Question

What is the source of information from natural materials which can be used to reconstruct climate conditions prior to the modern period?

Answer 1

There is a branch of science called as paleoclimatology which deals with obtaining data from various sources like rocks, tree rings, fossils etc .

Below mentioned are some natural materials :

• 1 Fossil pollens: These are preserved structures of plants; each plant has different and specific pollen structure thus if we obtain any particular pollen we can conclude that in what climatic conditions that plant was growing. (as plants need specific climatic conditions for growth)
• 2 Tree rings: Tree rings are of 2 types - wide and narrow. They grow wide when climate is wet and warm while they are narrow in cold and dry climate.Thus we can use this as a reference for climate in that area.

• 3 Ice cores: Oxygen isotope ratio in ice indicates the temperature at time when ice is deposited, also air bubbles in ice can be analysed to measure CO2 and methane concentration of that time when these bubbles are trapped.  
• 4 Lake sediments : Composition of lake and sedimentation rate changes with respect to climatic conditions. Sediments like pollen grain can be utilized to determine which climatic conditions were present.
• 5 Glaciers : These plays a very crucial role in climate determination of ancient times . Glacier models can be used to reconstruct past climate from geological evidence of past glacier extent. Like we can see that cool summer temperature was only influencing factor foe glacier deposition in New Zealand. Thus this helps us to understand climate exhibited there.