Question

The current concentration of carbon dioxide in the atmosphere is 365 ppmv. It was indicated in the text that annual anthropogenic additions to the atmosphere are about \(7 \mathrm{Ct}\) (as C) of which about \(4 \mathrm{Gt}\) are removed into oceans and the terrestrial environment. Use these numbers to estimate the yearly net increase in atmospheric carbon dioxide mixing ratio in ppmv.

Short answer

The yearly net increase in atmospheric CO2 is approximately 1.41 ppmv.

Step-by-step solution

Determine the Net Increase in Carbon Emissions

First, we need to calculate the net increase in carbon emissions due to anthropogenic activities. According to the problem, there are \(7 \mathrm{Gt}\) of carbon emitted annually, and \(4 \mathrm{Gt}\) are removed. So, the net increase in carbon is \(7 - 4 = 3 \mathrm{Gt}\) annually.

Convert Net Carbon Increase to CO2 Increase in ppmv

Next, we need to determine how this net carbon increase translates to an increase in the atmospheric CO2 concentration in ppmv. Since 1 \(\mathrm{Gt}\) of atmospheric carbon corresponds to approximately 0.47 ppmv increase in concentration, we can calculate: \(3 \mathrm{Gt} \times 0.47 \text{ ppmv/Gt} = 1.41 \text{ ppmv}\). Thus, the yearly net increase in atmospheric CO2 is approximately 1.41 ppmv.

Key concepts

Anthropogenic Carbon Emissions

Anthropogenic carbon emissions refer to the release of carbon into the atmosphere due to human activities. These activities primarily include burning fossil fuels such as coal, oil, and gas, as well as deforestation and land-use changes.
Human activities are a significant contributor to the increase in atmospheric carbon levels, with the problem indicating that approximately 7 gigatonnes (Gt) of carbon are emitted every year.

• Fossil fuel combustion accounts for the majority of these emissions.
• Deforestation, which reduces the number of trees available to absorb CO2, also plays a crucial role.
• Industrial processes, including cement production, contribute as well.

Understanding anthropogenic carbon emissions is essential for developing strategies to mitigate climate change. It emphasizes the need to transition to renewable energy sources and implement energy-saving measures to reduce these emissions.

Atmospheric CO2 Increase

The rise in atmospheric CO2 is mainly due to the imbalance between carbon emissions and the planet's capacity to absorb carbon. In our context, the net increase in atmospheric carbon, resulting from human activities, is around 3 Gt per year. This amount remains in the atmosphere after accounting for natural removal processes.
Although humans emit around 7 Gt of carbon annually, the earth's oceans and land absorb approximately 4 Gt of it. This, however, leaves a significant portion—the 3 Gt we mentioned earlier—contributing to increased CO2 concentrations in the atmosphere.
The atmospheric CO2 level is reported in parts per million by volume (ppmv), and each tonne of carbon left unabsorbed increases this concentration. Calculations show that 1 Gt of atmospheric carbon correlates to roughly a 0.47 ppmv increase in CO2 concentration. Thus, annually, atmospheric CO2 increases by about 1.41 ppmv due to anthropogenic activities.

Carbon Removal Processes

Carbon removal processes are crucial in balancing the carbon cycle. They work by absorbing and storing carbon from the atmosphere. The primary natural processes include ocean uptake and terrestrial absorption via photosynthesis.

• The oceans absorb carbon dioxide, converting some of it into carbonates, which play a role in forming shells of marine organisms.
• Vegetation, especially forests, absorb CO2 through photosynthesis, storing carbon in plant biomass.

The problem suggests that around 4 Gt of carbon is sequestered annually through these natural processes. Enhancing these processes could include:

• Protecting and restoring forests to increase carbon sequestration.
• Improving soil management to boost carbon storage in soils.
• Encouraging practices that enhance the ocean's ability to absorb carbon.

These measures are vital for mitigating climate change by offsetting anthropogenic carbon emissions and reducing the net increase in atmospheric CO2.