Holding temperature rise to 2C – let alone hitting the aspirational target of 1.5C in the climate agreement concluded in Paris at the weekend – is going to require the deployment of technologies to suck carbon out of the atmosphere, the pope’s climate change adviser said.
Hans Joachim Schellnhuber, who provided scientific advice in the drafting of the pope’s encyclical, said countries would have to move quickly to build up new solar arrays and wind farms, as well as scale up technologies still in the lab phase, to have any hope of reaching the target.
“One thing is clear is that in order to even aspire to 1.5C you need not only rapid decarbonisation of the global economy by the middle of century, but you probably have to remove some carbon from the atmosphere, in particular afforestation on degraded lands, which is a win/win option anyway,” said Schellnhuber.
Scientists have long said that governments may need to deploy carbon sucking technologies to avoid dangerous warming. The agreement may give more momentum to such technologies, because of the wording on the emissions goal.
There is no mention of zero carbon or an explicit plan to phase out fossil fuels. Instead, the formulation calls for “a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases” after objections from oil producing states, such as Saudi Arabia and Malaysia.
The UN climate science panel has been asked to develop its own analysis of what it would take to get to 1.5C by 2018.
Schellnhuber, who heads the Potsdam Institute for Climate Impact Research, said he expected the agreement would give a boost to technologies such as carbon capture and storage (CCS), which have been in use for decades, but not as a remedy for greenhouse gas emissions.
But he said the main route to reaching temperature targets, and another goal to reach net zero emissions by the middle of the century, would have to be decarbonisation. “I would warn you against the illusion you can just extract huge mounts of carbon from the air in order to restore the atmosphere,” he said.
Scientists fear those new technologies, still untested, could have huge side effects.
Also, they are extremely costly. The UK government recently scrapped its £1bn CCS project. In the US, industry has for years used aspects of carbon capture technologies to prime old oil and gas wells. But early attempts to build a commercial coal-fired power plant that would bury carbon dioxide emissions underground have run into delays and cost-overruns.