test 3: science of climate change
What are model scenarios? Why are they used? What was the IPCC's strategy for model scenarios in AR5?
model scenarios are Educated guesses for initial conditions. you build scenarios around a set of Guesses. Most models list results with a variety of scenarios to provide a range of outcomes. The IPCC's strategy build scenarios for total anthropogenic radiative forcings -2.6, 4.5, 6.5. 8.5 w/m2
Describe how a Coupled General Circulation Model works.
page 3 of handout with graphs. A keynote for the exam is cgcms can model weather but a smaller grid is needed, short and local.
Explain what factors stabilize climate.
A model can evaluate an equilibrium level that indicates what will happen to the climate after an extended period Of time stabilizing climate. A Transient level is also helpful in determining what can stabilize climate.
Why do the atmospheric oxygen measurements disprove an oceanic or volcanic source for the increase in atmospheric CO2?
Because only CO2 emissions from fossil fuel combustion should be accompanied by a drop in atmospheric O2 as part of the combustion reaction. This drop would not accompany volcanic or oceanic emissions
Explain the impacts of heat due to climate change.
Both 1 & 2 above cause stress to all living things, posing higher risks to the elderly, mentally ill, children, and the poor. It becomes an issue for livestock due to droughts and lack of food/water for them. Change in transportation and power distribution (a/c will be used in heavier quantities). Ecosystems will have a hard time adjusting to warmer temperatures and will degrade. Crops will be negatively affected due to change in temperature preferences and droughts.
Explain how isotopes help us identify human activities as the reason atmospheric carbon dioxide is increasing.
Carbon from the biosphere has low amounts of carbon-13, but (relatively) large amounts of carbon-14. Carbon from a volcano has large amount of carbon-13 and low amounts of carbon-14. Carbon from fossil fuels has has low amounts of carbon 13, and low amounts of carbon-14. Analysis of the carbon added to the atmosphere shows that its isotopic composition matches fossil fuels.
Explain why fossil fuels are depleted of carbon-14. Explain how burning fossil fuels alters the fraction of carbon-14 in the atmosphere.
Carbon-14 is a naturally occurring, radioactive form of carbon, and it decays over thousands of years. ... Because they're so ancient, coal and oil no longer contain any carbon-14, so when emissions from fossil fuel combustion enter the atmosphere, nonradioactive carbon floods the mix
What is a radiative forcing? What is the difference between a positive forcing and a negative forcing? What are the main positive and negative forcings on our planet? What is the sign of the net forcing?
Cause planet so warm up or cool down changes the balance energy flow on the planet. A positive forcing tends to make the Earth warmer. A negative forcing offset the positive factors and contribute a cooling effect. Main positive forcings is carbon dioxide at 1.7W / M squared, 1.3 W / m squared (all other greenhouse gases) The Main negative forcings are aerosols and particulates. Net forcing is, with respect to 1750, 2.3w/m squared. Energy in is greater than energy leaving the Earth. Differences by 0.5 m/w squared.
Explain climate lag. What processes change quickly when Earth's temperature changes? What processes change slowly?
Climate lag is not an instantaneous change in temperature. This is primarily due to deep oceans and ice sheets. It will take several centuries for the deep ocean to warm up and for the entire climate system to come to equilibrium
Describe the differences in predicting weather and predicting climate.
Climate models are used to predict the consequences of greenhouse gases added to the atmosphere. It enables us to understand the what ifs. predicting weather Is not possible beyond a few days.
What is climate sensitivity? How can it be determined?
Climate sensitivity tells us how much the temperature of the planet will need to change to restore its energy balance. Two approaches to determine it: 1) Computer models (calculations), and 2) Paleoproxy data, or the use of climate records to look for similar findings of temperature changes associated with it
What is commitment? What causes it?
Commitment is when greenhouse gasses that have been put into the atmosphere have not yet caused all the warming they will cause. Since they have already been emitted, their effects are committed to cause further warming in the coming decades, centuries, or milenia. GHGs don't immediately cause warming due to climate lag.
