Studying Past Climates [so super cool]

Paleoclimatologists study past climates They use Proxy records; which are stores of information in Ice cores Fossils Tree rings that can be measured to give clues to what the climate was like in the past

Ice Cores

Ice Cores carbon dioxide methane nitrous oxide Ice in Greenland and Antarctica contains air bubbles that have been trapped for thousands of centuries containing carbon dioxide methane nitrous oxide that was in the air when the bubble formed Scientists drill deep into the ice and extract long cylinders of ice The ice at the top of the ice core is recent and the bottom ice can be up to 800 000 years old What d

Recall… What do we know about the gases carbon dioxide (CO2) Methane (CH4) nitrous oxide (N2O)? What clues might they give us about past and present climates?

Ice Cores Ice cores have shown scientists that the concentration of these greenhouse gases has changed dramatically over Earth’s history Feedback Loops in Global Climate Change Point to a Very Hot 21st ...newscenter.lbl.gov 

Ice Cores Scientists can also obtain information about the earth’s temperature precipitation volcanic eruptions through preserved layers of dust in an ice core

TED Talk on Ice Cores http://www.ted.com/talks/lee_hotz_inside_an_antarctic_time_machine.html

Coral Reefs Like trees, coral reefs add layers of growth each season Scientists drill cylinders of coral and study their layers Information from coral layers help determine the temperature of the surface ocean water when each layer was growing

Red Sea coral growth 'to halt by 2070’ Title Is link to http://www.bbc.co.uk/news/science-environment-10646290 Homework option: Assign article + questions for critical reading & problem solving (What? So What? Now What?)

Rock and Soil Layers of soil and rock build up on the earth over time and each layer gives clues to the climate at that time, such as plants or fossils

Tree rings (Dendrochronology) Tree cookies Tree cores

What is Dendrochronology? Dendro= Tree Chrono= Time Logy= Study

How do Trees Hold Information about Climate? Trees grow in both height and width. The xylem tissue in trees conducts water and dissolved nutrients from the soil throughout the entire tree Tree Rings are formed in the xylem layer each growing season Each Annual Ring has a Spring Ring/Early wood Thicker because there is more water present Summer Ring/Late wood Thinner and darker in colour because there is less water and the growing xylem cells are smaller The width of an annual ring is affected by the climatic conditions of that growing year.

This tree grew in a region where growth is dictated primarily on availability of water

Cool stuff trees have told us The analysis of the oak planks making up one Viking Longship (found in Norway) showed that the wood was from trees cut down some time between 1060-1070 CE. The Oseberg ship was built around 820 AD. It had iron riveted planks in oak. Lenght 21,5 m, width 5,0 m, 15 pairs of oars, 0,65 m from water to rail, joint in the keel, mast ca 9 m, sail approx. 6 x 12 m, mast base 1,75 m long, weight ca 11 tons. Oseberg was a decorative ship, with several ornate carvings covering its hull, and it was not built for strength as a war ship might have been. Thus, it likely was built to be used specifically as a burial vessel. The Oseberg burial mound was excavated in 1904, revealing a well preserved ship and tremendously rich grave goods. Tools found on the Oseberg ship included two small axes, found with kitchen equipment near a butchered ox. The handles on both were well-preserved, with a characteristic herringbone pattern known as spretteteljing in evidence. A small wooden chest was also identified. Animals represented in the faunal assemblage included two oxen, four dogs, and 13 horses. Personal belonging included beds, sledges, wagons, textiles and a vertical loom. Grave Chamber The grave chamber was a tent of roughly hewn oak planks and posts, placed in the center of the ship. The chamber had been disturbed shortly after the burial, by either grave robbers or local animals. The fragmented skeletal remains of two women were found buried in the ship, one aged in her 80s and the other in her early fifties. Some historians (such as Anne-Stine Ingstad, associated with the discovery of Leif Ericsson'sL'anse aux Meadows camp in Newfoundland) have suggested the elderly woman was Queen Asa, mentioned in the Viking poem Ynglingatal; the younger woman is sometimes referred to as a hofgyðja or priestess.  http://archaeology.about.com/od/oterms/g/oseberg.htm Discovered in Norway in 1906, the Oseberg ship, the best preserved Viking ship ever found, reveals its Norse shipbuilders' graceful construction style. Photo credit: © Svergies TV

