study shows earths river ice is rapidly decliningtexas a&m geographys dr george allen co-authored research showing river ice has dramatically decreased over the past 30 yearsjan 16 2020a view of the frozen hudson river on jan 5 2018 in dobbs ferry new york (getty images)dr george allenin what is believed to be the most comprehensive study of its kind a team of researchers that includes a texas a&m university geographer has found the amount of ice in the earths rivers has rapidly declined over the past three decades and the trend is likely to continue dr george allen assistant professor in the department of geography at texas a&m university is part of the study led by researchers at the university of north carolina that is published in the current issue of nature magazine more than a third of the earths land mass is drained by rivers that seasonably freeze over forming river ice examining more than 400 000 satellite images over the past 34 years the team found that the overall amount of river ice has been declining and will almost certainly continue to do so as global temperatures continue to rise the researchers found that for every degree of increase in global temperature there will be about 6 days less of ice per year on rivers that freeze we found that 56 percent of earths rivers are seasonally affected by river ice which amounts to a much greater proportion of rivers than previously thought allen said we found that almost all the river ice is located in the northern hemisphere with only rivers in southernmost portions of new zealand patagonia and australia it is important to note that we only observed rivers with widths over 300 feet so it is likely that there a lot of smaller rivers and streams that also freeze but we did not detect them allen said that rivers are natural hotspots for greenhouse gas emissions to the atmosphere and these emissions typically slow down or completely stop when rivers freeze the teams findings that the occurrence of river ice is declining suggests that the global river network is contributing more and more to the atmospheric greenhouse gas emissions the anticipated acceleration in the decline of river ice is not evenly distributed around the world allen said in the united states river ice is expected to decline most rapidly in the rocky mountains and in the northeast if youve lived in texas for a long time you probably havent thought that much about the importance of river ice allen said however in many parts of the world river ice plays important roles in transportation and in ecosystems for example during the winter many remote arctic civilizations rely on frozen rivers as ice roads in the spring during river ice breakup ice jams can cause unpredictable and hugely disruptive floods but these floods actually benefit ecosystems by distributing nutrients across floodplains allen said the study is made possible by two recent technological developments one is the first global map of river location and width from optical satellite images and the second is cloud- based data provided by google earth engine that makes processing hundreds of thousands of satellite images relatively easy the study was funded by the nasa/cnes surface water and ocean topography (swot) satellite mission which is planned for launch in september 2021 and is expected to provide unprecedented observations of earths rivers and lakes by keith randall texas a&m marketing & communications