Explain feedback speed. Give examples of fast and slow feedbacks.
Feedback speed is the time it takes for feedbacks to take into effect. Fast feedbacks are somewhere between immediate and a few years. → ice albedo, water vapor & clouds, changes to the carbon cycle in the atmosphere and biosphere or atmosphere and ocean Slow feedbacks can take thousands of years to take effect → ice sheet contributions to the ice albedo effect, permafrost, clathrate melt, and chemical weathering
Explain three major effects that climate change has on oceans.
Ice loss: As the globe warms, the world's glaciers and ice sheets are sure to melt and contribute to rising sea levels. Sea-level rise: melting ice caps will cause a higher volume of oceans in the future, meaning that future generations will have to commit to living in a world with much higher seas. Ocean acidification: more emissions of carbon dioxide in the atmosphere will find their way into rainfall and oceans. Carbon dioxide becomes carbonic acid when reacting with water. The ocean will become more acidic as it absorbs more carbon dioxide.
Explain how population, affluence, and technology influence total greenhouse gas emissions.
Overall, Population and affluence is increasing while technology is decreasing. Environmental impacts of population: increased land use, increased resource use, increased pollution and climate change Environmental impacts of affluence: Increased consumption increases human environmental impact Environmental impacts of technology: efficiency in technology can decrease environmental impacts. However, since population (P) and affluence (A) impacts are increasing, technology (T) efficiency has no made significant change to the overall environmental impact (I).
Be able to recognize statements from Parts 1 and 2 from the IPCC's AR5 Summary for Policymakers.
See handout on IPCC
Explain how climate changes in temperature and precipitation affect land.
Temperature Hotter days Record setting for hottest days in history will be the norm Heat waves will be more frequent Hotter evenings Less cooling off at night due to thick atmosphere (GHGs), making it retain more heat Night time low temperatures will rise more than day time highs Precipitation Super charged water cycle Warmer atmosphere & ocean will accelerate evaporation More precipitation & potential for severe precipitation events Wet areas get wetter & dry aras become dryer Higher risk of flooding and drought More rain, less snow More irregular precipitation but also more intense
Explain the two functions of climate modeling.
To understand our climate system We use past data to predict the present If successful, we can have confidence in our understanding of the climate and the ability to predict future climate To predict consequences of future climate change We use current data and future assumptions about future actions to predict the climate's future response. Example: I = PAT is the mathematical notation of a formula put forward to describe the impact of human activity on the environment
Explain how we know that the depleted carbon-14 entering the atmosphere comes from fossil fuel combustion and not volcanic activity.
While CO2 emitted from volcanoes is 14C depleted as we observe in atmospheric CO2, the sheer volume of CO2 into the atmosphere would require enormous volcanic activity that we just don't see. While there could be sub-marine volcanoes, the fact that we also observe a decrease in atmospheric O2 that is consistent with fossil fuel combustion points towards away from volcanoes as an answer.
What is a feedback? Differentiate between a positive and a negative feedback. Give examples of each.
a feedback is a process that influences other processes, which can influence original processes. Positive feedback amplifies the original process (snowball effect). → Examples: Less snow = less reflectiveness = more absorption of energy = warmer planet = less snow More evaporation with increased temperatures = more water in atmosphere as a GHG = atmosphere warms up more Decaying of plants release carbon into the atmosphere = increase of carbon dioxide concentrations and temperature Increase in ocean temperature = less carbon dioxide absorbed by oceans Negative feedback dampens the original process. → Examples: More clouds from evaporation = albedo effect increases (reflectiveness) = solar energy decreases warming As temperature increases and concentrations of carbon dioxide increase, plants grow better, which = plants remove carbon dioxide from the atmosphere More carbon dioxide in the atmosphere = more carbon dioxide absorbed by oceans
Describe the impacts of precipitation due to climate change.
in the U.S., there will be a shift of water resources While precipitation increases, climate patterns will shift In west, much of the water supply is based on snow melt. Less snow precipitation will decrease access to freshwater.
