INTRODUCTION Thanks to human-induced greenhouse warming, the Earth''s average temperature today is about 1.2° C (2.2° F) higher than it was in the pre-fossil fuel era. The Intergovernmental Panel on Climate Change (IPCC)[1] reported in 2018 that if warming is allowed to surpass 1.5° C, the world will risk widespread ecological destruction and human suffering. To keep temperatures below that limit, they concluded, global greenhouse emissions would have to be cut almost in half before 2030, and net-zero emissions would have to be achieved by 2050.[2] Now, climate groups in the United States are drafting a Green New Deal, a plan that calls for cutting net U.S.

greenhouse emissions to zero through a just transition to an economy that runs on non-fossil energy. The still-evolving plan has given the climate movement a big shot in the arm, providing a sweeping national policy initiative that millions now regard as something worth rallying around. In that, the Green New Deal is part of a long tradition. The women''s suffrage movement, the civil rights struggle, the movement to end the Vietnam War, the nuclear freeze of the 1980s, and the fight for reproductive choice have all focused on big demands: groundbreaking national legislation, concrete policy changes, or explicit reinforcement of Constitutional rights. The Green New Deal has revived interest in public planning, and the kind of massive investment that can secure basic needs, including energy, for all. It has eclipsed previously popular half- and quarter-measures that would have only nibbled around the edges of the climate crisis. It has inspired vigorous resistance to the Trump administration''s obsessively pro-fossil fuel, anti-ecological policies. It has explicitly linked the need for climate mitigation to the need for social and racial justice, inclusion, and workers'' power.

It intends to shift the economic center of gravity away from the owning and investing classes toward those who do the nation''s work. Those visionary features have not only positioned the Green New Deal at the heart of the climate movement, but have also earned support for it from a host of other movements, institutions, networks, scientists, and scholars. History holds other lessons. For example, passage of the 1964 Civil Rights Act was an important and essential victory for the movement against racial oppression, but it was not the end of the struggle. To be effective, it had to be followed up by the Voting Rights Act of 1965, the Fair Housing Act of 1968, and other major legislation--and the struggle is still not over. Passage of a Green New Deal, like that of the Civil Rights Act, is widely viewed as a vital step toward righting a wrong that threatens the nation. But one act of Congress cannot fully tackle a multifaceted threat like the emerging climate emergency. Like the Civil Rights Act, the Green New Deal Act must be accompanied by other essential legislation.

For example, the Green New Deal has not yet specified a mechanism by which the nation can safely guarantee the elimination of greenhouse emissions by a hard-and-fast deadline. The absence of a direct, airtight mechanism to achieve the necessarily rapid decline and elimination of fossil fuels is not unique to the Green New Deal. None of the climate proposals debated so far, either in Washington or at international climate talks, have included such a component. But the intensifying symptoms of our climate predicament now require an immediate switch from the current steady rise in fossil-fuel use to a much steeper decline--something like doing a U-turn at eighty miles an hour in a tanker truck. There''s no time left for legislating corporate-friendly policies and waiting to see if they work. If, in 2030 or 2040, such policies turn out to have been insufficient, it will be too late for a do-over. The most widely discussed emissions-reduction strategies depend on three general elements: building up "green" energy capacity and infrastructure (with, in the case of the Green New Deal, lots of public investment); seeking to maintain or accelerate economic growth without increasing energy demand; and intervening in the market by setting a price on carbon in the event that greenhouse emissions are not declining fast enough. If we are to increasingly keep fossil fuels in the ground, the development of non-fossil energy capacity as called for by the Green New Deal will be urgently needed.

But the national climate discussion appears to be based on an implicit assumption that as new energy capacity comes online in the coming decade or two, it will push an equal quantity of fossil-energy capacity off-line. But history and research show that with economic growth, new energy sources tend to add to the existing energy supply rather than replace it.[3] The idea that investment in solar and wind technology and green infrastructure can work its way through the market to automatically eliminate fossil-fuel use and emissions is not supported by the evidence. So various interventions have been suggested to give new energy sources a leg up in the market. For example, governments could tax each of the fossil fuels based on the carbon emissions it produces; require energy companies to buy permits to burn or sell fossil fuels; or provide home- and business-owners incentives to produce or buy solar or wind energy. Governmental and grassroots approaches to making fossil fuels more scarce or expensive include eliminating subsidies to the coal and petroleum industries; pressuring institutional investors to disinvest from those industries; banning leases and drilling on public land; and pressuring the industry through direct action, as with the anti-pipeline and "Keep It in the Ground" movements. Most of these actions have been pursued in one or more places around the world. Worthy as they are, all are indirect approaches to driving down carbon emissions.

Research tells us, as I show in Chapter Three, that none of those approaches, separately or together, can make that necessary eighty-mph U-turn. None of the widely debated climate strategies has included an element that is essential for fairly and humanely stopping greenhouse emissions: a mandatory, impervious cap on the quantities of fossil fuels entering the economy, one that lowers year by year, and is accompanied by planned allocation of the nation''s energy resources and fair-shares rationing of energy. I will outline how this might be done in Chapter Four. The Green New Deal is a stimulus package in both name and aim. If not implemented with great care, it will encourage the same pursuit of economic growth that got us into this climate predicament in the first place.[4] Resource use must be carefully restrained during the transition; otherwise, the new non-fossil energy coming online will feed growth rather than displace oil, natural gas, and coal. Full displacement of fossil energy by non-fossil energy can only happen if a cap is imposed on fossil fuels, and that cap is lowered year by year in order to eliminate their emissions on schedule. Even an urgent buildup of green energy capacity cannot proceed quickly enough to compensate for all of the fossil-fueled capacity being withdrawn, so our society will need to operate on a smaller total energy supply.

The national economy will need to reorient toward ensuring sufficiency for all rather than feeding the accumulation of wealth by the few. Successfully enacting such a system will not be easy. Time is running out. As the struggle for the Green New Deal and other legislation proceeds, there will be much wrangling over the question of what is politically acceptable. That''s inevitable, but we must keep at the center of the public debate the most urgent question of all: What actions must be undertaken to eliminate greenhouse emissions in time? The IPCC''s 2018 report calls for a stepped-up rate of emissions reductions and highlights the devastating impacts expected if warming is allowed to rise past 1.5°.[5] Letting the global temperature blow up to 2° or beyond would, says the report, risk irreversible loss of the Greenland and West Antarctic ice sheets, eventually raising sea levels by one to two meters. At 2°, one-fourth to more than one-half of all permafrost will disappear, irreversibly releasing a surge of stored carbon into the atmosphere.

Storms, wildfires, and pest outbreaks will cause far more widespread forest dieback at 2°, especially in Central and South America, the Mediterranean Basin, South Africa, and South Australia. Eighteen percent of insect species would see their geographic range shrink by half or more, threatening many with extinction. The report expresses "high confidence" that warming of 2° would generally increase the risk of extinctions in general, and the "irreversible loss of many marine and coastal ecosystems" in particular. Between 70 and 90 percent of coral reefs will be lost at 1.5°; at 2°, virtually all will die off. The IPCC cites evidence that suggests if we allow temperatures to rise from 1.5° to 2°, the percentage of the world population exposed to severe heat waves in at least one out of five years would rise from 14 percent to 37 percent, an increase of 1.7 billion people.

An additional 420 million more people will be "frequently exposed to extreme heatwaves," and about 65 million additional people will be exposed to "exceptional heatwaves," facing prolonged high temperatures that have only occurred very rarely up to now.[6] The IPCC also projects enormous increases in crop loss and habitat degradation. From the report: Impact Number of people exposed at