GEOL Exam 3 Review

tree rings

Annual layers reflect variations in environmental conditions such as rainfall, temperature, and fire occurrence.

coral growth

annual layers, indicate environmental changes such as temperature, light availability, nutrient conditions; can be used for paleotemperature reconstructions.

speleothems

cave formations like stalactites and stalagmites that grow as calcium carbonate precipitates from evaporating water

speleothems in paleoclimate research

can be dated using radioactive isotopes and used as temperature proxies or indicators of rainfall through oxygen isotopes and layer thickness

ice cores resolution

annual to centennial

ice core range

up to 800,000 years

what can be measured from ice cores

Precipitation (estimated from layer thickness), temperature (inferred from oxygen isotopes), CO2 concentration (trapped air bubbles), dust content (indicative of wind velocity and direction)

ice cores archives of paleoclimate information

provide information on atmospheric composition (CO2, dust) and temperature

sediment cores archive of paleoclimate information

offer insight into changes in sediment composition, chemistry, microfossil species, and isotopic changes in fossils, indicating environmental changes over longer timescales (centennial to millennial)

age of earth

around 4.5 billion years old

indicators of glaciation (icehouse world)

u-shaped valleys, cirque horns, moraines, erratic boulders, hanging valleys

coal formation

Abundant vegetation compressed and heated over time

organic-rich clay formation

Accumulation of organic material in anaerobic conditions

petroleum formation

formed from organic residue of plants and animals buried in sedimentary rocks and subjected to slow heating

coal, clay, and petroleum deposits’ role in carbon distribution in the earth system

These deposits represent a major carbon sink, sequestering carbon that was once in the atmosphere

alluvial fans

Formed by tectonic activity and enhanced erosion, indicating periods of increased weathering and CO2 drawdown from the atmosphere through silicate weathering

limestone

Formed in warm marine environments, acting as carbon sinks by sequestering carbon dioxide

chalk

limestone derived from phytoplankton cells

indicators of deserts/dry conditions

large cross-bedding (ancient dunes) and evaporites that form in areas of intense evaporation/subtropical arid zones

Laterite and bauxite as tropical soil indicators

Iron and aluminum-enriched soils formed in hot and wet tropical climates by weathering

Volcanic activity and climate

Causes short-term cooling due to aerosols but can lead to long-term warming if there is a sustained release of CO2

Sedimentary structures

Ripple marks and desiccation cracks indicate evidence of shallow water, evaporation, and changing water levels

fossil leaves shape

used to estimate paleotemperature (smooth leaf for warm, toothed leaf for cold)

fossil leaves stomata

used to estimate atmospheric CO2 concentration (high density for low CO2, low density for high CO2)

pollen in sediment

indicate changes in vegetation, reflecting shifts in climate and environment

when did Permian end?

252 million years ago

Permian climate

high temperatures, arid conditions, extreme weather events, toxic environments, and widespread ecological disruptions, culminating in one of the most catastrophic extinction events in Earth's history

what caused the rise of CO2 in atmosphere in Permian era

likely caused by volcanic activity

Siberian Trap Basalts

a key trigger of the extreme "hothouse" climate conditions and ecological collapse that characterized the end of the Permian period on Earth

end-permian ocean

no deep ocean ventilation(not circulating/mixing), lack of ocean circulation, ocean acidification, ocean anoxia (lack of oxygen), development of toxic, anoxic conditions in sunlit layers of the ocean, and subtoxic-anoxic conditions (expansion of OMZ)

end-permian extinction

Severe extinction event with 95% of marine species and 70% of terrestrial vertebrates extinct

end-permian: which toxic gases were released from oceans

hydrogen sulfide (H2S) and methane (CH4)

end-cretaceous sea level

extremely high; went from 330-660 (beginning of cretaceous) feet to 660-820 feet

when did cretaceous period end

66 million years ago

cretaceous ocean anoxic event

intense volcanism released greenhouse gases

end-cretaceous extinction event

extinction of approximately 75% of all species on Earth, most likely caused by major meteorite impact, caused massive earthquakes, tsunamis, wildfires, and the injection of large amounts of dust, soot, and sulfur gases into the atmosphere, acid rain, and lead to period of intense darkness and cooling

when did paleocene-eocene thermal maximum (PETM) occur

56 million years ago

PETM gas additions

rapid spikes in CO2 and methane (greenhouse gases)

PETM gas addition causes

likely from release of methane from seafloor hydrates and coal deposits

cooling trend 50 million years ago

Potentially caused by falling CO2 levels, mountain building, and the growth of ice sheets

mountain building global cooling

enhances silicate weathering and draws down atmospheric CO2

miocene ice sheets

increased growth of ice sheets, specifically in Antarctica and Greenland, caused sea levels to fall and altered ocean currents and circulation patterns

