Climate Reconstruction Flashcards
Why did past climates change?
Natural processes
What is climate sensitivity?
Change in climate for a given forcing
When did central England temperature records begin?
- Monthly since 1659
- Daily since 1772
Advantages of climate proxies …
Very long record
Disadvantages of climate proxies …
- no proxy record responding solely to one variable
- limited resolution (space and time)
- must be preserved
- overprinting of original signal
What controls the width of tree rings?
Temperature and moisture availability
How are tree rings biased?
They are biased towards the growing season
How old is the oldest tree ring record?
9000 years
What is an isotope?
Chemically identical form of an element with a different atomic mass
What percentage of seawater has O18?
0.19%
What percentage of fresh water has O18?
0.15%
Which oxygen isotope is preferentially evaporated?
O16
Which oxygen isotope is preferentially ‘rained out’?
O18
What two uses are there for O isotopes?
- Glaciation
- Temperature indicator
What happens to O18 during glaciation?
Enrichment of O18 in sea water (colder temperature, O18 remains in oceans as it’s heavier)
How do ice cores date?
By counting layers of by analysing dust layers
Where was the longest ever ice core drilled?
Antarctica
How many glacials cycles did the longest ice core display?
8 glacial-interglacial cycles
What is the difference between Antarctic and Greenland ice cores?
Greenland ones have a shorter record (only covers the last glacial cycle) BUT they have a higher resolution … same length of core but shows a shorter amount of time
Typically how far back do written records go?
1000 years
Example of a written record: when was it? who noted it? what did it show?
1801: William Herschel noted a correlation between sunspot numbers and wheat prices
What is the little ice age?
Movement of Europe into a cold period during the 16th century
What were temperatures like during the Little Ice Age?
From 1550 for about 150 years, temperatures were lower than at any time since the last glacial ended over 10,000 years ago
Who painted ‘Hunters in the Snow’? When? What was it inspired by?
Pieter Brueghel, 1565 … said to be inspired by the longest and most sever Dutch winter at the time
What happened to sea ice extent during the Little Ice Age?
Sea ice extended as far south as the Faeroe Islands … 1695: sea ice surrounded Iceland, blocking ports and disrupting supply
What impact did advancing glaciers in Scandinavia during the Little Ice Age have?
- highland farms destroyed
- outburst floods from stored meltwater
- famine due to damaged harvests
Impact of the little ice age …
- N Sea flooding in 1570
- Failure of cod fisheries from 1615 for a century
- 1703 great storm
What is the Medieval climate anomaly?
Warming from 600 AD to 1250 AD in Europe
The period between 1983-2012 was …
- very likely the warmest 30 year period of the last 800 years
- likely to have been warmest in last 1400 years
What is the difference between the Medieval Climate Anomaly and 20th century warming?
Regional warm periods in the past were not as synchronous across regions as modern warming
