MODULE 3.2 Flashcards
study of the Earth’s climate before instrumental records were available.
Paleoclimate
The past ______________ years is far more stable than the previous ______________ years.
10,000; 400,000
warmest temperature of Planet Earth
Paleocene-Eocene Thermal Maximum (PETM)
coldest temperature of the Planet Earth
Last Glacial Maximum (LGM)
sits between the warmest and coldest temperature of the Earth
Younger Dryas
The 19th century is then characterized by_____________
rapid warming
Before the 19th century, the temperature was caused by _______________, proven by ________________.
natural variability; paleoclimate archives
During the 19th century, rapid warming is caused by ________________ and _________________.
human activities; instrumental records
These are what paleoclimate scientists use to study past climates, otherwise known as geologic archives. Examples include ice cores, tree rings, sediments, corals, cave deposits, and more.
Paleoclimate archives
physical, chemical, and biological materials preserved within paleoclimate archives that can be analyzed and correlated with climate or environmental parameters in the modern world
Paleoclimate proxies
These are examples of physical proxies
sediment composition, sediment texture, color, density, and magnetic properties
These are examples of chemical proxies
stable isotopes, elemental analyses, biomarkers, and Biogenic Silica
These are examples of biological proxies
charcoal and micro/macrofossils like Pollen, Foraminifera, Ostradoces, Diatoms, Dinocysts, and other Algae, Corals, and Mollusks
Direct measurements from instrumental and historical records have time limitations, specifically spanning ______________ and _______________ years respectively.
100, 1000
Historical records are often ____________________
qualitative and incomplete
____________________ allows scientists to reconstruct a more reliable, consistent story, and longer climate history.
Comparing multiple proxy sources against each other
This paleoclimate archive collects data from oxygen and carbon isotope from bottom dwelling deep sea foraminfera and reveals what climate looked like 70 million years ago.
Deep sea record
Most of the trends from the data are controlled by __________________ and reflect sudden input of _________________ from deep inside the Earth.
tectonic activity; hydrothermal fluids
Global temperatures reached a maximum at about ________________, after which cooling began.
55 million years ago
This cooling resulted from three main events:
- collision of India with Asia
- reduction in seafloor spreading rates
- rise of Andean Mountain
The first half of the Cenozoic likely saw _______________ polar regions.
ice-free
major drivers of climate on the scale of millions of years of change
Plate tectonics
Discuss the implications of fast seafloor spreading
Rapid CO2 input —> Warm greenhouse climate —> Increased chemical weathering —> Increased CO2 removal —> Reduced warming
Discuss the implications of slow seafloor spreading
Slow CO2 input —> Cold greenhouse climate —> Decreased chemical weathering —> Decreased CO2 removal —> Reduced cooling
The position of continents affects _________________ and _________________, which are the two conveyor belts responsible for _________________ from the equatorial regions and moving it to the polar regions.
ocean, atmospheric circulation; taking excess heat
This paleoclimate archive is layered annually, contain trapped air bubbles, which preserve atmospheric gases like CO2 and methane; tell us about the climate 400,000 years ago (though the last 10,000 years have been more stable)
Ice cores
Sometimes, these can be found in ice cores, which help to date the ice; from volcanic activity
Dark ash layers
This concept allows us to use modern relationships to infer past climate conditions.
Uniformitarianism
This caused changes in temperature when the snow fell.
Variations in the ratio of lighter and heavier isotopes of oxygen and hydrogen
Which is heavier: 16-O or 18-O? What are the implications of this?
18-O; Due to 16-O being lighter, it evaporates faster.
During colder times, there are more _______ than _______ because _________________.
18-O and 16-O; The evaporated 16-O gets stored in ice sheets on continents.
pioneer in the use of mass spectometry to determine changes in climate as recorded in the oxygen isotope composition of calcareous microfossils (Foraminifera)
N.J. Shackleton
The last magnetic field reversal was _________________
780,000 years ago
The Ice Ages have periods of about:
100,000; 40,000; 20,000
Shackleton along with ________ and _________ concluded that the periods of the Ice Ages correspond with Earth’s ________________
orbital pattern
The dominant, 100,000-year climatic comonent has an average period close to, and is in phase with, ______________.
orbital eccentricity
Eccentricity changes how close Earth is to the sun, affecting ____________________.
the amount of solar radiation the planet receives
During the Younger Dryas, temperatures in _________________ reached near-glacial conditions; _________________ experienced a 10 degree Celsius change
Northern Hemisphere; Greenland
The ___________________ carries warm water to the region around Iceland where cooling by cold Canadian air masses densifies the water, allowing it to sink to the bottom, forming a southward-moving water mass.
