EVST 431 Midterm Review

Major wind patterns

- At the equator, moist, warm, air rises and heads poleward, starting a Hadley Cell. - Polar front occurs as cold air sinks at poles and flows to equator - Polar cells create H pressure at pole, L pressure at 60 degrees, Hadley L at equator H at 30o. These pressure gradients set up westerlies (wind moving from high to low pressure)

The Ocean Biological Pump

- Decomposition and grazing occur in the surface ocean -Particles sink and carry the bound CO2 to deeper waters of the sea floor - Dependent on the rate of primary production, degree of recycling, species of phytoplankton (sinking rates), depth of water column (sinking rates), and efficiency of microbes (temperature, nutrients) - For the biological pump to "sequester CO2" this organic material needs to be pumped into deeper ocean waters or deposited in sediments

Land carbon cycle components

- GPP (gross primary production): amount of atmospheric CO2 photosynthesized annually. - NPP (net primary production): Net carbon gained in new biomass. - NEP (net ecosystem production): Net carbon accumulation in an ecosystem. - NBP (net biospheric production): Net carbon accumulation in the landscape - Ra (autotrophic respiration): Carbon respired by plants - Rh (heterotrophic respiration): Carbon respired by soil microbes. - CWD: Coarse woody debris. - Respiration: CO2 release into the atmosphere by decomposing organisms. **NPP is the best measure of carbon sequestration because it represents amount being stored in biomass Relationships: NPP = GPP - Ra NEP = NPP - Rh NBP = NEP - Fire Loss - Offsite Loss

Thermal or Longwave Radiation

- Molecules that absorb this radiation are GHGs. - Good absorbers/emitters include: H2O, O3, CO2, CH4, and N2O

Factors Impacting Terrestrial Soil Organic Carbon Storage

- Physical Protection from microbes (OM in the interior of soil aggregates) - Chemical Protection from microbes (Mineral protection of OM on particles) - Drought (Inhibit diffusion (through water) of soluble OM and enzymes to microbes) - Flooding (Slows O2 diffusion for aerobic decomposition) - Freezing (Diffusion slows/stops. Microbes freeze) - Movement of OC through microbial biomass and storage of cell walls

Solar Radiation Facts

- Solar radiation at TOA is approx 1/4 of the solar constant 341 W m^-2 (recognizes that the area of a sphere is four times the area of a circle with the same radius) - Globally, about 30% of the solar radiation is reflected back to outer space (planetary albedo) - The rest is absorbed by the climate system (about 240 W m-2).

Ocean Water Specific Heat Capacity

- Specific heat capacity is the amount of energy (heat) required to raise 1 g of material 1 degree C. - Water has a specific heat capacity 4x air (remember- per unit mass) - Just the top 3 meters of ocean has same capacity of entire atmosphere

Major ocean currents

- Start with wind stress - Further impacted by Coriolis - Land mass barriers collectively form major gyres

Mixed layer/Heating Stratification

- Surface ocean has strong connection to the atmosphere. - Surface ocean depth extends fro 10s (coastal) to 100s of meters deep. - Mixed layer is well-mixed due to interactions with wind. - Warmer, less-dense water on top (can mix due to fresh water input and salinity gradient) - Exchange heat with atmosphere (weeks to years)

Radiation Balance at TOA (Radiative Forcing)

- The climate at perfect TOA radiation balance - equilibrium climate. - Amount of radiation change at TOA resulting from some anthropogenic perturbation and before the temperature has adjusted. - Occurs when there is an energy imbalance between shortwave solar radiation entering and longwave thermal radiation leaving.

Conditions for cloud formation

- abundant water vapor - existence of cloud condensation nuclei (CCN) - cooling via upward air motion

Conditions for precipitation

- abundant water vapor - existence of cloud condensation nuclei (CCN) - cooling via upward air motion - cloud droplets must grow sufficiently large

Plant functional types

Definition: A group of plants that share similar climate functional traits like albedo, leaf nitrogen level, height, and phenology. Types differ at: High-latitude (Boreal), mid-latitude, tropical, and can differ even within species (C3 arctic grass vs C4 grass).

Climate Proxies

- tree rings - corals - snake proxy

3 phases of water and their roles in the climate system

- water vapor (absorbs some solar radiation & is a strong GHG) - liquid water (lakes and oceans: low albedo, high heat capacity; in (warm) clouds: high albedo, efficient emitter of longwave radiation) - ice (in cold clouds: high albedo; does not emit much longwave radiation because of low temperature; high albedo on earth's surface (ice))

Solar constant: definition, magnitude

Definition: Total solar radiation energy that reaches upper atmosphere on a surface perpendicular to sun's rays. Magnitude: 1,366 W/m^2

Contributions to and Limits of Terrestrial Primary Production

Demand for these elements for high rates of PP. - CO2 - Water - Light - Temperature - Nutrients Radiation is the primary ingredient, limited by clouds and latitude. Nitrogen and Phosphorus are important nutrients. With enough water these can be used. Temp impacts rate of PP.

