GEOL 1330 FINAL REVIEW

Weather

• Atmospheric changes with short timescales of days to a few weeks referred to as weather

• Limited predictability

Climate:

• Atmospheric changes with long timescales of months or more referred to as climate

• Potentially predictable

• averages of weather over time

continuous deviation from established average

atmosphere-air

hydrosphere-ocean

cryosphere-frozen

lithosphere-rock

biosphere-life

constantly exchanging energy, momentum, matter (carbon and water)

water is very important

radiative forcing: imbalance between Earth’s incoming and outgoing radiation

measured at top of atmosphere

48% absorbed at surface

23% absorbed in atmosphere

29% reflected off atmosphere

incoming solar radiation (340 w/m2)

The solar constant is the average intensity of the Sun’s radiation at a distance of 1 astronomical unit (the average distance of the Earth from the Sun).

1,361 watts per square metre (W/m²).

In fact, the Sun can be directly overhead  only  in the tropics.  As shown below, when the Sun is lower in the sky, the intensity of the solar radiation is reduced because its rays are spread out over a larger area and because they must pass through more atmosphere before they hit the ground. At night when the Sun is below the horizon the solar intensity is clearly zero.

If we average out over an entire 24 hour cycle the amount of solar radiation hitting the Earth’s surface (known as the solar irradiance) on a clear day at the equator on the equinox is approximately 340 W/m².

positive: amplify (ice albedo)(affects arctic north the most)

negative: deamplify (silicate rock weathering draws down co2 from atmosphere)

better for comparing different regions over time

shows deviation from established baseline

get rid of uncertainties that appear in plain temp measurements

we are about 1C from baseline

30 year motzart at least

high altitudes warming faster

sea ice melt (every summer a lot melts and refreezes in the winter)

each year more and more is melting over the summer and some not refreezing

accelerated ice loss, declining ice mass

melting permafrost releases methane (bacteria releasing, more greenhouse gasses, organix material uncovered and decomposing->co2 also)

lack of continent in north arctic->less reflectivity so heating more than antarctic ice albedo

sea ice minimum decreasing (younger+thinner)

age decreasing

snow covering decreasing

sattelite altimeter: exact level/location

tide gauge: comparitive tide and land, may be misleading

has been rising since at least 1880 (about 210-240 mm) (21-24 cm)

rate of sea level rise past 2-3 decades (3.4± mm/year)

thermal expansion, hotter water larger space (OHC has been increasing)

glaciers and ice sheets melting into water

NOT CAUSED BY SEA ICE (volume already in water)

causes: thermal expansion (40%), Greenland ice sheet (21%), glaciers etc

greenland ice sheet: if melt: 7m increase

antarctic: 60m

west antarctic: 6m(The warming Southern Ocean is flowing under the WAIS, so it's melting and losing mass)

increasing in:

frequency

intensity

length

season length

dry drier, wet wetter

intenser rainfall and increased flooding

central/east america (Esp northeast) precipitation increase

west (southwest) drier

~15 k: core

~6,000 k: surface

total solar irradience (TSI) at top of earth's atmosphere: 1,360 w/m2 (solar constant)

solar irradiance average for a region over 24 hrs: 340 w/m2

dark spots on the surface of the sun

magnetic disturbances/magnetic fields on surfaces

cooler areas of the photosphere

surrounded by bright spots (facculae) (can lead to solar flares)

solar flares near sunspots

therefore->more sunspots is brighter

affect TSI in 11 year cycles (increase TSI when more sunspots)

+/- .01% change

last few cycles have been decreasing schwabe

orbital parameters/cycles

eccentricity: shape of earth's orbit around sun (100,000 yr cycles) o O 0

obliquity: The angle Earth's axis of rotation is tilted as it travels around the Sun. tilt of earth on axis (NOW: 23.5. varies 22-24.5^o) 40,000 yr cycle

precession: position on axis As Earth rotates, it wobbles slightly upon its axis, like a slightly off-center spinning toy top. ~23,000 yr cycle. direction that axis points

caused by gravitational forces

do not explain climate change because would indicate cooling trend

atmospheric composition:

nitrogen: 78%

oxygen: 20.9%

argon: 1%

GHG: <.1%

carbon dioxide CO₂ .0407%

current spx co2: 420 ppm

anthropogenic carbon emissions: 10 gigatons/yr

water vapor

methane

nitrous oxide

ozone O₃ lower atmosphere=greenhouse gas

biomass burning, car exhaust, interfere w/stratosphere

in stratosphere

protects earth from UV light

Chlorofluorocarbons CHC plastic, break down and thin ozone (hole inozone-> cooling)

halocarbons

chlorofluorocarbons

shorter wavelengths mean more power, because more ocncentrated, has to travel less far distance

most of suns energy comes in the form of visible spectrum

infrared (long) - ultraviolet (short)

less than 400nm is utraviolet

over ~720 nm infrared

Top of atmosphere receive most energy (visible), sea level mostly infrared and less

receive more at equator->hotter

incoming sunlight gives each overall region same sun, but some of it is at a direct angle (equator) and some are not. These indirect angles are spreading the radiation over a much larger area, so the region is less warm as a result.

