Intro to Climate System

What are the two main types of climate change discussed in Earth's history?

Tectonic-Scale Climate Change and Orbital-Scale Climate Change.

What characterizes the current climate period in Earth's history?

We are currently in an ice-house period.

What must a molecule do to be considered IR active?

It must undergo a change in dipole upon vibration.

What is the positive feedback mechanism involving albedo?

Climate cooling leads to increased snow/ice, which raises reflectivity, resulting in less solar radiation absorbed and further cooling.

How does increased water vapor contribute to climate warming?

Increased atmospheric water vapor traps more solar radiation, leading to further warming.

Why is water vapor not considered climate forcing?

It is a product of increased temperatures rather than an output from human activities.

What role does vegetation play in precipitation feedback mechanisms?

Increased precipitation leads to forest growth, which increases water transpiration and further precipitation.

What are some examples of climate archives?

Pollen, lake levels, ocean cores, tree rings, corals, and ice cores.

What information can ice cores provide about past climates?

They contain air bubbles of CO2 and CH4, snow layer thickness, and dust that indicates wind direction and strength.

What is the Gaia Hypothesis?

It suggests that Earth acts as a self-regulating organism that maintains conditions suitable for life.

What is the Faint Young Sun Paradox?

The paradox that the early Earth should have been frozen due to a dimmer sun, yet evidence shows it was warm enough for liquid water.

What is the proposed solution to the Faint Young Sun Paradox?

The Earth's Thermostat, which involves cycling greenhouse gases between reservoirs to maintain temperature.

How does chemical weathering contribute to Earth's temperature regulation?

Increased weathering removes CO2 from the atmosphere, reducing warming as temperatures rise.

What is the Snowball Earth theory?

The theory that the Earth was once nearly entirely covered in ice during extreme ice-house periods.

What evidence supports the Snowball Earth theory?

Evidence of glaciation in various continents around 850-550 Ma, suggesting they were near the equator at that time.

What is the Polar Position Hypothesis?

It states that ice sheets will only form on continents that are near the poles due to lower solar intensity.

What was the climate condition during the time of Pangaea?

Pangaea was a hothouse period with no evidence of ice sheets and was warmer and drier than today.

What are biotic proxies in climate studies?

They are changes in plants and animals, such as pollen or microfossils, used to infer past climate conditions.

How do isotopes inform about past climates?

Isotopes can indicate temperatures, precipitation, and nutrient levels based on their ratios in various materials.

What are speleothems?

Cave mineral deposits that record groundwater composition over thousands of years.

What role do tree rings play in climate studies?

The width of tree rings indicates the amount of cellulose deposited, reflecting past precipitation and temperature conditions.

What is the significance of ocean sediments in climate research?

They provide information about past temperatures and pH levels based on isotopes and alkenones present.

What evidence suggests that Pangaea had high CO2 levels?

Evidence of palm-like vegetation at 40° latitudes indicates CO2 levels of 1650 ppm.

What is the BLAG Hypothesis?

Proposed by Berner, Lasaga, and Garrels, it suggests that plate tectonics influence CO2 changes through increased seafloor spreading and magma release.

What is the Uplift Weathering hypothesis?

It posits that continental collisions increase uplift, forming mountains that enhance weathering and CO2 removal, leading to global cooling.

What two factors determine the occurrence of icehouse periods?

1) Presence of polar continents for ice sheet formation. 2) Tectonic movement affecting atmospheric CO2 levels.

What characterized the hot house world around 100 Ma?

There was no ice, even in Antarctica, and coral reefs extended to 40° from the equator.

How do ocean systems affect temperature distribution?

Oceans transport warmer and cooler water effectively, influencing global climate.

What is the relationship between salinity and density in seawater?

Cold water is denser than warm water, and salt water is denser than fresh water.

What drives thermohaline circulation?

Differences in seawater density due to temperature and salinity.

What is the overturning time in ocean circulation?

The time it takes for a water molecule to complete a full loop of the globe.

What is the Ocean Heat Transport Hypothesis?

It suggests that warm, salty water can sink and spread warmth globally, contributing to hothouse conditions.

What is palaeoceanography?

The study of Earth's ocean history, focusing on past circulation, chemistry, biology, and sedimentation.

