Lecture 26 Global Anthropogenic Impacts Flashcards
Threats to Biodiversity
Local and global scale processes lead to biodiversity loss
slide 16
Pollution
- Pollutants are harmful materials
that damage the quality of air,
water, and land - Pollution can be:
- Chemical (industrial
compounds, pesticides,
pharmaceutical) - Plastic
- Environmental (light and
sound) - Pollution can spread globally
from source
Pollution: Chemical
- Some toxins are metabolized or excreted,
others accumulate in tissues - Chlorinated hydrocarbons and inorganic
compounds (e.g., mercury) are found in
industrial chemicals and pesticides - Pollutants enter ecosystems through
industrial waste, sewage, and combustion - They are often endocrine disruptors that
interrupt normal physiological functions
(including in humans) - They can also accumulate and magnify in
ecosystem…
Pollution: Biological Magnification
- Bioaccumulation: Pollutants (toxins) are stored
in tissues - Biomagnification: pollutants become more
concentrated at each higher trophic level
slide 19
Pollution: Acid Rain
Combustion releases sulfur and nitrogen oxides
that react with water in air to make acids
slide 20
Pollution: Ozone Depletion
- Atmospheric ozone (O3) provides UV
protection - Has been thinning since 1970’s because of
ozone-destroying pollutants like
chloroflurocarbons (CFCs) - Worst in the south pole because cold air
allows ozone-depleting reactions to continue
year round - Global regulations have stabilized ozonedepleting chemicals, but pollutants already in
the atmosphere will continue depleting
ozone for 50+ years
Pollution: Plastics
- 11-28 billion pounds of
plastic waste end up in the
ocean every year - Plastic can persist for 100’s
of years! - How does it harm wildlife?
- Animals eat it & get
entangled by it - Can carry bacterial
pathogens - Many unknown effects of
consuming microplastics
Pollution: Environmental
Noise and light pollution impact animal communication, behavior, and physiology
Nutrient Enrichment
- Nutrient enrichment
(mainly N & P) from:
industrial pollution, sewage,
agriculture, and crop fertilizers - Problems arise when nutrients
exceed the critical load:
the amount of nutrients that
can be absorbed by plants - Excess nutrients leach into
aquatic systems to contaminate
water supply and cause
eutrophication
slide 24
Nutrient Enrichment: Agriculture
- Agricultural practices affect
nutrient reserves in soil: - Crop harvesting removes
nutrients leading to depletion
of natural reserves over time - Fertilizers supplement
nutrients, but excess
nutrients remain in the soil - Nitrate concentrations in
groundwater are elevated in
agricultural regions sometimes
reaching unsafe levels for
drinking
Nutrient Enrichment: Eutrophication
- Nutrient levels in an aquatic ecosystem exceed critical load leading to
explosive growth of primary producers - Primary producer growth leads to “dead zones” and harmful algal blooms
slide 26
Nutrient Enrichment: Dead Zones
Algal blooms deplete oxygen as plant matter decomposes
* Hypoxic (oxygen depleted) water kills wildlife
slide 27
Nutrient Enrichment: Harmful Algal Blooms
- Harmful algal blooms produce elevated
levels of toxins that kill wildlife - HAB toxins can bioaccumulate!
