Manisha Sashital, a student in Environmental Engineering and Environmental Policy at Carnegie Mellon University, worked on a botanical glossary under the supervision of Dr. Mori at the Garden this summer. As part of her internship she prepared a cartoon illustrating the relationship between photosynthesis and respiration.

Scott A. Mori has been studying New World rain forest plants for The New York Botanical Garden for over 35 years. His interest in tropical forests as carbon sinks have been stimulated by his studies of trees in old growth tropical  forests.

Global warming has become one of the planet’s deadliest threats. Since the Industrial Revolution, carbon dioxide concentrations have risen from 280 ppm to nearly 390 ppm, with the potential to reach 550 ppm by 2050 if carbon emissions from fossil fuel combustion are not controlled. The earth has experienced major warming three times; but the Cretaceous warming period took place over millions of years and the Paleocene/Eocene warming happened over thousands of years. In contrast, today’s temperature changes are happening over decades. As a result, many species, perhaps even humans, may not be able to adapt to such rapid and high increases in temperature. One concern that is generally unknown to the public is that photosynthesis, the source of energy for nearly all organisms on the planet, shuts down at around 104° F. Mankind’s extreme disruption of the carbon cycle is causing and will continue to cause serious consequences for life on earth.

Carbon dioxide levels contribute to global warming through the greenhouse effect. Greenhouse gases trap radiation from the sun in the atmosphere, which causes global temperatures to rise because the radiation is not reflected back out of the atmosphere. The reason for today’s increased atmospheric carbon levels can be attributed to the combustion of fuels used for the production of electricity and in transportation, both of which are essential to modern societies; as well as to cutting and burning forests throughout the world. Since there is no precedent for the rapidity of current temperature increases, it is impossible for humans to predict which areas of the world will be affected and at what magnitude. The unpredictability of global warming makes it an especially serious environmental problem.

Rain forests as well as other vegetation types play an important role in reducing the levels of carbon dioxide in the atmosphere. Annually, plants in tropical rain forests around the world take in millions of tons of carbon dioxide and release millions of tons of oxygen through photosynthesis, and this balances the respiration of microbes, plants, and animals, which take in oxygen and expel carbon dioxide. As seen in the accompanying cartoon, plants take in carbon dioxide and water and use the energy of the sun to create carbohydrates that are, in turn, oxidized to produce the energy needed for plants to sustain themselves. The carbohydrates are also the building blocks plants use to make leaves, stems, flowers, and fruits. Oxygen, the byproduct of respiration, is used by organisms to break down ingested carbohydrates to produce the energy needed for them to grow and reproduce. Mankind’s extreme disruption of the carbon cycle is and will continue to have serious consequences for life on earth.
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What is it about the sunlight in September that makes everything look so magical?

Photo by Ivo M. Vermeulen