A study published in the journal "Science" by a group of scientists from UNH and Tulane University revealed that Hurricane Katrina, one of the biggest ecological disasters in United States history, damaged about 320 million large trees.
The dead and dying trees will release about 105 million metric tons of carbon dioxide into the atmosphere, equaling the net amount of carbon dioxide taken out of the atmosphere by all of the forests in the United States in one year. This large amount of carbon dioxide raises concerns about possible effects on global warming in the future as well as the importance of the human role.
"I think we're going to recognize it's not just hurricanes," said Dr. Berrien Moore III, director of the UNH Institute for the Study of Earth, Oceans, and Space. "It's not Hurricane Katrina, it's humans… We are going to have to monitor very carefully the state of the planet. There will be other Katrinas."
Dr. George Hurtt, associate professor of natural resources at UNH, participated in the study. The scientists used extensive field studies in conjunction with satellite images of the area before and after Katrina to assess damage. Hurtt said that when the team of scientists added up their data the damage was more than they had predicted.
"We were expecting big numbers, but we got huge numbers," Hurtt said. "That's a tree for every person in the country."
He said the amount of carbon dioxide released into the atmosphere could potentially create a "severe crisis" in the future by making global warming worse.
Hurtt said the crisis he is concerned about is a positive feedback cycle. If carbon emissions outpace carbon sink processes, which take carbon dioxide out of the atmosphere, excess carbon dioxide collects in the atmosphere and traps heat. The earth becomes warmer, and as a result more intense storms occur that destroy more trees. More dead trees release more carbon dioxide, which contributes to further global warming.
Hurtt said the concern is that human activities may be contributing to a change in the frequency and intensity of storms. This could mean that in the future there may not be enough time in between major storms for forests, which absorb carbon dioxide during photosynthesis, to recover and balance out carbon emissions. He said science is discovering that nature is not as resilient to global warming as previously thought.
Dr. Jeffrey Chambers, lead author of the study and assistant professor of ecology and evolutionary biology at Tulane University, said the problem is when carbon emissions from processes like tree decay gain faster than the earth's natural carbon sink. The resulting imbalance in natural processes would be the same as if humans increased their emissions. The key question, he said, is if the earth's carbon sink will keep up at its current rate, grow weaker or grow stronger.
He said that while the deforestation from Hurricane Katrina only accounts for a small percentage of carbon dioxide emissions, it must be taken into account with other disasters, like wildfires and typhoons, which also result in forest destruction and carbon emissions.
"We need to start adding up the pieces," Chambers said.
Moore compared the damage from Hurricane Katrina to throwing a large rock in a pond. He said that due to the large scale of the disaster it can affect the global atmosphere and create a ripple effect even though the forests will gradually recover.
The team of scientists is planning to quantitatively assess how strong this feedback system could be. This includes studying how fast the carbon dioxide is being released and how fast the forests are recovering. The scientists will also study other storms and disasters that have caused destruction of trees.
"We don't know if that's [positive feedback system] quantitatively important yet," said Chambers. While the connection is there, he said they have to find out if the numbers are large enough to cause concern.
Hurtt said that while the carbon dioxide released from the destroyed trees cannot be prevented, there are other ways people can prevent carbon emissions.
Hurtt said people can be aware of carbon dioxide pollution and control it through methods like driving hybrid cars or using compact fluorescent light bulbs. He said many of these methods are easy and save people money.
"We need to get control of our carbon emissions," Chambers said. Adding that reducing our carbon emissions could stabilize and control climate change.
"In the end, it's [the study] another reason why people should be concerned about global warming," Hurtt said.
Be the first to comment on this article!