Earth in 1000 Years

Summary

Earth’s ice—glaciers, sea ice, permafrost, snow, and the Greenland and Antarctic ice sheets—helps regulate climate by reflecting sunlight, influencing ocean circulation, and affecting weather. The documentary examines evidence that major ice stores are losing mass and explains how scientists use past climate changes to assess possible long-term effects, particularly sea-level rise.

Climate history and feedbacks

• Earth has experienced at least five major ice ages over roughly two billion years. Climate changes have been driven by interacting factors, including volcanic activity, the evolution of life, ocean circulation, and the movement of continents.
• Around 55 million years ago, global temperatures rose sharply and atmospheric CO₂ reached about 1,000 parts per million. Later, changes in continental positions helped cool the climate. A more isolated Arctic allowed freshwater and the CO₂-absorbing aquatic plant Azolla to spread. Meanwhile, the uplift of the Himalayas exposed rock to weathering, which removed CO₂ from the atmosphere.
• The documentary describes Milankovitch cycles: periodic changes in Earth’s orbit and rotation that alter how much solar energy reaches the poles. These cycles can help initiate glacial periods, while feedbacks amplify the change:
  • More sea ice reflects additional sunlight back into space.
  • Colder oceans absorb more CO₂, reducing the greenhouse effect.
  • In warmer conditions, oceans release more CO₂, which traps more heat.
• Antarctica’s gradual isolation, declining CO₂, and the development of the circumpolar ocean current helped establish its extensive ice cover. The continent is now described as Earth’s coldest, driest, and windiest region.

Greenland

• Greenland’s ice sheet is losing mass, particularly near its coasts. The documentary reports that GRACE satellite measurements showed a loss of about one trillion tons of ice from 2003 to 2009.
• Coastal glaciers act as channels draining the inland ice sheet. As they thin or break up, the ice behind them can flow faster into the ocean—a process associated with calving, in which icebergs break away.
• The Jakobshavn Glacier was reported to be advancing toward the sea at about 17 kilometres per year, three times its mid-1990s rate. The Zachariae ice stream retreated around 20 kilometres and lost about 10 billion tons of ice between 2003 and 2014.
• Surface meltwater can collect in ponds and drain through cracks toward the base of the ice sheet. This may reduce friction between ice and bedrock and speed up ice flow.
• Greenland’s entire ice sheet contains enough ice to raise global sea levels by roughly seven metres. The documentary also notes that extreme melting would alter local sea levels: the loss of the ice sheet’s gravitational pull and the land’s gradual rebound could lower sea levels near Greenland while raising them farther away.
• Evidence from the Eemian interglacial period (about 130,000–115,000 years ago) suggests that Greenland’s ice retreated but did not disappear. Researchers estimated that Greenland contributed two metres or less to the period’s sea-level rise; warmer, expanded ocean water contributed additional rise.

Antarctica

• Antarctica contains about 90% of Earth’s ice and 70% of its freshwater. Its eastern region rests largely on stable continental crust, while parts of West Antarctica lie below present sea level and are more exposed to ocean-driven melting.
• The documentary reports that West Antarctica is losing ice rapidly. CryoSat-2 measurements indicated an average Antarctic loss of 159 billion tons per year from 2010 to 2013, 31% greater than the average in the preceding five years.
• Stronger winds around Antarctica can bring relatively warm deep ocean water to the surface. That water can erode the undersides of floating ice shelves. Shelves also help hold back inland glaciers; when they weaken or collapse, those glaciers may accelerate.
• A field team drilling through the Pine Island Glacier’s ice shelf found warm-water erosion beneath it, with melt rates reported at about six centimetres per day. Satellite and airborne radar observations tracked faster glacier flow and the retreat of grounding lines—the points where glaciers cease resting on the seabed and begin floating.
• On the Smith Glacier, the grounding line retreated about 35 kilometres from 1996 to 2011. Retreat can allow seawater to move farther into deep subglacial basins, potentially encouraging further ice loss.
• The documentary discusses geothermal activity beneath parts of Antarctica, including beneath the Thwaites Glacier, as another possible contributor to melting.
• East Antarctica is much larger and has generally been considered more stable, but the Wilkes Land basin may be vulnerable. Its ice is held back in part by undersea ridges. If warming water undermines the ice resting on those ridges, the ice sheet could begin flowing toward the sea.
• Antarctic sea ice has, in contrast to Arctic sea ice, increased in extent and thickness in some periods. Possible explanations discussed include stronger winds compacting the ice and meltwater creating a cold, fresh surface layer that freezes readily.

Long-term implications

The documentary presents projections—not certainties—of substantial future sea-level rise. It cites a study estimating a possible rise of about two metres by the end of this century and more than 15 metres by 2500 if Antarctic ice loss continues at an accelerating rate. It emphasizes that heat already stored in the ocean could sustain melting for centuries, even if greenhouse-gas emissions are brought under control.

Rising seas could threaten coastal cities, ports, communities, and livelihoods, and displace large numbers of people. The documentary’s central conclusion is that Earth will continue to change, but the scale and pace of future impacts depend in part on human choices.

Researchers and sources featured

• Milutin Milankovitch — Serbian scientist associated with the orbital cycles that influence the timing of glacial periods.
• An unnamed 19th-century Dutch scientist — identified in the documentary as the discoverer of the Eemian period.
• NEEM (North Greenland Eemian Ice Drilling Project) — ice-core drilling project used to investigate Greenland’s past climate and ice extent.
• GRACE satellite — used to track changes in ice mass across Greenland and Antarctica.
• CryoSat-2 spacecraft — radar measurements used to estimate changes in Antarctic ice elevation and mass.
• Vostok Station — Russian Antarctic research station associated with the recorded natural temperature cited in the documentary.
• Other sources and methods mentioned: satellite imagery, airborne and satellite radar, field drilling on the Pine Island Glacier, and reconstructions of past ice-sheet conditions. The documentary does not name the individual researchers involved in these studies.