g What are proxy data, and why are they necessary in the study of climate change? Proxy data are indirect evidence of past climates taken from natural recorders of climate variability. These data are necessary because they provide the margins of error within which the data are found. Proxy data are indirect evidence of current climates taken from natural recorders of climate variability. These data are necessary because it is not always possible to take direct measurements of variables related to the climate. Proxy data are indirect evidence of future climates taken from natural recorders of climate variability. These data are necessary because it is not possible to take direct measurements of future climates. Proxy data are indirect evidence of past climates taken from natural recorders of climate variability. These data are necessary because direct measurements of past climates are limited to the recent past. Proxy data are indirect evidence of current climates taken from natural recorders of climate variability. These data are necessary because they provide the margins of error within which the data are found.