2015 to Be Hottest Year on Record

Just days before international negotiations on climate change are set to begin in Paris, the United Nations’ World Meteorological Organization has announced that 2015 is shaping up to be the warmest year on record.

Climate change has surpassed "symbolic thresholds," the organization warns in a report released Wednesday from Geneva, with global surface temperatures set to breach a 1 degree Celsius rise from pre-industrial levels. The previous warmest year was 2014 and the past five years are shaping up to be the hottest such period.

Spurring the warming are the twin forces of human-induced climate change and a strong El Niño this year, according to the report.

Tellingly, the three-month average for carbon dioxide (CO2) in the northern hemisphere has reached 400 parts per million for the first time. Scientists have previously argued that the long-term concentration should stay below 350 parts per million in order to stave off the worst impacts of global warming, which include intensified storms, rising sea levels, and bizarre weather.

Although greenhouse gases are thought to be the primary driver, the effects of El Niño are adding to this year’s warming, reports the World Meteorological Organization. El Niño is the periodic warming of the Pacific Ocean every few years. That warming water tends to boost global air temperatures by at least 0.1°C, meteorologist Jeff Masters writes for the Weather Underground.

“This extra bump in temperature, when combined with the long-term warming of the planet due to human-caused emissions of heat-trapping gases like carbon dioxide, makes it virtually certain that 2015 will be Earth's second consecutive warmest year on record,” Masters writes.

El Niño is already thought to have contributed to October 2015 being the warmest on record, at 0.98°C (1.76°F) above the 20th century average for the month.

"This is all bad news for the planet," World Meteorological Organization Secretary-General Michel Jarraud said in a statement.

World leaders from 190 countries are meeting in Paris from November 30 to December 11 with the goal of hammering out an agreement to cut greenhouse gases. (Learn about the people most at risk.)

“Greenhouse gas emissions, which are causing climate change, can be controlled,” Jarraud said. “We have the knowledge and the tools to act. We have a choice. Future generations will not."

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