CLIMATE CHANGE

weather

• here and now, actual state at a particular time

• What’s the weather like today/ should I wear a jacket/ this morning my windows are covered in condensation

climate

long term & large area, averages, extremes, statistics

Does it snow here every winter?

Behaviors of hurricanes seem to have changed a lot over my lifetime

Tropics

30 degrees north and south of the equator

Mid-latitudes

30 degrees - 60 degrees

where most of us live

Tempting Shortcuts to “answers”

first-hand experience, personal values, opinion leaders

Crackpot Einstein Scale

method for rating scientific claims from unsupported to widely accepted

Anomalies

difference between what is measured and a reference point

Advantages of looking at Anomalies

• eliminates high local variation noise - reference can be local average

• can measure changes when absolute cannot be measured - reference a fixed temperature

• determines averages

Thermometers

• go back a few hundred years

• measured on land and water

• earth surface only

What do thermometers show?

• warming is not uniform

• land more than ocean, northern hemisphere more than southern

• over time

Issues with Thermometer Data

changes in equipment, location, observing, urbanization

Satellites

• since 1978

• measured anywhere on Earth

• surface and lower atmo

• agree with thermometers

Issues with Satellites

doesn’t go far back, can’t be calibrated once up there

Natural Processes that indicate changing temperature

• loss of ice

• rising sea levels

paleoclimate

how the climate changed before we got involved

paleoproxies

contain a climate signal, from long ago, can tell how long

types of paleoproxies

tree rings, ice cores, ocean sediment cores, geological feature such as sedimentary rocks

How do we know if something is true?

multiple independent data sets and corroborating evidence, backed by science and multiple tests conducted my different experts in the field

ex: ipcc

How do we know something is false?

Not peer viewed, based on personal experience or beliefs instead on data, from person who isn’t an expert in the field most likely not always

What geological era are we in now?

Holocene

icehouse

ice covers earth in many places, existence of permanent continental ice

greenhouse

limited/scarce ice higher temps

ice age

specific time withing icehouse climate state that lasts for millions of years and produces ice sheets

glacial period

period where temperatures drop

interglacial period

• warm periods between ice ages

• last 10,000-30,000 yrs

What does temperature measure

internal energy

Greenhouse Gases

Water Vapor, Ozone, Methane, Carbon Dioxide

• Infared cannot pass through b/c dynamic shape of molecules

• gases that make atmo livable b/c they trap heat

Non-Greenhouse Gases in Atmosphere

Oxygen 21%, Nitrogen 78%, Argon 1%

What GHG is most important?

Water Vapor: keeps in 50% heat, 60% of GHG emissions, lighter than air

Albedo

• amount of incoming light that is reflected

• determining factor in temperature

Energy Budget

energy in = energy out

solar constant

• energy per sq area based on proximity to Sun

• doesn’t mean everywhere on planet gets equal amount of solar radiation

equilibrium

• energy flows change until energy out = energy in

• doesn’t mean stable temperature

• takes time= thermal inertia (momentum)

• in response to a forcing temperature adjusts so balance can be reestablished

Which of the following is true about blackbody radiation?

The wavelength of photons emitted is determined by a blackbody's temperature.

Radiative Forcing

the mount that the energy balance is disrupted by a change in climate input, a change in Earth’s energy balance: Energy in- Energy out, changes that alter the energy absorbed or emitted by the earth and its atmosphere

Example of a positive forcing

decrease in atmospheric aerosols

example of feedback

ice-albedo effect, water vapor, lapse rate

Feedback

processes that respond to changes in the surface temperature, forcings are unrelated surface temperature

If we consider a "pulse" of new carbon dioxide added to the atmosphere, how long would it take the natural carbon cycle to remove half of this to the biosphere and ocean?

50 years

How is Carbon Distributed?

Carbon is distributed 40% Atmosphere, 30% water, 30% land cover varys over year b/c decay/growth

how long does carbon stay in one of these reservoirs?

Atmo: 5 years

land biosphere: 20 years

upper ocean: 6 years

deep ocean: 371 years

crust and mantle: 420,000 years

fossil fuels: 50-300 million years

Rocks in the Carbon cycle

sooooo slow

into atmo: carbon rocks vaporized by eruptions

out: weathering

sedimentation, continental drift, subduction

What radiation do we get from the sun

infrared, ultraviolet, visible

Examples of forcing

solar rotation - every 27 days up to several 10ths of % variation of energy put out

sunspot cycle- 11 years variation of 0.1%

Milankovitch cycles- shape of earth’s orbit changes every 100,000 years

What is the main way the biosphere and ocean interact with the Atmosphere?

• through the exchange of carbon dioxide

• biosphere: photosynthesis and respiration cycle

• ocean: carbon dioxide dissolves in water, reacts w/ water to form carbonic acid, easily taken in and stored, deep ocean= carbon sink

Two ways humans disrupt the carbon cycle

• burning of fossil fuels→ releases carbon from dead plants at high-rate earth struggles to balance

• deforestation to create urban areas, agricultural land, grazing areas = bulldozing/burning and soil decomposition as we expose organic materials