How is Climate Change Observed and Objectively Measured

How is Climate Change Observed and Objectively Measured?

Objective, reproducible observations and measurements are the basis of the scientific method: making objective unbiased observations. First scientists must agree upon a set of parameters to observe that are considered to be caused by or indicative of climate change. Below are these parameters:

  • Air and sea temperature: This is the most obvious; comparing current temperatures to historic ones and looking for statistically significant trends.
  • Icon for Greenhouse Gases Climate Change IndicatorsGreenhouse gas levels: it has been established and generally accepted among scientists that air and sea temperatures rise as the level of greenhouse gas emissions increases, s up to a maximum.
  • Icon for Snow and Ice Climate Change IndicatorsSnow, glacial and permafrost thickness: As global temperatures increase, ice and snow will melt; similarly as they decrease, the size of glaciers and ice packs increases.
  • Icon for Oceans Climate Change IndicatorsOceans and Sea level: If polar ice and regional glaciers melt, the water eventually makes its way to the oceans and sea levels rise.
  • Ice core samples: As ice forms it traps dust particles, atmospheric gas and microscopic organisms, all of which provide clues to changes in the environment over time. And since ice made of oxygen and hydrogen, we can examine the ratio of oxygen isotopes in the water, which helps to determine conditions when the ice was formed..
  • Lake sediments: Core samples collect through the bottom of a lake also show us the different isotopes of Oxygen and Carbon, as well as species of plants and animals that lived in or near the lake. Since different animals and plants can prefer and tolerate different temperatures and conditions, this provides clues to the climate in the past.
  • Radiocarbon dating: carbon also has different isotopes, C12, C14, etc. which reflect changes in the atmosphere. When this carbon is taken up by living things, such as wood or animals, we can later compare the ratios of isotopes to the age of the organism. Indirectly, then , this can be used to look at changes in populations of organisms over time, which may (or may not) be due to changes in climate)
  • Tree rings: Every child knows the thickness of tree rings tells us abut the tree's seasonal growth, such as thicker rings (more growth) in a wet, warm year.
  • Icon for Weather and Climate Climate Change IndicatorsExtreme weather events: in some cases climate change can also be an increase in extreme weather events, for example hurricanes and storms. However, there is substantial normal variation, so these must be looked at over a much longer period of time to be significant.
  • Animal and plant migration distributions: animals and plants can migrate over time toward or away from areas that are well suited toward them, or they can adapt and change to changing conditions.
  • Phenology: The timings of natural life cycles, such as when birds come out of the eggs, to determine if there are changes in seasonality.


So, the list above are the natural phenomena that scientists examine to help determine if there is climate change. But remember, there can be other causes for changes in these parameters other than the climate. So a scientist must be careful not to draw conclusions too quickly, without eliminated other possible interactions.   So what data has been collected and what does it show us?