Low investment rates in oil development projects could have long-term consequences, the CEO of Mubadala, Khaldoon El Mubarak, warned, according to CNBC.

“When you look at the investments in exploration projects all over the world … It has been depleted, and I believe we will see the results in the coming years,” El Mubarak said.

In 2014, the price of Brent crude dropped precipitously from a high of over $115 per barrel to as low as $27.88 per barrel in January 2016, according to Bloomberg.

The lower prices led to lower oil and gas investments, CNBC reports.

In June, the CEO of Saudi Aramco estimated that investments in the oil and gas sector had been reduced by $1 trillion due to low oil prices, Reuters reported.

Mubadala is a state-owned sovereign-wealth fund of Abu Dhabi.