Environmental Science Exam 2 - Part 2

Does global warming mean temperatures rise everywhere at every time by the same rate?

No: temperatures can increase in one region and decrease in another

Why is warming greater over land than over oceans?

Thermal intertia: water is slower to absorb and release heat

Thermal inertia

The tendency of a material to resist changes in temperature

What range of years is the standard against which other years are measured for global temperatures?

1951-1980

What number of global degree change is significant?

One-degree global change (in Celsius)

When were temperature anomalies first recorded?

1880

How can we look even farther in time at global climate change, before there were instrumental records?

By looking at climate proxy records, such as tree rings, ice cores, corals, etc.

What is the significance of this graph?

This is the “hockey stick” graph. It depicts that the average temperatures in the northern hemisphere held roughly steady for 900 years or so, until the 20th century, when they rose sharply.

The basic premise = the planet’s recent warmins is unprecedented over at least the last millennium

Percent of excess heat caused by greenhouse gases that is stored in the oceans

90%

What is the main driving force of climate change?

Greenhouse gases

Which three greenhouse gases have increased in the atmosphere since pre-industrial times (1750)?

Carbon dioxide (CO₂), Methane (CH₄), and Nitrous Oxide (N₂O)

Where do carbon dioxide, methane, and nitrous oxide come from?

CO₂: from fossil fuel burning, agriculture (deforestation, tilling soils, burning)

CH₄: from cattle, etc.

N₂O: from fertilizer pollution

What is the Keeling Curve?

It includes the direct measurements of atmospheric CO₂ at Mauna Loa since 1958. It has shown the increase of atmospheric CO₂ concentration over time.

Why does carbon dioxide (CO₂) contribute the most to climate change?

• CO₂ sticks around, remaining in the atmosphere for longer than the other major heat-trapping gases emitted as a result of human activities

• CH₄ takes about a decade to leave the atmosphere (it converts to CO₂)

• N₂O emissions take about a century to leave the atmosphere

• CO₂ emissions take about a century to (mostly) leave the atmosphere. About 20% will still exist in the atmosphere approximately 800 years from now

• *** CO₂ has the highest positive radiative forcing of all the human-influenced climate drivers ***

Radiative forcing (RF)

The measurement of surface warming ability

Atmospheric aerosols

Suspensions of liquid, solid, or mixed particles

What are some sources of atmospheric aerosols?

• VOlcanic eruptions (ash and sulphate)

• sea spray (sea salt and sulphates)

• desert storms (mineral dust)

• biomass burning

• coal power plants

• ships

• cooking

• road transport

How often do the patterns of ice age/interglacial cycles repeat?

Roughly every 100,000 years

What is different about the current change compared to past climate change?

Magnitude

• higher concentrations of carbon dioxide, methane, and nitrous oxide today than any level recorded in the 800,000 year ice core record

Rate

• higher average rate of increase of these three gases observed over the past century, exceeding any observed rate of change over the previous 20,000 years

What is the significance of climate models?

Computer models help us to break down the complexity of climate change. Models have done a good job replicating past and current events, so we trust that they can predict what will happen in the future.

*** Computer simulations of temperature change in response to greenhouse gas concentrations and other drivers are the best predictive tool of future climate change ***

In what ways have we seen climate change already?

• increased average temperature of Earth

• incluence on the patterns and amounts of precipitation

• reduced ice and snow cover, as well as permafrost

• raised sea level

• increased acidity of the oceans

• increased frequency, intensity, and/or duration of extreme events

• shifted ecosystem characteristics

• increased threats to human health

• impacts on food supply, water resources, infrastructure, ecosystems, and even our own health

note: changes impact vulnerable populations the most

Ocean acidification

Carbon dioxide naturally dissolves into seawater. Water and carbon dioxide combine to form carbonic acid (H₂CO₃), a weak acid that breaks (or “dissociates”) into hydrogen ions (H⁺) and bicarbonate ions (CHO₃-). Excess CO₂ from human activities dissolves in the ocean and acidifies it, dropping the pH of the ocean waters

Phenology

The timing of natural events (e.g., egg laying, flowering time, leaf fall). Almost like nature’s calendar

Trophic mismatch

When the availability of food shifts in response to warming temperatures

Effects of climate change on bird populations

• birds are adapted to a set of conditions in a habitat as defined by temperature, moisture, and the interspecific interactions that occur there

• climate cahnge causes these conditions to change and so birds, if they have the option, will move .. o smaller spaces with different resources, increased competition, and possibly new predators

Why should we care about what is happening at the poles?

