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Climate > Week 19 > Flashcards

Week 19 Flashcards

1
Q

Termination I

A

Last deglaciation

Several meltwater induced climatic events

Antarctic cold reversal led YD

8.2ka event not global?

Rest of holocene fairly quiet

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2
Q

Holocene Climatic Optimum

A

= warm period 9000-5000 years BP

~5’C warmer at Poles > present

Different moisture distribution

Predictable from orbital forcing calculations

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3
Q

Climate over the last 2000 years

A

Includes (1) Medieval Warm Period and (2) Little Ice Age

Proxies/instrumental data

Prior = land-based records

Mild climate fluctuations

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4
Q

Proxy examples for the last 2000 years

A

Ice cores

Tree rings

Historical documents

Painting e.g. Peter Robinson ‘Weather’ 2005
- LIA = colder/cloudier in N Europe > Med

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5
Q

Medieval Warm Period

A

Vikings = colonies on Greenland
- exploration from Norway/Sweden/Denmark 800-1200AD

Inuits from Alaska hunting Bowhead Whales colonise E Canadian Arctic

England Wine

Farming higher altitudes/latitudes through Scandinavia

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6
Q

The Little Ice Age

A

Began 1300AD with increasing sea ice in N Atlantic (stopped travel)
- by 1400AD Greenland Viking Colonies lost

Glaciers grew
Lakes froze
Rivers/canals NW Europe froze
Europe crops less productive

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7
Q

Cause of the LIA

A
  1. SOLAR ACTIVITY

2. VOLCANIC ACTIVITY

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8
Q
  1. SOLAR ACTIVITY
A

Wolf/Sporer/Maunder/Dalton sunspot minima

More sunspots = more active/bright sun

Solar irradiance matches with sunspot index = solar activity proxy

CYCLES:
11 years = Schwab
22 years = Hale
88 years = Gleissberg

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9
Q

Sunspot =

A

area of v high magnetic activity

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10
Q

Sunspot components

A

Umbra = sunspot

Penumbra = around sunspot

Faculae = compensate = brighter

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11
Q
  1. VOLCANIC ACTIVITY; eruptions
A

1815 Tambora = largest in recorded (!) history = 150m3
1816 = year without summer

1812 = Soufriere, Saint Vincent

1814 = Mayon, Philippines

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12
Q
  1. VOLCANIC ACTIVITY; results
A

Taranto, S Italy = red/yellow snow

N England coldest July 20 years (-~5’C)

Lasted 1-3 x longer than sulphate aerosol residence time = +ve feedback?

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13
Q
  1. VOLCANIC ACTIVITY; mystery eruptions
A

1257 = Rinjani/Samalas
- GISP2 ice core T anomaly/S

+ another mystery

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14
Q

Climate since the LIA

A

If no industrial revolution = ice age?

BUT

  • initial ~1880-1940 warming
  • little change (cooling?) 1940-mid 1960s
    (coal = pyrite = oxidised = sulphate aerosols)
  • parts of word more/less rain, overall more
  • more CO2 in atmosphere now than any point in RECENT history
  • CH4 + NOx higher than past
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15
Q

Mauna Loa

A

Longest instrumental CO2 record

Pollution doesn’t contaminate

Seasonality due to northern hemisphere

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16
Q

Climate since 1850; effects

A

Rate is alarming

Distribution of cities/population/agriculture

T/rain/drought

Coastal cities and SL rise

= adaptability is good

17
Q

Climate since 1850; facts

A

Holocene T
- lat-dependent insolation = main control under 1850 when all lats increased

SL rise (tide gauges/satellites) = 30cm/century

  • glacier melt
  • thermal expansion
  • spatial differences (due to ice age/plate tectonics theory)
18
Q

Glaciers

A

Warm Arctic warm permafrost = reduce permafrost area = release CO2 = +ve feedback

WAIS>EAIS (newer = less stable)

OERLEMANS:

1) receding worldwide
- 83% of mountain glaciers receding
- -1m/yr average

2) T matches other proxies

3) Scandinavian anomaly; Engabreen glacier, Norway +0.64m/yr
- snowfall increased in some places due to warming

N.B. CHERRY PICKED????

19
Q

Why has an Anthropocene been defined?

A

Due to species extinctions/climate changes

20
Q

Classic Anthropocene theory

A

Natural processes controlled climate until Industrial Revolution

Then +CO2/hockey stick graph

N.B. Volcanic 20th century cooling
Solar activity increases from LIA

21
Q

Friss-Christiansen and Lassen 1991

A

Sunspot cycle LENGTH most important = ctronols climate

Nearly perfect correlation; much better than CO2

22
Q

Effects of climate change

A

More heat extremes

Drought

Increase in SL
- thermal expansion

Temporary severe cold spell?

Rapid migration of ecological zones

23
Q

Long term forecast; general

A

Increase in solar irradiance

Slow warming next few billion years

Increase in humidity

24
Q

Long term forecast, 1.1 billion years

A

Sun 10% bright than now
Some water escaped to space

= warm with abundant rainfall

25
Q

Long term forecast; 3.5 billion years

A

Runaway greenhouse effect, boiling/evaporation of oceans

= very warm, cloudy, widely scattered showers

26
Q

Long term forecast; 6 billion years

A

Sun –> red giant, mercury (+Earth) engulfed by sun

= hot

Climate (11 decks)

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