Evaluating Natural and Human Activities Effects on Earth's Clima

Evaluating Natural and Human Activities Effects on Earth's Climate

What happens when the amount of energy entering into the Earth system does not equal the amount that exits? This is a simple question with a complicated answer.

Energy into Earth - Energy leaving Earth = Radiative Forcing Amount

Imbalances in the Earth's Energy Budget are called radiative forcings. They cause chemical and physical changes in the Earth system that impact the climate. An example of this imbalance is the current trend in Earth's Energy Budget; the Earth system has more energy entering than leaving (called a "positive forcing"). Conversely, if more energy exits than enters the system, the planet would cool ("negative forcing").

Prior to the Industrial Revolution, the radiative forcing was nearly balanced, and Earth's atmosphere was relatively stable. Scientists use a year prior to this era, 1750, as a baseline. This baseline year is used to compare radiative forcings and measure the impact of anthropogenic activities of modern times that affect our climate. See the chart below to identify and analyze the warming or cooling effects of these forcings. Notice that there are two main categories: anthropogenic (human-caused) and natural.

Open Ended

What is the net total value of radiative forcing (in watts per square meter) of natural activities?

Multiple Choice

Why is the year 1750 selected as a baseline?

• That's when scientists started measuring gases in the atmosphere

• It is before the Industrial Revolution

• There were no human activities before 1750

• Greenhouse gases did not exist before 1750

Multiple Choice

Short-lived gases have the greatest effect on climate change

• True

• False