HS-ESS3-6: Modeling How Humans Change Earth's Systems
Also called NGSS HS-ESS3-6 · Topic: Human Sustainability · Earth and Space Science
The Official Wording
Use a computational representation to illustrate the relationships among Earth systems and how those relationships are being modified due to human activity.
Clarification statement: Examples of Earth systems to be considered are the hydrosphere, atmosphere, cryosphere, geosphere, and/or biosphere. An example of the far-reaching impacts from a human activity is how an increase in atmospheric carbon dioxide results in an increase in photosynthetic biomass on land and an increase in ocean acidification, with resulting impacts on sea organism health and marine populations.
Assessment boundary: Assessment does not include running computational representations but is limited to using the published results of scientific computational models.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What HS-ESS3-6 Means in Plain English
Students use the results of computer models and long data records to show how Earth's spheres, the air, water, ice, rock and living things, are connected, and how one human change ripples through them, like extra carbon dioxide reaching the ocean and the creatures in it.
Students are not asked to run the models themselves. They read and interpret published model output, such as graphs and maps of future conditions. It builds on HS-ESS2-6 and HS-ESS3-5, and links to ecosystem change in HS-LS2-6.
HS-ESS3-6 I Can Statements
- I can trace how carbon moves between the air and the ocean.
- I can read a model graph to describe a future Earth system change.
- I can explain how one human change affects several Earth systems.
HS-ESS3-6 Worked Example
A data analysis a class can do with the free ocean records from Station ALOHA near Hawaii.
As carbon dioxide in the air rises, what happens to the chemistry of the open ocean?
Set It Up: Downloaded records of atmospheric carbon dioxide and seawater pH from the Hawaii Ocean Time-series at Station ALOHA, plus a published projection map of surface ocean pH for 2100.
- Graph carbon dioxide in the air and in the surface water from 1988 onward.Both climb together
- Add seawater pH on the same time axis.pH drifts down as CO₂ rises
- Find the pH change across the record.About 0.05 lower in 30 years
- Read the projection map for 2100 under high and low emissions.Bigger drop under high emissions
- Trace the effect on shell builders such as pteropods and corals.Less carbonate for shells
Carbon dioxide in the air and in seawater rose together while pH fell, and the models show the drop continuing unless emissions fall.
Why it works: The ocean absorbs carbon dioxide, which forms carbonic acid, lowering pH and leaving less carbonate for animals that build shells.
Common Mistakes with HS-ESS3-6
Acidified means acidic
“The ocean will soon burn like lemon juice.”
Try this: Seawater is still basic, around pH 8.1. Acidification means pH is moving toward acidic, enough to stress shell builders.
One system at a time
Explaining extra CO₂ only as an air problem
Try this: Follow the change across systems: from the atmosphere into seawater, then into living things and their food webs.
A small number means a small change
“pH only dropped 0.1. That is nothing.”
Try this: The pH scale is logarithmic, so a drop of 0.1 means about 26% more hydrogen ions in the water.
Where HS-ESS3-6 Fits
Practice HS-ESS3-6
Quick Check
- Why does adding carbon dioxide to the air change the ocean?
- Why are pteropods and corals at risk from acidification?
- Seawater pH falls from 8.2 to 8.1. Is the ocean now acidic?