Climate targets may not be enough to avert catastrophes

Eric J. Lyman | Special for USA TODAY

PARIS — Negotiators at climate change talks here are working to produce a realistic plan to limit global warming to no more than 2 degrees Celsius (3.6 degrees Fahrenheit) from pre-industrial levels, but many scientists say that may still be too warm to avert climate catastrophes.

More than 100 mostly developing countries at the Paris conference that runs through Dec. 11 have called for the official goal to be shifted toward a rise of only 1.5 degrees Celsius. (Climate negotiators use Celsius temperatures).

“We have to limit the warming as much as possible, to 1.5 degrees or even less, if we are to save the planet,” Bolivian President Evo Morales told delegates at the opening of the talks this week.

That lower threshold is unlikely to become the official goal anytime soon because of opposition from industrialized countries, including the United States. They point out that even if all man-made greenhouse gas emissions that cause global warming were halted immediately, temperatures would still rise nearly 1.5 degrees.

“We have already seen some impacts of climate change: more and stronger hurricanes and typhoons, more severe droughts, higher temperatures, rising sea levels,” said Alden Meyer of the Union of Concerned Scientists. “That is with warming up until now of a little less than 1 degree, and warming to 1.3 or 1.4 degrees probably already locked in.”

A consensus among scientists is that in the coming decades, the world could see some animal species will become extinct, most coral reefs will die, sea levels will rise by more than 1 meter (3.3 feet), and much of the world’s agricultural production will be at risk.

Changing weather conditions will force millions in poor and developing countries to leave their homes, creating waves of climate refugees from low rainfall areas, small island nations or low-lying countries like Bangladesh. Meanwhile, big cities at or near sea level — New Orleans, New York City and Miami in the United States; Amsterdam, Hong Kong, and Venice internationally — will risk frequent flooding that will make them more susceptible to extreme weather.

“It’s hard to predict exactly when the world gets to the tipping point on some key things," said Sven Harmeling, from CARE International, a humanitarian aid organization.

"For example, look at the Greenland ice sheet,” Harmeling said. “All that ice is on the land right now, but if it melts completely, it could make sea levels rise by as much as 7 meters (23 feet). We don’t know the exact level of temperature rise that would cause that. But at 2 degrees, we’re probably too close to it for comfort.”

The 2-degree target can be traced back to Yale economist William Nordhaus in 1975, when he first mentioned “2 or 3 degrees” as a level of warming not seen in the last several hundred thousand years. Scientists from the predecessor organization to the Intergovernmental Panel on Climate Change (IPCC), the United Nation's climate research body, subsequently determined that a rise of 2 degrees is where the world would begin to face “grave damage to ecosystems.” It was adopted as a formal goal in the 2009 U.N. climate negotiations.

Even limiting warming to 2 degrees could prove difficult. Emissions pledges made by 184 countries that account for around 95% of the world’s emissions before the Paris talks started are on pace to allow warming to reach 3.5 degrees Celsius by the end of the century, a level that scientists say would be “catastrophic.”

Still, veteran climate negotiators and observers say they are hopeful. Greenpeace campaigner Kaisa Kosonen said she put off having a child until she felt more optimistic about the climate.

“I remember reading the IPCC reports about the risk of the melting ice sheets in Greenland and Antarctica, and it made feel like I would vomit,” Kosonen said. “If I had a child, how could I explain this?”

Now she says reductions in coal use in China and the increase in renewable energy use have given her hope. Her 7-month-old daughter is with her in Paris.

Stanford professor Chris Field, a leading climate researcher and a former IPCC board member, said he’s also cautiously optimistic about the future.

“The future worries me, but I’m an optimist by nature,” Field said. “I believe we can solve the climate challenge, but the question is when. I hope the world will learn in time that ignoring evidence and taking half steps won’t do it. “