Climate change Flashcards
What is the definition of climate?
Definition of climate: statistics of weather over long periods of time
What are the natural drivers of climate?
1,000-100,000 years:
Earth-orbital change result from variations in Earth’s orbit around the sun. These orbital changes alter the amount of solar radiation received on Earth by season
1000,000 years: Tectonic processes generated by Earth’s internal heat affect its surface by processes that alter the basic geography of the Earth’s surface
10-100 years:
Inherent (random) atmospheric variability
Inherent or forced changes in ocean dynamics
Variability in volcanic aerosols
Solar variability
What is the most common natural driver of climate change?
Changes in the strength of the sun (e.g. sun spot cycles) affect the amount of solar radiation arriving on Earth
What is a solar cycle?
11 year cycle during which the sun undergoes changes in its activity and appearance
What happens during a solar cycle?
Levels of solar radiation go up and down
There are changes in the amount of material the sun ejects into space
Changes in the amount of sunspots and solar flares
Energy output changes by up to 0.15% over the course of a cycle
What does the evidence on solar cycles so far suggest?
Current warming NOT caused by changes in solar activity
So far no evidence to suggest the solar cycle influences surface temperature, rainfall or wind patterns
Why is the response of a climate to forcing complex?
Response of a climate to forcing is complex because of the interplay between components that make up our climate system
What components make up our climate system?
Atmosphere
Vegetation
Ice
Ocean
Land surface
What are the external forcing’s (causes) internal responses (climate variations)?
External forcing’s-
Changes in plate tectonics
Changes in Earth’s orbit
Changes in Sun’s strength
Internal responses-
Changes in atmosphere
Changes in ice
Changes in vegetation
Changes in ocean
Changes in land surface
How does the Earth’s climate system components respond to a driving factor?
Characteristic response time: a measure of the rate at which the system approaches equilibrium
What are rates of forcing versus responses?
Fast response times to permit the climate system to fully track slow forcing
Slow response times allow little climate change to fast changes in forcing
Roughly equal times scales of forcing and response allow varying degrees of response of the climate system to forcing
What are the typical fast responses?
Atmosphere- Daily heating and cooling, gradual buildup of heat wave
Land surface- Daily heating of upper ground surface, midwinter freezing and thawing
Sea ice- Late winter maximum extent
What are the typical slow responses?
Mountain glaciers- Widespread glacier retreat in 20th century
Deep ocean- Time to replace world’s deep water
Ice sheets- Advances/retreats of ice sheet margins
Growth/decay of entire ice sheet
What can we learn from Paleoclimate reconstructions?
Understand natural climate change
Longer-term evolution, forcings, response times and feedbacks of various components of the climate system
Validation for climate models
