4 ways man is pushing Earth to the brink

Mother Earth is hurting. And it's our fault.

That is the assessment of an international team of researchers who found that four out of nine crucial systems responsible for keeping Earth stable and healthy "have become dangerously compromised by human activity."

Their study this week in Science concluded that we have significantly changed land use patterns as a result of widespread deforestation, altered biogeochemical cycles due to the overuse of fertilizers, and weakened biosphere integrity on account of increased extinction and biodiversity loss. And then, of course, there's climate change, driven by human consumption, which has contributed to rising temperatures across the globe.

The study coincides with a finding Friday from NASA and the National Oceanic and Atmospheric Administration that 2014 was the hottest year since modern records were first kept in 1880.

Much of the changes, the researchers said, occurred since 1950 and go beyond the "natural variability" that was seen over the past 12,000 years.

To come up with the score card, the researchers charted the "Great Acceleration" in human activity from the start of the industrial revolution in 1750 to 2010, and the subsequent changes in the Earth System -- greenhouse gas levels, ocean acidification, deforestation and biodiversity deterioration.

"Almost all graphs show the same pattern. The most dramatic shifts have occurred since 1950. We can say that around 1950 was the start of the Great Acceleration," said lead author Professor Will Steffen, who led the joint project between the International Geosphere-Biosphere Programme (IGBP) and the Stockholm Resilience Centre. "After 1950, you can see that major Earth System changes became directly linked to changes largely related to the global economic system. This is a new phenomenon and indicates that humanity has a new responsibility at a global level for the planet."

The researchers said much of the blame for the worsening environment could be put on the West. They found that globalization was driving the Great Acceleration and that the developed world was responsible for the majority of economic activity as well as the bulk of consumption -- accounting in 2010 for 74 percent of the GDP despite representing only 18 percent of the population.

If the destructive trends aren't altered soon, the researchers wrote that it "could lead, with an uncomfortably high probability, to a very different state of the Earth System, one that is likely to be much less hospitable to the development of human societies."

But not everything was hopeless. We seem to have done a good job shrinking the ozone hole.

"Of all the socio-economic trends, only construction of new large dams seems to show any sign of the bending of the curves -- or a slowing of the Great Acceleration," said Lisa Deutsch, a senior lecturer at the Stockholm Resilience Centre. "Only one Earth System trend indicates a curve that may be the result of intentional human intervention -- the success story of ozone depletion."