Geog 3900 Exam 1 (option 2)

Ice albedo feedback

The feedback in which warmer temperatures melt ice, there is a less reflective surface (i.e. more ocean is exposed which absorbs heat), which leads to more warming and melting of ice

POSITIVE FEEDBACK (more ice melt leads to MORE ice melt)

Solar Irradiance

Energy we receive from the sun

Proxy Data

The data that paleoclimatologists gather from natural recorders of climate variability (tree rings, ice cores, fossil pollen, ocean sediments, coral and historical data)

Biogeochemical cycle

The cycling of substances that creates a pathway by which a chemical substance moves through both biotic (biosphere) and abiotic (lithosphere, atmosphere, and hydrosphere) compartments of Earth

Temperature

measure of average KE of molecules in a body

Radiative forcing

The measurement of the capacity of a gas or other forcing agents to affect that energy balance, thereby contributing to climate change. Put more simply, RF expresses the change in energy in the atmosphere due to GHG emissions.

Stefan-Boltzman Law

P/a = εσT⁴

Intensity increases to 4th power of its temp

P/a = power / area

ε = emissivity (unitless; 0-1, 1 for BB)

σ = Stefan-Boltzmann constant (5.67 x 10⁻⁸ W

m⁻² K⁻⁴)

T = temp. (K)

ITCZ

The Inter Tropical Convergence Zone, or ITCZ, is a belt of low pressure which circles the Earth generally near the equator where the trade winds of the Northern and Southern Hemispheres come together.

Albedo

amount of SW reflectivity, given as % (range: 0 - 1.0)

Aerosols

particles so small they're unaffected by gravity, but remain suspended in atmosphere for days or weeks

Normal period

30 years

Coriolis force

deflects a freely moving object to the right in the Northern Hemisphere and left in southern

Negative feedback

If evaporation from the oceans causes more low-level clouds to form, they will reflect more sunlight back into space, causing a slight decrease in surface temperatures.

Anomaly

difference between the actual temperature and a reference temperature

Wien's Law

λmax = (constant / T)

wavelength of object decreases with temperature

HOT sun = shorter wavelengths

COOL Earth = longer wavelengths

Thermohaline circulation

Is a part of the large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes.

drives the mixing of surface water and deep water

Climate change

change in the statistics of the atmosphere over decades

Holocene

epoch that began after the Pleistocene (and last glacial period) at approximately 11,700 years BP

part of Quaternary period

Greenhouse gas

A gas that contributes to the greenhouse effect by absorbing and re-emitting infrared radiation

e.g., carbon dioxide and chlorofluorocarbons.

re-emit up and downwards

Inversion

A reversal of the normal decrease of air temperature with altitude, or of water temperature with depth.

Latent heat

Heat released or absorbed during a phase change

"Latent" since heat is not felt

Climate sensitivity

The equilibrium global mean surface temperature change following a doubling of atmospheric CO2 concentration.

Residence time

The average time spent in a reservoir by an individual atom or molecule

With respect to greenhouse gases, it refers to how long on average a particular molecule remains in the atmosphere.

Weather

instantaneous state of the atmosphere

Climate

statistical description of the weather over a period

of time

How do we know global warming is occurring?

Satellite temperatures

Glacial record

Retreat of glaciers

Sea level rise/Sea ice decline

Sea surface temps (SSTs)

Stratosphere cooling, ozone lessening/Troposphere warming

Probability of extreme events

How do we know increasing CO2 in the atmosphere is produced by human activity? Again, explain the scientific evidence we have for this.

Geochemical signal

The fossilized carbon has different isotopes that can be measured

Isotope "fingerprint" - CO2 from burning FFs has different signature than CO2 from atmosphere; Suess effect

Energy

The ability to do work (force x distance) on some

form of matter (mass)

What are the greenhouse gases? What units do we use to measure them?

water vapor, carbon dioxide, nitrogen, methane

GWP

Which GHGs are increasing? What are the relative warming potentials of GHGs compared to a molecule of CO2?

CO2 = 1

Methane = 25

Nitrous oxide = 300

CFCs = 12,000

Suess effect

decline in atmospheric C14/C12 ratio to carbon from fossil fuel burnin

1st Law of Thermodynamics

energy is neither created nor destroyed, just changed form

2nd Law of Thermodynamics

heat always goes from hot to cold; entropy (disorder) increases

Fundamental unit of energy

Joule (J)

Power

rate of energy flow/use/transfer per time

Fundamental unit of power

Watt (W) = (J/s)

Temperature conversions

F → C

C → K

C = (F- 32) * 9/5

K = C + 273.15

Difference between heat and temp

Heat = energy in process of being transferred between objects (particles) b/c of temp difference

Methods of Heat Transfer

Conduction

Convection

Radiation

Conduction

Molecule to molecule transfer

Heat flow: warm to cold

ex. leather seats in a car

Convection

transferred by vertical movement; physical mixing

ex. boiling water

Radiation

directional energy transfer; propagated w/o medium (can travel thru

vacuum) at speed of light (300,000 km/s)

ex. solar radiation

What provides nearly ALL energy to Earth?

the SUN

via solar radiation

How does temperature affect the density of the atmosphere?

