GEOL 1330 UNIT THREE

Atoms deviant from base element with a different # of neutrons therefore different atomic mass

Named after atomic mass eg 18o or 16o

atoms= smallest unit of an element that maintains physical and chemical properties of that element

Same number of protons 16O

Stable isotopes vs radioactive, stable don’t change over time

Oxygen 16

8 protons, 8 neutrons, Most abundant: 99.98%

O18

8 protons 10 neutrons .02%

o 17 least abundant wiith <.01%

Used as paleoclimate proxies

The preserved physical characteristics of the environment that can stand in for direct measurements

stand-ins when you can't go back and accurately measure

Can figure out where it came from how it moved etc

Examples: oxygen during evaporation, carbon in marine organism shells

Differentiation into different isotopic signals/values

Rings: connected to environmental conditions (rainfall, temp, fires) in the region

Thin lines mean low precipitation

Only go back a few thousand years

Corals

Seasonal patterns in coral as it builds on itself

Indicators of environmental change based on light, density, temperature, and nutrients

Can be used for isotope studies

Annual cove deposits (stalactites, stalacmites)

Gtow as water dissolves valvium carbonite

Caco precipitates from evaporating water. Some drips slowly, some drip down 

Can ve dated using radioactive isotopes

See miscrioscopic patterns, look at layer look at isotopes within

Tells us about temperatures and water cycle changes

Can go back up to ~800,000 years (the age of oldest one we have currently)

Sometimes hard while going down because ice deformed/damaged

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

~4.6 billion years

U shaped valleys indicate ice

Rivers only cur down into V shapes

“Horns”

Eroded on all sides leaving a peak

Hanging valleys

Due to tributary glaciers off main

Water falls 

Coal

Made of plants. Swamp areas on land. Peat compressed over time becomes coal

Coal depostirs act as amajor carbon sink and can help lower the levels of co2 by taking it out of the atmosphere

Indicates abundant vegetation

Sedimentary structures formed in dessication cracks (mud cracks) and drying sediment, sometimes filled in and preserved, evidence of shallow water

Tropical soils look different than other soils because iron and other coumpinds. Aluminum and iron compounds color, laterite and bauxite indicator of tropical climate hot and wet tropical climates by weathering

Organic plant residue and animal residue forms in marine areas buried in mud, slow heating (50c-150c)

High petroleum formation can lead to cooling as it takes carbon away

Forms from water in a flat valley, water drops sediment being cariedm doesn’t necessarily mean desert, means sediment deposit at mouth of fountain, indicates mo u ntain building/weather, long timescales (evidence of tectonic activity and advances erosion, weathering draws down co2 from atmosphere

An alluvial fan is a triangle-shaped deposit of gravel, sand, and even smaller pieces of sediment, such as silt. This sediment is called alluvium. Alluvial fans are usually created as flowing water interacts with mountains, hills, or the steep walls of canyons.

Alluvial comes from the Latin alluvius, which meant “washed against.”

warm marine environment, carbon sequestration

Limestone is made of calcites, 

CaCO3 chalk limestone phytoplankton shells

Lots formed in tx when tx was still basically underwater

Carbon cycle fixed in rocks

Starts in tropical warm shallow seas

Evaporites

Immense evaporation areas (subtropical arid zones)

Dissolves materials start to precipere out of solution

Ancient dune

Sand transported bh wind gers obstacle and iles up 

Keeps on obuolding

Cross  bedding lying ar angle to main bed surface

Utah exposed dry dunes

Availability sand and wind

Doesnt automatically mean desert

indicate warm and wet (tropical) weather

look different than other soils because of components

ash falls into layers after erutption,

cause short term cooling due to particles blocking the sun/dimming

Eruptions potential warming effect from release of carbon into atmosphere

Mud cracks filled in and pressured bu being filled with newe layer. Evidence of shallow water, ripple means moving water

Types of leaves, shaffy vs smooth

Stomatal density used to estimate co2 concentration in atmosphere

Stomara: opening how leaves take up co2 atmosphere

Leaf margins used to estimate paleo temp

Low co2 levels more stomata density on leaves and high co2 low stomata

Because there is a lot of pollen and it doesn't fall apart easily, it is often preserved in layers of sediments and can become fossilized within rocks – even in places where other plants and animals are not likely to be preserved as fossils. This makes pollen a good source of data about past climates.

Paleobotanists – paleontologists who specialize in ancient plants – have far more fossilized pollen to study than fossilized plants. Whenever possible, they try to correlate pollen records with the fossil leaves, trunks, seeds or pinecones found nearby to confirm that the plants were in the area. Counts of ancient pollen tell us both the types of plants that grew in an area and the relative abundance of each plant species.

While pollen can be found in ice cores and seafloor sediments, the most common place to find ancient pollen is in sediment from the bottom of lakes.

