Scientific evidence indicates that the CO₂ added to the air by the burning of wood and fossil fuels is contributing to global warming, a rise in global temperature. Tropical rain forests are estimated to be responsible for approximately 20% of global photosynthesis, yet the consumption of large amounts of CO₂ by living trees is thought to make little or no net contribution to reduction of global warming. Explain why this might be the case. (Hint: What processes in both living and dead trees produce CO₂?)

Global warming is an increase in the overall temperature of the Earth’s atmosphere. Long-term heating affects the climate of the Earth as more and more greenhouse gases get trapped in Earth’s atmosphere.

Human activities such as industrialization, specific agricultural methods, burning of fossil fuels, and deforestation are some factors that contribute to global warming. All these activities trap greenhouse gases like carbon dioxide, water vapor, and methane.

Of all these gases, carbon dioxide is the primary gas resulting from human activities that contribute mainly to global warming.

Living plants remove carbon dioxide from the atmosphere by taking it in during photosynthesis. As a result, plants and tropical rainforests with abundant vegetation are expected to reduce carbon dioxide from the atmosphere significantly.

However, living plants also respire and hence undergo cellular aerobic respiration. In this process, plants take in oxygen, oxidize the organic substances for energy production, and release carbon dioxide into the atmosphere as waste.

Therefore, more carbon dioxide is added to the atmosphere by plants, increasing the global burden of atmospheric carbon dioxide.

Plants contain stored carbon dioxide. During deforestation, burning of trees, or death, the stored carbon dioxide gets released into the atmosphere. In this way, dead plants also increase the global carbon dioxide concentration.

As a result, the large amount of carbon dioxide reduced from the atmosphere by the plants during photosynthesis is compensated or counteracted by dead plants and cellular respiration in living plants.