The Earth's climate has changed throughout history. Just in the last 650,000 years there have been seven cycles of glacial advance and retreat, with the abrupt end of the last ice age about 7,000 years ago marking the beginning of the modern climate era — and of human civilization. Most of these climate changes are attributed to very small variations in Earth’s orbit that change the amount of solar energy our planet receives.
Scientific evidence for warming of the climate system is unequivocal.
The current warming trend is of particular significance because most of it is extremely likely (greater than 95 percent probability) to be the result of human activity since the mid-20th century and proceeding at a rate that is unprecedented over decades to millennia.
Earth-orbiting satellites and other technological advances have enabled scientists to see the big picture, collecting many different types of information about our planet and its climate on a global scale. This body of data, collected over many years, reveals the signals of a changing climate.
This graph, based on the comparison of atmospheric samples contained in ice cores and more recent direct measurements, provides evidence that atmospheric CO2 has increased since the Industrial Revolution. (Credit: Vostok ice core data/J.R. Petit et al.; NOAA Mauna Loa CO2 record.)
Discussion
Discuss the following in a group or as a class:
- What do you know about Climate Change?
- How do organisims cohabitate on Earth?
- What are some mysteries or misconceptions about Climate Change?
Video
Please watch the following video. Please note that the narrator speaks about a lot of specific dates, terms, and uses academic vocabulary; do not worry about taking notes. Simply listen closely to absorb the information.
Reflection
Discussion
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