What's up, sunshine?

New day, new stories, new chances to get smarter.

I'm Koi Wire.

This is CNN 10 and today we are going from a planet breaking temperature records to corals sending scientists a warning from beneath the waves.

And then we are making sense of the stock market.

10 minutes, big world.

Let's rise up.

We begin with our big world itself.

Coming off an August unlike any scientists have ever recorded before.

Studies show that August was the hottest August on record.

The global average about 63 degrees Fahrenheit.

May not sound hot, but remember that's averaging temperatures across the entire planet, day and night.

Here's what really jumps out.

August was hotter than July.

And it's almost never hotter globally than July.

It's happened only four other times since 1940.

Scientists say two forces are combining.

Long-term human-caused warming and a strengthening El Nino, a natural Pacific Ocean pattern that can temporarily turn up Earth's thermostat.

Ocean temperatures also reached record territory in August.

And sometimes warmer oceans mean that we see consequences beneath the surface.

Off South Korea's Juju Island, divers and scientists are watching normally vibrant soft corals droop and collapse, a phenomenon researchers call slumping.

As divers explore along a South Korean island, they're alarmed to what they see below the water.

Slumping coral.

A group of divers say many corals are collapsing as climate change pushes up water temperatures and contributes to intense weather events.

>> Today, the outdoor air temperature is a bit high.

And when I went underwater, even in the deep area, so many corals are lying collapsed >> off the coast of Jeju Island.

The UNESCO listed habitat is made up of soft coral.

Unlike hard corals, which have stony skeletons and form reefs, soft corals are bendable and flow with the currents.

They stay upright through fluid pressure.

But if the environment changes, they can sag or collapse.

This puts clusters of coral at risk of dying.

A record heat wave hit the Korean Peninsula this summer.

While the South suffered heavy rains, researchers say weather conditions such as these are potential triggers for soft coral slumping.

The researchers say the dying coral has widespread effects.

>> If this foundational ecosystem collapses, there is a very high possibility that the entire marine ecosystem could collapse as well.

The warmer waters have also caused fisher catch to decline.

A local fisher says the water has become too hot for species to spawn, and her typical 5-hour workday has dwindled to just 3 hours, partially because there's less to catch.

That place, the coral habitat in Ju is so beautiful and has been a source of comfort in my life.

Watching it collapse like that turning white, I was so bewildered and felt afraid, wondering, is the sea now completely collapsing?

>> 10sec trivia.

Which two animals represent a rising or falling stock market?

Cat and mouse, bull and bear, dog and pony, or moose and squirrel?

Answer is bull and bear.

A bull market occurs when stocks rise by at least 20% over a certain period.

A bare market is when stocks fall by at least 20% over that same time frame.

Memory trick.

Bulls thrust horns up, bears swipe claws down.

The stock market, we've all heard about it.

Maybe you're even invested in it.

Because sometimes investing can feel less like a way for us to build wealth and more like a game where Wall Street already knows all of the cheat codes.

We are here with our friend David Goldman to help us make sense of the stock market.

Great to see you, David.

If folks are anything like I am and don't know the difference between a bull market and a bull dog, how are we supposed to make money investing?

>> Yeah, it can be overwhelming.

I mean, you got these people on Wall Street.

They're day traders.

They got Bloomberg terminals.

You know, they're hedge fund managers.

with seven monitors that help them watch the market.

How could I possibly win?

Well, the best way to make money in the market, it's not to buy a few or even a bunch of stocks and sell them for a profit.

The best way is to buy just about every stock that there is and hold on to it until you're ready to retire.

Okay, that sounds great in theory.

I get it.

But also sounds like a lot of money.

Most of us can't just stroll into Wall Street and buy everything.

So, how do we know which stocks are the right stocks?

>> Yeah, it's a great point.

So, let's talk about something called the S&P 500.

It's one of the best ways to invest in the stock market because you can buy tiny pieces of every company.

So, you see, the S&P 500 is a stock market index.

It's a list of stocks that includes 500 of the biggest and most successful companies in the United States.

Think of it like a report card on the American economy.