What conditions make for a ‘good growing year’ for trees? Length of growing season (temperature: the longer the growing season, the more the tree will grow – affected by latitude) Water availability (severe droughts can drastically reduce the growth of a tree)

Describe the climate during the (short) life of this red pine… A cross section from a small red pine (Pinus resinosa) that shows excellent variability in its ring widths, despite its young age (photo © H.D. Grissino-Mayer).

Fire scars are evidenced by the change in the pattern of growth rings as they heal around the scars A close-up of a cross-section of a giant sequoia (Sequoiadendron giganteum) showing numerous fire scars and the growth patterns that resulted (photo © A.C. Caprio).

Comparing Douglas-fir trees Increment cores taken from Douglas-fir trees (Pseudotsuga menziesii) growing at El Malpais National Monument (photo © H.D. Grissino-Mayer). The "18" on the side of the cores shows the location of the year "1800." The dark lines connect narrow and wide rings, demonstrating crossdating between the trees. http://web.utk.edu/~grissino/treering-gallery2.htm

During which decade did the climate suppress tree growth in this conservation area? Cores extracted from Nuttall oak (Quercus nuttallii) growing at the Northeast Corner site in the Dave Donaldson Wildlife Management Area in northeastern Arkansas, showing a major period of suppressed growth in the 1960s (photo © H.D. Grissino-Mayer).

A remnant piece of wood from a ponderosa pine tree (Pinus ponderosa) found at El Malpais National Monument. This one dated back to the early 1300s, and it was far from being the oldest in the area! (photo © H.D. Grissino-Mayer)

Why study tree rings? Tree rings provide evidence of environmental events such as Floods & droughts Insect attacks Forest fires Lightning strikes Earthquakes Volcanoes *Anything that can affect the growth of the tree - be it sunlight, temperature, nutrient levels, grazing, fire, smog, smoke, water or even just dust in the air, can leave traces/evidence in the tree rings.  In the vast majority of cases tree rings or coral growth rings will show earthquakes and other natural events because the event in some way interrupts the growth (of the tree or the coral)  An earthquake on land may well dislodge branches and cause damage to trees, which can be seen in the growth rings, or the tree may be killed outright, in which case fossil stump will all show a ring set which finishes at the time of the earthquake. In the oceans, as well as damage, there may be increased turbidity caused by stirring sediment up from the sea bed. This can show in the coral as dirty layers in the growth rings.  Similarly, fire and volcanoes can cover the tree or the coral in ash which becomes incorporated in the growth rings to be seen later. If there is sufficient ash fall the growth of the tree may be hindered or even stopped for a season or two - and this too will be reflected in the rings. In some cases rings may be missing altogether! See http://vulcan.wr.usgs.gov/Projects/TreeRings/tree_ring_dating.html  Anything which can affect the growth of the tree - be it sunlight, temperature, nutrient levels, grazing, fire, smog, smoke, water or even just dust in the air, can all leave traces in the tree rings which are produced. 

Activity Developing your Dendrochronology Skills Analyzing tree cores to find evidence about a past climate event Activity: Trees: Recorders of Climate Change (Little Ice Age) [Climate Discovery Teacher’s Guide] Hand out a copy of the Little Ice Age student page to each student Have students divide into groups of 4 or 5, provide one pack of simulated tree cores to each group (already cut), go over instructions on student page with them, have them complete the assignment as homework.

Summary Proxy records are indirect records of past climates contained in natural materials Analyzing air bubbles in ice cores provides data on greenhouse gases and temperature from the past Analyzing the growth rings on ancient trees and coral provides data on temperature and precipitation from the past

Homework! [Yay!] Complete the assignment (to be handed in next class)