5.3: Energy Budget and Climate Change

Earth's Energy Budget

So far, we have explored the concept of Earth's energy budget applied to daily, seasonal, and global heat and temperature variations, and have concluded that, in an energy surplus, a location should warm, whereas in an energy deficit, it should cool. We can now apply that same concept to the science behind climate change. Figure \(\PageIndex{1}\) presents a more detailed and holistic view of Earth's energy budget.

Figure \(\PageIndex{1}\): Earth's detailed energy budget. (Public Domain; NASA via Wikimedia Commons). Alternative Description of Image.

The figure may look overwhelming, but let’s take it step-by-step. The yellow numbers represent incoming solar radiation, while the orange numbers represent radiation/heat emitted by Earth. Let’s focus on the top of the Earth’s Atmosphere, where energy either enters (incoming) or leaves (reflected or outgoing) the Earth system. The units for radiation are Watts per Square Meter (W/m²), i.e., how many watts flow through a square meter. These numbers are determined by direct measurements and analysis by the Intergovernmental Panel on Climate Change (IPCC).

9. Based on Figure \(\PageIndex{1}\), the amount of incoming solar radiation equals approximately ______________ W/m2
   1. 163.3
   2. 398.2
   3. 340.4
   4. 239.9
10. Meanwhile, the total amount of radiation leaving Earth can be found by adding the three items at the top of the diagram (namely, reflected by clouds/atmosphere, reflected by the surface, and total outgoing infrared radiation). This total is:
    1. Equal to the amount coming in
    2. Greater than the amount coming in
    3. Less than the amount coming in
11. Therefore, Earth’s temperature should:
    1. Stay the same
    2. Increase
    3. Decrease
12. While there is some year-to-year variation, Earth's average temperature has been trending upward since records began in 1880. This _______________________ the conclusion you made in question 11.
    1. Confirms.
    2. Does not confirm.

So far, we have covered heat, radiation, temperature, absorption, and energy balance. However, the reflectivity of Earth, along with what is present in the atmosphere at a given time (i.e., clouds), can also have a significant impact on Earth’s Energy Budget.