Though human-made ponds both sequester and release greenhouse gases, when added up, they may be net emitters, according to two related studies by Cornell researchers.
The studies begin to quantify the significant effects that both human-made and natural ponds have on the global greenhouse gas budget, measurements that aren’t well understood.
“Global climate models and predictions rely on accurate accounting of greenhouse gas emissions and carbon storage,” said Meredith Holgerson, assistant professor of ecology and evolutionary biology in the College of Agriculture and Life Sciences and senior author of the studies. Nicholas Ray, a postdoctoral researcher in Holgerson’s lab, is a co-author of both papers.
Holgerson and colleagues have previously estimated that ponds – defined as 5 hectares (12 acres) or less and of which there could be 1 billion on Earth – may contribute 5% of the global methane emissions to the atmosphere. But without accurate measurements across many water bodies, the true number could be as little as half or as much as twice that percentage. At the same time, very few estimates of carbon burial rates in ponds exist.
One paper, “High Rates of Carbon Burial Linked to Autochthonous Production in Artificial Ponds,” published Aug. 18 in the journal Limnology and Oceanography Letters, examines how much carbon is sequestered in 22 Cornell Experimental Ponds. The identical ponds – there are 50 – constructed in 1964, provided highly controlled environments, with detailed records from previous studies. The data allowed Holgerson and Ray to evaluate how management activities contributed to carbon storage.