Voters care about climate change. It’s become a top issue in the Democratic presidential race. Republicans worry, too, especially in places like Arizona and Alaska where hotter summers and melting permafrost have become impossible to ignore.

Caring about climate is a good start. But it’s not enough. Voters need to be able to choose candidates whose climate plans will actually make a difference.

Unfortunately, the Democratic contenders aren’t making it easy for them. Neither of the two most popular moves — endorsing the Green New Deal and promising to spend trillions of dollars — would necessarily slow down the baking of Arizona or thawing of Alaska.

Here’s what any serious climate plan should do.

First, it should leverage American strengths to enable global action. Even cutting U.S. emissions to zero will not come close to solving the problem.

Second, it should cover all sectors that produce emission, taking a comprehensive approach that addresses industry, buildings and agriculture as well as electric power and transportation.

Third, it should embrace a broad and growing portfolio of potential solutions. Surprises are inevitable, and the world needs to be able to sustain its momentum toward zero emissions even when problems emerge.

Finally, it should be built to last. Solutions will take decades to put in place. The plan must receive deep and wide public support to withstand changing political tides over such a long period.

Why emphasize these four features? And what ought each entail a winning candidate to do?

Global action is crucial because climate change is the quintessential global problem. The United States contributes only about 15 percent of global greenhouse gas emissions, a share that will decline as developing countries like China and India raise their living standards and energy consumption. Eliminating U.S. emissions by 2050, as the Green New Deal calls for, would only slow sea level rise by a few years, absent action elsewhere.

Yet, the United States has substantial leverage to make action happen elsewhere. The obvious first steps in any plan are for the United States to set a good example by cutting its own emissions and to use its diplomatic might to spur other nations to achieve more ambitious goals within the nationally determined framework of the Paris climate accord. A serious plan, though, would mobilize America’s technical and business communities to develop clean energy systems that are cheaper and better than dirty ones. That is the only way the world will make the switch. The United States must sustain and extend its position as the clean energy innovation leader and drive progress globally if the worst consequences of climate change are to be avoided.

A serious climate plan would be just as comprehensive in its coverage of emitting sectors as in its coverage of the globe. Electricity, the sector in which the most progress has been made and which has a promising pathway forward, represents only about a quarter of the world’s emissions. Industry and agriculture each emit roughly the same amount, and neither is expected to decline unless something changes dramatically.

The United States must focus the talent and resources of America’s globally preeminent universities and national labs on finding solutions that will reduce emissions from industry, agriculture, and other hard-to-abate sectors worldwide. Contrary to the belief in many quarters, climate solutions are not merely a matter of political will but also require transformative innovations and rapid progress in science and engineering. Plans that call only for deployment of existing technologies are not serious.

Any plan that evinces certainty about the pathway to a zero-emission world is equally unserious. “It’s tough to make predictions,” the American philosopher Yogi Berra once said, “especially about the future.” No energy expert predicted that the United States would become the world’s largest producer of oil and gas. Few foresaw that Japan would suffer a major nuclear accident. Yet, both of these happened in just the past decade, shaking up the global energy and emissions landscape.

To hedge against such uncertainties in the future, a serious climate plan would seek to generate as many emissions-reducing options with the potential to scale globally as possible. In the electricity sector, that means not limiting support to renewables or nuclear or fossil fuels with carbon capture, but instead exploring how and under what conditions each of these technologies, as well as others, might be made to work affordably. In agriculture, that means using the tools of biotechnology as well as traditional crop-breeding methods to reduce emissions. It also means making major investments to develop technologies that can remove carbon from the air in case efforts to cut emissions fall short, as now seems likely.

Any plan that aspires to build a global, comprehensive portfolio of emissions-reducing options must anticipate outlasting the candidate who puts it forward. The global light-duty vehicle fleet, to pick a relatively simple example, is now well over a billion in number and grows by more than 80 million annually. Each vehicle lasts a decade or two and is made in a factory that lasts far longer. These factories comprise the world’s largest manufacturing industry, employing tens of millions of workers directly and indirectly and supporting entire regions, like the one stretching from Detroit to Nashville in the United States and its counterparts elsewhere. Whether the cars of the future are powered by batteries, fuel cells, biofuels or something not yet invented, the transition from internal combustion will be far from complete at the end of any four- or eight-year term in office.

To see through such momentous and sustained changes, a serious climate plan should seek to create a durable societal consensus like the one that allowed the United States to win the Cold War. For more than 40 years, through the bitter conflicts of Korea and Vietnam and the turbulent presidencies of Lyndon Johnson and Richard Nixon, America’s Cold War consensus sustained massive investments in military technology and international alliances.

A comparable climate consensus in the 21st century will require an inclusive approach that spans party, geography, and interest and thus allows our fragmented policymaking institutions to be knitted together in a common cause. Extreme proposals will not only fail to get widespread support but will also lead opponents to dig in their heels. Procedural fixes like eliminating the filibuster or extending federal authority over the states may make it easier for controversial climate policies to be implemented in the short run, but they will also invite reversal after the next election. The verdict on such approaches: not serious.

Is the plan focused on innovation that can be deployed globally? Is it comprehensive? Surprise-resistant? Politically durable? If the answer is yes, the candidate has a serious plan to address climate change.

The current administration’s climate plan is as far from serious as one can imagine— it would be a joke if the situation weren’t so sad. But that doesn’t mean that the challengers, however well-meaning, will get better results. Voters should only support candidates with serious plans.