STUDYING PAST CLIMATES

STUDYING CLIMATE IN THE PAST Paleoclimatologists study past climates They use Proxy records; which are stores of information in tree rings, ice cores and fossils that can be measured to give clues to what the climate was like in the past

ICE CORES Ice in Greenland and Antarctica contains air bubbles that have been trapped for thousands of centuries 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 years old

ICE CORES Scientist cut ice cores into very thin slices and test the air bubbles in each slice for various gases This measures the amount of carbon dioxide, methane and nitrous oxide that was in the air when the bubble formed Ice cores have shown scientists that the concentration of these greenhouse gases has changed dramatically over Earth’s history

ICE CORES Scientists can also obtain information about the earth’s temperature, precipitation and volcanic eruptions through preserved layers of dust in an ice core Ice cores tell scientists that the earth’s climate has gone through many changes in climate (including warmer and colder periods)

TREE RINGS When a tree grows, it creates one growth ring per year The rings are the thickest during the years of good growing conditions Some trees live for thousands of years and scientists can assemble clues from living and dead trees about the climate during that time

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

ROCK, CAVES AND OCEAN SEDIMENT Layers of soil and rock build up on the earth over time and each layer gives clues, such as plant or fossils to the climate at that time Sediment cores from the ocean floor contain clues that provide data about past climates

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