L. 6:Neo-Paleo, C. 5-Cook

Question 1

Neopaleo

Answer 1

230-1000 years past

Question 2

Proxy

Answer 2

Used to create approximation of climate. Tree rings, sediment (elevated charcoal for drought), corals, increased salinity.

Question 3

Plant/Tree facts

Answer 3

As it gets hotter, plants close stomata so less water loss, more efficient water use. There is more CO2 in air, so ok if open stomata less. Average water use is 140 L/day, moves up average of 32 feet against gravity. Most moisture from soil.

Question 4

Type of poplar

Answer 4

Poor at closing stomata, so drops leaves during drought. It is drought-sensitive.

Question 5

PDSI

Answer 5

Palmer Drought Severity Index– measurement of dryness based on recent precipitation and temperature. The Palmer Drought Index is based on a supply-and-demand model of soil moisture. Supply is comparatively straightforward to calculate, but demand is more complicated as it depends on many factors - not just temperature and the amount of moisture in the soil but hard-to-calibrate factors including evapotranspiration and recharge rates. Palmer tried to overcome these difficulties by developing an algorithm that approximated them based on the most readily available data — precipitation and temperature. The index has proven most effective in determining long-term drought — a matter of several months — and not as good with conditions over a matter of weeks. It uses a 0 as normal, and drought is shown in terms of negative numbers; for example, negative 2 is moderate drought, negative 3 is severe drought, and negative 4 is extreme drought. Palmer’s algorithm also is used to describe wet spells, using corresponding positive numbers. Palmer also developed a formula for standardizing drought calculations for each individual location based on the variability of precipitation and temperature at that location. The Palmer index can therefore be applied to any site for which sufficient precipitation and temperature data is available.

Question 6

Dendrochronology

Answer 6

The scientific method of dating based on the analysis of patterns of tree rings, also known as growth rings. Dendrochronology has been used to generate estimated Palmer index values for North America for the past 2000 years, allowing analysis of long term drought trends. Ring width increases in time y=mx+b.

Question 7

Stand

Answer 7

20 trees. Note: tree rings get smaller as tree gets bigger.

Question 8

Precipitation trends

Answer 8

Precipitation varies a lot spatially and through time. P and temperature not always correlated. Mean precipitation does not change much. Don’t know what drives precipitation in areas that are not influenced by ENSO.

Question 9

Long-term trend

Answer 9

100 years.

Question 10

U.S. precipitation

Answer 10

Wetting in NE and NW, drying in SW and SE (La Nina drives some). N & S increasingly out of phase. Bermuda High influence. But varies seasonally, annually, spatially, decadally. No change in mean, just more extreme events. Overall aridity in west has increased irregularly. Current drought not as extreme as others in past.