Melting Permafrost and the Arctic Ocean
Yukon River Delta, Sediment Runoff, and Phytoplankton Bloom (credit: NASA & USGS)
Environmental relationships between landscapes and coastal zones directly interact where waters feed from river deltas. Any sediments moving downstream are eventually deposited into a bay, estuary, or ocean. Seasonal flows from the Nile, Yangtze, and Mississippi rivers have told stories of history, civilization, commerce, and agriculture for millennia. This is still true.
Rivers in the Arctic are less well know but are especially useful to track climate change, virtually in real-time now. NOAA's Arctic Report Card offers yearly updates on the observations in progress, including the regions rivers. Arctic soils, long frozen as permafrost, are now melting rapidly and the runoff carries heavy sediment loads that is being directly deposited into the Arctic Ocean. One study measured changes to the Yukon River over more than 30 years analyzing changes in water chemistry as a timeline guide. According to the investigators:
"the Yukon region has experienced a warming climate over the last century that has altered air temperature, precipitation, and permafrost. Using a water chemistry database from 1982-2014 for the Yukon River and its major tributary, the Tanana River significant increases of dissolved calcium (Ca), magnesium (Mg), and sodium (Na) were found in both rivers. Additionally, sulfates (SO4) and phosphorus (P) increased in the Yukon River.
and their report concluded:
"the thawing permafrost enables the release of more greenhouse gases to the atmosphere and also allows much more mineral-laden and nutrient-rich water to be transported to rivers, groundwater, and eventually into the Arctic Ocean.”
Nutrients including calcium, magnesium, and phosphorus are essential for healthy plant growth. However, when present in over-abundant amounts this chemistry allows for the spread of phytoplankton blooms in lakes, bays, and oceans.
A video shows the consequences of melting permafrost on cities, landscapes, and the regional ecology. Unlike historical knowledge experienced from the Nile, Yangtze, or Mississippi, the changes underway with Arctic rivers is just being quantified and interpreted. WHB