Midterm #2 Flashcards
Units used to measure incoming solar radiation
W/m^2
What energy is not included when calculating energy in (Ein) for the energy budget
energy reflected by the earth’s albedo
The Solar Constant
the intensity of the sunlight at the distance of the planet’s orbit
Average solar constant: S = 1360 W/m^2
Ein Formula
Ein = S(1-a)/4 where S is the solar constant and a is the earth’s albedo
Eout Formula
σT^4 where T is temperature
What causes changes to the earth’s albedo
- land use changes
- ice cap, ice sheet, and glacier melt
- sea level rise
- volcanoes
What causes changes to the Solar Constant
- sunspots
- solar flares
- sudden changes that affect the earth’s orbit
What causes changes to greenhouse gas emissions?
- deforestation/wildfires
- burning of fossil fuels
- volcanic eruptions
- chemical weathering
Gigaton
One billion metric tons; one metric ton = 1,000kg OR 2,200 lbs
1 part per million (ppm) of atmospheric CO2 in Carbon
2 Gigatons of Carbon
Parts Per Million (ppm)
A measure of the concentration of something
How to convert from Carbon Dioxide (CO2) units to Carbon (C) units
Divide by 3.67
because the atomic weight of CO2 is 3.62 times the atomic weight of carbon
What does the overall trend of the Keeling Curve show us?
CO2 in the atmosphere has been increasing (shown by consistent measurements since the 1950s)
What causes the “sawtooth” cycle/annual variance in CO2 levels on the Keeling Curve
Photosynthesis in the Northern Hemisphere and the fluctuations in photosynthesis due to the seasonal cycle
Only the Northern Hemisphere because there’s more land and vegetation in the Northern Hemisphere
Atmosphere and Biosphere exchange
Respiration and Photosynthesis transfer CO2 in and out of the atmosphere at a generally 1 to 1 ratio but it varies throughout the year (causes the sawtooth trend on the Keeling Curve)
Atmosphere and Ocean Exchange
Ocean Acidification through the absorption of atmospheric CO2 into the ocean
Atmosphere and Lithosphere Exchange
Volcanoes release CO2 from the rocks directly into the atmosphere
Chemical weathering deposits the CO2 in the atmosphere back into the rocks, this is through acid rain taking CO2 out of the atmosphere and breaking down rocks through weathering and eventually depositing the broken down rock and initial CO2 back into the rock layer.
Used to be at a 1-1 ratio BUT more recently has been a slightly uneven ratio with CO2 returning to the rocks quicker than it is released but this is a very very slow process
Aerosols effect on the energy budget
Aerosols have a cooling effect because they increase the albedo of the clouds
Climate Forcings
Drive/Initiate climate change
Are themselves unaffected by the climate
Climate Feedbacks
Responses to changes in the Earth’s surface temperature
Climate Sensitivity
The temperature change that occurs as a result of a climate forcing and the associated feedbacks
Determined by calculating the temperature increase caused by a doubling of atmospheric CO2
Radiative Forcing + Feedback
About 3 C for us now
Fast Feedbacks
- water vapor feedback (+)
- ice albedo feedback (+)
- high clouds (+)
- low clouds (-)
Committed Warming
How much warming we have already committed to within how much CO2 has already been released into the atmosphere
Currently 0.5 C
Climate Simulation
A model-based representation of the temporal behavior of the climate system under external forcing and boundary conditions
The result of these simulations are the modeled response to the imposed forcing & variability
Climate Projection
A climate simulation that extends into the future based on a scenario of future external forcing
What factors control future emissions
human activities:
- population growth
- land use change
- GDP (production + consumption = more emissions)
- agricultural practices
IPAT Relation / Kaya Identity
Equation to determine total emissions
Equation to determine total emissions
I = P x A x T
I = total emissions of greenhouse gasses into the atmosphere P = population A = affluence T = greenhouse gas intensity
The greenhouse-gas intensity term T equation
T = EI x CI
EI = energy intensity CI = carbon intensity
Energy Intensity
the number of joules of energy it takes to generate one $ of goods and service
Carbon Intensity
the amount of greenhouse gas per joule of
energy generated
Stefan-Boltzmann equation (what is it not the equation itself)
Total power radiated by a
blackbody
Stefan-Boltzmann equation
P/a (or Eout)= σT4
P = power a = area (in m2) σ= 5.67x 10-8 W/m2 /K4 T = temperature in Kelvin (K). where K = C + 273.15
Simple Climate Model
Simplifies all of the effects of the atmosphere concentrated in a single layer
Adding a second layer of atmosphere increases a planet’s surface temperature which continues for every additional layer
The layers represent the amount of greenhouse gasses in the atmosphere
Top ocean layer transfer with atmosphere
The top 100m of the ocean is the mixed layer and it exchanges carbon rapidly with the atmosphere
Deep ocean exchange
The deep ocean contains most of the carbon in the ocean, exchanges carbon with the mixed layer in a process called the biological carbon pump
Why is the combustion of Fossil Fuels so significant
Fossil Fuels would have origionally returned to the atmospere over billions of years but is now returning to the atmosphere rapidly
What determines the speed of warming caused by energy imbalance in the earth’s energy balance
Initially is set by the heating of the ocean’s mixed layer which heats very quickly so the warming would occur very quickly, then it would slow down as the warming would have to occur in the deep ocean which takes much more energy
It will take millennia to reach equilibrium
How long does the planet warm from energy imbalance?
The planet warms until Eout balances for the planet as a whole AND for each individual component of the climate system (biosphere, lithosphere, ocean)
Ice-Albedo Feedback
Positive
A warming planet causes ice to melt which lowers the albedo of the planet and induces more warming
Water-Vapor Feedback
Positive
A warming planet holds more atmospheric water vapor which is a greenhouse gas which then causes more warming
Cloud Feedbacks
Positive and negative
Positive: Absorbs Eout
Negative: Reflects sunlight (reduces Ein)
ENSO (El Nino/Southern Oscillation)
Large scale shifts of rainfall and temperature patterns across the globe
Shared Socioeconomic Pathways
Predictions of the future (including politics and emissions) depending on a variety of changing factors and future possibilities
SSP 1 Sustainability
Gradual shift to environmentally friendly practices, economic equality across countries, slow population growth, shift to renewable energy
SSP 2 Middle of the Road
Similar to historical patterns
SSP 3 Regional Rivalry
Rich get richer poor do not, increased conflict; Nationalism is strong, population growth is down in rich and up in poor countries, consumption is resource-intensive & development is slow; heavy reliance on high-carbon fuels
SSP 4 Inequality
World is divided, rapid technological and energy development
SSP 5 Fossil Fueled Development
Similar to SSP 1 but instead of a shift to renewable energy and environmentally friendly practices the world stays reliant on fossil fuels
Warming for the next century
Regardless of what path is taken, warming remains relatively similar up until 2040-50ish
Why is predicting Climate different from predicting Weather
Weather predictions are exact while Climate predictions are predicting the statistics of the weather over time periods of years
How does the albedo affect the temperature of the planet?
Lower albedo = Higher Temperature
Higher albedo = Lower Temperature
Why? Higher Albedo = more energy reflected away from the planet
Net Radiative Forcing Since 1750
2.5 W/m^2
