthesis, elemental uptake, decomposition

physical processes: precipitation, evaporation, runoff and seepage, groundwater recharge, rock weathering

include both nutrient and non-nutrient cycles (both are important to survival and reproduction of living organisms)

nutrient cycles

types of biogeochemical cycles involving “essential elements” required for living organisms to complete their life cycles

3 non-mineral (C, H, O) and 14 mineral elements (don’t need to remember the mineral elements)

e.g. iron cycle, mercury cycle, nitrogen cycle, phosphorus cycle

global carbon cycle

naturally, most C is locked in rocks and doesn’t move between compartments

deep ocean H2O has second largest amount, very little moves from there; a little bit moves between deep ocean and surface waters via upwelling, mixing, sinking/decaying plants and animals (detritus) (e.g. whalefalls)

terrestrial C pool above and within soil: living and decaying plant, animal, microbes (2x more in soil (microbes, detritus) than in living vegetation)

most natural movement of C between compartments occurs between atmosphere and terrestrial biosphere or ocean surface H2O

between atmosphere and terrestrial biosphere (plants and animals): largest natural exchange pool; CO2 is absorbed for photosynthesis and released via respiration/decomposition (also CH4); exchange between atmosphere and terrestrial pool is naturally roughly equal in both directions (human activities now cause movement of C from terrestrial pool → atmosphere to exceed movement from atmosphere → terrestrial pool)

between atmosphere and ocean surface H2O: receives C as CO2 from atmosphere and from rain as carbonic acid (H2CO3), releases CO2 into atmosphere

humans have altered it by releasing large amounts of stored C from lithosphere into atmosphere

emission levels of C are positively correlated with human population size

anthropogenic movement of C into atmosphere: fossil fuel burning, deforestation

anthropogenic carbon emission into atmosphere: fossil fuels

globally, most anthropogenic (human-sourced) C emissions are from burning fossil fuels for production of energy (64.5% of GHG emissions)

most of that is for electricity (28% of total, 43% of energy)

in US, transportation (29%) and electricity (28%) are equally significant sources of atmospheric C

(transportation accounts for 2x more C emissions compared to world avg, most of that is from personal vehicles)

anthropogenic carbon emission into atmosphere: deforestation

C stored in vegetation and soil is moved to atmosphere

removing trees warms soil → increased decomposition rate of detritus and of tree roots

burning trees released CO2, CO, and CH4 into atmosphere

also leads to increased air temp and soil erosion

global nitrogen cycle

naturally, 99.9% of N is locked in the atmosphere as N2, does not move between compartments

N2 in atmosphere is very stable, not usable by most organisms

small amounts of N2 from atmosphere move into biosphere via fixation; occurs on land and in water

fixation: conversion by certain bacteria and some archaea of N2 into a form usable by plants (many N-fixing bacteria live in plant root nodules (symbiotic), especially of legumes (e.g. soybeans, alfalfa, peanuts, clovers, kudzu)

largest biologically important N pools are in soil (pedosphere of lithosphere) and near ocean surface (hydrosphere)

N moved from soil and ocean pools into biosphere (plants and zooplankton). On land, bacteria and fungi decompose dead organisms and nitrogenous waste into NH4, other bacteria can convert that into a form usable by plants

N moved back from biosphere to lithosphere when plants and animals die or excrete nitrogenous waste

“denitrifying” bacteria move a little bit of N from soil and ocean surface back to atmosphere

N is biologically essential, although little occurs in terrestrial and ocean surfaces

only a little bit moves between terrestrial and aquatic regions via rivers, but essential for primary production estuaries

human altering of the N cycle

even more than altering of C cycle

rate of terrestrial N2 fixation by humans now exceeds that by natural biological fixation

N2 removed by humans from atmosphere is converted to biologically abailable forms and either released back to atmosphere or directly deposited into terrestrial and aquatic ecosystems

if released back into atmosophere: alters atmosphere, redeposited into terestrial and aquatic ecosystems causing excess N and altering pH

if directly deposited into ecosystems, causes excess N

3 anthropogenic processes increasing N availability: fertilizer manufacturing, agriculture, emissions of certain gaseous forms of N

fertilizer manufacturing

converts stable unavailable N2 into usable forms (i.e. fixation)

conversion also requires a lot of energy from fossil fuels

agriculture

growing huge amounts of N-fixing crops (peas, soybeans, alfalfa, etc)

flooding fields for rice, e.g. increases fixation by cyanobacteria

emissions of certain gaseous forms of nitrogen

from:

burning fossil fuels and trees (deforestation)

volatilization of fertilizers

livestock feedlots

human sewage plants

problems with excess N availability

H2O pollution:

much of fertilizers applied is unused by plants since most plants don’t need much N, and it leaches deep in soil and is unavailable to plant roots