Great Ocean Conveyor
The flow of water (20 million cubic meters per second) is equal to the _____________________
amount of annual global rainfall
The heat released to the atmosphere keeps Northern Europe _________________ than it would be were the conveyor to shut down.
5 - 10 degrees Celsius warmer
Instrumental record since 1850 includes:
weather stations, weather balloons, aircrafts, and a variety of satellites
Period of regional cooling from the 1300s to the 1850s, particularly pronounced in the North Atlantic Region.
Little Ice Age
Under LIA, glaciers across ______________, ______________, and ______________ were more prominent. Temperatures ______________ in Spring and ______________ in Autumn.
Alaska, Europe, New Zealand; rose later, dropped sooner
Agricultural records show that growing seasons during LIA were __________________ than in the 20th century due to the extreme cooling period
15 to 20% shorter
Even an average temperature drop of just ________ can have a marked effect on agriculture.
0.5 degree Celsius
LIA was a time of more extremes in _____ prices. Using the price of this crop as an indicator shows that more frequent extreme weather leads to more frequent economic difficulty.
Rye
accounts for as much as 40% of the decadal-scale variance during the LIA
Volcanism
measure of stratopheric transparency to incoming solar radiation
Aerosol optical depth
Discuss how sulfur-rich volcanic eruptions can induce surface cooling.
The most significant climate impacts from volcanic injections into the stratosphere come from the conversion of sulfur dioxide to sulfuric acid, which condenses rapidly in the stratosphere to form fine sulfate aerosols. The aerosols increase the reflection
of radiation from the Sun back into space, cooling the Earth’s lower atmosphere or troposphere.
period of extremely low solar activity from approximately AD 1650 TO 1715; a reduction in total solar irradiance likely contributed to the LIA at a level comparable to changing land use.
Maunder minimum
A lighter 18-O indicates a ___________ East Asian monsoon rainfall.
stronger
a period of strong rainfall about AD 1000 when rice became the dominant staple of the Chinese diet and there was a great expansion of the Chinese population.
Northern Song Strong Monsoon Period
In contrast, there were times of weak monsoon and political instability.
- Late Tang Weak Monsoon Period
- Late Yuan Weak Monsoon Period
- Late Ming Weak Monsoon Period
these show a record of the weakening and strengthening of the East Asian monsoon over the past _______________.
Stalagmites in a cave at Wanxiang, China; 1,800 years
used changes in the ratio of 18-O and 16-O to show strengthening and weakening of the East Asian monsoon
Zhang et al (2008)
is actually isotopically “heavier” that water that falls a couple days later, farther inland.
The rain that falls on the Chinese coast
In years when the monsoon is stronger, that is, when more rain falls as the storms move across China, the water __________ is lighter than in years when the monsoon is weak.
falling inland
During wet periods around __________________, the water laden with calcium and carbonate dripped from the ceiling of the cave and evaporated, leaving the calcium carbonate (limestone) as a _______________.
65,000 and 39,000 years ago; stalagmite
fueled by a drought, when locusts swarmed the land, and led to the end of the Tang Dynasty
Huang Chao Uprising of the 870s and 880s
At the end of the ________________, there were a series of
droughts and a peasant uprising. In 1368 _________________, the leader of the uprising, took Beijing. His
parents and older brother all died during the droughts.
Yuan Dynasty; Zhu Yuanzhang
known as one of the most severe droughts in Chinese history at the end of the Ming Dynasty (1637-1643); affected more than 20 provinces in N and S China. The prolonged drought helped Li Zicheng organize a popular uprising and overthrow Chongzhen in 1644.
Chongzhen Drought
Variations in climate can be dangerous to societies and civilizations because it challenges:
political stability, food security, water security, and human progress
