There’s some recently published research on climate change¹ that you can easily incorporate into your next lesson on metric conversions and unit analysis. The article gives a report on ocean heat content (OHC) measurements. Because 90% of the energy in our climate system is stored in the oceans, OHC measurements provide a strong indicator of global warming. In the report, the authors note that climate change and global warming are caused when:

“Human activities release greenhouse gases (GHGs) into the atmosphere, increasing their concentration and trapping heat within the climate system, which drives global heating.”¹

In particular, the report focuses on changes in energy in our oceans. To this end, the authors state that:

“Global ocean heat content changes... show that there has been an unequivocal ocean warming trend in recent decades…Since 2007, the upper 2000 m ocean warming rate has been 11.1 zettajoules per year.”¹

You can also see in the report that between 1958 and the end of 2024, the oceans have taken in about 420 ZJ of energy.¹

Note that the authors use the metric prefix “zetta”, which refers to multiplication by 10 to the power of 21. Students can be challenged to write 11.1 ZJ or 420 ZJ in the numerical form with the appropriate amount of zeros: 11,100,000,000,000,000,000,000 and 420,000,000,000,000,000,000,000, respectively.

These amounts of energy are so ridiculously large that it’s hard to gain an understanding of the meaning of these measurements.

Some context can be provided by informing students that one of the atomic bombs detonated at the end of World War II released 63 TJ, or 63 terajoules, or energy.²  The prefix "tera" refers to multiplication by 10 to the power of 12, so 63 terajoules is 63,000,000,000,000 joules. Once this is determined, students can calculate the number of atomic bomb detonations it would take to release the same amount of energy in 11.1 ZJ or 420 ZJ (this works out to 11.1 ZJ = 176 million bombs and 420 ZJ = 6.7 billion bombs, respectively). If desired, students can be challenged to convert the current rate of warming (11.1 ZJ per year) to units of atomic bombs per second (this works out to 5.6 atomic bombs per second).

Further context can be added by noting that hurricanes can release up to 10,000 atomic bombs worth of energy.³ In this context, 11.1 ZJ and 420 ZJ compare to the energy released by 18,000 and 670,000 large hurricanes, respectively.

References:

1. Cheng, L.; Abraham, J.; Trenberth, K.E. et al. Record High Temperatures in the Ocean in 2024. Adv. Atmos. Sci. 2025. https://doi.org/10.1007/s00376-025-4541-3
2. Pearson, E. F. Hurricane Ike versus an Atomic Bomb. J. Chem. Educ. 2013, 90, 90-92.
3. Graham, S.; Riebeek, H. Hurricanes: The Greatest Storms on Earth. 2006. https://earthobservatory.nasa.gov/features/Hurricanes (accessed January, 2005).