Air is heated → molecules move more → get further apart = density decreases

Air cools → molecules slow → get closer together = density increases

Photosphere

surface of the Sun

Sunspots

"cool" regions, ~1500 K cooler

indicate solar activity; 11 year cycle

Earth receives _____ radiation from the sun and re-emits _____ radiation.

recieves SHORTWAVE radiation

re-emits LONGWAVE radiation `

T/F: Everything above absolute 0 emits radiation.

TRUE

Hotter objects emit (more/less) energy and at (longer/shorter) wavelengths.

more energy, shorter wavelengths

Blackbody (BB) radiation

Any object that is a perfect absorber AND a perfect emitter

Insolation

amount of sunlight (SW radiation) shining on Earth

Why are the tropics hotter?

amount of insolation received at Earth's surface varies by latitude, season, time (i.e. day to night; summer to winter; Equator to high latitude)

Same amount of light can be distributed over different surface area when it has a different angle of incidence

At ____ latitudes, infrared cooling exceeds warming. At _____ latitudes, the opposite is true.

HIGH

LOW

Global circulation is about transferring heat (energy)

from _____ to _____.

HOT TROPICS to COLD POLES

Global circulation

redistribution of global heat

What causes global circulation?

Differential heating of surface causing

pressure differences (low and high pressure direct surface winds)

What holds more heat, oceans or atmosphere? What about carbon?

OCEANS (1000x more)

ALSO OCEANS

What is the primary controller of CO2 levels in the atmosphere?

Oceans

Special properties of the ocean

High thermal capacity

Circulation moves heat around planet

Exchange carbon with atmosphere

Global conveyor belt

Constantly moving system of deep-ocean circulation driven by temperature and salinity.

Global warming

surface of the earth will be come hotter than it presently is, in part due to the "enhanced" greenhouse effect (more GH gases)

The more energy in the system, the ______ the temperature.

higher

Composition of Earth's atmosphere

1/1,000,000 of Earth's mass

78.08 Nitrogen

20.95 Oxygen

0.93 Argon

0.038 CO2

0.04 Trace gases (Neon, Helium, Methane, Krypton, Hydrogen, others)

Atmospheric layers we're concerned with

Troposphere

Stratosphere

Mesosphere

Thermosphere

Stratosphere is hot because:

it has ozone (O3) which absorbs UV

Greenhouse Effect (GHE)

The atmosphere gains temperature from the

surface, AND warms the surface temperature by making it harder to loose energy to space

The atmosphere gets heat from (above/below).

BELOW

Carbon cycle

biogeochemical cycle through Earth

System (between lithosphere, biosphere, hydrosphere and atmosphere)

moderates the radiative balance as a GHG in the atmosphere

Most carbon is stored in _______, and the

natural fluxes to/from it are very _____.

the lithosphere (rocks)

small

Short-term reservoir: main ways CO2 is removed from atmosphere and enters OCEANS

takes months to centuries to recycle

1. growth and death of plants, animals, and microbes

2. dissolved C in ocean, helps maintain stable pH for life

Long-term reservoir: main ways CO2 is removed from atmosphere and enters ROCKS

~99.9 percent of the total carbon

atm. CO2 + water + minerals = calcium bicarbonate

ends up in oceans where it becomes shells of various marine organisms

shells accumulate on ocean floor and transform into rocks and fossil fuels

Over millions of years this material is buried and heat and pressure melts the rocks and converts the carbonate back to CO2

Some rocks become part of volcanoes and release CO2 via eruptions

removed from atmosphere by plants and burial of dead plant matter

swamps = material transformed into coal

river deltas = carbonaceous shale

The biogeochemical cycle

The flow of carbon (C) among global "reservoirs"

that store C

might mistakenly assume most C is in living

organisms or coal & oil. NOT! (99.9% in ROCKS - limestones, carbon-rich shales, coal & oil)

Carbon Sources v. Sinks

sources = processes that release CO2 to the atmosphere (volcanoes, fires, decomposition, respiration, digestion, burning fossil fuels)

sinks = processes that absorb carbon (photosynthesis, forests, oceans and freshwater bodies, fossil fuels and carbonate rocks)

Radiative forcing factors

trace gasses = −0.05 W/m2

aersosols = −1.2 W/m2

land use changes = −0.2 W/m2

Assumptions of simple GHE model

Like glass, atm transparent to visible sunlight (SW), but not LW; absorbs and re-radiates up & down

Energy in = energy out

We can balance energy budgets for each part of the model: (1) atmosphere; (2) ground; and (3) boundary to space that is the planet as a whole

How to find temp of earth in simple model

Eout = σ(TE)4

James Hansen

loaded dice

extreme weather events

Svante Arhenius

pioneering 1896 study of how changes in the amount of CO2 may affect climate

Joseph Fourier

1820s - intuition about Earth radiation and greenhouse action of atmosphere

Charles Keeling

Developed an instrument that measures CO2 in air

Guy Stewart Callendar

theory that linked rising carbon dioxide concentrations in the atmosphere to global temperature