having to spread more: high latitudes

water vapor absorbs the most

48% sun radiation absorved by surface

29% reflected at the top of the stmosphere

23% reflected by clouds and atmosphere

7% reflected by surgace

surface radiation from earth 117%, back radiation from greenhouse gases 100%, atmospheric window 12% _{(approximately at wavelengths of infrared radiation between 8 and 14 micrometres}.)

intercept 90% of outgoing heat

solar radiation enters easily but has a hard time exiting because of greenhouse gases so rereadiated heat and more heat trapped in atmosphere and less escapes into space

earth reemits heat/energy: infrared radiation

non-GHG do not absorb infrared radiation, which is why it can pass to bottom of atmosphere.

A molecule can only absorb IR radiation if it experiences a change in dipole moment during a vibration, like stretching or bending

that outgoing infrared absorbed by ghg and emitted in all directions (like back to earth)

ocean the biggest carbon pool (DIC dissolved inorganic Carbon) (vertical transfer biologic pump the phytoplankton eaten and creatures droppings sink)

Examples of rapid carbon fluxes in the Earth system

Gas exchange between atmosphere and ocean 

photosynthesis/respiration

(also there are slower/longer-term fluxes like weathering of rocks, limestone formation, etc)

Sources of anthropogenic carbon

Fossil fuels, Land use changes

(we add 10 gigatons to atmosphere each year)

isotopic data indicate anthropogenic carbon sources

causing ocean acidification

High latitudes receive less intense radiation than low (equator)

High latitudes emit more heat than they absorb and low latitudes absorb more heat than they emit. (~40^o lat the in/out about same)

heat transport(meridional)(keep tropics from too hot etc)

https://youtu.be/oZ6exQoU_CM

3 convection cells per hemisphere

Coriolis effect: the earth is constantly rotating, like a merry go round. Appears “deflected” due to rotation

Wind is air going from higher to lowe r pressure

Air rising from equator to top of troposphere, sinks down around 30*

Going from lower to higher latitude sink about 30 rise about 60,

Horse latitudes 30, doldrums around equator

https://youtu.be/KBKmKI3tl4Q

wind friction on the surface current, moves

wind blows and eachlayer of water friction to move the next layer down gradually lose power but because coriolis slightly to the right each time ekman spiral so when the water moves it is roughly 90 angle from the wind original dirction (on average) (the NET transfer)

gulf stream:

actually a current., very powerful

speed: 1ms^-1

transport up to 100 sverdrups

helps brings heat to europe

antarctic circumpolar current:

strongest current (>100sv !)

eastward flow around antarctica

p[en passage, land not there to get in the way

deep water mixed to surface

Moves water around and up and down density moves it around atlantic lower to higher latitudes denser water cooler + salinity greact ocean conveyor. Water come back to surface upwellig when water freezes leaves salt in non frozen water makes that non frozen water more salty "great ocean conveyor"

thermo=temperature, haline=salinity

The densest deep water mass is formed in the Weddell Sea of Antarctica, and becomes the Antarctic Bottom Water (AABW). Similar processes in the North Atlantic produce the North Atlantic Deep Water (NADW) in the Greenland Sea

Thermohaline circulation (properly described as meridional overturning circulation) of the world's oceans involves the flow of warm surface waters from the southern hemisphere into the North Atlantic.

ENSO (el nino southern oscillation)

ocean and atmospheric change

Occurs every 3-7 years-Lasts 9-12 months

Trade winds weaken, slacken

This means heat spreads eastward, no coastal upwelling, nutrient rich col water doesnt surface-bad fishing

Evaporation in central pacific, flooding to southern us, droughts to west us

La nina is like el nino but the opposite:normal to extreme degree, strong trade winds, cooler temp in eastern pacific, wet west pacific, usually follows strong el nino

La nina: cold north us, wet northwest, dry south, warm east. push jet stream up

El nino: wet southwest dry southeast warm noth

vapor enriched in O16 (lighter) meaning that oceans relatively more 18O

( polar precipitation (the air carried from equator evaporation) relatively 18O depleted)

less 18O in atmosphere as it gets colder (more enrich 18O ocean indicates more ice)

Oxygen 16

8 protons, 8 neutrons, Most abundant: 99.98%

O18

8 protons 10 neutrons .02%

o 17 least abundant wiith <.01%

12C is fractionated into living tissue.