Hothouse climates, one of the big five mass extinction events

panathalassa=all ocean

Continents fit together, evidence of animals and bones together where they connected, continents used to be in different climate zones from today

252 million years ago or so

Extremely hot biggest mass extinction in earth’s history

Very hot and usually dry

volcanic explosion impact from deep within earth pangea surrounded by big trench magma forced to surface. Methane under the water large amounts of methane hydrate melts at time of eruption

Mwelted methane hydrate in ocean 

Increased carbon in atmosphere

Impact from deep within earth carbon eruption bond with oxygen to form co2

No deep ocean ventilation part of ocean became anoxic (low oxygen levels)

Water became more toxic, 95% marine species extinct (about 70% on land). Ocean extremely hot ocean chemistry change

Water became more toxic, 95% marine species extinct (about 70% on land). Ocean extremely hot ocean chemistry change

Extremely hot

Overabundance of certain plants indicate low oxygen environment

Heat+low oxygen

Impact dep within earth, vertical movements of rock plates in crust (this is more likely in supercontinents), panagea surrounded by deep trench, plates drop, force magma to surface, methane hydrate melts at time of eruption caused by pushing up the magma, release more xo2, bolvanic eruption

Relatively short timescale for eruption

Methane hydrate trapped in ice/frozen water melted from the immense heat and released more c12 into the ocean and atmosphere, heated up ocean. 

No deep ocean ventilation, low oxygen levels meant toxic

95% marine species extinct

Methane hydrate

Ocean chemistry change

(66 million years ago)

what was sea level like?; 

High sea levels, interior ocean body inside north america, cretaceou sinterior sea way

66 mya

Oceanic anoxic event or anoxic event (anoxic conditions) allude to interims in the Earth's past where parts of seas get to be distinctly exhausted in oxygen (O2) at profundities over a substantial geographic region

Oceanic anoxic events most commonly occurred during periods of very warm climate characterised by high levels of carbon dioxide (CO2) and mean surface temperatures probably in excess of 25 °C (77 °F).

uch rises in carbon dioxide may have been in response to a great out-gassing of the highly flammable natural gas (methane) that some call an "oceanic burp". Vast quantities of methane are normally locked into the Earth's crust on the continental plateaus in one of the many deposits consisting of compounds of methane hydrate, a solid precipitated combination of methane and water much like ice.

Asteroid, 

10-14 km across, 

Impacts near modern day mexico: sends massive shockwave and intense volcanism

Ashes cover sky, gets bery dark, plants cannot photosynthesis

~55.6 mya

potential causes?; 

why/how does mountain building lead to global cooling?; 

first big ice sheets in the Miocene

Methane gas bursts, spikes in co2 (about 2000-3000 gigatons),

Release of methane from methane hydrates, plant or methane origin, coal deposits in magma, eruption trigger, calcium carbonite came oceanmore acidic

Proto antarctic circumpolar current, used to have land together, plate tectonic change, now isolate antarctica->antaractic circumpolar current. Leads to colder

was critical to the water exchange between the Atlantic Ocean and the Arctic Ocean, and caused the transition from a restricted to a ventilated Arctic Ocean during early Miocene

Gateway allowing deep water exchange

Panama, used to be open, led to great american interchange (species migrating across land bridge across south and north americas) separate pacific from atlantic ocean, develop differently in temp and salinity. Led to enhancement of gulf stream. More moisture towards northern latitudes, help ice build up

Last 2.7 million years

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

pleistocene and holocene

2.58 million years ago - 0.012 million years ago

Global temp ~5.6 c lower than today!

Up to 3km thick ice. Lower sea level (100-130m lower than today). Cooling trend more land exposed. Co2 levels about ~200 ppm (half as much as present) even during interglacial it was only about ~280 (pre-industrial average)

(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

Orbital parameters-eccentricity (o to 0), obliquity (how tilted on axis 23.5), precession (the rotation of earth on axis)

Affects what incoming radiation  drive remperature in pleistoccene

Plesistocene last glacial state/glacial maximum, rapid climate change. Co2 levels cooler. Ocean had higher co2 maximum when it’s cold and less co2 in atmosphere enhances the ocoling 

100-130 lower meters than today (most water was ice) (feedback contribute albedo)

Part of pleis-holo transition

About 14,500 years ago, 

Earth's climate began to 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.

Cooling trend (in accordance with orbital parameter)

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

Curving down but sudden spike in the past few years through anthropogenic forcing 

no

decreasing atmospheric CO2 levels.

Pangea (or Pangaea, either spelling correct)

False. It had lots high sea levels, no glaciers really no big ice masses, lots of water on top of north am literally splitting

lower sea levels

anthropogenic

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

Up to ~2° is typical resolution

20-30 layers in atmosphere and ocean

Through a model in grids and changes in variable amounts 

Both fixed and variable. 

Fixed: like typography of ocean, solar radiation constant, orbital parameters (set as constant because don’t change significant enough over 100 years)

Variable: land use, GHG,

Compare results with specific variables to the observed actual changes (Also comparing models to each other) (mainly against observed tho)

Intergovernmental panel on climate change

Puts out a multi model report from data from different work groups and studies

Work group 1 does climate modeling

Latest assessment report was AR6 from August 2021

1850 values used as the pre-industrial average

Time range about 2015 to 2100

Shared socioeconomic pathways: scenarios predicted by IPCC

Ssp1, ssp1, ssp2, ssp3, ssp5

The radiative forcing per square meter. 

SSP1-1.9

SSP1-2.6

SSP2-4.5

SSP3-7.0

SSP5-8.5

SSP1-1.9: about 1-1.5C

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

wet areas get wetter and dry areas get drier. wetter at equator and high latitudes

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 expect decreased sea ice

Ssp1 (both 1.9 and 2.6) sea ice will stabilize (about ~2050) before losing all sea ice (both just above (1) and below (2.6) 2 10^6 km^2)

All other scenarios predict no sea ice (by about ~2075

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

Ssp5 less than 7.7 ph

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)

4.5 c

Coupled model intercomparison project 

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

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

high lat animals being replaced with low lat animals

more likely more occurences of wildfires

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