Exam 5 Flashcards
Climate records w/ averages require
30 years of data
Climate determines what?
The species (plant/animal) communities in an area
Who keeps official climate records?
NOAA (National Oceanic and Atmospheric Administration)
What is the main source of climate data for the Western U.S.?
WRCC (Western Regional Climate Center)
Factors that control climate include…
Latitude, continentality, mountains
Climate Zone A
Tropics
Climate Zone B
Dry
Climate Zone C
Mild Mid Latitude
Climate Zone D
Severe Mid Latitude
Climate Zone E
Polar
Climate Zone H
Highland
Paleocene-Eocene Thermal Maximum (PETM)
global temps were app. 8C warmer than now, sea level was app. 100m higher than now (no ice caps)
Methods for measuring past climates
Ice caps, fossils, ocean cores
Pleistocene
2.6 million years ago, ice caps began to grow, oscillations between glacial and interglacial periods begins
Holocene
the last 12,000 years, warm, post LGM, modern humans and ecosystems developed
Last Glacial Maximum (LGM)
15-20 thousand years ago, global temps 5-7C colder, sea level much lower, ice sheets deflected jet stream
What are interglacial cycles controlled by?
orbit cycles: periodic and predictable changes in earth’s orbit with respect to the sun
Milankovitch cycles
eccentricity, obliquity, precession
Eccentricity
the shape of orbit- circular or elipse
Obliquity
the angle of earth’s tilt relative to its axis
Precession
the “wobble” changing the time of year each hemisphere faces the sun
Long time scale factors contributing to climate change are
changes in orbit, changes in arrangements of continents, major changes in ocean circulation, greenhouse gases/atmospheric chemistry changes
short time scale factors contributing to climate change are
volcanic eruptions, changes in land use, minor changes in ocean temps/circulation patterns (El Nino), greenhouse gas concentration changes
Volcanic eruptions
inject aerosols into the stratosphere, blocks sunlight to cause net cooling
Changes in ocean temp/circulation
reserve of energy that drives global weather systems
El Nino
temporary warming of sea surface temps in Eastern Tropical Pacific, colder, wetter winters in southern U.S., warmer in north
Where is the most rapid warming due to the GHG concentration rising?
the Arctic
Major impacts of rising GHG concentrations
rising temps, shifts in precipitation, rising sea level, stronger storms (more extreme warm and cold snaps), habitat changes
Projected temps by 2100
best scenario: 1.5 C warmer, worst scenario: 4.8 C
Warmer temps will cause
hotter summers/warmer winters, shrinking glaciers, upward/poleward expansion, sea level impacts, ocean acidification
Ocean acidification
increased CO2 concentration makes ocean water acidic, small shelled creatures are the base of the food chain and shells dissolve in acidic water
Precipitation
more water vapor, stronger storms, deserts expand
How much have humans warmed the earth compared to pre-industrial averages (1850-1900)?
+1.2 C
How much has the global mean sea level increase between 1901 and 2018?
0.2 m (20cm, 200mm)
What is the recent rate of sea level rise?
3.7mm/year
How far back do you have to go to find CO2 concentrations as high as they were as of 2019?
2 million years
What % of the heating of the climate system is accounted for by the warming of oceans?
90%
Contributors to sea level rise include
22%: ice loss from glaciers, 20%: ice loss from ice sheets, 8% changes in land water storage, 50% thermal expansion from warming oceans
SSP1- 1.9
Best case, emissions reach net zero by 2050
SSP1-2.6
good, emissions reach net zero by 2075
SSP2-4.5
intermediate emissions
SSP3-7.0
high emissions w/ some mitigation
SSP5-8.5
worst case scenario, business as usual w/ no mitigation
Under the worst scenario, what are global temps likely to be by 2100?
4.4 C warmer
Under the best scenario, what are global temps likely to be by 2100?
1.4 C warmer
If global temps increase by 4 C, rainfall will likely increase where?
the Arctic, Northern Africa, Middle East, Equatorial Pacific
Under the best scenario, what should sea level be by 2100?
0.6 m higher
Positive Feedbacks
amplifies climate change, change that causes more of that same change, potential runaway effect
Example of positive feedbacks
when a fruit ripens, it leads to other fruits that were exposed to it ripening too
Negative Feedbacks
change in some direction that causes other changes that ultimately slow the original direction of change, helps maintain equilibrium
Example of negative feedbacks
homeostasis, shivering to stay warm
Positive Feedbacks in Climate
ice albedo, ocean CO2, permafrost melts
Limiting GHGs
deployment of low emission energy sources, improve energy efficiency in buildings, reduce installation of fossil fuel infrastructure
GHG Sources
25%: electricity production, 24%: agriculture/land use, 21%: industry, 14%: transportation, 6%: buildings, 10%: other