liiving prefers lighter c12

– Carbonate shells reflect changing 12C/13C of seawater

annual snow layers turn into ice

annual to centennial resolution (up to 800,000)

high resolution, doesn't stretch as far back

precipitation can be estimated from layer thickness

temperature from oxygen isotopes

co2 from trapped ait

dust measure of wind velocity + direcition local erosion

retrieved from drill chips

longer resolution (up to 180 million years)

changes in sedmient composition/chemistry can indicare environmental change

microfossil species indicators of environmental change

isotopic changges in pelagic or benthic fossils as proxies of paleotemperature and productivity

_{benthic foraminifera are marine amoebas that make fossilizable shells of calcite or cemented sediment grains.}

_{Pelagic sediment or pelagite is a fine-grained sediment that accumulates as the result of the settling of particles to the floor of the open ocean, far from land}

Hothouse climates, one of the big five mass extinction events

biggest extinction event in earths history

95% marine species extinct

70% land vertebrates exctinct

252 mya

Extremely hot biggest mass extinction in earth’s history

hot and dry

pangea and panthalassa

Heat+low oxygen (plant proxy ind)

Impact dep within earth, vertical movements of rock plates in crust (this is more likely in supercontinents), panagea surrounded by deep trench, plates drop, magma to surface,

siberian trap basalt erupt

Relatively short timescale for eruption

Methane hydrate trapped in ice melt from heat

released c12 into ocean +atmosphere,

heat up ocean. 

No deep ocean ventilation, anoxic

Ocean chemistry change

56 mya

best analog of modern climate change

spikes in co2 (2000-3000 gigatons input)

relatively short period (10-20,000yrs)

temperature spikes (5-8c global warming)

proof:

soil color, dry western US, alligator and palm tree fossils in arctic areas

Ocean acidification: calcium carbonate depth shallower (~2m). extinct foraminifera

c12 enriched

hypotheses: methane hydrate melting

earliest true primates develop

hot house to ice house

sea level fall

temp fall

co2 fall

mountains rise

ice sheets grow

sea floor spread slowing down

Miocene (23 mya): ice growth Antarctica + greenland

continental collisions

Opening drake passage (between south America and Antarctica) through tectonics

isolates Antarctica-> antarctic circumpolar current->colder->more ice

pliocene (5.3 mya): closing isthmys of Panama,

great American interchange. land bridge created for animals/species cross

enhancement gulf stream, more to higher latitudes ice build up

east African rift->hominids

himalayas rise change wind directions

quaternary period

Last 2.7 million years

Add an antrhopocene to say how much humans have changed enviro?

pleistocene and holocene

RAPID climate change-ice age

global temperatures reached ~5.6C lower than it is today

sea level was about 100-130 meters lower that it is today during glacial stages

co2 was ~200 ppm (half current concentration)

eurasian ice sheet

up to 3km thick ice. sea level 100-130m lower than today

cooling trend (more land->albedo)

cooling trend over past 8000 years in accordance with parameters

recent temperature increase has reversed this trend

co2 concentration atmosphere was relatively constant (280 ppm) until industrial revolution

HOCKEY STICK curve

9-13th century medeival warm period: higher solar activity, solar intensity

16-19th century: little ice age. explosions-> particles in atmosphere, dimming effect 

Both these are only plus or minus .02c ish

5 (8.5)

3 (7.0)

2 (4.5)

1 (2.6)

1 (1.9)

scenarios start in 2015

2nd number radiative forcing/Wm2 in 2100

Precipitation increase at high latitudes, equatorial Pacific, and monsoon regions

• Decrease in subtropical areas

The more co2, the more in the atmosphere as relative to land and ocean because the land and ocean carbon sinks reach capacity for carbon absorption

all scenarios decreased sea ice

Both ssp1 conditions stabilize a little above/below 8.0 ph by 2100

Ssp5 less than 7.7 ph

sea level:

High level of uncertainty

Might have crossed threshoholds. Hard to account for, ice shelves can break off, west antarctica melting faster than predicted

Ssp1 about .5m

Ssp5 about 1m (low likelihood high impact scenario to 1.75 m)

10 year event 50 year event

No region with decrease in hot weather extremes since 1950

Many hot weather regions confident it is anthropogenic

Pretty much everywhere getting hotter

We’re already at about ~1.0c 1.2c hotter 28 times more likely

Extreme events: x-year events, happen every x years on average. When just 1.2c hotter, 10 year event 2.8 times more likely to occur! Frequency increase and intensity increase. Bith will happen more and be more extreme when occur

Hot places getting hotter, wetter wetter, dry drier

hot extremes: western us

drought: north(???) western us

precipitation: eastern/northern us

Rising temperature->coral bleaching. Colored symbiotic zooxanthellae are expelled from coral polyps. Can mean coral dies because eject zoo at certain temp threshold

