What If the World Had Only One Central Bank and One Global Currency?

Picture a world where all currencies have vanished, and a single currency, let's call it "Gold Coins," reigns supreme. This currency would be used for everything - from salaries to purchases, and even between countries. An omnipotent Global Central Bank (GCB) would manage this currency. While this single currency would simplify many aspects of life like travel and online shopping, it could also lead to a dystopian outcome.

Countries have distinct histories, resources, and needs that vary greatly. An oil-producing nation reacts to rising energy prices differently than a country that imports oil. During a disaster, a recovering country has different priorities than a booming one. Thus, central banks use tools like interest rates to manage their own local economic conditions.

If we apply this to a world with Gold Coins, the GCB's uniform monetary policy would have opposite effects in different regions. For instance, a severe drought in South America would require cheaper credit for recovery (lower rates from the GCB), while East Asia with record industrial growth may need tighter policy to curb inflation (higher rates from the GCB). The GCB cannot fully satisfy these needs simultaneously.

The Optimal Currency Area (OCA), proposed by Robert Mundell, suggests a group of regions or countries with similar economies, easy movement of people for work, and stronger areas helping weaker ones during downturns. Under these conditions, one central bank could manage monetary policy more effectively for everyone. The Eurozone in Europe is the closest real-world example, but it also highlights the challenges of an OCA.

During the European debt crisis, countries like Greece and Spain were in recession while Germany was doing well, demonstrating the difficulties of balancing diverse economies.

Another potential "global currency" is the Special Drawing Rights (SDRs) by the International Monetary Fund (IMF). They're not physical coins you can spend, but a global reserve asset. However, neither the Euro nor the SDR has replaced the majority of national currencies. While international monetary cooperation is achievable, it becomes increasingly difficult when diverse economies join the system.

A centralized GCB is a single point of failure and a massive target for malicious actors. It would accumulate vast resources for humanity but could become a curse if it makes a bad call with its global currency. Everyone would share the same fate, and corrupt officials or hackers could lead to catastrophic failures. The GCB's immense power could turn it into a financial version of "Big Brother" with the ability to monitor and control people's money.