In a paper released last week, leading climate scientists warned that current global warming limits are not enough. According to the paper, warming of the magnitude agreed upon by global leaders could prompt dangerous results.
In 2009, world nations decided to attempt to limit global warming to 3.6 degrees Farenheit above the preindustrial level. However, the Earth has already warmed by half that amount, resulting in melting ice and rising ocean levels.
The paper, published by European science journal Atmospheric Chemistry and Physics, states that consequences of this increase could include major storms, melting of giant portions of polar ice sheets, and a resulting sea level rise that could begin flooding coastal cities before the end of this century.
Authors of the paper believe that the influx of fresh water in the oceans from melting land ice will cause a chain of events, which in turn will cause parts of giant ice sheets in Greenland and Antarctica to rapidly melt.
“We’re in danger of handing young people a situation that’s out of their control,” said James E. Hansen, a retired NASA climate scientist who led the research.
Dr. Hansen’s focus on how climate change will impact young people has made him popular among millennials. He also has joined a group of young people who sued the federal government for failure to limit global warming. Dr. Hansen first entered the public spotlight in 1988, when he warned Congress that global warming had begun.
Dr. Hansen’s newest paper, published with 18 other scientists, focuses on the last time the Earth warmed on its own. About 120,000 years ago, temperatures reached a level slightly higher than today. Melting polar ice caused the sea level to rise by about 20 to 30 feet.
Most climate scientists have assumed that a similar increase in sea level, caused by today’s human activities, would take centuries. The new paper claims that it could occur much faster. According to the paper, in a worst-case scenario, there would be several feet of sea-level rise over the next 50 years. This would be followed by even larger increases, forcing humanity to move away from coastal regions.
“That would mean loss of all coastal cities, most of the world’s large cities and all their history,” said Dr. Hansen.
When a draft of the paper was released last year, it prompted a large debate amongst climate scientists. The debate is likely to continue in coming weeks.
“Some of the claims in this paper are indeed extraordinary,” said Michael E. Mann, a climate scientist at Pennsylvania State University. “They conflict with the mainstream understanding of climate change to the point where the standard of proof is quite high.”
However, even Dr. Mann admits that Dr. Hansen should be taken seriously.
“I think we ignore James Hansen at our peril,” he said.