GEOG3900 exam 1 - climate change osu

John Tyndall

(1862) discovered in his laboratory that certain gases, including water vapor and carbon dioxide ( CO2), are opaque to heat rays.

Albedo

Albedo = amount of SW reflectivity, given as % (range: 0 -1.0) Clouds and ice cover are more reflective, higher albedo

Explain how anthropogenic global warming (AGW) is a biogeochemical issue involving carbon. Include a description of the rates (with approximate magnitudes) at which carbon is exchanged (fluxes) between the important reservoirs (atmosphere, the terrestrial environment and the oceans, and the lithosphere), and specifically how human activity alters that cycling.

Ans 1?? Atmosphere (740GtC), Ocean(deep 38,000GtC, mixed 1000GtC), and Land Biosphere(2,000GtC) have roughly 40,000 GtC, Rocks have millions and millions. The flux between the two is naturally about 0.1 GtC/yr each way (volcanic activity, chemical weathering). Burning fossil fuels bumps that up by +9 GtC/yr. Fossil fuels were formed when plants that grew hundreds of millions of years ago were buried before the carbon in them could be released back into the atmosphere by respiration. Under high pressure and heat, applied over millions of years, the carbon in the plants was converted into the substances we know today as oil, coal, and natural gas. Deforestation is an important source of carbon dioxide for the atmosphere, and estimates are that it contributed approximately 1.5 to 2 GtC to the atmosphere per year during the 2000s

Ice albedo feedback

As warming from the buildup of CO2 causes sea ice to melt, a higher proportion of solar energy gets absorbed by the ocean because there is less ice to reflect that energy, which enhances warming, causing the ice to felt faster. It is a positive feedback.

Guy Stewart Callendar

CO2 increasing, advocated greenhouse idea/global warming

What units do we use to measure greenhouse gases?

CO2 parts per million ( 0.039% corresponds to 390 parts per million or ppm, meaning that there are 390 molecules of carbon dioxide in every million molecules of air.), Gigatons Methane ppb (parts per billion)

Troposphere

Closet layer to the earth. Where weather occurs. Most of planet-insulating greenhouse gases are contained, motions of the atmosphere transport water vapor and heat here. Temp decreases, as elevation increases.

Anomaly

Difference between actual temperature and a ref temp (usually average over base period of 30 yrs).

How is energy of radiation related to wavelength?

Energy of radiation is inversely related to wavelength (shorter wavelength = more energy; longer wavelength = less energy)

Global circulation is about transferring heat (energy) from HOT TROPICS to COLD POLES Hot air rises....why? What heats faster, land or water?•What stays warmer longer? •What happens with evaporation?-Latent heat transfer

Hot air rises because as it heats, it expands and density goes down Evaporation transfers heat from the surface to the atmosphere.

fundamental energy unit

Joule (J)

ITCZ (intertropical convergence zone)

Northern and Southern hemisphere trade winds meet. large-scale upward motion of air results in low surface air pressure.

Explain the general circulation of the Earth's atmosphere and oceans. Describe what causes it, and its characteristic features. Also, describe the special properties of the ocean and explain how the ocean impacts the climate system.

Ocean may have a carbon saturation point, which may have passed aka 350ppm, and at that point more carbon will remain in the atmosphere and intensify climate change.

Aerosols

Particles so small that they do not fall under the force of gravity, but remain suspended in the atmosphere for days or weeks Aerosols tend to cool rather than warm the surface. It is a negative forcing factor. The second most important forcing factor after GHGs.

Radiative forcing

Radiative forcing (often abbreviated RF) is the change in E in − E out for the planet as a result of some change imposed on the planet before the temperature of the planet has adjusted in response the change, relative to the year 1750, in incoming energy minus outgoing energy in response to a factor that changes energy balance.

James Hansen

The "pause" in global warming is a myth, despite the controversial news Earth's Energy Imbalance: Confirmation and Implications Our climate model, driven mainly by increasing human-made greenhousegases and aerosols, among other forcings, calculates that Earth is now ab-sorbing 0.85T0.15 watts per square meter more energy from the Sun than itis emitting to space. This imbalance is confirmed by precise measurements ofincreasing ocean heat content over the past 10 years. Implications include (i) theexpectation of additional global warming of about 0.6-C without further changeof atmospheric composition; (ii) the confirmation of the climate system's lagin responding to forcings, implying the need for anticipatory actions to avoidany specified level of climate change; and (iii) the likelihood of acceleration ofice sheet disintegration and sea level rise.

