There are many types of physical evidence for climate change. Here are the main ones:
Ice cores: Ice cores are a record of past climate conditions stored in the ice sheets and glaciers. They provide information about temperature, wind patterns, and precipitation over time. The cores can be dated by comparing the ratio of oxygen isotopes in snowfall to the ratio found in the air at that time.
Tree rings: Tree rings are used to determine past weather conditions because they reflect annual changes in moisture levels, temperature, and sunlight availability. Tree ring widths tend to be wider during wet years and thinner during dry years; this allows scientists to determine whether a particular year was wet or dry by measuring its width.
Ocean sediments: Ocean sediments (or “sediment cores”) contain layers of material that have been deposited into oceans over time; these layers can be dated using radiometric methods like carbon-14 dating. These layers can provide information about sea level rise or fall over time, as well as other environmental conditions such as temperature change or changes in ocean circulation patterns.
Coral reefs: Coral reefs are formed when tiny polyps build their skeletons around hardenings from dead coral polyps or shells from planktonic organisms.