Three Milankovitch cycles and cycle lengths

1) Eccentricity: the shape of the earth's orbit; "flatness" of Earth's orbit varies in a cycle of 110,000 years. 2) Obliquity: the angle of Earth's axis is tilted with respect to Earth's orbital plane; tilt angle varies in a cycle of ~40,000 years. 3) Orbital Precession: the direction Earth's axis of rotation is pointed; Earth's position at NH summer solstice (June 21) varies in cycles of 23,000 and 18,800 years Why are these cycles important? --> The earth's position relative to the sUn is a strong driver of Earth's long-term climate, and are responsible for triggering the beginning and end of glaciation periods (Ice Ages)

Processes that cause global precipitation changes

1) Ocean evaporation increases in higher temperatures. 2)Most of the extra evaporation returns to the oceans as precipitation, but a small fraction moves to land. 3)Extra water from the oceans leads to more intense land precipitation. 4)Increase in soil moisture leads to increased evapotranpiration and runoff. 5)Most of the extra evaporation returns to the land as precipitation, but a small fraction moves to the oceans.

Weather v climate example: Which of the following numerical quantities describe weather and which describe climate? (1) The expected January temperature for Paris, France, is 5.0 oC; (2) According to a weather forecast, a severe rainstorm will produce 50 mm of rain in New Delhi tomorrow; (3) The record-breaking 2013 European heatwave is a rare event with a return period of ~10,000 years; (4) The urban heat island intensity for San Paulo peaks at 5.6oC under low wind conditions; (5) Hurricane Katrina made landfall in southeast Louisiana with sustained winds of 125 mph (56 m s-1).

1) climate (since across the span of 30 days) 2) weather (the forecast for one day) 3) climate (over the period of ~ 10,000 years) 4) climate (no exact time period specified) 5) weather (specific instance)

Four types of upward motion and their scales

Convection: hot air "bubbles" rise due to buoyancy Orographic Lifting: air flows up the side of a large mountain Convergence: in a low pressure weather system: Wind field contracts Frontal Lifting: Air slides up a weather front

What were the main findings of 4 early climate papers (be able to associate scientist with main finding)

1827 - Jean-Baptiste Fourier is credited with the discovery of term-0the greenhouse effect (more GHGs -> more long-wave radiation trapped -> radiative forcing). 1861 - John Tyndall measures how different gases trap term-0radiation. Heat absorption increased with gas concentration until saturated. (Discovered by Eunice Newton Foote 3 years earlier but sexism so no credit). 1891 - Svante Arrhenius calculated absorption coefficients of CO2 and water vapor in atmosphere. Factored in ice albedo, water vapor feedback, transfer to poles (predicted 1000 years to double CO2). 1938 - Guy Stewart Callendar claims that humans are changing CO2 levels through artificial production. Linked increase in CO2 with increase in temperature, thought little warming could be good.

Biome

A large community of plants and animals that have common characteristics for their environment. - Broader term than ecosystem.

Ecosystem

A system of living organisms in conjunction with the nonliving components of their environment. - Tightly linked through nutrient cycles and energy flows. - Typical size is (10,000m^2)

NAO (North Atlantic Oscillation)

A weather phenomenon in the North Atlantic Ocean of fluctuations in the difference of atmospheric pressure at sea level between the Icelandic low and the Azores high. Positive phase - stronger than normal pressure gradient Negative phase - weaker than normal pressure gradient

Absolute humidity, water vapor pressure, relative humidity

Absolute Humidity: measured by pressure exerted by water vapor molecules; standard unit is mb or hPa; typical range is .5 to 35 mb near the ground Water Vapor Pressure: pressure is expressed as hPa (hectopascal) or mb (millibar); conversion: 1 mb = .0145 psi Relative Humidity: the relative degree of saturation; Relative Humidity = actual vapor pressure/ saturation vapor pressure x 100(%)

Aerosol forcing (Direct vs Indirect; Scattering vs absorbing)

