Question

Q2.33. With the current configuration of Earth's continents, global atmospheric CO 2 peaks in late April. Imagine that all of Earth's land mass was instead bunched tightly together around the South Pole. Assume that seasonal patterns of growth and respiration are otherwise the same, with summer occurring June-August in the Northern Hemisphere and December-February in the Southern Hemisphere. How will this new configuration affect seasonal swings in average global CO 2 ? Seasonal swings would be larger, but CO 2

would still peak in late April. Seasonal swings would be a little smaller, but CO 2 would now peak in late August. Seasonal swings would be larger, but CO 2 would now peak in late August. Seasonal swings would be much smaller, perhaps even undetectable. Q2.34. Changes in CO 2 levels in light and dark bottles can be used to measure ocean net ecosystem production (NEP) and gross primary production (GPP) but not net primary production (NPP). Why is this? NPP cannot be estimated without measuring changes in CO 2 levels. The bottles include both primary producers and heterotophic consumers. Dark bottles measure changes caused by autotrophic respiration only. Light bottles measure changes caused by heterotrophic respiration only.

Answer 1

The configuration of continents affects the seasonal swings in global atmospheric CO2, with movements of continents potentially making these swings much smaller or even undetectable. The measurement methods involving light and dark bottles can assess NEP and GPP but not NPP because dark bottles only account for autotrophic respiration.

Step-by-step explanation:

Regarding the hypothetical scenario where all of Earth's land mass is clustered around the South Pole, the seasonal swings in average global CO2 would be much smaller, perhaps even undetectable. This configuration would drastically alter the current global carbon cycle, as a significant portion of the Earth's vegetation, which plays a crucial role in absorbing atmospheric CO2, is located in the Northern Hemisphere. Seasonal growth and respiration, which are largely driven by the biomass and activity in these vegetated areas, currently contribute to the observable seasonal fluctuations in CO2 levels, peaking in late April due to the onset of spring growth in the Northern Hemisphere.

In the case of net ecosystem production (NEP) and gross primary production (GPP), changes in CO2 levels can be measured in light and dark bottles. However, net primary production (NPP) cannot be estimated this way. This is because the dark bottles account for carbon dioxide changes due to autotrophic respiration only, occurring without the influence of light, and the light bottles take into consideration the impact of light on both autotrophic and heterotrophic organisms, including their respiration and photosynthesis processes, but do not distinguish between the two to offer a measure of actual net primary productivity.