A new report in the journal Science reveals that early humans across the globe were changing their environments as far back as 10,000 years ago. “We can see that there was global environmental impact by land use at least 3,000 years ago,” says Gary Feinman, MacArthur Curator of Anthropology at the Field Museum Pennsylvania , one of the study’s authors. “And that means that the idea of seeing human impact on the environment as a newer phenomenon is too focused on the recent past.” Looking into the past is essential to understand what’s happening to today’s climate say some scientists.
The study, led by the University of Pennsylvania, is a part of a larger project called ArchaeoGLOBE, using online surveys to gather information about land use has changed in 146 different areas around the world. Land use can be anything from hunting and gathering to farming to grazing animals.
“We saw an accelerated trajectory of environmental impact,” says Ryan Williams, associate curator and head of anthropology at the Field Museum and co-author of the study. “While the rate at which the environment is currently changing is much more drastic, we see the effects that human impacts had on the Earth thousands of years ago.”
“The patterns start 3,000 years ago,” says Feinman. “It shows that the problems we face today are very deep-rooted, and they are going to take more than simple solutions to solve. They cannot be ignored.”
Also published in Science Advances is an assessment of surface phosphate distribution in oceans worldwide showing significant differences between models and observations.
Martiny et al analysed over 50,000 high-sensitivity phosphate observations collected from 42 cruises seeing clear differences in phosphate concentrations within and between basins as well as identifying several previously unknown low phosphate regions. It is essential for scientists to accurately estimate the global distribution of phosphate, accounting for specific variations in low phosphate levels, to model the future impact of climate change on carbon storage and ocean ecosystem productivity.
The new research suggests that current climate models overestimate future declines in phytoplankton — the microscopic algae that form the basis of the marine food web and use phosphorus for photosynthesis. This is important because even minute differences in phosphate concentration can radically impact ocean ecosystem processes.
Reassessing The Carbon Cycle
Reporting in Science Advances scientists have found evidence that the horizontal circulation of carbon-rich ocean water in the subpolar Southern Ocean works in association with vertical circulation, together controlling how much carbon the region stores in the deep ocean or releases to the atmosphere.
MacGilchrist et al. examined the Weddell Gyre using data obtained from cruises along with satellite observations. They discovered that the gyre transports carbon-containing phytoplankton from the open ocean out of the region at a rate of about 80 trillion grams per year, indicating that the gyre plays a key role in Southern Ocean carbon transport. What is important is that these studies contradict the conventional understanding of carbon cycling in Antarctic waters, which attributes carbon uptake to vertical circulation while overlooking the contribution of large systems of swirling ocean current called gyres.
Reassessing the carbon cycle in the Southern Ocean is an essential step towards more accurate computer models to predict how climate change affect ocean acidification and changes in sea-ice cover.