What kinds of data do scientists use to study climate change and global warming?

Given that any analyses of climate change and global warming require researching a diverse range of inputs, how do scientists and climate change experts approach data collection and analyses?

To a significant extent, the work of scientists so far had been to confirm cause-effect relationships – that it, to ascertain the extent to which each greenhouse gas resulted in global warming, and the correlation between global warming and changes in other aspects of climate – such as rainfall, droughts etc.

Such cause-effect relationship analyses require scientists to collect past data on earth climate – from periods dating back thousands of years to recent dates.

Such data for cause and effect for the recent past – say the past hundred years – are not such a big problem as there are enough authentic published sources and data banks available. For instance, since the 1950s, NASA satellites have been observing Earth’s atmosphere, oceans, land, snow, and ice from high in space. But how do they collect data on climate for hundreds of years prior to now?

Scientists have discovered many ways to study the earth’s climate, going so far back – thousands, or sometimes even millions, of years. They analyze historical climates by studying samples of and clues present all over the ecosystem:

• Proxy Data – One of the avenues they employ uses natural elements in the environment that help them find “proxy climate data” related to the past. When they study these types of data, scientists typically use several different methods, so they are assured of forming the most accurate analysis possible.
• Water Bodies – Clues about ancient climates are not found only in bodies of freshwater such as lakes and ponds, but are also buried in sediment that has settled in the earth’s deep oceans. Scientists also gather and study sediment from different bodies of water to gather substances such as pollen that can say a lot about habitat conditions that would have been necessary. Data from coral reefs can also provide important clues to climates of the past. Every time a piece of coral skeleton is created, it leaves a record of the conditions under which it was created.
• Ancient Ice – In fact, some of the most revealing indicators of historical climates come from studies of glaciers and ice sheets in the world’s polar regions.

Data on the following are collected to arrive at inferences for climate change and global warming:

• Amount of greenhouse gases present in the atmosphere
• Temperature – Earth’s surface, and sea surface temperature (SST).
• Precipitation – Rainfall, Snowfall etc. – May include humidity or water balance, and water quality.
• Biomass and vegetation patterns – provide evidence of how ecosystems adapt to climate change.
• Sea levels
• Solar activity
• Volcanic eruptions
• Chemical composition of air or water

Using these types of data, scientists develop climate models.