Chapter 10: Future Projections and Extremes of Climate
What is moist enthalpy?
A combination of temperature and moisture. It has been increasing in recent decades.
How does a general circulation model work?
A map of Earth is fragmented into gridded spatial coordinates resulting in a three-dimensional representation of the climate system. ECV variables are computer at each grid point and predicted into the future.
What has the melting of the west antarctic ice sheet caused?
A raise in sea-level worldwide and an alteration to the albedo and other feedbacks at the South Pole, dramatically altering the climactic character regionally and globally
What are thunderstorms?
A result of vigorous convection that extends high into the troposphere, sometimes reaching the tropopause or even higher. Consists of one more more convective cells.
What is parametrization?
A technique of using estimates for small processes on a larger scale modeling
What is the chaos theory?
A theory that says that changes in systems are highly sensitive to the conditions of their initial state so small difference in their initial conditions can lead to vastly different outcomes over long periods of time (butterfly effect)
What is a general circulation model?
A type of climate model, that consists of equations that describe the physical interactions among the various components of the climate system; simulates the circulation of the atmosphere, plus numerous processes that control energy transference and exchange
What is a tornado?
A violent rotating column of air in contact with the ground, usually associated with a thunderstorm
What is a time step?
An interval between one set of solutions and the next, and is a function of the grid spacing utilized in the GCMs
What is the Atlantic Multidecadal Oscillation?
An ongoing series of long-duration changes in the SSTs of the North Atlantic Ocean, with cool and warm phases that may last for 20 to 40 years
What are models?
Approximate representation or simulation of a real system, incorporating only the essential features, or variables, of a system while omitting details considered non-essential or non-predictable.
Why is modeling climate difficult?
Because of different spatial scales, feedbacks, and no single equation that explains the behavior of all interacting parts
What is the atmospheric lifetime of CH4 and what would an emission reduction of less than 30% do?
CH4 has a lifetime of only 12 years, allowing a reduction by less than 30% to stabilize its atmospheric concentration within a few decades
What are the 4 categories of models?
Conceptual, graphical, physical or numerical
When do half of all tornados usually develop?
During the warmest hours of the day
What are the two dominant factors in determining frequency and intensity of winter storms in the U.S?
ENSO and NAO
What is precipitation mostly associated with?
Extratropical cyclones, tropical cyclones, and thunderstorms
If greenhouse gas emissions were to stabilize at present levels, what would happen?
Global warming would likely continue well beyond the 21st century
What is needed in order for a hurricane to form?
High SSTs, adequate Coriolis Effect, and weak winds aloft
How do hurricanes move?
Hurricanes that form over the Atlantic Ocean near the Cape Verde Islands usually drift slowly westward with the trade winds across the tropical North Atlantic and into the Caribbean. Many hurricanes drive northward from the Caribbean . After moving northward, about 30 °N, an Atlantic hurricane may begin to transition into an extratropical cyclone.
What do GCMs indicate about climate in the near term?
If all other boundary conditions remain fixed, rising concentrations of CO2 and other greenhouse gases would cause global warming to persists throughout this century and well beyond
What happens if CO2 is stabilized at current levels?
If stabilized at current levels, CO2 concentration would continue to increase beyond this century. Only complete elimination of anthropogenic CO2 emissions would stabilize at current levels.
Where do tornados mostly occur in the U.S?
In Central U.S
When is a hurricane categorized as such?
Initially, it is just a cluster of thunderstorm clouds over tropical seas. If a center of low pressure is detected at surface and cyclonic circulation develops, then it is considered a tropical disturbance. Once max winds reach 74 mph or higher, then it is designated as a hurricane.
When do 75% of tornados occur?
March-July
What is skill?
Measure of how greater the accuracy of a prediction is compared to the accuracy of some typically simple prediction (e.g., assuming that recent anomalies in climate will persist during the period predicted)
What is the atmospheric lifetime of CO2?
More than 50% of CO2 emitted into the atmosphere cycles out within a century but about 20% remains for millennia
What is the atmospheric lifetime of N2O and what would an emission reduction of more than 50% do?
