Is this the first summer Friday of the year? While Americans were firing up the grill this week, a deadly heatwave spread through Europe. Perfect timing then, for the new season of our climate podcast “How We Survive.” The show headed to Northern California this week to meet geoengineers attempting to do what Mr. Burns couldn’t: block out the Sun.

That’s not all we’ve got for you in today’s newsletter, read on for several big money stories:

But before all that, I wanted to extend a heartfelt thank you to everyone who donated to Marketplace’s spring fundraising drive this month. We moved a lot of “Let’s Do The Numbers” hats, “Liquid Assets” Nalgenes and David Brancaccio t-shirts. There’s still time to get yours if you missed out. Have a great weekend!  — Tony Wagner, newsletter editor

The planet is rapidly warming. Even if we manage to stop emitting fossil fuels, the carbon dioxide already in the atmosphere will continue to keep temperatures high.

Scientists say there is something that could help: If we were to release sulfur dioxide into the stratosphere, the particles would reflect sunlight away from the earth — and cool the planet.

This is a solar geoengineering intervention known as stratospheric aerosol injection, and it’s controversial. It would add more of a toxic pollutant into the atmosphere, but geoengineering experts like David Keith say that the lives we save from extreme heat could be worth it.

“It might make sense to do this, understanding that the benefits would be pretty large and the risks appear to be pretty small,” Keith said.

The idea of solar geoengineering has been mostly theoretical — until now. At an undisclosed location in Northern California, co-founders of the startup Make Sunsets are taking matters into their own hands by releasing balloons full of sulfur into the sky.

“It sounds crazy, and I'll be the first to agree that this should not be a private company doing this. But the only thing worse than a private company doing this is no one doing this at all,” said Luke Iseman, one of the co-founders.

Still, many scientists and climate activists remain concerned about this type of intervention.

Shares in the Japanese investment firm SoftBank hit a record high this Memorial Day, exceeding the valuation of Toyota, thanks to reports that OpenAI — one of its biggest portfolio companies — is preparing to go public. 

The expected initial public offering filing from the ChatGPT-maker follows an out-of-this-world prospectus from SpaceX last week. It’s set to become the biggest public market debut in history, with an estimated valuation of $1.75 trillion. OpenAI and Anthropic, which is also predicted to go public this year, are both pushing trillion dollar valuations.

Markets have never seen three IPOs of this magnitude in quick succession, and new rules on Wall Street mean index funds — the kind of investment that dominates American retirement funds — will be buying into these companies faster than ever before.

Stock indexes like the Nasdaq or S&P 500 are just lists of top companies. There are trillions of dollars of investment that just track those lists. Each index has its own methodology for inclusion, like company profit levels or how many shares are available, said New York University finance professor Aswath Damodaran.

“What do you do about inclusion criteria that are keeping out some of the largest companies in the market,” he said. Well, you change the rules.

Several indexes are fast-tracking SpaceX so it will be included in a matter of days rather than months.

“So you're going to see massive mandatory buying,” said Michael Monaghan at Founder ETFs.

Index funds have to buy stock in proportion to a company’s size, no matter the price, Monaghan said. This passive investing has grown bigger than funds managed by investors who research companies and make active bets.

“The index funds are going to set the price of SpaceX, and the active managers will be the price takers,” he said. “That’s unprecedented.”

We’re just a few weeks away from the start of the FIFA World Cup, which will be held in North America for the first time in 32 years.

So far, much of the buzz around the world’s most popular sporting event has been about its high costs: Tickets that run anywhere from hundreds to thousands of dollars, public transit fares to some matches of $50 or more.

For fans, this year’s tournament is shaping up to be much more expensive than past World Cups.

Manuel Rueda, a freelance journalist who lives in Bogota, Colombia, has been to every World Cup since 1994. He goes with his dad, who now lives in Venezuela.

The two typically go to at least 9 matches each time, Rueda said.

Sometimes they catch Colombia in the group stage, and they’ve often attended some of the big games toward the end of the tournament, including the final. The total cost of those trips adds up fast.

“It's usually a minimum, like $10,000 per person,” Rueda said. “It's not cheap, even if it's in Qatar or in Russia or in Brazil.”

But this year, in the U.S., he expects they’ll pay almost twice that much. That includes the cost of hotels, flights, and especially tickets, even though they’re skipping the final this year. They’ll also miss Colombia playing Portugal in the group stage, because tickets for that match were in the thousands of dollars, Rueda said.

“Yeah, whatever, Cristiano Ronaldo is in the game, but it's not worth it,” he said.

Listen to “Wool In The Wash” on YouTube | Apple Music | Spotify

Americans are scared of microplastics and worried about climate change. Increasingly, that means Americans want wool.

Wool is not just for suits and sweaters either; it can be used in summer garments and even packaging. It’s breathable, and odor resistant. Depending on how it’s harvested, wool production can be net negative for carbon emissions. 

The wool industry is ready to embrace renewed demand, Stepan Sveshnikov reported for Offrange, but there’s a big problem: The American sheep herd.

“There's not enough sheep in the world, not even in big wool-producing countries like Australia,” to meet demand, Sveshnikov told Kai Ryssdal on “Marketplace” this week. For now, farmers are raising prices as they work to breed more sheep, more mills need to come online too.

Until then, I recommend buying vintage or even dumpster diving. Just remember to give your finds a wash before you wear them (and hang dry).