The Wilkins Ice Shelf extends from the lower part of the Antarctic Peninsula, visualized on the far left in this illustration.

Illustration by National Geographic Maps
  • On March 25, 2008, scientists announced that a large piece of the Wilkins Ice Shelf in Antarctica had collapsed. Roughly 414 square kilometers (160 square miles) of ice started melting on February 28, 2008. It melted so quickly scientists feared that over the next 15 years, the entire shelf would collapse.

    This collapse was the newest evidence for global warming. Global warming is the current period of climate change. Human activity contributes to global warming by the emission of greenhouse gases into the atmosphere. Some greenhouse gases are carbon dioxide (CO2), methane, and nitrous oxide. Carbon dioxide is released through the burning of fossil fuels. Methane is released by landfills and agriculture. Nitrous oxide is used in fertilizers. Greenhouse gases trap heat in the Earth’s atmosphere—like in a greenhouse. When the planet becomes too hot, glaciers melt, ocean levels rise, and habitats are destroyed.

  • Term Part of Speech Definition Encyclopedic Entry
    agriculture Noun

    the art and science of cultivating the land for growing crops (farming) or raising livestock (ranching).

    Encyclopedic Entry: agriculture
    atmosphere Noun

    layers of gases surrounding a planet or other celestial body.

    Encyclopedic Entry: atmosphere
    climate change Noun

    gradual changes in all the interconnected weather elements on our planet.

    Encyclopedic Entry: climate change
    collapse Verb

    to fall apart completely.

    evidence Noun

    data that can be measured, observed, examined, and analyzed to support a conclusion.

    fertilizer Noun

    nutrient-rich chemical substance (natural or manmade) applied to soil to encourage plant growth.

    fossil fuel Noun

    coal, oil, or natural gas. Fossil fuels formed from the remains of ancient plants and animals.

    glacier Noun

    mass of ice that moves slowly over land.

    Encyclopedic Entry: glacier
    global warming Noun

    increase in the average temperature of the Earth's air and oceans.

    Encyclopedic Entry: global warming
    greenhouse gas Noun

    gas in the atmosphere, such as carbon dioxide, methane, water vapor, and ozone, that absorbs solar heat reflected by the surface of the Earth, warming the atmosphere.

    habitat Noun

    environment where an organism lives throughout the year or for shorter periods of time.

    Encyclopedic Entry: habitat
    ice Noun

    water in its solid form.

    Encyclopedic Entry: ice
    ice shelf Noun

    mass of ice that floats on the ocean but remains attached to the coast.

    landfill Noun

    site where garbage is layered with dirt and other absorbing material to prevent contamination of the surrounding land or water.