Aerosols: liquid or solid particles suspended in the air; ie: dust, volcanos, sea spray, vegetation; ie: dust, sulfates and aerosols from powerplants, black carbon from fossil fuels and biomass burning - can be emitted directly (dust, sea salt, Black Carbon (BC), and volcanic aerosols) - can be emitted indirectly through chemical reactions (sulfate, nitrate, ammonium, and secondary organic aerosols) - short lifetime; peak near their sources - high concentration regions: desert, industrial, biomass-burning regions Scattering: primary climatic impact; reflect short wave radiation back to space (cooling); diverse structure and composition impacts how much radiation aerosols scatter or absorb Direct: absorption of radiation (warming); black carbon (soot) is the largest absorber Indirect: increase number of cloud droplets and therefore reflectivity (cooling) but they can also produce lots of smaller cloud droplets that take longer to precipitate

Intrinsic Climate Sensitivity

Amount of temperature change per unit change in radiative forcing as a result of longwave radiative feedback - 0.3 degrees C per (W m^-2). - This parameter is also referred to as the Planck feedback parameter.

Clausius-Clapeyron equation

An equation that describes the water-holding capacity of the atmosphere as a function of temperature (capacity goes up around 7% per K of temperature increase). - Relative humidity remains constant regardless of temp changes. (Don't need to know eq. just know that, higher temp = higher water vapor capacity)

Approximate volumes of sea level rise stores in ice

Antarctic: enough water to raise sea level by 58m. Greenland (and peripheral islands): enough to raise sea level by ~7m. Rest of the world: enough to raise sea level by ~ 65m.

Ocean Acidification

Anthropogenic CO2 dissolves in water. - CO2 reacts with water to form carbonic acid. - Carbonic acid dissociates into hydrogen ions and bicarbonate ions. - The hydrogen ions combine with carbonate ions in the seawater, reducing the concentration of carbonate ions available for marine organisms to build their shells and skeletons. - Lower pH shifts equilibrium towards formation of bicarbonate and hydrogen ions, and away from formation of carbonate ions.

Biogeochemical vs. biophysical effects of deforestation

Biogeochemical effects: - Arise from changes in atmospheric CO2 concentrations (this concentration changes in response to carbon source/sink strength) - Quantified in terms of radiative forcing at TOA - Global consequence Biophysical effects: - Associated with changes in albedo, surface roughness, and evapotranspiration. - Causes changes in both global radiative forcing and local energy balance. Impacts are both global and local.

Biological processes and methane

Biological: - methane is produced via methanogenesis/fermentation by microbes after systems go anoxic (lose all their O2) - methane is broken down biologically by methanotrophs (bacteria that utilize methane as their source of carbon and energy) Methane is the second most important GHG after carbon dioxide contributing to human-induced climate change - global warming potential 28 times larger than CO2 - methane is responsible for 20% of the global warming produced by all greenhouse gases so far - concentration of methane in the atmosphere is 150- % above pre-industrial levels

Production and Oxidation of Organic Carbon

CO2 + H2O <--> CH2O + O2 Decomposition occurs aerobically with oxygen by decomposers (small percentage in anaerobic conditions - anoxic) Photosynthesis occurs with water, CO2 and energy (ocean and land plants). Balance between these two impacts global CO2. More photosynthesis = CO2 uptake More decomposition = increase in atmospheric CO2

Chemical Weathering (example)

CaCO3 + CO2 + H2O -> Ca+2 + 2HCO3- Dissolution of solid minerals to ions (carbonate or silicate minerals in soil). Consumes atmospheric CO2 producing bicarbonate (HCO3-) for storage in Earth's reservoirs. Bicarbonate delivered to oceans via rivers that pick up dissolved ions. Century time-scale implications for carbon cycle (long-time sink with some control factors like ocean acidification and CO2 and H2O input).

Atmosphere: permanent versus variable gases, chemical versus physical atmosphere

Chemical Atmosphere: refers to the abundance and distribution of chemical species in the atmosphere in tracer amounts - tracer species include GHGs, air pollutants, and aerosols and do not directly impact air density and sir motion; their climate effects are often expressed as radiative forcing; for some trace gases, climatic effects are independent of the location of emission Physical Atmosphere: describes dynamic aspects of the atmospheric state - the energy cycle is an important driver of air motion; the hydrological cycle is part of the physical atmosphere; water vapor is a major gas it is directly involved in air motion, it is a greenhouse gas, but its climate effect is studied through climate feedback, not radiative forcing; standard weather and climate variables describe the physical state of the atmosphere Permanent Gases: gases in the atmosphere whose concentrations do not change; Nitrogen, Oxygen, Argon, Neon, Helium, Hydrogen, Xenon Variable Gases: gases that have such low concentrations that they make little difference; ex: water vapor; carbon dioxide, methane, nitrous oxide, ozone, particles, chlorofluourocarbons (CFCs)

Contributions to and Limits of Marine Primary Production

Demand for these elements for high rates of PP. - Light (Latitude, season) - Mixing of water column (Mixed out of light) - Nutrients (Fe also important) - Grazing Dominated by phytoplankton (small global biomass) that are very easily grazed. Phytoplankton undergo photosynthesis, more efficiently during ideal light and season conditions. Constrained to upper mixed layer. Mixing due to seasonal temperature changes (deeper in winter - colder water mixes deeper). Phytoplankton must be in Euphotic zone for PP.

