Climate proxies
Also called: Evidence of past climate · Topic: Climate Change: Causes, Evidence and the Global Response · NCERT: Class 11, Ch 11 "World Climate and Climate Change"
Meaning
Climate proxies are indirect records of past climate. Nobody measured temperature or rain thousands of years ago, so scientists read nature's own records instead. Glacial landforms in high mountains and high latitudes show where glaciers advanced and retreated. Sediments in glacial lakes show warm and cold periods. Tree rings show wet and dry years, and historical records describe past weather. Beyond NCERT, scientists also use ice cores, pollen, corals, cave stalagmites (stone columns that grow upwards from a cave floor) and ocean sediments. Proxies matter because they show that climate has always changed, and they let us compare today's warming with the past.
Example
A stalagmite from Mawmluh Cave in Meghalaya recorded a sharp dry spell about 4,200 years ago. In 2018 scientists used it to define the Meghalayan Age, the latest stage of the Holocene. Ice cores from EPICA Dome C in Antarctica go back about 800,000 years. They show CO2 and temperature rising and falling together.
Don't confuse with
- Instrumental record: this is direct measurement with thermometers and rain gauges, and it covers only about the last 150 years. Proxies are indirect clues that reach back much further.
Related concepts
- Climate change
- Glacial and interglacial periods
- Pleistocene epoch
- Holocene
- Past climate of Rajasthan