Representatives from more than 150 countries will gather at the United Nations on Friday to officially sign a global accord aimed at slashing greenhouse gas emissions and slowing climate change. But in the four months since that historic pact was negotiated in Paris, a drumbeat of grim scientific findings has underscored that staving off the worst consequences of global warming may take far more aggressive actions.
The first three months of 2016 were the warmest on record in 136 years — by large margins. The massive Greenland ice sheet has melted this spring to an extent that scientists say they’ve never seen this early. New research suggested that if high levels of emissions continue unabated, sea levels could rise by nearly twice as much as expected by the end of this century. A global coral bleaching event fueled by warm seas is turning some once-majestic reefs into ghostly underwater graveyards.
The list goes on and on.
“The strongest hurricane on record for both the Northern and Southern Hemisphere, unprecedented continuing drought in California, the warmest start to a year that we’ve ever seen, on the heels of what was the warmest full year on record for the globe,” ticked off Michael Mann, a climate researcher at Pennsylvania State University. Such developments, though driven in part by strong El Niño conditions, are a “reminder of how perilously close we are now to a permanent crossing into the global-warming danger zone,” he said. “We are at a critical juncture when it comes to preserving our climate.”
Amid these bleak signs, there is general consensus that the Paris accord is simultaneously an important milestone worth celebrating – Friday is expected to draw the largest number of countries to sign a U.N. agreement on a single day – and, by itself, only a start to what must be a more aggressive effort to mitigate the worst effects of climate change.
Because of how it is structured, the agreement is also only as good as the countries that join it. Meeting the global goal relies on each country fulfilling, and eventually increasing, its individual pledge. But the document does not specifically dictate what any one nation must do.
It now appears that, even with participants’ current pledges, the planet would still blow past the 2-degrees-Celsius increase over pre-industrial temperatures that scientists expect would trigger ever more drastic changes in Earth’s climate. Under these pledges alone, there is little hope of hitting the more ambitious 1.5-degree target that also was included in the agreement at the behest of small island states and other particularly vulnerable nations.
“If you take Paris as the last word, of course it’s not enough,” said Michael Oppenheimer, a professor of geosciences and international affairs at Princeton University. “[But] no one who has followed the climate policy discussion for a significant amount of time thinks this is the last step. It’s merely the first step in a new direction. . . . It’s very important, and it’s certainly better than the alternative of countries having left Paris with their hands up in the air.”
Even after Friday’s ceremony, the agreement won’t take effect until at least 55 countries, representing 55 percent of the world’s emissions, also ratify it. That means approving it at home based on myriad domestic political processes. It’s unclear how long that timeline will be, although the United States and China, the world’s two largest emitters, have pledged to move swiftly.
But the question remains: Can they and other countries move swiftly enough? Given that the world appears to be warming steadily, can nations do more than lurch toward lower levels of greenhouse gas emissions?
Gavin Schmidt, the head of the NASA Goddard Institute for Space Studies, recently suggested that there’s a 99 percent chance 2016 will set a record for the warmest year since reliable measurements began in 1880. If accurate, that would mean a third consecutive year of record temperatures.
Other news in recent months has further increased the sense of urgency. The Greenland ice sheet, which contains the long-term potential for 20 feet of sea level rise, saw a startling April melt event. The result was that almost 12 percent of the ice sheet’s surface featured a layer of water at least a millimeter deep.
The Antarctic ice sheet has long been considered more stable than Greenland’s, but research published last month suggested that it, too, could melt much faster than previously thought. Adding new physics to their computer simulations, a duo of scientists from Penn State and the University of Massachusetts at Amherst found that if countries continue to pour high levels of carbon dioxide into the atmosphere, Antarctica alone could raise seas by more than three feet in this century.
Perhaps less noticed, but no less unnerving: A group of scientists recently reported that far Arctic landscapes, filled with thick wedges of ice embedded in the frozen ground, also are thawing faster than expected. This could trigger new emissions of greenhouse gases into the atmosphere as once-frozen permafrost soil, which contains the preserved remains of long-deceased plants, warms and allows the material to decompose.
Scientists this week also declared that 93 percent of the Great Barrier Reef is now seeing at least some coral bleaching — and in some parts of the reef, preliminary estimates suggest this is triggering significant levels of coral death. Rising sea temperatures, worsened by El Niño, have put severe stress on once-majestic and pristine reefs, so much that the corals expel the algae that they need to survive and turn white. If corals don’t get a long enough reprieve from those temperatures, they can die in large numbers — and in some places they already have, not only in the Great Barrier Reef but around the island republic of Kiribati in the central Pacific.
Some scientists have even suggested that this bleaching event, which signals a warming of the seas at a rate too quick for a major planetary ecosystem to adapt to, may itself indicate that the world is crossing over into the realm of “dangerous” climate change — precisely what the Paris agreement hoped to prevent.
Those and additional problems will linger in the background as Secretary of State John F. Kerry and other leaders arrive at the United Nations to sign the agreement on Earth Day.
Paul Bledsoe, a former adviser on climate in the Clinton White House and now an independent energy and environmental consultant, said the drumbeat of troubling climate news should not overshadow the symbolic importance of Friday’s ceremony. But it should be a reminder, amid the pomp and circumstance of the moment, that the Paris accord is at once “essential and insufficient.”
“I can’t overestimate the political importance that every country is involved. That’s absolutely crucial,” he said. “It really is a testament to a profound political evolution. But we do have to recognize what it is and what it isn’t. It’s an incredibly important step that gets us halfway there, but it’s not in and of itself the ultimate solution.”