Ep final
What are the four stages seen in the temperature anomaly measurements after 1750 to present?
1-Steady (1850-1910) 2-Rising (1910-1945) 3-Steady (1945-1975) 4-Sharp rise (1975-2000)
What is the approximate duration of the interglacial phase in a glaciation cycle (ice-age)?
100,000 years
stage1 seen in the temperature anomaly measurements after 1750 is steady. What years
1850-1910
stage2 seen in the temperature anomaly measurements after 1750 is rising. What years
1910-1945
stage3 seen in the temperature anomaly measurements after 1750 is steady. What years
1945-1975
If humans stopped dumping carbon-dioxide into the atmosphere "today" what fraction of anthropogenic carbon will still be there in the atmosphere after thousand years? (Fig 13.12)
25%
By how much (in %) has the atmospheric carbon-dioxide concentration increased from its pre-industrial value?
42%
What is the meaning of the term Climate Forcing? When is it positive and when is it negative?
A climate forcing or radiative forcing is any factor that upsets Earth's Energy Balance. A positive forcing results in warming, A negative forcing results in cooling
What is more important. Temperature nomalities or absolute temperature? And why
Abnormality. Because large areas average temperatures correlate and absolute temperature does not
Is global warming uniform all over the world? If not, where is it prominent?
Actual warming is distributed unevenly. **Note the greater warming over land, in the northern hemisphere, and especially at high latitudes.
What are Aerosols?
Aerosols are fine particulate matter suspended in tiny liquid droplets
Determine the sign of the radiative forcing for the following situations? a. Increase / decrease in sun's luminosity,
An increase of 5 W/m2 in solar input is a forcing of + 5 W/m2 .
What is the typical atmospheric lifetime of an individual carbon-dioxide molecule?
An individual carbon-dioxide molecule has a mean atmospheric life of only about 5 years.
What is the Urban Heat Island Effect?
An urban heat island (UHI) is a city or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities.
What is the meaning of the term anthropogenic forcing?
Anthropogenic Forcing is forcing due to humans instead of natural factors
How has the atmospheric carbon content changed from the preindustrial times? At what rate is the atmospheric carbon content increasing?
Atmospheric concentration of Carbon-dioxide is increasing drastically with time. Before AD 1750 : 275 ppm "Today" (AD 2000) : 390 ppm [ 42% increase ]
What causes the Stratospheric Ozone Depletion?
CFCs (Freon) rising to the stratosphere are photo decomposed by solar UV rays to release chlorine. The free chlorine destroys ozone
What is climate sensitivity?
Climate system's response to a forcing is characterized in terms of Climate Sensitivity. Climate Sensitivity describes the climatic change that results from forcing.
Why does Table 13.1 list atmospheric life time of carbon-dioxide as 1000 years? (Figure 13.12)
Collectivly they live longer
Look at the Greenhouse Term in Equation 12.3 and answer the following questions a. Under what conditions will there be no greenhouse effect? b. For a given concentration of greenhouse gases (fixed ea) which will enhance the greenhouse warming - a cooler atmosphere or a warmer atmosphere?
Cooler atmospheric temperature implies stronger greenhouse effect.
Was younger dryas event aa warming event or a cooling event?
Cooling
Which is the dominant factor contributing to Venus's huge surface temperature - its proximity to the Sun or the greenhouse effect?
Greenhouse effect.
What causes the urban heat island effect?
Human factors
What trend is observed in the ocean heat content since the mid twentieth century?
Increase in ocean heat content since the early 1990s In units of 10^22 joules Relative to an arbitrary zero The increase results from excess energy trapped by anthropogenic greenhouse gases and other forcing agents Imbalance between earths incoming and outgoing energy flows
f carbon-dioxide has the lowest global warming potential among the greenhouse gases why is it a problem? (Hint: long term fate of carbon-dioxide).
Individual molocules are not too bad and die off quickly, but But collectively Carbon-dioxide has an extremely long atmospheric lifetime. Atmospheric concentration of Carbon-dioxide (390 ppm) is overwhelmingly larger than the other gases. ~ 217 times higher than methane (1800 ppb), ~ 2 million times higher than HFC (190 ppt).
How much of carbon is there in Earth's atmosphere, in land and in oceans?
Land: 2000 GT + 500 GT Oceans: 39, 000 GT
What willhappen to the albedo of the planet in the following situations? : a. Large scale glaciation / de-glaciation of Earth's surface, b. Increased cloud cover of low altitude clouds/ high altitude clouds?
Low lying clouds lead to warming whereas high altitude clouds lead to cooling
Why is the ozone hole found only in the polar region?
Low temperatures allow formation of low polar stratospheric clouds, Clouds provide a reaction base that accelerates ozone destruction
What are Microwave Sounding Units (MSUs)? What trend is observed in the MSU analysis of the temperature anomalies of lower troposphere and lower stratosphere?
Microwave sounding units are a more consistent approach to air temperatures that come from satellite instruments that measure atmospheric microwave emissions The lower troposphere and the lower stratosphere behave oppositely Enhanced warming in the lower troposphere relative to the surface.
Examples of positive feedback cycles and negative feedback cycles.
Negative Feedback cycle tends to reduce the magnitude of a change in a system and puts the system back into its original state. Examples : Carbon-dioxide - Plant Growth Feedback. Atmospheric Temperature - Cloud Cover Feedback Positive Feedback cycle tends to exacerbate initial changes in the system and takes the system away to a new equilibrium state. Examples : Water vapor - Atmospheric Temperature Feedback. Ice Cover - Albedo Feedback
By how much (on an average) has the Earth's surface temperature increased in the past century?
