Emission of greenhouse gases from Indian wetlands: an overview

Given that wetlands, especially man-made wetlands including paddy fields, are a major source of the greenhouse gases methane and nitrous oxide, a study of the present status of knowledge in this area was carried out with reference to India. Based on printed material, digital repositories, and personal correspondence an up-to-date assessment of all studies reported so far has been conducted. It is shown that despite India having 4.6% of its area covered by natural or man-made wetlands, being home to a very large number of wetlands, and being the second largest cultivator of paddy in the world, its wetlands—including paddy fields which are intermittently flooded as typical wetlands are—have been very poorly studied in terms of their GHG emissions. Even the reports that are available have been mostly confined to a few regions of India, and as many as seven of the most wetland-rich states—Bihar, Chhattisgarh, Jharkhand, Madhya Pradesh, Maharashtra, Himachal Pradesh, and Jammu & Kashmir—have not been studied in this respect at all. A major finding is that, contrary to a recent report published by authors based in USA, intermittently irrigated rice fields have not been found to emit exceptionally high quantities of nitrous oxide. The study brings out the urgent need for carrying out assessments of GHG emissions from wetlands throughout India with a view to finding strategies to minimize such emissions.