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 Climate change, biodiversity loss, changes in land use, and
altered biogeochemical cycles due in part to fertilizer use have
fundamentally changed how the planet functions, the study said.
These changes destabilize complex interactions between people,
oceans, land and the atmosphere, said the paper "Planetary
Boundaries: Guiding human development on a changing planet" by 18
leading international researchers.
Passing the boundaries makes the planet less hospitable, damaging
efforts to reduce poverty or improve quality of life.
"For the first time in human history, we need to relate to the risk
of destabilizing the entire planet," Johan Rockstrom, one of the
study's authors and an environmental science professor at Stockholm
University told the Thomson Reuters Foundation.
Scientists in 2009 identified and quantified the nine planetary
boundaries within which humanity can develop and thrive.
The five other boundaries - ozone depletion, ocean acidification,
freshwater use, microscopic particles in the atmosphere and chemical
pollution - have not been crossed.
Passing the boundaries does not cause immediate chaos but pushes the
planet into a period of uncertainty.
Scientists consider climate change the most serious crossed
boundary.
The amount of carbon dioxide in the atmosphere, a gas causing the
planet to warm, has exceeded 350 parts per million to the present
395 parts per million, crossing the boundary of what scientists
think to be acceptable.
"We are at a point where we may see abrupt and irreversible changes
due to climate change," Rockstrom said, as warming could cause
Arctic ice sheets to melt releasing more greenhouse gases and
creating a vicious feedback loop.
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The study results are set to be incorporated into the new global
development goals that will be finalised in September at the United
Nations in New York to replace the Millennium Development Goals on
poverty alleviation expiring this year.
Scientists hope the new study will help balance competing demands
for economic growth and environmental sustainability which are
likely to arise during the conference.
Despite a steady drumbeat of grim warnings, food prices have
declined the past four years, indicating that wild weather linked to
climate change is not destroying harvests worldwide.
Commodity prices, a measure of scarcity for energy and other basic
goods, are also falling, leading some economists to question
warnings from climate scientists and environmentalists.
"Just because we are not seeing a collapse today doesn’t mean we are
not subjecting humanity to a process that could lead to catastrophic
outcomes over the next century," Rockstrom said.
(Reporting By Chris Arsenault, editing by Alisa Tang.)
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