Triffin’s Dilemma is that the country that issues the world’s reserve currency will have to choose between:
1 ) running a trade deficit in perpetuity - risking of a loss of confidence in its currency and solvency while the rest of the world enjoys an adequate supply of USDs.
2) running a trade surplus and enjoying an appreciation in the value of the dollar while the rest of the world suffers from a lack of liquidity and collateral.
Either way, there are negative implications for world growth. In the first example – in which the US runs a trade deficit in perpetuity – the US continues to add to its debt and risks undermining its ability to pay off that debt. In the second example – in which the US runs a trade surplus – emerging market currencies are put under pressure by the USD potentially leading to capital outflows, a higher cost of debt, and global financial instability.