Hurricanes can be brutal, extreme releases of weather, and are often perceived negatively for their destructive power. But what if they were also a help? What if they were responsible for soaking up vast quantities of carbon dioxide?
According to new findings by Duke University’s Pratt School of Engineering, tropical cyclones cause forests in the southeast of the United States to draw in more carbon than is annually emitted by all the cars in the country. ‘The water cycle and the carbon cycle are tightly linked with plants acting as a medium between the two,’ says Ana Barros, Environmental Engineer at the university and co-author of the research. ‘Depending on the weather conditions, plants can vary in the amount of carbon dioxide they uptake with photosynthesis.’
Tropical storms can be an asset by breaking summer periods of drought, when plants and soils become too stressed to uptake much CO2. ‘Soil layers can dry out and roots cannot extract the water needed for transpiration,’ says Barros. ‘At that point, the plant’s pores – or stomata – close to reduce further water loss. Closed stomata means they cannot uptake CO2.’
“We often forget that in some parts of the world, tropical storms are not ‘extreme’, in the sense that they happen often, and are essential mechanisms of the regional water cycle”
According to her research, a hurricane’s sudden release of rainwater into the cycle ‘resets’ the amount of soil water available, allowing photosynthesis to resume. Meanwhile, surplus water can be stored in the soils, allowing for rates of photosynthesis to remain at normal levels until the next hurricane landfall or rain event.
Is this information likely to change how hurricanes are perceived? ‘We often forget that in some parts of the world, tropical storms are not “extreme”, in the sense that they happen often, and are essential mechanisms of the regional water cycle,’ says Barros. With tropical storms likely to increase in frequency and intensity, it might be that they become appreciated for the relief they can bring to the water cycle and the role they play in carbon budgets at local, regional and global scales.
This was published in the July 2016 edition of Geographical magazine.