"Each layer of ice tells a story about what Earth was like when that layer of snow fell."
Yep
"The icy layers also hold particles—aerosols such as dust, ash, pollen, trace elements and sea salts—that were in the atmosphere at that time. These particles remain in the ice thousands of years later, providing physical evidence of past global events, such as major volcanic eruptions."
Or less
"Additionally, as the ice compacts over time, tiny bubbles of the atmosphere—including greenhouse gases like carbon dioxide and methane—press inside the ice. These air pocket “fossils” provide samples of what the atmosphere was like when that layer of ice formed, LeGrande said. “Scientists can directly measure the amount of greenhouse gases that were in the atmosphere at that time by sampling these bubbles,”
Whether the layers were 4 hours apart or 100 years apart.
"Scientists also use ice core temperature data to validate climate models that predict Earth’s future climate."
BS
"They also have to add in any variables that may alter the climate system at different points in time"
I bet they do.
"The oldest ice cores, from East Antarctica, provide an 800,000-year-old record of Earth’s climate. How do we know they’re that old? Each season’s snowfall has slightly different properties than the last. These differences create annual layers in the ice that can be used to count the age of the ice, just like rings inside a tree."
Once again, this thinking reflects that of a very slow gradual build-up of everything in the layer, never considering the possibility that the layers of ice were also laid down quickly with a smorgasbord of snow contents belched up from a world being torn apart, and that could or could not be related to the time frame in which it was occurring. For scientists, it has to be a slow orderly process because that’s all they can understand, and have to keep that model throughout for TOE.