Dynamic vs. Thermodynamic argument for intensification of individual rain events

Dynamic argument: Large-scale atmospheric circulation patterns cause air to rise and condense, leading to precipitation. - Warm moist air enters a cold front and is forced to rise and cool leading to the formation of clouds and precipitation. Air circulation leads to convergence, where air converges on one location and rises upward leading to more condensation and precipitation. Thermodynamic argument: Focuses on the properties of air (temp, humidity, stability) and its capacity to hold water vapor. - Warm moist air rises through a cooler layer, leading to more condensation and more precipitation (think the rain shadow effect from earlier on the opposite side), reinforcing the upward motion. *In reality, both probably contribute.

Dynamic feedback (w/Example)

Dynamic feedbacks are processes (cloud, water vapor content, carbon cycle, ice albedo...) that respond to (and modify) changes in Earth's temperature. - They do not initiate climate change. Example: Gregory Method - Abruptly raise CO2 levels and hold constant - Record temp imbalance and change in surface temp over time. - The system will eventually reach a new equilibrium.

Relationship between seasonal change and tilt angle of earth's rotational axis

Earth's axis is tilted at 23.5 degrees. A consequence of the axial tilt is seasonal change in climate. Another consequence is extensive dark and daylight periods near the poles.

Anthropogenic Carbon Budget Equation

Ef + Eluc = Gatm + Socean + Sland + Bim Ef = Fossil emissions Eluc = Land use change emissions Gatm = Growth rate of atmoshperic CO2 concentration Socean = Ocean Storage Sland = Land Storage Bim = Budget imbalance

Effective Climate Sensitivity

Effective climate sensitivity factors in dynamic feedback mechanisms - Can impact the effects of increased CO2 and other GHG's including both direct and indirect. - Greater than the intrinsic climate sensitivity because feedback mechanisms can intensify warming.

Energy flux and unit

Energy Flux: expressed as the amount of energy incident on or emitted by a unit ground surface area per unit time; standard unit is Wm^-2 (watts per square meter)

Equilibrium Climate vs. Transient Climate

Equilibrium Climate - Condition of perfect TOA radiation balance. Transient Climate - Climate in the process of adjusting itself to some anthropogenic perturbation.

Connection between water cycle and energy cycle

Evaporation at the Earth's surface takes heat from the environment. Condensation in clouds releases heat to the environment. Annual precipitation and evaporation = 1040 mm

Global hydrological cycle: two interlinked cycles,

Evaporation: vaporization of liquid water in soils, lakes, rivers, and oceans Transpiration: vaporization of liquid water in living plants On average, transpiration accounts for 57% of land evapotranspiration (the combined processes)

Energy, Carbon, and Water Cycles

Evapotranspiration links the Energy and Water cycles. Soil water links the Water and Carbon cycles. Stomatal control links the Energy and Carbon cycles.

Longwave Radiative Feedback

Extra energy in the climate system will warm up the surface. - This increases amount of longwave radiation emitted to outer space. - Continue until the longwave radiation leaving TOA balances shortwave radiation entering.

Open land vs Forest (deforestation)

Open land - Weak C sink (or source) - High albedo - Smooth (low roughness) - Low evaporation Forest - Strong C sink - Low albedo - Rough (high roughness) - High evaporation

External drivers of climate change; anthropogenic; examples

Fossil Fuel Burning Land use change Agric intensification

What are the main types of carbon

Four major types: - CO2 is inorganic carbon in the gas phase found in water, the atmosphere, and soil environment. - Organic Carbon is reduced containing energy, and is formed through photosynthesis. Living and dead plant material. - Bicarbonate and carbonate are forms of inorganic carbon found as dissolved ions in water. CO2 + HCO3- + CO3 = Dissolved Inorganic Carbon - Carbonates are solid inorganic carbons found in soils and ocean sediments (formed by living organisms).

Current global mean surface temperature, annual precipitation, and atmospheric CO2 concentration

Global Atmospheric CO2 Concentration: ~400ppm Global Mean surface temperature: 58.6°F (14.8 °C) Global Annual precipitation: 1000mm

Global precipitation temperature sensitivity

Global precipitation increases by 1 to 3% for every K rise in temperature. Lower relative change per K is expected in a higher emission scenario. - Global mean precipitation ~1000 mm/year or 2.73 mm/day.

