The correct option is 2005.
Explanation
The Kyoto Protocol is an international treaty that operationalizes the United Nations Framework Convention on Climate Change (UNFCCC) by committing industrialized countries and economies in transition to limit and reduce greenhouse gas (GHG) emissions in accordance with agreed individual targets.
Timeline of the Kyoto Protocol:
- Adoption: The Protocol was adopted on 11 December 1997 in Kyoto, Japan.
- Entry into Force: Due to a complex ratification process, it entered into force on 16 February 2005. This occurred after the condition that at least 55 Parties to the Convention, incorporating Annex I Parties which accounted for at least 55% of the total carbon dioxide emissions for 1990, ratified it.
- Commitment Periods: The first commitment period started in 2008 and ended in 2012. The second commitment period (Doha Amendment) began in 2013 and ended in 2020.
Key Takeaway: While the Kyoto Protocol was adopted in 1997, it only became legally binding and went into effect in 2005 following the ratification by Russia, which satisfied the 55% emissions requirement.