While there are natural sources of the primary greenhouse gases,
human activities have without a doubt overloaded and changed the
atmosphere. Ever since the Industrial Revolution, we’ve been
steadily producing and releasing carbon dioxide and other heat-
trapping gases into the atmosphere. In 2005, global atmospheric
concentrations of carbon dioxide were 35% higher than they were
before the Industrial Revolution.1 Today, climate scientists,
meteorologists and oceanographers are using high-tech tools and
models to figure out just how much human activities have
contributed to global warming. Using sophisticated computer
programs and models, scientists can get a picture of how the
Earth’s atmosphere and oceans respond to natural and human
factors. Then they compare past climate patterns with these
models to see which factors have contributed the most to global
warming. You can learn more about how scientists measure climate
from the Natural Resources Defense Council. Measuring the human
fingerprint The science pr