Meaning of climate change and Earth’s long-term shifts

Summary

Climate change refers to long-term changes in Earth’s temperature, precipitation, and other atmospheric conditions. In everyday discussions, it often means human-caused global warming happening now, driven mainly by increased greenhouse gases such as carbon dioxide and methane from activities like burning fossil fuels, deforestation, and industrial processes. These changes can lead to impacts including more extreme weather, rising sea levels, and disruptions to ecosystems and agriculture. Earth’s climate has also shifted naturally over very long periods—tens or hundreds of millions of years—alternating between hotter and colder times, including ice ages. Ice ages are long cold periods when more ice forms at the North and South Poles, and sometimes Earth has even been largely covered in ice. There is no single cause for ice ages; factors can include changes in Earth’s orbit, variations in the Sun’s brightness, and changes in Earth’s tilt, as well as influences from living things over geologic time. Scientists also assess the role of the Sun. Although the Sun varies slightly (for example, through the 11-year sunspot cycle), current scientific consensus is that solar variations play only a very small role in recent climate change. Warming from human-produced greenhouse gases is far stronger than effects from recent changes in solar activity.

Key Points

• 1

  Climate change includes long-term shifts in temperature, rainfall, and atmospheric conditions; today it usually refers to human-caused global warming.

• 2

  Earth’s climate has repeatedly changed over tens or hundreds of millions of years, including ice ages, driven by multiple natural factors such as orbital changes and Earth’s tilt.

• 3

  Solar variations have only a minor influence on recent climate change compared with warming from increased human greenhouse gas emissions.