Clarifying the matter of nominal and real interest rates

Nominal long-term interest rates are now rising in the United States and the euro zone. Real long-term interest rates are also rising, although they remain low (lower than real growth). So should one be concerned that nominal interest rates are rising ? O r reassured that real interest rates remain low? As long as the real long-term interest rate is lower than real growth, the public debt ratio dynamics is stable. The public debt ratio cannot diverge, but it may converge towards a limit that exceeds the country’s borrowing capacity. A first thing to watch is therefore the relative levels of the real long-term interest rate and real growth; If the nominal interest rate and inflation rise in parallel (the real interest rate does not change), the public debt ratio dynamics is unchanged. But the total fiscal deficit rises. There are then two scenarios: Either this does not pose a problem , if savers want to stabilise the weight of government bonds relative to income in their portfolios; Or it can pose a problem if savers think in terms of flows (not stocks) and have a limit to their government bond purchases in a given period or to the amount of savings used to buy government bonds.