The turmoil in emerging markets that has seen Argentina's peso devalued and interest rates raised in Turkey, South Africa and India will have a negative impact on the U.S. economy, says Eswar Prasad, a Cornell University economist.

"It's certainly not good for the U.S. economy," he tells Yahoo.

Emerging markets now account for about 40 percent of global GDP, and have taken up a bigger share of global growth since the 2008 financial crisis, Prasad notes.

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"If that group of economies slows down, then the world is again going to be looking to the coattails of the U.S. to pull it along, and that's not so good for the U.S.," he adds.

Moreover, the weakness in emerging markets boosts the dollar, "which means fewer exports and fewer jobs here. It makes our imports cheaper, but it's not good for job growth."

Since the financial crisis, whenever turmoil has arisen, whether it's been in emerging markets, Europe or the United States, investors have rushed here for safety, Prasad explains. "The U.S. is the only place to run and hide."

Meanwhile, Russ Koesterich, chief investment strategist at BlackRock, writes in a commentary obtained by The Wall Street Journal that emerging markets are naturally volatile, that each one has its own unique issues and that emerging markets are good bargains now.

"Emerging markets offer deep value," he states. "Given that they're generally growing faster than their developed world counterparts, emerging markets still look cheap by most metrics."

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