LONDON - The amount of debt owed by the world’s governments will jump to a record $53 trillion by the end of the year, S&P Global estimated on Thursday, with $8.1 trillion set to borrowed this year alone. About 70%, or $5.8 trillion, of sovereigns’ gross borrowing will be to refinance maturing long-term debt, though the expected $2.3 trillion of new borrowing will still be worth at least 2.6% of global GDP. S&P said the increase reflected the higher borrowing needs of the largest countries. The U.S. at $3 trillion and Japan at $1.75 trillion will remain by far the...