Directions: Use the information provided and your knowledge of Life Science to answer the following questions. Show all work where necessary.
Directions: Use the information provided and your knowledge of Life Science to answer the following questions. Show all work where necessary.
Major cities around the world are hotspots of carbon cycling because they burn large amounts of fossil fuels for electricity, heating, transportation, and industry. Fossil fuels - coal, oil, and natural gas - are long-term carbon reservoirs stored deep within the geosphere. When they are extracted and burned, carbon that has been locked away for millions of years moves rapidly into the atmosphere as carbon dioxide (CO2). This urban-driven shift illustrates how carbon moves among the atmosphere, biosphere, hydrosphere, and geosphere.
Once CO2 enters the atmosphere, it becomes part of the global carbon pool. Some CO2 is absorbed by urban vegetation, especially in parks, street trees, and green roofs. Trees use CO2 during photosynthesis to create organic molecules that store carbon in leaves, wood, and roots, returning part of the atmospheric carbon back to the biosphere. However, the amount of carbon absorbed by urban vegetation is generally very small compared to the enormous amount released by vehicles, buildings, and industrial activities. This imbalance leads to net increases in atmospheric CO2 that contribute to global climate change.
Urban areas also impact the hydrosphere. Rainfall washes carbon-rich particles from vehicle exhaust, building materials, soil surfaces, and decaying organic matter into storm drains and waterways. Rivers transport both dissolved and particulate organic carbon toward the ocean. As emissions rise, the total carbon entering river systems from urban runoff also increases, linking city emissions directly to the hydrosphere.
The geosphere remains central in the urban carbon cycle. The carbon stored in fossil fuels moves from deep geological formations to the atmosphere within seconds during combustion. Over longer periods, carbon from atmospheric CO2 can accumulate in soils, building materials (such as concrete), or sediments transported by rivers. These relationships show how human activity drives rapid transfers among Earth’s spheres, but also how slowly carbon may return to long-term storage.
Mathematical patterns reveal measurable trends: Fossil fuel emissions rise steadily with urban growth, carbon uptake by vegetation increases only slightly, and carbon transported into rivers increases with expanding city footprint. These data allow students to model carbon movement across spheres and support claims about the imbalance created by human activities.
Diagram 1.
Diagram 2.
Diagram 3.
Table 1.
City | Fossil Fuel CO | Urban Vegetation Uptake (Mt/yr) | Net Atmospheric Increase (Mt/yr) |
|---|---|---|---|
Metro A | 220 | 12 | 208 |
Metro B | 310 | 18 | 292 |
Metro C | 410 | 24 | 386 |
Graph of Information - Figure 1.
Table 2.
Year | City Emissions Mt | Carbon to Rivers Mt |
|---|---|---|
2000 | 260 | 14 |
2005 | 290 | 16 |
2010 | 320 | 19 |
2015 | 355 | 22 |
2020 | 390 | 25 |
Graph of Information - Figure 2.
Using Table 1 and Figure 1, describe how the mathematical relationship between fossil fuel emissions and vegetation uptake leads to net atmospheric carbon increases in different metropolitan areas.
According to Table 1, which metropolitan area has the highest net atmospheric CO
Using Diagram 1 and the reading, explain how human-driven carbon transfers from the geosphere influence matter cycling among the atmosphere, biosphere, and hydrosphere.
Based on Table 2, in which year does carbon entering rivers reach 22 Mt?
Using Table 2 and Figure 2 (page 4), describe the mathematical trend in urban CO
Use mathematical representations to explain how fossil fuel combustion in cities alters carbon cycling among the atmosphere, biosphere, hydrosphere, and geosphere.
Respond using Claim, Evidence, and Reasoning.