How can sediment accumulation rates be explained?

Sediment sinks faster due to aggregation, allowing rates of 100-200 m per day.

What do Mg/Ca/O isotopes in CaCO3 skeletons indicate?

They provide information about past sea surface temperatures (SST) and ice levels.

What is isotopic fractionation?

The difference in energy required to bind heavier vs. lighter isotopes, affecting their distribution.

How are isotope abundances measured?

Using an Isotope Ratio Mass Spectrometer (IRMS), reported relative to a standard as δ.

What is the Kinetic Isotope Effect (KIE)?

The influence of isotopes on the kinetics of a reaction, where lighter isotopes diffuse faster.

What is the Equilibrium Isotope Effect (EIE)?

The impact of isotopes on the position of equilibrium, affecting bond strengths in reactants and products.

What happens to oxygen isotopes during warmer periods?

Lighter 16O evaporates more, leading to higher 18O concentrations in oceans.

What is Henry's Law in relation to oceanic CO2?

It relates the solubility of gases in seawater to the partial pressure of the gas.

Why isn't the ocean acidic despite dissolved CO2?

Chemical weathering introduces weak acids that buffer against pH decreases.

What role do bicarbonate ions play in ocean acidity?

They act as a buffer, helping to maintain ocean pH levels despite CO2 presence.

What is the primary component of dissolved CO2 at pH = 8?

HCO3- makes up around 80% of the total dissolved CO2.

What temperature increase occurred around 55 Ma during the PETM?

A temperature increase of around 6 °C.

What evidence indicates the PETM temperature increase?

A decrease in abundance of 13C and Ca in foraminifera, with an increase in Mg.

How do foraminifera adjust their skeleton composition at higher temperatures?

They use more Mg and less Ca to make their skeletons.

What trend is observed in boron isotopes in sediments at lower pH?

11B decreases at lower pH, indicating higher CO2 levels.

What does the relative abundance of B isotopes in marine carbonates indicate?

It can be used as a proxy for the partial pressure of CO2.

What are GDGTs and how are they related to temperature?

GDGTs are indicators of temperature; their cyclopentane rings relate to sea surface temperature.

What geological event around 30 Ma affected Antarctica's climate?

The opening of Drake's Passage isolated Antarctica with a ring of cold water.

What significant geological change occurred around 3.5 Ma?

South America moved towards North America, closing the gateway between the Pacific and Atlantic.

What are Milankovitch cycles?

Processes that cause changes in solar forcing, leading to glacial and interglacial periods.

What is the significance of summer temperatures in ice sheet build-up?

Summer temperatures are more important than winter temperatures for ice sheet formation.

How can glacial and interglacial periods be inferred?

From oxygen isotopes, with even numbers indicating glacial periods and odd numbers indicating interglacial periods.

What role do cave deposits play in climate history?

Cave deposits, like stalagmites, can provide records of past climate conditions.

What is the process of amino acid geochronology?

It measures the ratio of L to D forms of amino acids to determine the age of organic materials.

What happens to CO2 during glacial periods?

Some CO2 dissolves in oceans, is taken up by phytoplankton, and a larger proportion dissolves into global deep water.

What triggers the shutdown of thermohaline circulation?

An increase in fresh water in the North Atlantic prevents salty water from sinking.

What was the Younger Dryas?

A period around 12.8 to 11.5 ka marked by a prolonged shutdown of thermohaline circulation.

How do long-lived species like arctica islandica provide climate data?

They grow shells with rings that indicate long-term temperature changes.

What is the relationship between stomata size and CO2 levels?

Smaller stomata indicate higher atmospheric CO2 concentrations.

What is ocean acidification?

The process where increased CO2 leads to lower ocean pH and affects marine life.

What happens to carbonate ions as atmospheric CO2 increases?

The proportion of CO3^2- decreases, leading to ocean acidification.

What is the stoichiometric solubility product (KSP) for calcium carbonate?

KSP = [Ca2+][CO3^2-], indicating the saturation state of seawater with CaCO3.

What does it mean if Ω < 1 in seawater?

It indicates that CaCO3 will dissolve, as the seawater is undersaturated.

What is the impact of increased atmospheric CO2 on ocean chemistry?

It leads to decreased pH, increased HCO3-, and decreased CO3^2-.