slide 28
Climate Change
- Instrumental records
of sea surface and land
temperatures have
been recorded since
1800s – there has
been a steady increase - Scientific consensus is
that warming is due to
increased
concentrations of
greenhouse gases
slide 30
Climate Change: Greenhouse Gases
- Human activities have
increased multiple
greenhouse gases:
Methane, Nitrous
Oxide, Carbon Dioxide - Greenhouse gases
reflect heat that would
otherwise escape to
space back toward
Earth
slide 31
Climate Change: CO2
- CO2 has been continuously
monitored since 1958 at
Mauna Loa, Hawaii & other
global locations - Air bubbles in glacial ice
provide a longer record - Over past 170 years
concentration of CO2 in
atmosphere has been
increasing as a result of human
activity - Rising CO2 coincides with rising
annual global temperatures - Isotopic fingerprint of atmospheric CO2
- Plants have more 12C
- Volcanic eruptions have more 13C
- Young organic matter has more 14C
- Atmospheric CO2 has high values of 12C
and low values of 14C and 13C, indicating
the carbon is very old and comes from
organic material à only fossil fuels meet
this criteria
slide 32-35
Climate Change: CO2 & Temperature
Increasing temperatures & CO2 concentrations are highly correlated
slide 36
Climate Change: Temperature
- Over past 100 years, Earth has
warmed 0.74 ± 0.2ºC - Warming rate is increasing and faster
than any time in last 1000 years - Freeze-free periods at higher
latitudes are lengthening - 10% decrease in snow and ice extent
since 1960s - Most thermal energy has been
absorbed by the ocean, contributing
to rising ocean temperatures and sea
level
slide 37
Climate Change: Impacts
- More than just global warming!
- Increased climate variability with regional differences
slide 38
Climate Change: Impacts
- Increased precipitation
- Extreme events:
increased severity and frequency - Heat waves & Droughts
- Storms & Hurricanes
- Wildfires
- Desertification
- Snow/glacier/ice loss
- ”Tipping points” could start feedback
chains of irreversible ecosystem
change (e.g., collapse of global
currents)
Climate Change: Oceans
slide 40
Climate Change: Primary Productivity
- Net Primary Productivity
(NPP) is increasing in some
areas, but gains are offset
by decreases in other
regions & increased
respiration - Overall decrease in global
NPP - Some ecosystems are
switching from carbon sinks
to carbon sources (positive
to negative NEP) - Most projections: global
shift to carbon source
slide 41
Rising Temperatures: Biological Effects
Cellular
* Cellular processes like DNA replication, cell division,
enzyme activity are all impacted by temperatures
* Temperature stress can impair immunity and
physiological function
Organismal
* Rising temperatures push organisms outside of their physiological limits
leading to behavioral changes and altered and increased mortality
* Increasing temperatures affects metabolic rate: ectotherms grow more
rapidly but also consume more food
Populations
* Population size and phenology (timing of
growth and reproduction) altered by
temperature and food availability
* Migration patterns altered by
temperature changes
* Overall earlier onset of spring activities
May be mismatch with interacting species!
Communities & Ecosystems
* Changes in temperature and precipitation impact fundamental niche space
* Species expand or contract ranges, or move
to new locations, to track suitable climate
slide 42-46
Climate Change: Ocean Acidification
- CO2 diffuses into water to produce carbonic acid; acid formation lowers pH
- pH has dropped in ocean water 0.1 units since preindustrial times (scale is
logarithmic = 25% increase acidity); projected 100-150% increase by 2100 - Impacts calcification of marine organisms
slide 47
Climate Change: Range Shifts
- Northern and upper elevation boundaries of ranges
reflect constraints by minimum temperatures - General shifts poleward in latitude and upward in
elevation
slide 47
Climate Change: Range Shifts & Disease
Climate change makes it easier for animals, mosquitoes, ticks, and infectious
diseases they spread to expand into new areas and infect more people
Climate Change: Disease
- Risk for infectious diseases is
increasing because of climate
change & interacting effects of
land use change - In addition to range shifts:
- Vectors (e.g., ticks, mosquitos) are
active more months out of the
year - Fungal and bacterial pathogens
are no longer killed in winter frosts - Also increased risk of noninfectious disease (e.g., heat
stress, malnutrition, respiratory
disease, injury, mental health)
slide 50
Climate Change: Future
- IPCC models predict future of earth under
different scenarios of carbon emissions:
higher temperature and more precipitation - 1.1 to 6.4ºC increase by 2100
- Warming will primarily affect northern
latitudes & winter - “Business as usual”: CO2 will double this
century & 4ºC higher in 2100 (vs 1900) - Emissions stopped immediately: temperature
will continue to rise! 1.5ºC higher in 2100 - Future of biodiversity?
slide 51