The melting at the poles causes:

• sea levels to rise

• changes in albedo

• greenhouse gases to be released from melting permafrost

= widespread ecosystem disruptions and infrastructure damage

What can be done about climate change?

• shift to renewable energy sources

• electrify everything (assuming renewable energy is accessible)

• increase energy efficiency

• put away CO₂ before it reaches the atmosphere through carbon capture and sequestration (CCS)

Pollution

The unwanted alteration of natural systems as a result of human activity

Point source pollution

Pollution from a precise origin, e.g., industrial plant

Non-point source pollution

Pollution from an unclear source, e.g., fertilizer in groundwater could be from any number of sources, such as homes, farms, golf courses, etc.

Biodegradable pollutant

A pollutant that can be broken down into less harmful components by bacteria. This only works to a point, because the biota can be overwhelmed by excess pollution. Some examples of biodegradable pollutants are: sewage, paper, wood, cloth, leather, wood, vegetable and plant matter

Non-biodegradable pollutant

A pollutant that can not be broken down of metabolized. They accumyulate over time and therefore become more dangerous. Some examples are PCBs, DDT, dioxin, and heavy metals (like mercury, arsenic, and lead)

What is bioaccumulation?

The repeated uptake of pollutants by an organism so that the concentrations in that organism become several orders of magnitude greater than their surrounding environment (e.g., a clam filters polluted water and concentrates the toxins in its tissue)

What is biomagnification?

When higher concentrations of a particular pollutant are reached in organisms higher up the food chain, generally through a series of prey-predator relationships (e.g., a hawk eats five contaminated mice)

Is this depicting bioaccumulation or biomagnification?

Both: The zebra mussels concentrating contaminants is an example of bioaccumulation. The mussels being eaten by small fish, and those fish being eaten by larger fish, and ultiamately eaten by humans, is an example of biomagnification.

How do pollutants get into the water?

• industry waste

• CSOs

• septic systems

• agricultural runoff

• leaking landfills

• golf courses and suburban lawns

• illegal dumping

• parking lot runoff

Mercury

Mercury is a pollutant from coal-fired power plants and incinerators. It is also a neurotoxin and interferes with reproduction even when it is consumed through biomagnification

Lead

Lead is a cumulative toxicant that affects multiple body systems and is particularly harmful to young children. Lead is distributed to the brain, liver, kidney, and bones, and accumulates over time. Human exposure is typically assessed through the measurement of lead in blood. There is no level of exposure to lead that is known to be without harmful effects

Chlorinated hydrocarbons (e.g., DDT, PCBs)

• lipid-soluble

• long-lived

• suspected human carcinogens

• hormone mimickers (endocrine disrupters)

• circulate globally in food chains

*** PCBs are oily solvents used in the electrical industry. Over 1 million pounds of PCBs were legally released into the Hudson River between 1946-1977. PCBs were banned in 1977 ***

The Clean Water Act (CWA) 1972

Protects surface water quality. Its goal was to reduce direct pollutant discharges into waterways, finance municipal wastewater treatment facilities, and manage polluted runoff. The CWA programs have shifted from a pollutant-by-pollutant approach to a more holistic watershed-based approach. Equal emphasis is now placed on protecting healthy waters and restoring impaired ones.

The Safe Drinking Water Act (SDWA) 1974

The main federal law that ensures the wuality of Americans’ drinking water. Under the SDWA, the EPA sets standards for drinking water quality and oversees the states, localities, and water suppliers who implement those standards. MCL is maximum contaminant level. Every town gets their water tested and this type of report is available to all residents. Any violation must be addressed

How do pollutants get into the air?

The majority of air toxins come from human-made sources, such as:

• factory emissions

• coal-fired powerplants

• motor vehicle exhaust

• gasoline vapor

• industrial sources such as chemical factories, refineries, and incinerators

• small industrial and commercial sources such as dry cleaners and printing shops

What is fine particulate matter (PM_2.5)?

Fine particulate matter PM_2.5 is an air pollutant that reduces visibility and causes the air to appear hazy when levels are elevated. PM_2.5’s size range is able to travel deeply into the respiratory tract

Sources of fine particulate matter (PM_2.5)

Outdoor:

• vehicle exhausts

• burning of fuels such as wood

• heating oil and coal

• forest grass fires

• power plants

Indoor:

• tobacco smoke

• cooking (e.g., frying, sautéing, broiling)

• burning candles and oil lamps

• fireplaces

• fuel-burning space heaters