Deadline 2020: Just Three Years, Say Experts, Before Global Tipping Point

Humanity has just three years left to accelerate action and drastically lower greenhouse gas emissions before risking a climate-safe world.

That's according to a new commentary by a group of six experts, including former executive secretary of the U.N.'s Framework Convention on Climate Change Christiana Figueres and Hans Joachim Schellnhuber, director of the Potsdam Institute for Climate Impact Research.

Their warning, published Wednesday in the journal Nature, notes there has been a leveling off of global CO2 emissions, yet "there is still a long way to go to decarbonize the world economy." It references "blustery political winds," such as President Donald Trump's decision to ditch the historic Paris climate pact.

The group of experts outline some of the most worrying climate change impacts already underway:

After roughly 1degC of global warming driven by human activity, ice sheets in Greenland and Antarctica are already losing mass at an increasing rate. Summer sea ice is disappearing in the Arctic and coral reefs are dying from heat stress--entire ecosystems are starting to collapse. The social impacts of climate change from intensified heatwaves, droughts, and sea-level rise are inexorable and affect the poorest and weakest first.

The reason for the three-year deadline, the group writes, is that "should emissions continue to rise beyond 2020, or even remain level, the temperature goals set in Paris become almost unattainable," referring to 2.0 Celsius (3.6 Fahrenheit) threshold of warming.

The year is thus a "climate turning point for greenhouse-gas emissions," they write. Ensuring that 2016 becomes year of peak emissions, said the group, would put the world on a more reasonable 25-year path towards a zero emissions scenario.

Their suggestions to meet the goal focuses on "milestones in six sectors," which reflect the focal points of the Mission 2020 campaign:

• Energy: At least 30 percent the world's electric supply come renewable sources, and no new coal plants can be built.
• Infrastructure: Cities and states must fully decarbonize buildings and infrastructures by 2050.
• Transportation: Mass transit use in cities is doubled, electric vehicles account for at least 15 percent of new sales, and there is "a 20 percent increase in fuel efficiencies for heavy-duty vehicles and a 20 percent decrease in greenhouse-gas emissions from aviation per kilometer traveled."
• Land: Forest destruction is decreased, and improved, CO2-sequestering agricultural practices are used.
• Industry: A goal is set for the halving of emissions from heavy industry "well before 2050."
• Finance: The financial sector mobilizes "at least $1 trillion a year for climate action. "

The G20 leaders set to meet next month in Hamburg, Germany should use the occasion to mobilize support for the milestones, they write , thus "pav[ing] the way for a year of raised ambition in 2018, when nations take stock of progress and evise national commitments under the Paris agreement."

Despite the short timeline for action, and potentially dire scenario, their commentary ends on a positive note, calling on people to "stay optimistic and act boldly together."