New study, led by James Hansen, is meant to bolster climate kids’ case against the federal government

The “shit is hitting is the fan,” said noted climate scientist James Hansen, countering “this narrative out there…that we have turned the corner on dealing with the climate problem.”

Hansen is lead author of a new study that warns that there “is no time to delay” on climate change efforts and argues that they must go beyond just slashing emissions of CO2—”the dominant control knob on global temperature”—to extracting CO2 from the air, or “negative emissions.”

The team of international researchers writes that “the world has overshot appropriate targets”—a conclusion that “is sufficiently grim to compel us to point out that pathways to rapid emission reductions are feasible.”

The goal, they write, should be getting atmospheric CO2 reduced to less than 350 parts per million (ppm), as that would lead to global average temperatures decreasing to about 1 degree Celsius of warming relative to pre-industrial levels later this century. The Paris climate accord, in contrast, has a goal of keeping global average temperature increase to under 2 degrees Celsius, and an aspiration 1.5 degrees of warming. But, they argue, the problem with those targets is that they are far above the Holocene [the epoch that began after the last Ice Age] temperature range. If such temperature levels are allowed to long exist they will spur “slow” amplifying feed-backs, which have potential to run out of humanity’s control. The most threatening slow feedback likely is ice sheet melt and consequent significant sea level rise, as occurred in the Eemian [the prior interglacial period], but there are other risks in pushing the climate system far out of its Holocene range.

For a safer scenario that limits irreversible climate impacts, what needs to happen is a “rapid phase-down of fossil fuel emissions,” bringing the rate of emissions right away to 6 percent a year, alongside reforestation and agricultural practices that draw carbon from the atmosphere into the soil.