The Euro currency was introduced and adopted by 11 Member States.
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The Maastricht Treaty came into effect, and with it, the European Union was formed.
The European Union's climate service declared that 2023 was the hottest year on record.
The European Union expanded the 1951 Stresa Convention.
The EU declared that single-use plastics would be banned by 2021.
The Paris Agreement was opened for signatures.