Permafrost gradual vs. abrupt thaw

Gradual Thaw: Warming of the arctic deepens the active layer (CO2 and methane source). However, it converts to shrubs and forests (CO2 sinks. - Vertical thickening of active layer as atmosphere warms (predicted to release ~200Pg of carbon by 2300). Abrupt Thaw: The process by which thawing permafrost causes land subsidence (thermokarst). - Second cause of melting permafrost. - Ice in deep parts of permafrost melts, causing land to subside. - Accelerates thaw (predicted to release ~80Pg C by 2300.

Albedo and ice surface area

Greenland ice sheet: 1.7 * 10^6 km^2 Antarctic ice sheet: 13.3 * 10^6 km^2 Mountain glaciers: 1.1 * 10^6 km^2 Permafrost: 22.8 * 10^6 km^2 Snow and ice are highly reflective. - Reflection of radiation back into space reduces radiation to warm the earth. - Impacts periods of energy input vs. no energy input - Periods when ice covered by fresh snow is most reflective (lease radiation available). - Albedo of snow decreases with age and pollution.

Permafrost

Ground which is <0 degrees C for at least 2 years. - Makes up 24% of land in the Northern Hemisphere - Can be >100m thick - Can increase in depth during some periods as vegetation freeze over. - Stores massive amounts of frozen organic carbon - When unstable, the organic carbon can be mobilized to CO2 and CH4 - Has an active layer which thaws annually (~1m) - One mode of permafrost thaw is through the deepening of the active layer.

Albedo of Natural Surfaces

High albedo surfaces: Fresh snow, ~Old snow Low albedo surfaces: Coniferous Forest, Deciduous Forest, Grassland

Some landmark years: 1850 - end of little ice age & start of industrial age; 1991- Mount Pinatubo

ICE AGE: 1300 - 1850 (important, climate modeling is based off of this often) atmospheric CO2 in 2021: 414.7 ppm, or about 1.5 x pre-industrial level Mount Pinatubo - 1991 - Phillippines - reduced the solar energy absorption by about 3.0 W m^-2 - Doesn't stay long because the dust particles go away over time

Ice Shelf Dynamics

Ice sheets typically have large ice shelves which can melt from below. - Ice shelves are exposed to the warming atmosphere. - Coastal ice cliffs can rapidly collapse because of ice shel disintegration

Continental scale deforestation feedbacks

Land albedo - sea ice feedback: Clearing northern boreal forests (north of 45 degrees N), lowers land temperature and adjacent sea temperature. Sea ice expands, increasing sea albedo (more coverage), and enhancing cooling. Evaporation - cloud feedback: At low latitudes, less land evapotranspiration (deforestation) leads to less cloud cover. As a result, less solar radiation is reflected back, causing surface temps to increase even further.

Energy Cycle in land models

Land energy fluxes are the bottom boundary conditions for modeling atmospheric motion. - Include flux parameterizations - Take solar radiation and downward longwave radiation from atmospheric model as inputs and calculates sensible and latent heat fluxes to atmosphere. - Uses heat fluxes to predict state of atmosphere at next time step (typically 30 minutes to an hour).

Land Model Structure - Big Leaf Parameterization

Land models represent ecosystems as one or more big leaves. - Calculates sensible and latent heat fluxes with Ohm's Law analogy. The diffusion pathway of heat and water vapor is represented by a network of diffusion resistances

Global methane budget (anthropogenic vs natural)

Largest natural contributor: wetlands Different factors: fossil fiel production and use; agriculture and waste; biomass and biofuel burning; wetlands; other natural emissions; sink in soils

Latent heat of vaporization, latent heat of fusion

Latent Heat of vaporization: heat required to vaporize 1 g of liquid water Latent heat of fusion: heat required to melt 1 g of ice

Known climate feedbacks

Longwave radiative feedback: Warming of Earth's surface -> more longwave radiation emitted to the outer space -> slower warming. Water vapor feedback: Warmer atmosphere holds more water vapor -> additional warming. Lapse rate feedback: Upper and lower atmospheric layers warm up at different rates -> decrease or increase warming via changes in longwave emissions to space. Cloud feedback: Clouds modify radiation balance of the atmosphere; "The best guess is that clouds amplify warming". Carbon cycle feedback: Longer growing season and faster growth with high CO2 conditions -> more land carbon sequestration (negative feedback). Decomposition of soil organic matter is faster at higher temperature -> more CO2 release from soils (positive feedback). Feedback via weathering (weathering thermostat): Rainfall increases as the Earth's surface warms -> increases the rate of chemical weathering -> removes CO2 from the atmosphere.

