We often think about the issue of global warming in terms of its effects on the polar ice caps, its role in changing or destroying sensitive animal habitats, or its known penchant for altering historical weather patterns. Few seem to realize, however, that one of the greatest threats global warming presents to our planet is its reduction of phytoplankton activity in the oceans, a phenomenon that results in less oxygen and more carbon dioxide in the atmosphere. In order to understand the full implications of this, we first need to look at what phytoplankton activity means for our planet.
The world today generally understands the role trees play in taking carbon dioxide out of our atmosphere, as evidenced by the flurry of tree-planting projects around the planet today. What is less well known, however, is that phytoplankton plays a similar, but much larger, role in keeping our world oxygen-rich.
The reason for this is that phytoplankton are quite efficient at photosynthesis, the same method by which trees absorb light to create usable energy, releasing life-giving oxygen as a byproduct. What is astonishing about phytoplankton is that it is responsible for about half of the world's photosynthesis! Without phytoplankton, our world would quickly become inhospitable for life, as the planet's CO2 levels would increase rapidly and its oxygen supply rapidly decrease. Any decrease in phytoplankton productivity contributes to this phenomenon as well.
Phytoplankton is incredibly efficient in its photosynthetic capacity, needing little mass to produce great quantities of oxygen. It is this same lack of mass, however, that makes it more sensitive to global warming than trees and plants. Because phytoplankton usually exists as a thin layer skimming the top of the ocean, it is consumed by ocean life and replaced, on average, every two to six days, depending on location and type. Its fragility makes it particularly susceptible to climate change.
Studies have indicated that rising ocean temperatures inhibit phytoplankton productivity by a significant percentage, making global warming the most dangerous threat to its oxygen-producing capacity. Worse still, extremely high temperatures can even result in its destruction, a disaster of epic proportions that would quickly make our world close to uninhabitable for life. The rich, abundant, and free operation of photosynthetic operation in the oceans is essential to life as we know it on this planet. It is the hidden sustainer of our continued existence.
Research has shown that phytoplankton productivity is off by as much as 6% in the past 30 years, and although determining the full explanation for this decline is an extremely complex and multi-factored undertaking, the decline in productivity has coincided with a 1.7 degree increase in North Atlantic summertime temperatures, as well as a .7 degree increase in the Pacific. Debate has raged over whether this increase is the cause or product of the decline in productivity. A chicken-or-egg discussion often ensues: which is the cause, and which the effect?
The key lies in looking at what other causes there might be for the decrease in phytoplankton productivity. To date, scientists have been unable to discover any other factors that might account for a decrease as large as the 6% number indicated by studies. It does appear that the only factor significant enough to decrease productivity on such a massive scale is climate change.
There is little doubt among most scientists today that global warming is at least partially due to human activity on our planet. The energy consumption required to sustain 6 billion human beings on an increasingly crowded planet has led to CO2 levels never seen before in history, indicating that we are in large part responsible for the warming phenomenon. Combating our own tendency to pump CO2 into our atmosphere seems to be our best hope for stopping this trend and its effects, including the decrease in phytoplankton productivity that, if left unchecked, could seriously endanger life on Earth as we know it.