By EDUARDO PORTER

Climate change is not an event in your children’s future. It is bearing down upon you now. And there is nothing you — or anyone else — can do to prevent the hit.

Over the next quarter-century, heat-related death rates will probably double in the southeastern states. Crop losses that used to happen only once every 20 years because of cataclysmic weather will occur five times as often.

This is our future even if every person on the planet abruptly stopped burning coal, gas, oil, wood or anything else containing carbon today and we hooked the world economy onto the wind and the sun tomorrow. The change is baked in, caused by CO2 spewed into the air long ago.

This stark future is rendered vividly in a comprehensive report released on Tuesday by the Risky Business Project, a coalition of political and business luminaries representing widely different political views — including the former Treasury secretaries George P. Shultz, Robert E. Rubin and Henry M. Paulson Jr. — that is intended to raise awareness about the impending perils of a changing climate.

The report is aimed squarely at corporate America, offering the kind of risk modeling a financial firm might make to assess the probable impact of a changing climate on an investment portfolio whose “assets” included farming, housing, labor productivity and crime.

Together with the latest assessment from the Intergovernmental Panel on Climate Change, reported in April, last month’s National Climate Assessment and the new rules proposed by the Obama administration to combat carbon pollution from power plants, it contributes to a new picture of climate change. And it is not pretty, puncturing the hopes held by some of the most uncompromising environmentalists and the most compromising politicians that humanity can still prevent climactic upheaval if we only start replacing fossil fuels today.

For starters, it seems clear by now that the world’s temperature will almost certainly rise more than two degrees Celsius — or 3.6 degrees Fahrenheit — above the average of the late 19th century, a ceiling that the world’s leaders have repeatedly promised never to breach and a point at which climate-related risks rise even more sharply.

One prominent energy economist told me, speaking anonymously to avoid looking too gloomy, that the world would be “extraordinarily unlikely” to stay below the two-degree ceiling. Every country would need to decarbonize at the same pace that France did during its nuclear renaissance in the 1980s and keep up the pace for decades. Then we would have to start taking CO2 out of the air.

Second, despite the rising awareness of the risks caused by our unrestrained consumption of fossil fuels, there is no evidence that we plan to break the habit and leave a substantial portion of the Earth’s oil, gas and coal in the ground.

“We are swinging to fossil fuels in ways that couldn’t have been imagined a few years ago,” said Michael Greenstone of the Massachusetts Institute of Technology. “We’ve made substantial progress in renewables, but there’s been even more innovation in fossil fuels. Incentives to invest in low-carbon energy are going down.”

As the Risky Business report lays out in detail, climate change over the next few decades is already a done deal. Whether we continue emitting CO2 at the current pace or somehow manage to buckle our belts and shift our economies onto something else, temperatures will increase by about the same amount.

“The economic benefits of mitigation do not start to be felt until midcentury and are most obvious in the second half of the century,” notes the report. Under the most pessimistic forecast — in which we do nothing to burn fewer fossil fuels — the average global temperature rises up to 1.8 degrees Fahrenheit over the next five to 25 years. Under the most optimistic, it rises about 1.6 degrees.

Reducing carbon emissions now is about helping prevent even more serious damage 50, 75 and 100 years from today. To address the more immediate risks, notes Trevor Houser, who heads the energy practice at the Rhodium Group, the economic modeling firm that performed the risk analysis for the Risky Business report, the best we can do is “invest in adaptation.”

What to do with this awareness? Homeowners in New York’s Red Hook and Coney Island neighborhoods should probably consider waterproofing, as both will fall into the one-in-100-year flood area over the next 25 years. Hospitals in the Southeast might want to staff up. The federal government may want to consider what will happen to the budget when it is left to reconstruct every city that gets pounded by a hurricane, not to mention the higher costs of heavily subsidized crop and flood insurance.

But there is more to be gained. A more realistic, detailed and nuanced assessment of both the damages that await us might allow for a more effective response.

Two degrees or bust not only commits the world to a probably unattainable goal, it promotes despondency once it becomes obvious we won’t meet it.

By contrast, the Risky Business analysis, which dispassionately lays out damages to specific places and economic sectors along a probability curve as the temperature rises well past two degrees, allows for the kind of cost-benefit assessment that could mobilize effective action.

By 2100, up to $507 billion worth of coastal property will be underwater if we continue emitting CO2 at the same pace as we have over recent decades. New York will face a one-in-100 chance of seeing the sea rise almost seven feet. Crop yields in the Southwest, Midwest and the lower Great Plains could fall up to 70 percent as extreme heat spreads throughout the middle of the country.

By the final decades of the century, Nebraska will face a one-in-20 chance that climate change will reduce its agricultural production by almost $2,000 for each man, woman and child in the state. North Dakota will face a one-in-20 chance that declining productivity will cost the state $1,600 per person, as workers stay indoors out of the sun. Arizona will face one-in-20 odds that energy costs will rise by $800 per person.

These odds are easier to understand than the panel on climate change’s abstract, abstruse estimate that keeping the temperature from increasing more than two degrees Celsius above the preindustrial era will cost up to 11 percent of consumption by 2100, in a world economy that would be three to nine times as large as today’s.

The question, for corporate chieftains, business leaders and voters remains: What is it worth to prevent these costs?

Perhaps our new understanding — detailed and specific — of their magnitude and timing will compel us to act. Mr. Paulson laid out an action plan in The New York Times on Sunday, centered on a tax on carbon emissions. Professor Greenstone supports a tax coupled with a major expansion of investment in research to develop cost-competitive technologies, which the United States could also make available to the big polluters of the future: China and India.

But don’t hold your breath.

Email: [email protected]; Twitter: @portereduardo