Climate Change Likely To Impact All The World’s Oceans By 2100
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Brett Smith for redOrbit.com – Your Universe Online
While previous studies have looked at various aspects of how climate change might impact the world’s oceans, a new study published in the journal PLOS Biology attempts to take a more comprehensive approach to the examining how carbon emissions and warming temperatures will affect the oceans and how humans could feel that impact.
Study researchers discovered that man-made biogeochemical changes could spread across every marine ecosystem, penetrating to the deep ocean and eventually affecting humans – all by the year 2100. The international team of scientists reached their conclusion by considering predictable changes such as the reduction of dissolved oxygen in seawater and a fall in productivity of ocean ecosystems.
“When you look at the world ocean, there are few places that will be free of changes; most will suffer the simultaneous effects of warming, acidification, and reductions in oxygen and productivity,” said study author Camilo Mora, a biodiversity expert at the University of Hawaii at Mānoa.
“The consequences of these co-occurring changes are massive—everything from species survival, to abundance, to range size, to body size, to species richness, to ecosystem functioning are affected by changes in ocean biogeochemistry.”
In addition to the impact on various species, humans could see their food chains, fishing, and tourism all disrupted by a climate change-affected ocean. The new study also said that about 470 to 870 million people around the world depend on the ocean for food, jobs, and income. Many live in countries where marine goods and services are susceptible to biogeochemical changes in the ocean.
In the study, the scientists used recent widely-accepted robust projections of climate change developed for the Intergovernmental Panel on Climate Change (IPCC). The team considered potential shifts in temperature, pH, and oxygen. They also looked at ecosystem productivity in two scenarios: a business-as-usual scenario and a model representing a rigorous, rapid emissions mitigation effort.
The international team found that most of the ocean surface around the globe will be concurrently affected by varying levels of ocean warming, acidification, oxygen reduction, or shortfalls in ecosystem productivity. Only a very small percentage of the oceans, mostly in polar areas, will see increases in oxygen or productivity.
“Even the seemingly positive changes at high latitudes are not necessary beneficial. Invasive species have been immigrating to these areas due to changing ocean conditions and will threaten the local species and the humans who depend on them,” said study author Chih-Lin Wei, an oceanographer at the Memorial University of Newfoundland, Canada.
The team also looked at 32 marine habitats and biodiversity hotspots to determine their potential susceptibility to the predicted changes. The team then considered data on human dependence on the ocean for goods and services, as well as the social adaptability of coastal populations to the projected changes.
“Other studies have looked at small-scale impacts, but this is the first time that we’ve been able to look at the entire world ocean and how co-occurring stressors will differentially impact the earth’s diverse habitats and people,” said co-author Andrew Thurber, a postdoctoral fellow at Oregon State University.
“The real power is in the quantitative, predictive approach using IPCC climate models that allow us to see how much it will all change, and also how confident we can be in our estimates.”
The researchers found that coral reefs, seagrass beds, and shallow soft-bottom marine habitats would see the largest absolute changes, while deep-sea habitats would see the smallest changes.
“Because many deep-sea ecosystems are so stable, even small changes in temperature, oxygen, and pH may lower the resilience of deep-sea communities,” noted co-author Lisa Levin, a professor at Scripps Institution of Oceanography at the University of California, San Diego. “This is a growing concern as humans extract more resources and create more disturbances in the deep ocean.”
“The impacts of climate change will be felt from the ocean surface to the seafloor. It is truly scary to consider how vast these impacts will be,” said co-author Andrew K. Sweetman, a former UH Manoa researcher who currently works at the International Research Institute of Stavanger in Norway. “This is one legacy that we as humans should not be allowed to ignore.”