Energy

The ability to do work(force x distance) on some form of matter (mass)• It is the capacity to cause things to happen• A conservative quality (neither created nor destroyed)

Stefan‐Boltzmann Law

The amount of energy radiated is proportional to the temperature of the object raised to the 4th power W/m2. F = σT4 F = flux of energy (W/m2) T = temperature (K) σis Stefan-Boltzmann constant (5.67 x 10-8W m-2 K-4)

Coriolis force

The apparent force, resulting from the rotation of the Earth, that deflects air or water movement. Deflects to the right in the Northern hemisphere and to the left in the Southern hemisphere.

Residence time

The average time a given particle will stay in a given system

Normal period

The base period is 30 years, and climatologists call this a "normal period"

Holocene

The current interglaciation period, extending from 10,000 years ago to the present on the geologic time scale.

Negative feedback

The feedback has a dampening effect on the process.

Wien's Law

The hotter the object, the shorter the wavelength (λmax) of maximum emitted radiation. λmax≈ 3000 μm K / T (K)

Solar irradiance

The power per unit area received from the Sun in form of electromagnetic radiation. amount of light energy per unit area (from the sun measured on the earth) - determines average temperature of any region

Power

The rate of energy flow/use/transfer per time

Stratosphere

The second-lowest layer of Earth's atmosphere. Above troposphere and below mesosphere. It is relatively warm due to the presence of the ozone which absorbs UV radiation from above and infrared radiation from below. Heats up as elevation increases.

Thermosphere

The uppermost layer of the atmosphere. Thin and heated by solar radiation and its interactions with solar wind. Temp increases as elevation increases.

Basics of atmosphere (composition, structure)

Troposphere, stratosphere, mesosphere, thermosphere. Layered because of how the atmosphere is heated. Atmosphere has mass, though only ~1 millionth of the Earth Weighs about 15 lbs per squre inch (1,034 g/cm2) -> pressure. Pressure changes when air rises or sinks. Pressure decreases with altitude. Composition of air: 78.1% N, 20.9% O, 0.93% Argon. The remaining 0.04% is H2O, CO2, CH4, O3, and N2O. Importance of gas depends on abundance and wavelength

Power unit

Watts (W) = J/s

Difference between climate and weather

Weather is what conditions of the atmosphere are over a short period of time (short-term, should I bring a coat today?), and climate is how the atmosphere "behaves" over relatively long periods of time (long-term, does this area get enough snow to build a ski resort?).

Climate change

any systematic change in the long-term statistics of climate elements (such as temperature, pressure, or winds) sustained over several decades or longer. Such statistics include not just the averages but also the measures of the extremes - how much the atmosphere can depart from the average.

What are the greenhouse gases?

carbon dioxide, methane, water vapor (most abundant), ozone, nitrous oxide

Methods of heat transfer

conduction (molecule to molecule), convection (transferred by vertical movement like boiling or mixing), radiation (solar radiation provides nearly all energy to Earth)

Latent heat

heat absorbed or radiated during a change of phase. EXAMPLES: evaporation, condensation

greenhouse effect

heating of the surface by the atmosphere the atmosphere warms the surface by making it harder for the surface to lose energy to space. Energy flows in from Sun, and then re-radiated back to space from Earth/atmosphere. If we end up with more GHGs, more radiation at surface => temperature increases

Climate sensitivity

how the climate system responds to a forcing change

What are the GHGs' relative warming potentials compared to a molecule of CO2?

methane is roughly 20 times more powerful than carbon dioxide on a per molecule basis - meaning that it takes 20 molecules or so of carbon dioxide to equal the warming from one molecule of methane. The most powerful greenhouse gases on a per molecule basis are the halocarbons. It takes several thousand carbon dioxide molecules to equal the warming from one halocarbon molecule.

Wavelength unit of measurement

micron (mum)

Proxy data

paleoproxies, which are long-lived chemical or biological systems that have the climate imprinted on them. In this way, we can make measurements today that tell us what the climate was like in the past. Examples: ice cores (chemical composition, crystal size & orientation, dust), pollen, tree rings, ocean sediment, speleothems, corals, etc ice cores only provide climatic information in regions and over time periods that are cold enough for permanent ice to exist. But there are other paleoproxies that provide data in other regions and over other time periods. For example, trees also store climate information in their tree rings. ocean sediments can provide information about water temperature, salinity, dissolved oxygen, atmospheric carbon dioxide, nearby continental precipitation, the strength and direction of the prevailing winds, and nutrient availability; this information goes back tens of millions of years.

Weather

the actual state of the atmosphere at a particular time.

Insolation

the delivery rate of solar radiation per unit of horizontal surface

If energy from the sun is constant, why do seasons occur?

the seasons are the result of changes in the angle and duration of sunlight across the planet's surface. This is due to the constant tilt of Earth's axis of rotation.

