Coming up, your four-decade forecast

The videos, produced by dozens of major media companies around the world — such as the U.S. Weather Channel, the South African Broadcasting Company and NHK Japan — are intended to convey in concrete terms what a day on earth could feel like should greenhouse gas emissions continue to increase at current rates. The U.N. stresses these are only “possible scenarios,” but said they are based on “the most up-to-date climate science.” The reports give a more palpable face to warnings that often seem ethereal or overly scientific.

The average temperature of Earth’s atmosphere could increase by 4 degrees Celsius (over 7 degrees Fahrenheit) by the end of the century, but perhaps that does not leave the same impression as daily highs in the 120s, which could be a regular part of a summertime forecast 35 years from now in eastern Europe or the southwest United States.

And while coastal cities and island nations expect to suffer from severe storms and rising seas, parts of Africa and the U.S. will see extreme drought well beyond current, already emergency-level situations.

But like the admonition from Dickens’s Ghost of Christmas Yet to Come, these are only shadows of what could be — this is not yet chiseled in stone. The U.N. stresses that with global action, the scenarios portrayed in the weather videos need not be the future.

U.N. Secretary-General Ban Ki-moon has called on world leaders to make “bold pledges” to fight climate change at September’s summit. The New York meeting is meant to ramp up negotiations in advance of the December 2015 U.N. Climate Change Conference in Paris. That conference is supposed to produce a legally binding treaty on global climate for all U.N. member states — like the 1997 Kyoto protocol, but this time with stricter limits and actual compliance from the world’s industrialized nations.

And for much of the planet, this is more than a fun project for the AV Club.

“Every study I have ever read makes it clear that developing countries have the most to lose from runaway climate change,” said Tony de Brum, foreign minister of the Republic of the Marshall Islands, who is attending the U.N. Conference on Small Island Developing States in Apia, Samoa. “For the small island states of the world, the science says we might be forced to pay the biggest price of all — the loss of our countries. We expect solidarity from our developing country compatriots, not excuses.”

Secretary-General Ban, also at the Small Island conference, concurred.

“The impacts of climate change are acutely felt in Samoa and on other islands, but they are now affecting every country on every continent,” Ban wrote on his blog. “And these impacts will only increase as global temperatures rise. … It is only a matter of time,” he said.

Also in advance of the Climate Summit, Sir David King, former U.K. chief scientist, launched what he called the “Global Apollo Program” — named for the 1960s’ push to put an American on the moon — a plan to make alternative, renewable energy sources cheaper than coal within the next decade.

“We are urging all governments to form a commission to spend 0.02 percent of their GDP,” said Sir David, projecting that would raise $10-20 billion each year to fund research and development of low-carbon technologies. The plan is designed to leapfrog traditional market incentives and ease the transition to renewables in both rich and poor nations.

That’s probably a good idea, as traditional markets (and the governments they influence) in countries like the U.S. still seem more excited about carbon-intensive tar sands and offshore oil drilling than about developing truly renewable, greenhouse-neutral energy sources, and refer to still-plenty-carbon-rich fracked natural gas as a “transition fuel.”

But the questions remain, “Transition to what and transition to when?” For island nations, coastal communities and drought-stricken plains, there isn’t much time to debate about it. Waiting for 2050 to see if the U.N.’s little fantasy film fest comes true is really not an option when so much life and livelihood is at stake.

As the U.N.’s Ban put it, “There’s no other time than now.”