Friday

Rocket arrives with a frozen juice-box-sized block from the freezer and sets it on the Station Rooftop table.

"Ice remembers," he says. "Scientists drill into glaciers and read the layers like pages."

Raven turns the block in the light. Tiny bubbles are trapped inside. "What do you notice in there?"

"Air," Rocket says. "Old air, if the ice is old enough."

Nova hovers close and glows through the ice. "Old air carries old carbon dioxide," she says. "And ice is only one witness."

"Sea level, sea ice, tree rings, satellites," Raven lists. "Each one keeps its own record."

Rocket grins. "Then let us call the witnesses."

NASA explains that ice cores drilled from Greenland, Antarctica and tropical mountain glaciers hold a record of past climate.

They show that Earth's climate responds to changes in greenhouse gas levels.

Ancient evidence also comes from tree rings, ocean sediments, coral reefs and layers of rock.

NASA notes that in the last 800,000 years there have been eight cycles of ice ages and warmer periods.

The last ice age ended about 11,700 years ago. Most of those old changes came from very small shifts in Earth's orbit.

NASA says the current warming is different. It is clearly the result of human activities since the mid-1800s, and it is faster.

The paleoclimate record shows warming today happening roughly 10 times faster than the average warming after an ice age.

NASA explains how the ice record forms. Year after year of snowfall piles up, and the weight of each new layer presses the older snow into ice.

As the ice compacts, tiny bubbles of air are pressed inside, including greenhouse gases such as carbon dioxide and methane.

Scientists can directly measure the gases in those bubbles. The oldest cores, from East Antarctica, hold an 800,000-year record.

Each year's snow is slightly different, so the layers can be counted like the rings of a tree.

NOAA reports that global average sea level has risen 8 to 9 inches since 1880.

The rise comes from two things: meltwater from glaciers and ice sheets, and seawater expanding as it warms.

The rate is speeding up. It was about 1.4 millimeters per year for most of the 20th century.

From 2006 to 2015 it was 3.6 millimeters per year, more than double the old rate.

NASA adds that the ocean has taken in about 90 percent of the extra heat in the Earth system.

Witness three is Arctic sea ice. Satellites have measured Arctic sea ice since the late 1970s. NOAA reports it has decreased in all months and nearly all regions.

In September 2024, the ice covered 4.38 million square kilometers. That is 2.03 million square kilometers less than the 1981 to 2010 average.

NOAA notes the missing area is larger than Alaska.

Between 1979 and 2024, end-of-summer sea ice shrank by 12.1 percent per decade compared with that average.

This course teaches the record as NOAA and NASA state it. It does not make predictions beyond those pages.

The evidence names a cause, not a culprit. No student and no family caused this record. It is the sum of a whole world's energy use.

NASA notes that Earth already removes carbon dioxide through plants, soil and the ocean. Plants take it in through photosynthesis.

Next week you turn to design. Communities make choices about shade, buildings and energy, and you will design a plan for your home.

A strong week of evidence. Tomorrow's Station Day builds a family question board.