The Carbonate System

More CO2 = Lower pH (acidic) Less CO2 = Higher pH (basic) CO2+H2O -> H2CO3 (formation of carbonic acid) - In adding acid, carbonates are converted to CO2. - In removing acid, CO2 is converted to bicarbonate.

Ocean heat storage

Most anthropogenic heat is currently stored in the mixed layer. - Equivalent to ~ 0.15 degrees celsius in warming Implications: - Warm water expands (seawater expansion contributes to rising sea levels). - Change in Volume = bt*ΔT bt = coefficient of thermal expansion (function of temperature, salinity, and pressure) ΔT = change in temperature *Only impacting surface ocean so far.

External drivers of climate change: natural; examples

Natural: - Land effects: Thermal effect: having lower heat capacity than water, land experiences larger temperature changes over time than lakes and oceans Dynamic Effect: mountains block air movement and moisture transport, causing regional variations in precipitation Biogeochemical effect: land vegetation absorbs carbon dioxide from the atmosphere - Solar cycle: solar constant varies in an 11-year cycle linked to sunspot activity - Volcanos: volcanos can change the amount of solar energy absorbed by the atmosphere; example: Mt Pinatubo (1991, Phillippines) reduced solar energy absorption by 3.0 W m^-2 - Milankovitch Cycles: - Orbital Precession: northern continents were warmer in the summer and colder in the winter about 9000 years ago; summer monsoons (and rainfall) were more intense - Earth Curvature; examples: solar radiation intensity is higher on a surface perpendicular to the solar beam than on a tilted surface; earth curvature leads to variation in the amount of solar radiation intensity with latitude - Earth's Axial tilt: results in seasonal change in climate and extensive dark and daylight periods near the poles

The Odum Paradigm

Net ecosystem production is a balance of two opposite carbon fluxes (energy inputs into an ecosystem must balance energy outputs). - NEP peaks at tens of years after initiation of the forest stand(new-growth forest). - NEP approaches zero in intact or old-growth forests.

Clean versus polluted clouds: aerosol direct effect and indirect effect

Polluted clouds generally have a higher albedo than clean clouds because polluted clouds have a longer lifetime and have smaller and more numerous droplets Aerosol direct effect: aerosols reflect and absorb shortwave and longwave radiation. effect strength depends on aerosol type, size and location, and can either cool or warm the climate Aerosol Indirect Effect: aerosols increase cloud albedo and cloud lifetime. The net result is climate cooling.

Ocean pH and chemical CO2 uptake

Pre-anthropogenic oceans were a net source of CO2. - Pumping CO2 into the atmosphere has reversed the concentration gradient - Flux = [CO2air - CO2water] * k CO2water = CO2 concentration in the water CO2air = CO2 concentration that would be in water if it were in equilibrium with air k = gas transfer velocity

Water Cycle in Land Model - Soil Bucket model

Precipitation is predicted by the atmospheric model. - Evapotranspiration is calculated using big-leaf parameterization. - Runoff is calculated using the Soil bucket model (occurs when the "soil bucket" is filled to field capacity or the max amount of water soil can hold).

Natural Greenhouse Effect

Radiation imbalance at TOA lets solar radiation into the atmosphere. The atmosphere does not absorb this radiation, but it is opaque to thermal radiation, meaning it reflects it.

Radiation Theory

Radiation is the transfer of energy through electromagnetic waves. - Wavelength describes distance between two adjacent wave crests; 1 micrometer (μm) = 10-6m - A blackbody is a perfect emitter radiating at maximum possible intensity (emissivity = 1) - Emissivity is a the ratio of energy radiated from a material's surface to that radiated from a perfect emitter. - Visible wavelengths, near infrared, and UV (these are shortwave radiation) - Far infrared, thermal (these are longwave radiation)

Topography, rain shadow, and river runoff

Rain shadow: One side of a mountain range receives significantly less precipitation than the other side. - When moist air is forced to rise up one side of a mountain range, it cools and condenses, leading to more precipitation on the windward side. - When the air descends on the opposite side of the mountain, it warms and dries out, resulting in less precipitation. -Rain shadow results in drier climate and less river runoff in shadowed areas. River Runoff: The amount of water that flows into rivers for transport to the ocean. - Water flows downhill due to gravity, therefore topography really dictates the degree of runoff. - This also depends on the amount of precipitation, so a rain-shadowed area would expect less runoff.