As more carbon enters the ocean, it chemically changes ocean composition and makes it more difficult for calcifying organisms (like crustaceans, corals, etc) to make their calcified shells or secrete calcium carbonate (caco3). Also makes it more likely for this carbonate to dissolve. This hurts not only the animals who need it, but the larger ecosystem that feeds on these smaller organisms

coastal flooding (protect or accomodare or retreat) (houston, miami, new york, san francisco, los angeles)

temperature mortality rate increasing

climate migration (up to 1 billion people by 2050)

weather fatalities, spread of diseases (malaria, zika), increases in respiratory illness (increased air pollution) (prolonged pollen season). lack of water supply from melting glaciers (outburts floods, ice avalanches), excessive erosion

caused by different air pressures, warm air masses less dense cold more dense. Pressure gradient from high to low pressure, so this air moves from high pressure to lower pressure areas and is fiverted because of the coriolis effect

polar jet stream dominates mid latitude weather

relatively narrow bands of strong wind in the upper levels of the atmosphere.

Polar jet stream dominates mid-latitude weather: Fast upper-level winds form at boundary between cold dense polar air and warm moist subtropical air

appears as a band of clouds consisting of showers, with occasional thunderstorms, that encircles the globe near the equator. The solid band of clouds may extend for many hundreds of miles and is sometimes broken into smaller line segments.

Piling up water into center, as water tries to flow outwards drifts to write and contributes to the gyre

WEST: low->high (bring heat)

EAST: high ->low (btungs colder)

2 clockwise north, 3 counter clockwise south

affect phytoplankton and nutrient availabilty

currents and deep ocean layers set into motion

like "gap" opening up at equator because trade winds push water and ekman transport mean 90 degrees away so a bunch of that top, warm water is pushed away and colder, nutrient rich water at the surface

leads to phytoplankton growth because more clorophyl in this water

North Atlantic Oscillaiton:

sea-level pressure difference between two pressure points across north atlantic (differences in how big the difference is)

can change position of jet stream

positive: large difference in pressure, wild westeries, mild air from atlantic leading to mild and stormy winter uk

negative: weaker jet stream, cold and dry, easterly (blocking)

pacific decadal oscillaion:

like ENSO but much longer timescale (20-30 yrs)

atlantic multidecadal oscillation:

sea surface temp anomaly oscillation north atlantic

estimated 60-80 yrs

potential link to hurricane freq??? controversial???

Ice Cores

Go back up to ~800,000 years

Really good resolution

(about 400,000 yrs is where good resolution ends. Further down damaged)

Yearly layers so climate info

Can find co2 and oxygen isotopes trapped inside as well 

Dust also found inside and can help estimate wind velocity

Sediment Cores

Go back further than ice cores, up to ~180 million years

Poor resolution, 

sediment gathers little and slowly

Microfossil species, shell composition, colors

Isotopic changes in pelagic or benthic fossils can show co2 levels and rough temp

pleistocene

2.58 million years ago - 0.012 million years ago

Bølling-Allerød

rapid warming, changing orbital parameters

Younger Dryas event

About 14,500 years ago, 

Earth's climates shift from a cold glacial world to a warmer interglacial state. Partway through this transition, temperatures in the Northern Hemisphere suddenly returned to near-glacial conditions.

holocene

(last 11,700 yrs)

Cooling trend over past ~8000 years in accordance with orbital parameters

Recent temp increase has reversed this trend

Co2 concentration constant on average (260-280 ppm) w/industrial revolution

Global circulation model (GCM)

Subdivide the earth into grids to predict what will happen

mass, momentum, energy, and pressure

Fundamental laws of physics (motions, thermodynamics) applied

Timesteps: can’t go all at once, need to calculate on slower timescale to account for changes and movement between squares

What is a typical grid resolution? 

~2°

20-30 layers in atmosphere and ocean

What kinds of boundary conditions are needed?

fixed & variable. 

Fixed: typography of ocean, solar radiation constant, orbital parameters

Variable: land use, GHG,

How model evaluated? 

Compare results with specific variables to the observed actual changes/each other

SSP1-1.9: about 1-1.5C

SSP1-2.6: 1.9-2.5

SSP2-4.5: 3

SSP3-7.0: 3.5

SSP5-8.5: about 4.4C by 2081-2100

Land warms more than oceans. High lat warm mote than low latitudes

MIP multimodal mean 20 years relative to 1850-1900

Prediction of poleward shift of biomes; biomes move further and further upward

Tundra will be replaced with taiga

Species in higher latitudes now might be replaced by lower lat species later as they move up

Overall greening but also increase in respiration