University of Canterbury scientists are part of a global research collaboration into the environmental impacts of dry riverbeds, with their findings published today in a new paper in one of the world’s top scientific journals (see AgScience report HERE).
New Zealand researchers, Professor of Freshwater Ecology Angus McIntosh and Dr Catherine Febria, of the School of Biological Sciences, UC College of Science, have been part of a global team from 22 countries evaluating what happens to plant litter that falls into in river beds when they are dry (i.e. not flowing).
They co-authored the paper titled ‘A global analysis of terrestrial plant litter dynamics in non-perennial waterways’ which was published today in Nature Geoscience.
“People might feel that a pile of plant litter accumulating in a dry river bed couldn’t possibly contribute to global climate warming, but the surprising reality is it very likely is,” Professor McIntosh says.
The contributions of drying rivers haven’t been included in global carbon accounting previously and their CO2 effects could be significant.
“This is especially important because, surprisingly, intermittent streams and drying rivers are thought to include more than 50% of the river length world-wide,” he says.
Dr Febria says it is known that when rivers dry up fish and insects die, and the whole food web of the river collapses.
“However, we haven’t previously appreciated the significance of all the decomposition that happens when the water comes back. The amount of carbon dioxide released in many cases is huge,” she says.
“We should all care about this because carbon dioxide in our atmosphere is the driver of global climate warming.
“Our research indicates that increasingly drying rivers, along with other land use changes, are contributing to global climate warming. Moreover, climate warming in many places like Canterbury is predicted to increase the frequency and magnitude of drought which could also cause more river drying.
“That is a really worry because that could form a positive feedback cycle by releasing even more carbon dioxide.”
This is the first piece of research published from this collaborative study involving 94 international partners from 22 countries studying the dry beds of 212 rivers from round the world, including Canterbury.
Until recently, drying and intermittent rivers had been largely ignored. This global study is beginning to reveal they really are very important and should not be ignored.
Such extensive global research efforts have traditionally been rare. That a very large group of researchers from around the world, led by a group in France, have come together to contribute is really quite significant, Professor McIntosh says.
He didn’t expect the magnitude of emissions to be so high. Therefore the findings should force a rethink of how the global carbon models are made so that they include CO2 emissions from intermittent rivers.
Source: University of Canterbury