Albedo-enabled feedbacks

Sea ice albedo feedback: Melting of sea ice due to higher temperatures reduces ocean surface albedo - amplifies warming. Snow albedo feedback: In higher temperatures, land albedo is lower because of less snow - amplifies warming. Forest albedo feedback: Higher temperatures encourage tree line to shift northward - amplifies warming (forests have much lower albedo than tundra). Shrub albedo feedback: Shrubs have lower albedo than other tundra plants. Once a clump is formed, warmer, more favorable climate for growth. Soil moisture - albedo feedback: Dry desert soil has higher albedo than wet soil. Less absorption of solar radiation by the ground means less atmospheric convection and less precipitation, causing desertification (The Charney Hypothesis)

Sea ice, ice sheets, and mountain glaciers

Sea-ice: Formation of sea-ice leaves out the brine, causing the water underneath to become more slaty and dense (Antarctic bottom water formation). - In polar ocean with colder temps, impacts of salinity on buoyancy are proportionally more important. - Increases albedo - We are currently losing old/thick ice. Mountain Glaciers: Alpine regions including tropical regions. - Important for albedo and sea-level rise. It is dynamic and flows, dictated by the surrounding topography. - Represents a long term storage term in the hydrologic cycle. - As glaciers disappear, new water is introduced into the hydrologic cycle from long term storage, contributing to rising sea-levels. Ice sheets: Continental scale ice sheets - Hundreds of thousands to millions of years in age. - Can influence global and regional climate characteristics and global seal level. - Impact on long time scales.

Earth surface energy balance: Sensible heat flux, latent heat flux, Bowen ratio, albedo

Sensible heat flux: the transfer of heat by moving air between a surface and the atmosphere Sensible heat flux = 20 W m-2 Latent heat flux: the transfer of heat through the vaporization of liquid water between a surface and the atmosphere Latent heat flux = 84 W m-2 Bowen Ratio: the ratio of sensible heat flux to latent heat flux; a measure of how wet or dry a climate is

Chronosequence

Series of spatially distinct sites of varying ages that is assumed to represent a temporal sequence of vegetation. (so basically: different forests that have been harvested and are experiencing new growth are tracked over time and plotted, comparing their rate of production and respiration) - As forests regrow, they are always sinks, as carbon uptake exceeds ecosystem respiration. - This plateaus and older forests have higher rates of respiration (decomposing organic matter). - NEP is high and has fast recovery in warm climate, bit is generally low in slow climate. - Old forests are still carbon sinks. Inconsistency with Odum Hypothesis: Three sites (around 30 years old) in Saskatchewan are C sources because of decay of large amounts of wood left on sites.

More rain vs. less snow

Snow has the ability to stick to the ground and reflects significantly more radiation as a result of its higher albedo. This is important in dictating the amount of energy entering or leaving the climate system.

Importance of earth curvature for regional climate and radiation energy distribution

Solar radiation intensity is higher on a surface perpendicular to the solar beam than on a tilted surface; Earth curvature leads to variation in the amount of solar radiation intensity with latitude. Surplus of radiation energy between 38 S and 38 N. Roughly 2/3 of the energy surplus at low latitudes is transported to high latitudes by atmospheric circulations and 1/3 by ocean circulations

Sources and Sinks of methane in inlands waters and wetlands

Sources of Methane: anthropogenic sources now greater than natural - Natural: wetlands, termites, inland waters, fires, geogenic (deep earth) - Anthropogenic: ruminants, rice paddies, biomass burning, landfills, coal mining, natural production. Sinks of Methane: - abiotic: troposphere OH-; OH (hydroxyl) radical is highly reactive; OH has a complex atmospheric cycle, change in OH can impact CH4 since it is major sink

Major fluxes and stocks of pre-anthropogenic carbon balance

Stocks: Atmosphere - 590 Fossil Fuels - 3700 Vegetation, Soil - 2300 Surface Ocean - 900 Intermediate/Deep Ocean - 37100 Surface Sediment - 150 Marine Biota - 3 Fluxes: Rivers to Surface Ocean (weathering from Sediments, Soil, and NPP from Respiration) - 0.8 Surface to Deep Ocean - 90.2 Deep to Surface Ocean - 101 Deep Ocean to Surface Sediments - 0.2 Marine Biota to Deep Ocean - 11 Atmosphere to Surface Ocean - 70 Surface Ocean to Atmosphere - 70.6 Atmosphere to Vegetation - 60 Vegetation to Atmosphere - 59.6

Radiative Forcing due to CO2 doubling

Suppose amount of CO2 is instantly doubled. - Amount of longwave radiation leaving TOA will be reduced by 4 W m-2 (trapping of longwave radiation by additional CO2). - The energy of the earth's atmosphere would no longer be in balance.

