New European satellite to study Earth’s ice, researchers trace early Native American carbon footprint
Compiled by Summit Voice
SUMMIT COUNTY — Australian researchers have linked warmer global temperatures with changes in deep-ocean salinity patterns, as the water is becoming less salty in areas dominated by rainfall, and the salinity is increasing where evaporation dominates.
The broad-scale patterns of change were documented based on historical records and data provided by a world-wide network of ocean profilers —‚ robotic submersible buoys which record and report ocean salinity levels and temperatures to depths of two kilometers.
“This is further confirmation from the global ocean that the Earth’s water cycle has accelerated,” said Paul Durack, an Australian university researcher. The changes are consistent with modeled predictions by the Intergovernmental Panel on Climate Change, he added.
The research is related to the oceans’ water-exchange cycle. Average ocean-surface temperatures have increased by about 0.4 degrees since 1950. As the near-surface atmosphere warms, it evaporates more water from and moves it to new regions where it’s released as rain or snow.
The salinity patterns reflect the contrasts between ocean regions where the oceans lose water to the atmosphere and other areas where it is re-deposited on the surface as salt-free rainwater.
The scientists said the salinity changes are expected at the surface of the ocean, but wide-scale study shows there much broader changes, driven by global warming, extending into the deep ocean.
The studies will also provide new benchmark data to help validate global climate models as they relate to ocean cycles.
The studies were conducted by the Commonwealth Scientific and Research Organization and recently published in the American Journal of Climate.
New satellite to study Earth’s ice
More useful data on climate change is starting to stream in from the European Space Agency’s CryoSat-2 satellite, launched April 8. The new space mission is Europe’s first dedicated to studying variations in the planet’s ice cover. The satellite entered a polar orbit and ground controllers last Sunday switched on its primary instrument, taking measurements of the Ross Ice Shelf in Antarctica that clearly show the ice cover and reflections from underlying layers.
The satellite is reaching latitudes of 88 degrees, bringing T it closer to the poles than earlier Earth observation satellites and covering an additional 4.6 million square kilometers — an area larger than all 27 European Union member states put together.
CryoSat-2′s instruments will measure changes at the margins of the vast ice sheets that lie over Greenland and Antarctica and in the marine ice floating in the polar oceans. By accurately measuring thickness change in both types of ice, CryoSat-2 will provide information critical to scientists’ understanding of the role ice plays in the Earth system. More info on the Earth’s cryosphere at the National Snow and Ice Data Center.
Early carbon footprint?
Ohio University scientists studying stalagmites in West Virginia say their research shows that land-use practices by early Native Americans may have left a bigger carbon footprint than previously believed. A chemical analysis of a stalagmite found in the mountainous Buckeye Creek basin of West Virginia suggests humans impacted global climate long before the modern industrial era.
Early Native Americans burned trees to actively manage the forests, helping provide harvests of nuts and fruit that were a large part of their diets.
“They had achieved a pretty sophisticated level of living that I don’t think people have fully appreciated,” said Gregory Springer, an associate professor of geological sciences at Ohio University and lead author of the study, which was published a recent issue of the journal The Holocene. “They were very advanced, and they knew how to get the most out of the forests and landscapes they lived in. This was all across North America, not just a few locations.”
The researchers started out studying carbon isotopes in stalagmites to trace historic drought cycles in North America. During the research, they found the carbon record contained evidence of a major change in the local ecosystem beginning at 100 B.C. This intrigued the team because an archeological excavation in a nearby cave had yielded evidence of a Native American community there 2,000 years ago.
Subsequent research on stream sediments showed high levels of charcoal and a carbon isotope history similar to the stalagmite.
This evidence suggests that Native Americans significantly altered the local ecosystem by clearing and burning forests, probably to make fields and enhance the growth of nut trees, Springer said.
This picture conflicts with the popular notion that early Native Americans had little impact on North American landscapes. They were better land stewards than the European colonialists who followed, he said, but they apparently cleared more land and burned more forest than previously thought.
“Long before we were burning fossil fuels, we were already pumping greenhouse gasses into the atmosphere. It wasn’t at the same level as today, but it sets the stage,” Springer said.
This long-ago land clearing would have impacted global climate, Springer added. Ongoing clearing and burning of the Amazon rainforest, for example, is one of the world’s largest sources of greenhouse gas emissions. Prehistoric burning by Native Americans was less intense, but a non-trivial source of greenhouse gases to the atmosphere, he said.