On average there is a recorded 0.5C increase over the 20th century
What causes the cycles of glaciations?
Periodic changes in the earths orbit and the tilt of its axis
How does the rate at which carbon is released to the atmosphere, through fossil fuel burning, compare with the rate at which carbon is removed from the atmosphere by photosynthesis?
Photosynthesis : 110 GT / Yr Fossil Fuel Burning : 9 GT/Yr
What is the Zero Dimensional Energy Balance Model and how does its prediction about Earth's radiative equilibrium temperature compare with the observed value?
Predicted average temperature for Earth. It is 4.14X10^9K^4. Observed value is T=255K(-18degrees Celcious)
What is zero dimensional energy
Predicts the average temperature of the earth
What are the indicators for the global climate change other than the temperature?
Reduction of snow and ice cover Species range shifts Increased temperatures mean more energy available to power tropical storms. Increased precipitation Sea-level rise due to thermal expansion and melting land ice
stage4 seen in the temperature anomaly measurements after 1750 is what. And what years What years
Sharp rising. 1976-2000
Why the fluctuations in the orbital parameters alone cannot explain the severity of climate variations seen during the glaciation cycles?
Temperature and atmospheric CO2 have a very tight correlation. Feedback mechanisms also enforce the correlation
Why are temperature anomalies more important than the absolute value of temperature?
Temperature anomalies are more important than the absolute value of temperature because Temperature changes are well correlated over large distances, but absolute temperatures are not Two thermometers might not agree on a certain temperature but they will give the same response to a change in temperature. The temperature anomalies are all relative to some average.
What does the zero dimensional energy balance predict?
The average equilibrium temperature
What is the range of the best estimate of Earth's climate sensitivity?
The best estimate of Earth's equilibrium climate sensitivity is in the range of 2oC to 4.5oC.
What are the major greenhouse gases present in Earth's atmosphere and which of these gases has the dominant contribution to the greenhouse effect?
The most abundant greenhouse gases in earth's atmosphere in order 1-Water Vapor 2-Carbon Dioxide 3-Methane 4-Nitrous Oxide 5-Ozone Chlorofluorocarbons
Which is the most dominant among the anthropogenic forcings?
The most dominant among anthropogenic forces ia HFC-23 (CHF3)
Why is carbon-dioxide more dangerous than the other strong greenhouse gases?
The reason CO2 is more dangerous than other strong greenhouse gases is the collective lifetime. After 50 years we have 50%of the original left After 1000 years we have 25% of the original left Atmospheric concentration of CO2 is also larger than other gases
What are the two models that were employed to understand the greenhouse effect? Take a good look at the Simple Two Box Model illustrated in Figure 12.3. Understand Equation 12.3 (Page 328) and identify the radiation term and the greenhouse term.
The two models used to understand the greenhouse effect is the Two Box Model and the Blanket Model Blanket Model More effective insulation (or lower k) requires a higher temperature to achieve the same loss rate, Temperature rises with increased insulation Two Box Model Shows the power radiated to space as the concentration of atmospheric greenhouse gases rise, so can surface temperature
Understand the idea of Radiative energy balance and Radiative Equilibrium.
Thermal equilibrium is achieved when the concentration of thermal energy is uniform throughout the system.
What is the net effect of anthropogenic aerosols on climate forcing? Do the aerosols lead to positive forcing or negative forcing? What is the main source of sulfate aerosols?
They produce a negative forcing of about .5W/m^2 Cannot compensate the positive forcings of greenhouse gases because they are neither dominant nor will stay for long in the atmosphere
Which of the inner planets has the highest greenhouse effect warming and which one has the lowest?
Venus has highest. Mars has lowest
Which of the inner planets has the highest albedo and which has the lowest albedo?
Venus-highest. Mars-lowest
What are the problems in defining a global average temperature?
We only have data from around 1850 and moving forward Heat is distributed unevenly across the world Early measurements were not standardized and did not have corrections implemented for variable changes
What is the meaning of the term albedo?
fraction of solar power that is reflected back to space by the clouds, surface etc.
What is greenhouse effect?
greenhouse effect simply refers to the warming effect of the atmosphere.
What is the Global Warming Potential (GWP) of greenhouse gases?
is the effect of a greenhouse gas relative to carbon dioxide. Depends on the strength of absorption and the atmospheric lifetime. Actual warming depends on the amount of gas present.
Was this a global event or a local event?
local, exaggerated in Greenland. Concentrates in higher latitudes of the northern hemisphere
What is the Younger Dryas Event? And what causes it
rapid nonlinear cooling related to changes in ocean circulation
What are the various anthropogenic greenhouse gases?
the various anthropogenic greenhouse gases Carbon Dioxide CO2 GWP- 1 Methane CH4 GWP- 67 Nitrous Oxide N2O GWP-291 CFC-11 (CCI3F) GWP- 6700 HCFC-22 (CHCIF2) GWP- 5200 HFC-23 (CHF3)GWP-12000
What are interglacials?
the warm, relatively short periods between ice ages
Why does the zero dimensional energy balance model fail to predict the correct equilibrium temperature for Earth and Venus?
zero-dimensional energy balance model doesn't take the warming effect of Earth's atmosphere into account!