unused fertilizer leaches into groundwater, lakes, estuaries

extreme N levels in waters: Norway, increased 2x in <10 yrs in 1000 lakes; in NE US and Europe, increased up to 15x in rivers in last 100 yrs

causes excess algal growth → O2 depletion as algae dies and decomposes → death of fish and other vertebrates and invertebrates

linked to human disease: reproductive problems, bladder and ovarian cancer, “blue baby” disease (low O2 in blood due to hemoglobin converted to methemoglobin)

decreased biodiversity:

certain plants can use more N and outgrow and kill off other plant spp

certain nonnative plants can spread rapidly

increases acidity (lowers pH) of soil and water; combines with H2O to form acid rain (HNO3 nitric acid in rain), most plants and aquatic animals or microorganisms cannot tolerate it

climate change

directional change in climate over a period of at least 3 decades

caused by excess gaseous emissions by humans of C, N, and other compounds

weather: current state of atmosphere at any given time or over short time periods

climate: long-term description of weather, including avg conditions and full range of variation

since 1976, every yr has had an avg global temp warmer than the long-term avg

since 1880, avg global temp has increased 1.6*F

2010-2019 was the warmest decade of the previous 1000 yrs

since 1976, temp has increased at an avg of 0.5*F/decade over land and 0.22*F/decade over ocean

rate of warming is presently faster than at any point in the last 1000 yrs

FL temps: avg temp 1895-2008 = 70.61*F. Trend = +0.04*F/decade

FL rainfall: increased. avg rainfall 1895-2008 = 54.02 in. Trend = +0.3 in/decade

anomalies: top warmest years since 1880

2023 was Earth’s hottest year since 1880

the last ten years are the warmest recorded since 1880

2013-2023 was warmest decade recorded since 1880

indicators of climate change

decreased: glaciers, snow cover, sea ice, and ice sheets

spring coming earlier

increased: spp migrating poleward and upward, tree-lines shifting poleward and upward, ocean heat content, sea level, sea surface temp, temp over land, air temp near surface (troposphere), temp over oceans, humidity, flooding, land submergence

climate determined by:

atmospheric and oceanic circulation patterns resulting from differential heating of Earth’s surface by the sun

review from mod 2

atmosphere influencing sunlight and heat

atmosphere determines how much sunlight reaches the earth and remains near earth vs reflected into space

greenhouse gases in atmosphere trap heat and help keep earth warm (greenhouse effect), but too much causes too much heat

greenhouse gases

92% of all greenhouse gases contain C: most as CO2 (76%), some as CH4 (16%)

US emits 2nd most CO2 of any country (15%) of total (behind China @ 30%), but 1st most per capita (2.5x more per capita)

CH4 (methane) is less abundant than CO2, but 25x more effective at trapping radiation than CO2 and takes much longer to break down, thus remains in atmosphere for longer periods of time

N2O (nitrous oxide): 3rd most abundant greenhouse gas, but traps 300x more heat than CO2 and can remain 100x longer in atmosphere

other: fluorinated gases not as abundant in atmosphere but extremely powerful and long-lived

global warming potentials: CO2 = 1, CH4 = 25, N2O = 298, HFCs = 12-14800, PFCs = 7390-12200, NF3 = 17200, SF6 = 22800

current atmospheric CO2, CH4, and N2O) levels are higher than any point in nearly 1 million years

past levels of greenhouse gases are mainly found by dating ice cores (air bubbles in ice cores)

amount of greenhouse gases in atmosphere and global temp are directly positively correlated

why climate change matters

warmer temps cause increased evaporation → drought and fires in some areas, increased rain, flood, landslides, or snow in other areas

warmer oceans → increased hurricanes, water expansion and increased glacial melt → raised sea levels

climate extremes (droughts, floods, extreme temps, high CO2) → crop and livestock loss, increased weeds, pests, and fungi, → food/job insecurity and other economic loss

study: increasing CO2 threatens human nutrition. Plants grown at higher CO2 levels have lower protein, zinc and iron concentrations

ocean acidification

increased CO2 in atmosphere → increased CO2 in oceans

CO2 + H2O → carbonic acid (H2CO3)

carbonic acid breaks down into bicarbonate (HCO3-) and hydrogen ions (H+)

increased H+ = increased acidity

bicarbonate further breaks down into carbonate (CO32-) and more H+ (increased acidity)

CO32- can either combine with Ca2+ to form animal/coral shells or recombine with H+

high acidity [H+] means greater likelihood of combining with H+ than with Ca2+ → decreased shell formation

coral bleaching

affected by ocean acidification; high [H+] dissolves calcium carbonate (shells and coral)

decline in calcification (shell formation) rate is correlated with lower pH and higher ocean temps

acidification and warming reduce calcification, reduce growth, increase coral bleaching

studies show bleaching in Great Barrier Reef is at its worst

only 7% of the reef system has avoided bleaching entirely

middle and southern sections will likely recover and regain color in coming months