Over time, buying the S&P 500 and holding on to it actually has the potential to beat those quote unquote smart people who buy and sell stocks for >> Okay.

All right.

Well, show me the receipt.

So, over the past 10 years, say if we put our money into the S&P 500 and let it ride, what might that investment have looked like?

>> Yeah, it's a great question.

So, in the last decade, you would have gotten a 14.4% average annual return on your investment.

But hedge funds, well, they only saw a 5% annual return.

So that means if you had put $100 in the S&P 500 in 2010, you'd have $364.68 in 2020.

That's an additional $264.68.

Now, if you put it in an average hedge fund, your $100 investment, well, that would only be worth about $159.98.

>> Wow.

Big difference.

Okay, so S&P 500 historically has performed well over time, but help us understand the stock market as a whole.

Make it make sense.

Yeah, think of the stock market like a bunch of companies selling little pieces of their businesses to the public.

So, for example, you know, you got a tech company, you got an umbrella company, a shoe company.

All of these companies make products that they sell to their customers.

Here's a good example.

So, let's just say jogging has become super popular.

Everyone wants to run.

So, everyone goes out and buys running shoes.

So, that shoe company stock, well, that's going to go up because they're making more money by selling more shoes.

Okay, but Goldman, you don't have a crystal ball, right?

None of us knows which companies are going to explode, which ones might implode, or what surprise might be lurking around the corner.

Talking about war, extreme weather, pandemics, political turmoil.

Shoot, one viral Tik Tok and suddenly people are rushing out to buy these overpriced drinking mugs.

>> Yeah, you're right.

That's a good point.

And that's why we diversify.

So instead of buying stock in the shoe company, we buy stocks from a huge variety of companies.

That's going to help take some of the risk out of our investment without reducing the potential return.

>> All right, Goldman, prove it.

Give us an example of how spreading your money around can protect you.

Okay, let's imagine we're in a town with just two businesses.

There's a business that sells umbrellas and the other one sells sunscreen.

So, weather can help or hurt both.

When it's sunny, the sunscreen business is booming and umbrella sales plunge.

But when it's raining, people line up to buy umbrellas and they're probably not buying a lot of sunscreen.

If it's sunny half the time though and it's raining half the time, well, that would give an investor in either company a pretty decent return.

>> I'm just glad you have the sun over your head today because I do not have sunscreen or a hat and my mom would kill me.

All right, so you're saying, David, if it's unusually rainy one year or if there's a drought in another, you could bet everything on one business, you could hit a home run, but you could also strike out.

>> Yeah, that's true.

But the if the same investor bought an equal share of both companies, then no matter what the weather, they'd get the same expected return.

So buying an index fund that gives you shares of the entire stock market, that follows the same principle across all industries and businesses.

But it's not foolproof.

Investing in stocks is always inherently risky.

In 2022, the market lost a fifth of its value.

But had you been invested in the S&P 500 over the past 10 years, your return would have been 300%.

Today's story getting a 10 out of 10.

A world where a trip to the dentist is not so scary.

At this Colorado dental office, patients have something to look forward to during their checkups.

A therapy dog named Annie.

When someone needs a little comfort, Annie hops up on top of them, wrapping them in what feels like a fuzzy four-legged blanket.

This calming K9 has basically become a star with millions of views on social media and now her very own children's book.

Patients say Annie has helped them calm their nerves so much that some now look forward to trips to the dentist.

Proof that sometimes maybe the scariest places just need a furry friend.

All right, before we go, I have a shout out going to Miss Jones and friends at Mir's Middle School in Anchorage, Alaska.

Rise up.

Thank you for the kind words about our 911 special.

We are here for you.

And some welldeserved love.

Mrs.

Barber at St.

Cecilia Catholic School in Clearwater, Florida.

35 years of teaching.

Mrs.

Barber, that's generations of students whose lives are different because of you showing up for them.

Thank you for all you do and for making us a part of your classroom.

Shine on sunshine.

That's our 10.

Go learn something.

Go teach somebody.

Go make somebody's day better.

The world needs the best version of you today.

I'm Cy Wire and we are CNN 10.