Time is running out. Photo: TED Conference/Flickr.com/CC BY-NC

Three years left to stop dangerous climate change

Former UN climate chief Christiana Figueres is one of the signatories, together with leading scientists, of a letter published in the science magazine “Nature” warning that the next three years will be crucial to stopping the worst effects of global warming.

The authors claim that the next three years will be crucial and have calculated that if emissions can be brought permanently lower by 2020 then the temperature thresholds leading to runaway irreversible climate change will not be breached.

Figueres, the executive secretary of the UN Framework Convention on Climate Change, under whom the Paris agreement was signed, said: “We stand at the doorway of being able to bend the emissions curve downwards by 2020, as science demands, in protection of the UN sustainable development goals, and in particular the eradication of extreme poverty. This monumental challenge coincides with an unprecedented openness to self-challenge on the part of sub-national governments inside the US, governments at all levels outside the US, and of the private sector in general. The opportunity given to us over the next three years is unique in history.”

The authors point to signs that the trend of upward emissions is being reversed, and to technological progress that promises lower emissions for the future. In the past three years, global emissions of carbon dioxide from the burning of fossil fuels have levelled after rising for decades. This is a sign that policies and investments in climate mitigation are starting to pay off and creating a foundation for permanently lowering emissions. Coal use is showing clear signs of decline in key regions, including China and India. Governments, despite Trump’s pronouncements, are forging ahead with plans to reduce greenhouse gases.

The authors set out six goals for 2020. These include increasing renewable energy to 30% of electricity use; plans from leading cities and states to decarbonise by 2050; 15% of new vehicles sold to be electric; and reforms to land use, agriculture, heavy industry and the finance sector, to encourage green growth.

The year 2020 is crucially important for another reason, one that has more to do with physics than politics. When it comes to climate, timing is everything. According to a report prepared by Carbon Tracker in London, the Climate Action Tracker consortium, the Potsdam Institute for Climate Impact Research in Germany and Yale University in New Haven, Connecticut, should emissions continue to rise beyond 2020, or even remain level, the temperature goals set in Paris become almost unattainable.

After roughly 1°C 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.

“There is a mean budget of around 600 gigatonnes carbon dioxide left to emit before the planet warms dangerously. At the current emission rate of 41 Gt of CO2 per year, the lower limit of this range would be crossed in 4 years, and the midpoint of 600 Gt of CO2 would be passed in 15 years”, the authors explain. “If the current rate of annual emissions stays at this level, we would have to drop them almost immediately to zero once we exhaust the budget. Such a ‘jump to distress’ is in no one’s interest. A more gradual descent would allow the global economy time to adapt smoothly. The good news is that it is still possible to meet the Paris temperature goals if emissions begin to fall by 2020 (see ‘Carbon crunch’ graphic)”, the authors conclude.

Compiled from Nature and the Guardian by Reinhold Pape

Source: Three years to safeguard our climate, Nature 28 June 2017, https://www.nature.com/news/three-years-to-safeguard-our-climate-1.22201

Photo: Figure: Carbon crunch. There is a mean budget of around 600 gigatonnes (Gt) of carbon dioxide left to emit before the planet warms dangerously, by more than 1.5-2°C. Stretching the budget to 800 Gt buys another 10 years , but at a greater risk of exeeding the temperature limit.
Sources: Stefan Rahmstorf/Global Carbon Project; http://go.nature.com/2RCPCRU


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