Climate

the statistics of the atmosphere over a period of time, usually several decades in length or longer. The slowly varying aspects of the atmosphere- hydrosphere- land surface system. It is typically characterized in terms of suitable averages of the climate system over periods of a month or more, taking into consideration the variability in time of these averaged quantities. Mark Twain: "Climate is what you expect; weather is what you get"

Why is the earth not heated by conduction or convection?

though the sun is very HOT, it is NOT the sun's temperature that heats the atmosphere because space is devoid of molecules; thus, conduction or convection don't work...but radiation.

How do we know increasing CO2 in the atmosphere is produced by human activity? Again, explain the scientific evidence we have for this.

-we know how much fuel we are consuming. (The remaining 7 gigatons, which is generated by cement production, deforestation, and agricultural activities, we know with less accuracy.) First, for the past half century, each year's increase in carbon dioxide in the atmosphere has been roughly half of what humans released into the atmosphere in that same year. -Second, the atmosphere's carbon isotopic composition is changing. Fossil fuels possess much lower ratios of carbon-13 to carbon-12 (13C/12C) than do the atmosphere and the ocean. Consistent with the buildup of atmospheric C02 as a result mainly of fossil-fuel burning is the observation that the atmosphere's 13C/12C ratio has been in steady decline since systematic measurement began in 1977

How do we know that global warming is occurring? Be able to LIST and explain the scientific evidence we have to account for this beyond just the plot of observed atmospheric temperatures rising.

1) Temperature change. -Ppl have measured temp since mid-19th century. Rock composition & other sources show us the temp of earth over its entire 4.5 billion yr history. We have a lot of temp data. -Temperature anomalies are typically used because temp varies from spot to spot, so it is more useful to know when spots' temps deviates from their own averages. -Dessler's 2.2 figures show that the global average temp anomalies have increase and that temp anomalies have increased in the Arctic (warmed more than other 2 prob due to ocean and atmosphere currents), tropics, and Antarctic. -satellite collected temps also show warming. 2) Ice Melt. - if the warming trend identified in the surface thermometer and satellite records is correct, then we should expect to observe the Earth's ice disappearing and we do. -glaciers: Of the 144 monitored between 1900 and 1980, 2 advanced and 142 retreated. Cloudiness or precipitation can't account for the GLOBAL length changes we see, so it must be temp. -sea ice: In the Arctic we see reductions in the area covered by sea ice during the summer, the ice has also gotten thinner. In the Antarctic we have seen minimal losses, but that is in line with the global distribution of the warming. -ice sheets: Greenland's ice sheet also greatly shrinking. 3) ocean temps -Temperature anomalies below the ocean's surface are also increasing. 4) sea levels are rising and at an increasing rate -water expands when its warm and ice melt adds water Precipitation. -global average sea level has risen by about 7-8 inches since 1900 5) Other corroborating evidence includes decreased northern hemisphere snow cover, thawing of Arctic permafrost, strengthening of mid-latitude westerly winds, fewer extreme cold events and more extreme hot events, increased extreme precipitation events, shorter winter ice seasons on lakes, and thousands of observed biological and ecological changes that are consistent with warming (e.g., poleward expansion of species ranges and earlier spring f lowering and insect emergence). Nights warming more than days, troposphere warming, stratosphere cooling Glacier loss, more precip + drier soil/drought 6) Experts say so 97% of climate experts think humans are changing global temps No other obvious external forcing that can account for the observed changes.

Radiation Laws

1. All objects emit radiant energy 2. Hotter objects radiate more total energy per unit than colder objects The amount of energy radiated is proportional to the temperature of the object raised to the 4thpower. (Stefan-Boltzmann Law) 3. The hotter the radiating body the shorter the wavelength of maximum radiation This is Wein's law. 4. Objects that are good absorbers of radiation are good emitters as well

Joseph Fourier

1820s intuition about Earth radiation and greenhouse action of atmosphere Because energy is always falling on the Earth from the Sun, why doesn't the Earth heat up until it is the same temperature as the Sun? The answer he determined is that the Earth is losing energy at a rate equal to the rate at which it is receiving energy from the Sun - otherwise, the Earth would indeed be continuously heating up Fourier hypothesized that this Earth radiation is an invisible emissions of radiation. atmosphere like a box with glass top

Svante Arrhenius

1896 study of how changes in the amount of CO2 may affect climate.

Charles Keeling

1958 First to begin measuring CO2 on top of Mauna Loa volcano. first to propose an anthropological contribution to greenhouse effect, raise alarm

Mesosphere

3rd layer of the atmosphere. Above stratosphere and below thermosphere. No greenhouse gases, coldest part of the atmosphere. Temp decreases as elevation increases.

Greenhouse gas

A gas that absorbs IR radiation emitted from Earth's surface.

Temperature

A measure of the average KE of molecules in a body is temperature (average speed of molecules). Temp is not heat, heat is the transfer of energy (heat always goes from hot to cold). Heat is determined by temp and amount of substance. Kelvin is proportional to internal energy