This year, global temperatures are set to reach 1 degree Celsius (1.8 degrees Fahrenheit) above preindustrial levels for the first time, researchers said — a sobering halfway point to the warming limit of 2 degrees Celsius that many scientists say cannot be surpassed if the worst effects of climate change are to be avoided.
“This is the first time we’re set to reach the 1 C marker, and it’s clear that it is human influence driving our modern climate into uncharted territory,” Stephan Belcher, the director of the U.K.-based Met Office Hadley Centre for Climate Science and Services, said in a news release issued Monday.
Most world leaders and the United Nations agree that warming must be limited to 2 degrees Celsius by 2100. If it is not, many believe the planet is likely to see storms, droughts and floods increase in force and frequency.
The U.N. has for two decades hosted climate change negotiations in an attempt to reach an international plan to cut carbon emissions and to shift to renewable energy sources.
World leaders are expected to sign a global climate treaty at a U.N. conference in Paris next month, and plans submitted so far by about 150 countries would slow the rise in temperature to about 2.7 degrees Celsius above preindustrial times, the U.N. has said.
For low-lying areas around the world — including remote atoll nations like the Marshall Islands in the South Pacific — that level of warming would pose an existential threat.
In addition to swamping low-lying islands and coastal areas, a world that is warmer by 3 degrees Celsius would suffer from a significant drop in food production, an increase in urban heat waves akin to the one that killed thousands of people this year in India and more droughts and wildfires, scientists say.
While such an increase in global temperatures would be unlikely to threaten the existence of humanity, scientists have said it would cause major global disruptions — including a refugee crisis that could dwarf the one unfolding in Europe.
Marshall Islands leaders have called for limiting the increase to 1.5 degrees Celsius, echoing some scientists who have said warming by 2 degrees would pose too many dangers, including possibly triggering feedback cycles, in which effects from warming lead to even more warming.
The closer the world gets to a 2 degree warming, the greater the chance that some of Earth’s major systems could become unbalanced. That worries scientists because effects such as coral reef die-off, combined with melting ice sheets and the destruction of the Amazon rain forest, could have grave global consequences.
Research suggests that it is still possible to limit warming to 2 degrees, the Met Office said in its press release. But it said that would require a higher level of ambition in the national climate plans that are expected to be formalized in Paris. As of 2014, the world has emitted two-thirds of the amount of carbon dioxide that can be released under a 2 degree warming limit, the news release said.
Early indications show that 2016 will be similarly warm, and scientists have said they expect warming to continue in the long term.
“This year marks an important first, but that doesn’t necessarily mean every year from now on will be a degree or more above preindustrial levels, as natural variability will still play a role in determining the temperature in any given year,” Peter Stott, the head of climate monitoring and attribution at the Met Office, said in the news release.
“As the world continues to warm in the coming decades, however, we will see more and more years passing the 1 degree marker,” he said. “Eventually it will become the norm.”