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EAS 100 > Lecture 32: Climate Change > Flashcards

Lecture 32: Climate Change Flashcards

-Proxy and Understanding Past Climate -Fast and Slow Feedbacks -Human Impact on the Atmosphere and Lead to Changes of the Other Earth Systems

1
Q

What is a proxy?

A

A source of climate information that is from natural and human records that can be used to estimate past climate conditions

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2
Q

How is proxy data helpful?

A

It allows to infer information about past climate and environments in the absence of direct measurements

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3
Q

What are some human records that can be used for proxy data?

A

1) Agricultural or shipping records
2) Pictures, sketches, paintings
3) Writings
- Egyptians recording the Nile flood levels going back to 3000 BC

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4
Q

What was the climate like in the last millennium?

A
  • Medieval Warm Period: around AD 900, lasting for a couple hundred years
  • Little Ice Age: followed the Medieval Warm Period, marked by biggest advances in glaciers since the end of the last glaciation
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5
Q

What are some natural records that can be used for proxy data?

A

1) Pollen, plant macrofossils, shells, tree-rings
- Can be related to temperature, humidity, precipitation
- Indicator species
- Landscape reconstruction
2) Isotopes
- Total solar irradiation
- Temperature, elevation, CO2, Ice volume

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6
Q

What are some examples of organisms that have annual growth rings?

A
  • Trees
  • Corals
  • Varves (lake sediment that has laminated beds)
  • Ice cores
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7
Q

How is pollen used as a natural proxy?

A

Each plant has unique looking pollen, so pollen fossils from a sediment core can reveal a plant assemblage.
-This can be used to estimate climate conditions

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8
Q

What are indicator species?

A

Organism (often a microorganism or a plant) that serves as a measure of the environmental conditions that exist in a given locale.
-have very defined habitats, temperature and/or precipitation requirements

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9
Q

Why are ice cores so important?

A

Because the ice preserves gas bubbles from past atmospheric compositions (also dust and aerosols)
-Isotopes of O and H can reconstruct past temperature, humidity, and precipitation patterns

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10
Q

What natural proxy has the longest and detailed records?

A

Marine sediment cores

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11
Q

The ratio of 18^O and 16^O in sea water depend on what?

A

Water temperature and ice volume of land

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12
Q

What is the advantage of marine sediment cores?

A

Global coverage, very long records but also very high resolution shorter records

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13
Q

What are the complications with marine sediment cores?

A
  • No direct measurements of atmosphere gas concentrations

- Complex proxies that only get more complex the further back you go

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14
Q

What are fast feedbacks?

A

Feedbacks that responds on shorter time-scales

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15
Q

What are slow feedbacks?

A

Feedbacks that take much longer to take full effect

-Can be considered forcings

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16
Q

What is climate sensitivity?

A

The sensitivity of the climate system to a change in radiative forcing.
-expressed in terms of the global mean temperature (GMT)

17
Q

What is Equilibrium (Charney) climate sensitivity?

A

The amount of warming that will occur once all the processes have reached equilibrium

18
Q

What is Transient (effective) climate sensitivity?

A

The amount of warming that might occur at the time when CO2 doubles, having increased gradually by 1% each year

19
Q

What is Earth system sensitivity?

A

Similar to equilibrium climate sensitivity, but on longer time-scales

20
Q

What are some main anthropogenic greenhouse gas sources?

A
  • CO2: fossil fuel combustion
  • CH4: natural gas leaks, landfills, livestock, coal (GWP=30)
  • N2O: agriculture (GWP=270)
21
Q

What is global warming potential (GWP)?

A

Warming potential of a greenhouse gas compared to CO2 over a defined time period.

22
Q

What is polar amplification?

A

the northern latitudes experience much higher rates of warming due to feedbacks

23
Q

What are the consequences of melting sea ice?

A
  • Less ice to reflect solar radiation back to space
  • Warmer sea
  • Higher sea level
24
Q

What is the current rate of sea level rise?

A

3.3 mm/yr

25
Q

Why is there a ‘cold blob’ in the North Atlantic?

A

It is the result of slowing of thermohaline circulation in the region likely due to fresh water

26
Q

What two things are causing global rise of sea level?

A

1) Thermal expansion

2) Melting glaciers and ice sheets

27
Q

How much CO2 has been absorbed by the oceans?

A

26%

28
Q

Why are oceans a major buffer?

A

Because they absorb ~93% of the excess heat caused by increasing greenhouse gases

29
Q

What are some consequences of warmer ocean water?

A
  • decreased capacity for CO2
  • increased CO2 = increased acidification
  • coral bleaching
  • more violent storms

EAS 100 (21 decks)

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