The world mostly ignored Ed Morse 11 months ago when the head of commodities research at Citigroup said the price of oil could drop as low as $20 per barrel.

It’s paying attention now that crude has tipped to about $30.

BP Plc slashed 4,000 jobs, Petroleo Brasileiro SA slashed its spending plan, and Petroliam Nasional Bhd. warned that it faces several tough years before crude futures in the United States sank into the $20s for the first time in 12 years.

Morse, who wrote in a Feb. 9 research note that oil could fall “perhaps as low as the $20 range for a while,’’ said Tuesday in Calgary that the world is now “confronting $20 oil.’’

“The $20 number is something you have to talk about,’’ Morse said. “When you’ve seen a $10 price slide and WTI is trading just slightly above $30, the likelihood is fairly great. Clearly oil markets cannot maintain a price at below the $30 level for very long. The question is how much longer.’’

West Texas Intermediate fell as low as $29.93 a barrel before settling at $30.44 Tuesday, the lowest level since December 2003.

Low oil prices could cause problems for US oil companies with debt covenants that specify certain debt-to-earnings ratios or interest coverage, and will make it even harder for those companies to obtain financing to continue to operate, said Mark Sadeghian, a senior director for the energy and commodities group at Fitch Ratings Ltd.

The Bloomberg Commodities Index fell to the lowest level since at least 1991 as demand from slowing emerging-market economies fails to keep pace with a flood of supply from investments made during the price boom of a half-decade ago.

Malaysia stands to lose 300 million ringgit ($68 million) for every $1-a-barrel decline in crude, according to government estimates. ConocoPhillips is losing $1.79 billion in net income each quarter for every $10 drop in prices, according to analysts at Barclays Plc.

Petrobras, as Brazil’s state-controlled oil producer is familiarly known, cut its five-year business plan to $98.4 billion, the latest adjustment to the original $130 billion announced last year.

The US Energy Information Administration reduced its forecast for WTI prices for 2016 by 24 percent to $38.54 a barrel. In its monthly Short-Term Energy Outlook, the agency said the oil market would come back into balance in 2017.

The call for oil in the $20s grew louder in recent months, with Goldman Sachs pinning a 50 percent chance of oil falling to $20 in September and Morgan Stanley saying Monday that a strong dollar could drop oil below $30. Morse was first with the $20s call, although he said last February that it could happen in the first half of last year followed by the market balancing.

“Right now the real driving factor is access to capital markets,’’ Sadeghian said by phone from Chicago. “$20 oil just digs an even deeper hole from where you need to be before the markets open up again.’’