Phys 2450 Test 2 Study Guide
Topics Returning From Previous Exam:
Data sets that can be formed from daily temperature averages:
Depending on what data you examine – trends will be different.
Land data trends > ocean data trends
High latitude trends > low latitude trends
Winter data can have a lot of cold extremes and summer data will have hot extremes. Human Daily Calorie Consumption: about 2000 calories.
Black Body Spectrum Changes: as an object becomes hotter, it changes color from dark red to bright red, orange, yellow, white, and then bluewhite
When the sun is directly overhead, it is “in zenith,” 90 degrees to the surface.
Maps of daily mean insulation show how much on average the atmosphere “insulates” the Earth. They can be affected by orbital changes.
Methane has risen rapidly in the last few years due to human emissions, mostly from agriculture (livestock, rice paddies), and waste.
We can know that carbon dioxide levels are rising at an extremely rapid rate from measurements out of ice cores that give us information about carbon dioxide levels in the past (hundreds of millions of years) Don't forget about the age old question of Is non-violent and aggressive pornography the same?
*From Assignment 2:
Absorption Bands for CO2, H2O, CH4, and O3.
Distinction Between Infrared Emission and Absorption*
Use the Archer model to see the affects of orbital changes on the absorption bands.
Frequency = speed of light/wavelength. Frequency = 3.0 x 10^8/wavelength
Unit Conversion: 1 MHz = 1,000,000 Hz.
Multilayered Atmospheric Models
We also discuss several other topics like What are the personal and social consequences of alcohol use disorders?
You should know how to use the temperature formula for 1 layer, 2 later, and dusty atmospheres, to calculate the temperature of the surface.
Also know how to calculate the temperature by adding a layer. This would change the variable n, the number of layers in the equation.
Forcing is an imbalance of energy forced onto Earth’s climate system, which it must then adapt in response to.
Radiative Forcing Examples:
Aerosols (these stay in the atmosphere for a time and block out sunlight)
Volcanoes (these happen on rare occasions, but they release aerosols as well. Such aerosols from volcanoes and coal pollution are frequently tiny drops of sulfuric acid, which is highly reflective and so increases the Earth’s albedo, cooling it.)
Clouds (indirectly behaving as an aerosol)
Land use changes (which change the albedo)
Total solar irradiation changes
The total net forcing for the time between 1750 and 2017 is greater than 2.3 Watts/square meters.
We can estimate the total global warming trend by making the assumption that all radiative forcing will go into warming the ocean.
A feedback is a response in the Earth’s climate to changes in temperature, or “forcings.” Feedbacks may be positive and enhance the change, or negative and counter it. Don't forget about the age old question of What is a second order reaction?
Fast Feedbacks – Positive:
Fast Feedbacks Negative:
Total for fast feedbacks: g ranges from 0.4 to 0.7.
Carboncycle feedbacks We also discuss several other topics like How do you solve logarithmic differentiation?
Weathering thermostat (carbon dioxide removal)
Methane clathrates, or frozen methane in the oceans
Defining a Feedback Parameter g: Don't forget about the age old question of What is the formula to be used in ephoton?
The final change in temperature = (the initial change in temperature x 11) g Tfinal = Tinitial * 11 g
Total feedback parameter g ranges from 0.4 to 0.7.
Therefore: Tfinal = Tinitial * (1.6…3.3)
Climate sensitivity is the total amount by which the temperature changed for a certain type of forcing, with feedbacks taken into account for the calculation.
When CO2 amounts are doubled from 280 ppm to 560 ppm, the temperature changes and the climate sensitivity is about 2 to 4 Kelvin.
When an initial radiative forcing is applied, the temperature changes and the climate sensitivity is about 0.75 K.
Causes of Changes in Climate
It is growing steadily brighter, so it is warming the Earth slightly more than it used to. It has an 11yearlong sunspot cycle, which changes its brightness by a little bit. There are other sun cycles that we do not understand well yet.
The solar constant is pretty much constant, for all practical purposes, but it can have a little variance. We also discuss several other topics like What communication promotes coordination between organizational units?
Wobbles in the Earth’s Orbit:
The Earth rotates once every 24 hours
Its axis tilt changes every 41,000 years.
The orbit is an ellipse, not a circle, which means that at various times in the orbit cycle, Earth’s eccentricity, or orbit shape, and its orientation, or approach toward the Sun, are different. When the Earth is at its point of closest approach, that point is called the perihelion. These differences change how solar radiation is distributed around the Earth at different times of year. It is believed to be the cause behind ice ages, especially the 41,000 year ice age cycle. However, there are counterexamples to this trend. The last 4 ice ages happened with 100,000 years in between them.
Continental drift. The continents were not always arranged as they are, so they used to have different effects on the Earth’s temperature. Today, their effects are generally these:
The Northern Hemisphere – a lot of land masses: warms more quickly
The Southern Hemisphere – mostly ocean: warms more slowly as the ocean absorbs excess carbon dioxide
Antarctica – giant ice sheet that is very cold: cools the Earth.
Natural Internal Climate Variance:
The ocean temperature varies naturally over several decades.
Air pressure also varies over the same time frame.
El Nino and La Nina events which occur in the Pacific Ocean cause fluxes in the climate.
None of these forces are fast or strong enough to explain the rapid warming of recent years.
Greenhouse gases change the Earth’s temperature.
The paleorecord shows evidence that greenhouse gases are connected to global temperature.
70 million years ago, CO2 levels were higher, and temperatures were warmer.
CO2 is not always the cause of temperature increase. It was a feedback to warming in the ice ages. However, CO2 increase means an increase in all temperatures and feedbacks.
It is “extremely likely” that humans are responsible, says the IPCC (95% certain).
The greenhouse gas emissions for the whole world can be calculated by this equation The IPAT relation:
(Population in capita)(Affluence in $GDP/capita)(Technology to produce $GDP) I= PxAxT.
Technology = (Energy intensity in J/$GDP)(Carbon Intensity in kgCO2/J or TCO2/J).
Population and Affluence have been rising steadily over the past few years, while Technology has decreased slowly. With rising Affluence, energy demand will rise, while Population will fall, or is expected to fall.
Actions in Response to Climate Change
Energy does have a cost, but our efficiency is improving and we are now able to do more with less energy than in years past. Energy that does not require carbon is very effective at reducing overall emissions (I). Examples include the production of electricity with gas instead of coal, and the use of wind, solar, and nuclear power. Although potential solutions to the climate problem, each strategy has its own problems.
Climate change on the scale of a few decades instead of hundreds of thousands of years is abnormally fast and very bad. Humans are adapted to the present climate, and changing that would throw everything off. Yet, there are some good impacts of a warming climate (fewer cold waves, for example).
Effects of Climate Change
Temperature will rise
Precipitation will increase
BUT dry places will be more dry
Albedo will decrease as ice melts, increasing the amounts of heat absorbed by the earth Higher latitudes will warm faster because as the albedo in the north melts, they will warm faster Sea levels will rise
The oceans will continue to acidify
Weather extremes will occur: droughts, heat waves, heavy rains, floods, more intense storms and hurricanes.
Sudden Climate Change Damage
The climate on earth has been changing for thousands of years, very slowly, oscillating between warmer periods and cooler periods, but when it changes this rapidly, a system as complex as earth’s may break down and suffer permanent damage.
Rapid ice sheet disintegration: this occurred during and after the ice age with large and decadelong (fast) temperature changes.
In modern times, rapid and large carbon dioxide level rise means that it will take a long time for the climate to adjust and return to normal, due to its timelagged response.