N2O has a lifetime of 110 years so an emission reduction of more than 50% would stabilize its atmospheric concentration near present-day values
Are both climate and weather simulations the same and if not, what is the difference?
No, they are not. Climate prediction is a boundary value problem whereas weather forecasting is an initial value problem.
What is the best possible manner to simulate the entire climate system and test its limits and sensitivities to external forcings?
Numerical approximations
Global climate models
Simulations of Earth's climate system using mathematics
What do the models indicate with regard to tropical cyclones in a changed climate with warmer SSTs and increased atmospheric temperatures and humidity?
Slight increase in the greater intensity hurricanes but a slight decrease in the frequency of weaker hurricanes
What systems are too complex to be described by a formula and what can you use instead?
Some examples are the fluid atmosphere or ocean. In these cases, statistics approximates the behavior of the system on a computer
What are some predictions of monsoons?
That they are likely to become more intense, their circulations are likely to expand and monsoon seasons are likely to get longer as well.
What is the atmospheric lifetime?
The approximate amount of time it would take for the anthropogenic increment to an atmospheric pollutant concentration to return to its natural level as a result of either being converted to another chemical compound or being taken out of the atmosphere via a sink.
What is climate sensitivity?
The equalizing temperature change in response to changes in external forces of the boundary conditions of climate
What have several studies concluded about extreme precipitation events?
There is an increase in number and intensity of them. Overall trend in mean precipitation has also increased.
What does the IPCC project for the 21st century? (Droughts wise)
There will be a reduction in renewable surface water and groundwater resources in most dry subtropical regions. In regions that already have arid conditions, drought frequency will likely increase. And water resources will increase in high latitudes.
What are physical models?
They are a small-scale portrayal of a system
What do graphical models do?
They compile and display data in a format that readily conveys meaning
What do conceptual models do?
They explore linkages among physical and biological sub-systems
What are numerical models?
They have essentially replaced physical models in investigating the climate system
What are some strengths and weaknesses of models?
They simulate surface temperatures better than precipitation events but extreme climate events is another area of improvement
What are some similarities between weather and climate models?
They use similar math equations and have limitations on how far skill will remain useful.
What are hindcasts?
Using boundary conditions derived from proxy climate data sources, GCMs simulate climates that prevailed in the geologic past, such as the last glacial maximum
What is variability in tropical cyclones correlated to?
Variability in tropical cyclones is strongly correlated to variations in thermohaline circulation
When does hail develop?
When an ice pellet is transported vertically through a cumulonimbus cloud
What is coupling?
When various sub-systems of climate are modeled in parallel to another
What is a transient run?
a mode of running a global climate model (GCM) in which a period of time (typically 1850-2100) is simulated with continuously-varying concentrations of greenhouse gases so that the climate of the model represents a realistic mode of possible change in the real world
What is an equilibrium run?
a mode of running a global climate model (GCM) in which greenhouse gas concentrations are suddenly changed (typically from pre-industrial values to twice pre-industrial values) and the model is allowed to come into equilibrium with the new forcing.
What are climate tipping points?
a relatively small, specific change in one region of the world (e.g., Arctic sea ice loss), which causes a much larger change on a grander scale, from which it may be difficult to reverse
What is a drought?
a unique climatic phenomenon, relative to local conditions and varies greatly in time and space, including a lack of accessible water and based on the regional balance between evaporation and precipitation in determining the amount of soil moisture
What is tornado alley?
an area of the Great Plains centered on eastern Kansas and Oklahoma and including parts of the surrounding states, where tornadoes are frequent.
What is an ice storm?
an event that is associated with large swaths of freezing rain; can also cause major societal disruptions. (Less frequent than snowstorms)
What is a hurricane?
an intense tropical cyclone that originates over warm ocean waters, usually in late summer or early fall, when SSTs are highest, and has a maximum sustained wind speed of at least 119 km per hr (74 mph)
What do scientists run global climate models on?
supercomputers
What is hail?
frozen precipitation in the form of balls or lumps of ice more than 0.2 in. in diameter
