The stated goal of recent international climate negotiations includes keeping global temperatures from rising more than 2 degrees Celsius above pre-industrial conditions. The Paris climate agreement included emissions limits that everyone recognized would be insufficient to meet that goal, but it was meant to get all countries on the path of controlling their emissions and set the stage for a progressive tightening of standards over time.

Talks going on in Marrakech are the first to take place after the Paris agreement went into force, and the US chose them as the stage to reveal just how much tighter its limits could be. And even as Donald Trump is preparing to roll back progress on emissions, the Obama administration described plans for cutting carbon emissions by 80 percent by 2050.

The report notes the US has now severely weakened the link between economic growth and carbon emissions. Over the last seven years, the economy is up by 10 percent, while energy-driven emissions are down by nine. It also argues that placing ambitious limits on future emissions is the best strategy for further economic growth: "Pursuing high-carbon strategies (or business as usual) will lead to large and possibly catastrophic damages to the future US and global economies." Starting sooner rather than later, the US argues, will help us avoid sudden economic jolts and the need to retire fossil fuel assets before the end of their useful lifetime.

While all of that is accurate, an 80-percent drop in emissions represents radical change. How do we get there?

The report proposes that, by 2050, the US grid will be supplied primarily by a mix of renewables (55 percent) and nuclear (17 percent). Of the fossil plants that remain in operation, 20 percent will be fitted with carbon-capture-and-storage technology. Efficiency efforts will allow the US to drop its total energy use by 20 percent, as well—these efforts will include better urban design to enable expanded mass transit options. Transportation and heating will be increasingly electrified in order get it using the increasingly renewable grid.

The report favors market-based solutions driven by government incentives. The incentive here would be a carbon price, although the authors are agnostic as to how that comes about—either a federal program or expanding of existing regional efforts would do.

But even the complete transformation of the energy economy wouldn't be sufficient to achieve an 80-percent reduction. So, the plan includes ways to offset the remaining emissions. This is primarily a massive reforestation program. In recent years, existing carbon sinks have offset more than 10 percent of our annual emissions, largely because the country has been reforested at a rate of one million acres a year. The Obama plan would act to double that rate, bringing back a third of the forest land lost since 1850.

Beyond that, the plan calls for a more efficient use of cropland and integration of bioenergy crops and carbon sequestration in a way that's not disruptive for traditional agriculture. In many ways, this seems like an effort to drive inefficiencies out of the system. "In Iowa alone," the report notes, "an estimated 27 percent of cropland, or 7 million acres, may not be profitable in commodity crop production but could be well-suited to perennial grasses or agroforestry."

The one place where the report comes up a bit short is in non-CO 2 greenhouse gases like methane and nitrous oxide. These are released in the production of everything from livestock to fire extinguishers, and there are no individually dominant sources. While the US calls for reducing them, the goals are not as ambitious and the specifics of how to do so are a bit sparse.

How much will all this cost? In recent years, spending on the grid has run about 0.2 percent of the GDP per year. The new analysis suggests that number will need to double or triple, but it adds that these expenses will be offset by a dramatic reduction in spending on fossil fuels. How those two balance out will depend on the prices of fossil fuels, which are notoriously volatile.

There's plenty to argue about in this plan. There are limits to the reforestation that the US can manage, so reliance on it seems like a small band-aid on a larger underlying problem. And the expectation that carbon capture and storage technologies will mature into something economical is hypothetical at best considering how little experience we have with them. But the plan overall is at least plausible technologically and is conservative regarding its assumptions about future price reductions in wind and solar.

Is there any value in releasing it now, when it's destined to become a "might have been" once Trump is inaugurated? In some ways, seeing official government documents use the term "deep decarbonization," which had previously been used primarily by academics, represents a sea change in thinking. But its primary value seems to be in driving home the point that addressing climate change at the levels needed to avoid widespread disruption isn't a complete pipe dream. Plus other entities beyond the federal government, from NGOs through states to other nations, can look through the document for ideas on how things could be done.