80% of northern sections were severely bleached, with confirmed 50% mortality in some reefs; percentage could eventually exceed 90%

recovery will take decades, result in very different community

will be dominated by fast-growing pioneer spp, without 200-yr-old corals that have died

up to 80% of west coast Australian corals are now bleached

time between major bleaching events is decreasing globally (happening in closer succession)

can be caused by alteration of environment

coral expels symbiotic algae (shows white CaCO3 exoskeleton); caused by environmental changes: abiotic (e.g. temp, turbidity, light, salinity), more than 2*F above avg can cause bleaching; biotic: e.g. nutrients

bleached corals can continue to live but most starve and die, others are more vulnerable to disease

corals are being grown and planted, Nature Conservancy; throughout FL reef tract, >50000 corals housed in nurseries, >10000 planted on damaged reefs

other ecological responses to climate change

coastal Louisiana: sea water moves in → coastal forests die, replaced by salt marsh

high N levels in soil in Great Britain → decreased plant spp diversity (→ faster-growing spp and nonnative spp outcompeting slower-growing spp, acidification and higher free Al3+ kill intolerant spp)

plant spp richness has increased from historical levels to present levels on mountain summits in the Alps (due to upward movement of spp from lower elevations, may be due to warmer temps at higher elevations)

63% of 35 nonmigratory European butterfly spp studied had a northward range shift due to warmer temps at northern latitudes

305 widespread North American bird spp have had a 20-70 mile northward shift in general occupied area

other spp have exhibited latitudinal and altitudinal shifts

amphibian breeding sites in southern England changed

frogs: 2 of 3 spp had avg times of first spawning was 2 to 3 weeks earlier in the last 5 years than in the 1st 5 years

salamanders: avg times of first spawning was 5-7 weeks earlier

hatching date shifts also exhibited in American crocodile in southern FL (relationship between sea surface temp and avg hatching date, 1.5 days earlier every 2 years; with every 1*C inc in temp, hatching occurs ~10 days earlier), other spp also

reduction of CO2 emissions

energy efficiency: travel in more fuel-efficient vehicle, use more efficient electrical appliances, improve building insulation

energy conservation: turn off lights and electronics when not in use, reduce distance traveled in vehicles, reduce purchases, repair instead of buying new, reuse containers

fuel switching: produce more energy from renewable sources, use fuels with lower carbon contents

carbon capture and sequestration (CCS): capture CO2 from coal-fired power plants before it enters the atmosphere, inject it deep underground into a subsurface geological formation, e.g. abandoned oil field, to be securely stored

reduction of fluorinated gas emissions

substitution of ozone-depleting substances in homes, businesses, and transportation: (for refrigerants used by businesses and residences) fix leaking AC instead of just refilling, upgrade to less-damaging substitutes, use better technology when possible, capture gases when repairing instead of just emitting to air

industry: adopt fluorinated gas recycling and destruction processes, optimize production to minimize emissions, replace these gases with alternatives

electricity transmission and distribution: reduce release of sulfur hexafluoride

good news regarding emissions

greenhouse gas emissions from electricity and industry, US CO2 and CH4 emissions have either decreased or leveled off (1990-2017)

bad news regarding greenhouse gas emissions

emissions from transportation are still increasing

US fluorinated gas emissions are still increasing

(1990-2017)

primary cause of climate change

humans: agreed on by nearly all experts

2013: 97% of climate research scientist data concludes current climate change is due to humans, not part of a natural cycle

57% of US public disagrees/is unaware that most scientists agree that climate change is due to human activity

myth 1: “the climate is always changing; it’s natural”

climate is always changing, but current rate is far exceeding the slow historical rate

climate models based on historical evidence suggest that earth should be cooling during human time, not warming

angle of tilt of earth determines climate: smaller angle = cooling, larger angle = warming

angle is currently decreasing (present = 23.4*, varies between 21.75-24.25* with periodicity of 42000 yrs)

angle is currently small/decreasing so Earth should be cooling, but it is warming

myth 2: “the 97% are wrong”

dissent usually comes from those not qualified to evaluate data, not credible climate research scientists

expert credibility in climate change (Anderegg et al. 2010): made list of climate researchers with >20 peer reviewed publications (908 researchers), considered experts by other scientists. Each researcher was classified as convinced by evidence (CE) or unconvinced by evidence (UE).

climate related peer-reviewed publications for each and number of citations for each paper were tallied

researchers with the most climate change publications and most citations by other researchers overwhelmingly agreed that humans have caused climate change

those unconvinced were the ones with the least number of publications and least number of citations

top myths about climate change

the climate is always changing; it’s natural

the 97% consensus is wrong

warming has paused

31000 scientists disagree

the models are wrong

CO2 is good, plants need it

Antarctic ice is growing

warming might be good