Temperature units, when to use which

Temperature is measured in °C, °F, and K; Conversion: C = 5/9(F-32); K = C + 273.16; use °C or °F to describe warmness of the atmosphere and use K for calculation of radiation energy emission

Coriolis Force

The apparent force, resulting from the rotation of the Earth that deflects air or water movement (not present at the equator).

Arctic amplification

The arctic is warming more rapidly than the rest of the planet. - Sea-ice retreats and exposes greater surface area of the ocean -> more evaporation and heat uptake -> more moisture delivery to the atmosphere (more GHG's, source of precipitation) -> more heat absorbed by arctic ocean. - Large influence on Arctic, but has global feedback influences. **Strongest heating in the fall/winter

Stefan-Boltzmann Law

The relationship states that an object emits energy at a rate proportional to the fourth power of its temperature, in Kelvin. Radiation intensity: L = ε σ T^4 [W m^-2] Emissivity ε ≤ 1 S-B constant σ = 5.67 ×10-8 [W/(m^2K^4)] Temperature T in K Inverting the S-B law to obtain temperature: T = [L /(ε σ)] ^ 1/4

Abiotic methane production and destruction

Thermal Production: cooking of ancient organic matter in deep earth (high pressure and temperature) - temperatures >150 degrees celsius - occurs in deep marine sediments and soils (~1000 meters down) - small natural souce, can be anthropogenically leaked; also occurs during biomass burning (incomplete combustion) Destruction: Methane is broken down abiotically in atmosphere; lifetime in atmosphere is about 10 years

Ocean Circulation - Deep Conveyor Belt

Thermohaline Circulation - Driven by buoyancy changes in ocean water (cold, slaty water sinks) - Primary method of transferring heat and dissolved materials to deep ocean - As water moves to the poles and cools and fresh water evaporates, it gets denser than water below and then sinks. - Conveyor belt moves large amounts of heat (centuries, generally poleward) - Deep water formation (heat and chemicals -> deep ocean) - Returned by upwelling at equator.

Albedo carbon equivalence

Total radiative forcing due to doubling CO2, summed up over the whole globe. - Total CO2 needed to double = 2.15 x 10^12 tonnes - TOA radiation change per tonne of CO2 added to the atmosphere = 0.91 kW / tonne CO2 Example: Albedo cooling effect after 1-ha of boreal deforestation in Canada. - Albedo of cleared land is higher than that of forest, leads to net cooling at TOA. - Equivalent to 178 t of CO2 in this case.

Natural Greenhouse Effect (Calculations)

Using Stefan-Boltzmann Law

Land system components/approximate area fractions

Vegetation and exposed land - 47% (weak CH4 sink, large C sink, variable albedo and evaporation rate) Cropland - 37% (weak C sink, large N2O source, large CH4 source) Glacier and ice sheet - 10% (no GHG activity, high albedo, contributing to sea-level rise) Lake and wetland - 4% (weak C source, large CH4 source, high evaporation rate, low albedo) Urban - 2% (high C emission, >70% of total anthropogenic C emissions), low evaporation rate, localized hotspots)

Ocean solubility pump

Warm waters become cooler as the move toward the poles. - Gases are more soluble in cold water - Poleward-moving waters have enhanced solubility (around 5% more CO2). - When warm water wells from the equator, there is outgassing (warm water = reduced solubility = less CO2)

Water vapor build-up and radiation

Water vapor molecules absorb some shortwave radiation. - Water vapor build-up leads to global dimming (reduction of solar radiation at Earth's surface). - Water vapor is a GHG, so more longwave emissions by atmosphere to Earth's surface. - Another consequence is an increase in rain intensity.

Weather versus climate

Weather: condition of the atmosphere at any particular time and location Climate: the "average weather"; the accumulation of daily and seasonal weather events over a long period of time

Black Carbon

aka, soot. is the largest absorber of radiation; produced mainly during coal combustion - also fires; can absorb in atmosphere; can impact absorption/reflection on snow/ice

Feedbacks - fast v slow

fast feedbacks: water vapor, clouds, snow cover, sea ice slow feedbacks: continental ice sheets, altered biogeochemical cycles - slow feedbacks that lead to warming can trigger fast feedbacks

Global warming potential

how much energy the emissions of 1 ton of a gas will absorb over a given period of time, relative to 1 ton of CO2

Climate Sensitivity

the global average temperature rise under steady conditions of 2x CO2 concentrations. vary depending on feedbacks

Four expressions of mass conservation

¤ Global Total Evaporation and Transpiration = Total Precipitation ¤ Atmospheric Transport to land = River Runoff to ocean ¤ Ocean Evaporation = Ocean Precipitation + Atmospheric Transport to land ¤ Land Precipitation = Land Evapotranspiration + River Runoff to ocean