The planet is now more than halfway to the line scientists say we can't cross if we're going to avoid catastrophic climate change.

Global temperatures for January to September 2016 were about 1.2 degrees Celsius, or 2.16 degrees Fahrenheit, higher than the preindustrial average, the United Nations' World Meteorological Organization (WMO) said Sunday.

The U.N. agency said 2016 will also very likely be the hottest year on record, a milestone that already has had serious consequences for coral reefs and Arctic sea ice.

World leaders are working to keep global warming to below 2 degrees Celsius, or 3.6 degrees Fahrenheit, above preindustrial levels through 2100 to avoid dangerous changes in sea level rise, extreme weather events and other effects.

The Paris Climate Agreement, which is now in effect, also contains a goal of limiting warming to 1.5 degrees Celsius, or 2.6 degrees Fahrenheit, above preindustrial levels. Scientists say this target has a better chance of avoiding devastating climate impacts, and leaders of small island nations fear any more warming will doom their countries to flooding beneath rising sea levels.

A security stands guard next to flags of participating countries at the U.N. climate change conference in Marrakesh, Morocco, Nov. 6, 2016. Image: AP Photo/Mosa'ab Elshamy



Under the Paris Agreement, which entered into force Nov. 4, countries have committed to slashing greenhouse gas emissions and shifting away from fossil fuels to avoid crossing the 2-degree threshold, although the commitments made so far are not enough to ensure the goal is met.

Negotiators are currently meeting for the second week in Marrakech, Morocco, to develop rules for implementing the landmark climate agreement.

Their work is considered particularly urgent due to the upset presidential election victory of Donald J. Trump, who has vowing to "cancel" the United States' involvement with the agreement and cut off climate assistance to other nations when he takes office on Jan. 21, 2017.

The WMO's report amounts to a status report on the planet's climate system, from the oceans to polar ice caps.

Status: Warming

The WMO said global temperatures for January to September 2016 are 0.88 degrees Celsius above the average for the 1961-1990 period. The rise is partly due to an unusually strong El Niño event in the Pacific Ocean in 2015 and 2016, the report found.

Global average temperature departures from the preindustrial average. Image: WMO

Preliminary October data indicate temperatures will stay high enough through the end of this year to surpass 2015's record warmth, when the year was 0.77 degrees Celsius, or 1.3 degrees Fahrenheit, above the 20th century average.

At the same time, atmospheric concentrations of major greenhouse gases are poised to hit the highest levels on record in 2016, WMO said.

Observations from Hawaii and Australia suggest this year will see the highest concentrations of carbon dioxide, methane and nitrous oxide in the instrumental record. Carbon dioxide levels have surpassed the symbolic threshold of 400 parts per million, which is their highest level in human history.

Levels of major greenhouse gases. Image: WMO

Global warming has contributed to massive coral bleaching worldwide, with particular damage occurring in parts of Australia's Great Barrier Reef.

In addition, Arctic sea ice has shrunk more rapidly than in previous decades, the WMO found, and Arctic sea ice has been at record low levels so far in October and November of 2016.

Some meteorologists suspect the loss of Arctic sea ice is altering the Earth's jet stream, resulting in more extreme weather events in the U.S. and Europe in recent years.

Image: WMO PROVISIONAL STATEMENT ON THE STATUS OF THE GLOBAL CLIMATE IN 2016

In Greenland, the island's ice sheet experienced substantially above average surface melting during the summer, and the Northern Hemisphere snow cover remained well below average for most of the first six months of 2016. In Antarctica, the sea ice extent fell to near average in early 2016 after several years of well-above-average ice levels.

The Trump effect

Negotiators in Marrakech will consult the WMO data this week as they craft an action plan for the Paris agreement.

U.S. Secretary of State John Kerry on Sunday said he would continue his efforts to implement the Paris deal until the day President Barack Obama leaves office on Jan. 20, 2017.

Speaking in New Zealand after a trip to Antarctica, Kerry took a swipe at Donald Trump as he ticked off some of the ways in which global warming is already affecting the planet: more fires, floods, damaging storms and rising sea levels.

U.S. Secretary of State John Kerry, front right, talks with New Zealand scientist Gavin Dunbar near the Ross Sea in Antarctica, Nov. 12, 2016. Image: Mark Ralston/Pool Photo via AP

"Now the world's scientific community has concluded that climate change is happening beyond any doubt. And the evidence is there for everybody to see," Kerry said.

He noted that the majority of Americans say they want the country to take action on climate change. "So we will wait to see how the next administration addresses this," Kerry said.

The secretary is slated to attend the Marrakech conference on Nov. 15 and 16.

Associated Press contributed reporting.