Effects of geological changes on Earth's climate

Opening of the Drake Passage, Fram Strait, and closing of the Isthmus of Panama influenced ocean currents, circulation patterns, and regional climates

Quaternary Period - pleistocene

2.7 million to 11,700 years ago

Quaternary Period - Holocene

last 11,700 years

Orbital cycles

Variations in Earth's orbit affecting solar radiation received by the planet

orbital cycles correlation to pleistocene glacial

times of lower eccentricity (more circular orbit), lower obliquity (smaller tilt), and certain configurations of precession that reduce summer solar radiation in the Northern Hemisphere

orbital cycles correlation to pleistocene interglacial

times of higher eccentricity, higher obliquity, and precession configurations that increase summer solar radiation in the Northern Hemisphere

pleistocene atmospheric CO2 and temperature

CO2 levels were around 200-280 ppm, with temperatures significantly lower than today's, temperatures were 5-6°C lower during glacial periods

pleistocene sea level changes

Sea levels were about 100-130 meters lower than today during glacial stages

Younger Dryas event

Rapid cooling period around 11,700-12,900 years ago, likely triggered by a slowdown in thermohaline circulation due to freshwater influx into the North Atlantic

temperature trend over past 8,000 years

Generally cooling trend, but recent temperature increase has reversed this trend

medieval warm period

9th to 13th century, possibly influenced by solar intensity and volcanic activity

little ice age

16ht to 19th century, possibly influenced by solar intensity and volcanic activity

hockey stick curve

reconstruction of Northern Hemisphere temperatures over the past 1,000 years, showing the recent sharp rise in temperatures after a relatively stable period, likely linked to human-induced climate change

climate model - grid resolution

Up to 2 degrees is typical, with 20-30 layers in the atmosphere and ocean

representation of earth system processes

applying fundamental laws of physics (motion, thermodynamics) to solve budget equations for each component, calculating the exchange of energy, momentum, and mass

boundary conditions

include solar radiation, greenhouse gas concentrations, orbital parameters, topography, and bathymetry

evaluation of model results

comparing output to observational data, looking at correlation coefficients for surface air temperature, terrestrial radiation, precipitation, and cloud radiative effects

IPCC

Intergovernmental Panel on Climate Change

time range for model prediction in IPCC report

Predictions are made for near-term (2021-2040), mid-term (2041-2060), and long-term (2081-2100) periods

SSP

shared socioeconomic pathway

SSP number indication

indicate the approximate radiative forcing in W/m^-2 by 2100 for that scenario

Temperature predictions

range from approximately 1.5 to 4.3 degrees Celsius increase by the end of the century, depending on the scenario

precipitation predictions

increase at high latitudes, in the equatorial Pacific, and in monsoon regions, but decrease in subtropical areas

prediction for change in carbon uptake

predicted to decline under higher emissions scenarios (SSP5-8.5, SSP3-7.0), indicating these natural sinks will become less effective. Under lower emissions scenarios (SSP1-2.6, SSP1-1.9), the sinks continue to absorb more carbon

predictions for sea ice coverage

decline significantly, potentially leading to an ice-free summer by mid-to-late century under the higher emissions scenarios in Arctic. Lower emissions scenarios still show decline but maintain some summer ice cover

predictions for ocean surface pH

decrease (increased acidification) significantly under higher emissions, with a less severe but still substantial decrease under lower emissions.

predictions for sea level

rise 0.38-0.77 m by 2100 under lower emissions, and 0.63-1.01 m under higher emissions

general trend in climate extremes

more frequent, intense, and prolonged

Areas in US with changes in climate extremes

The southwestern and southern United States increase in hot weather, northeastern US increase in precipitation

expected shift in vegetation biomes

expected to shift poleward, leading to the replacement of high-latitude and high-altitude ecosystems with species migrating in from lower latitudes and elevations

effects on species at high latitude or altitudes

likely to be negatively affected in a warmer climate as they may face habitat loss due to biome shifts and increased competition from species moving in from lower latitudes or elevations

wildfire occurence

projected to increase in many regions due to hotter and drier conditions, as well as changes in vegetation patterns

coral bleaching

occurs when rising ocean temperatures cause corals to expel the symbiotic algae living within their tissues, leading to the loss of the vibrant colors associated with healthy coral reefs

what is ocean acidification

process where increased absorption of atmospheric CO2 leads to a decrease in the pH of seawater

why is ocean acidification increasing

because of the absorption of excess CO2 emitted by human activities, primarily from the burning of fossil fuels

how does ocean acidification affect marine life

detrimental effects on marine organisms, particularly those that rely on calcium carbonate structures, such as shellfish and plankton.