Europe has limited options for finding natural-gas supplies from outside of Russia despite tensions over Ukraine, the International Energy Agency’s chief executive, Maria van der Hoeven, said on Monday. “In the short term, Europe has very, very little means to diversify its gas imports,” Ms. van der Hoeven said on the sidelines of the Offshore Northern Seas energy conference. “As far as we can see, Russian gas will be needed in Europe.” About a third of Europe’s gas supply comes from Russia and a fifth is supplied by Norway, while other key sources include imported liquefied natural gas and producers like the Netherlands and the U.K., Ms. van der Hoeven said. “If you want to change that and diversify, it takes time. You can’t do it overnight,” she said. The agency—which advises industrialized nations on oil and gas policies—forecast last year that the European Union’s annual gas imports […]