Further efforts in climate change adaptation and mitigation are indispensable

The establishment of the Intergovernmental Panel on Climate Change (IPCC) and the publication of its first assessment report (FAR) in 1990 marked the commencement of the international climate policy. Two years later, in 1992, the United Nations Framework Convention on Climate Change (UNFCCC) was signed at the Earth Summit in Rio de Janeiro (Brazil), which offers a crucial basis for international climate negotiations. Since 1995, the last 2 months of each calendar year have been earmarked as the intensive negotiation period for a UNFCCC Conference of the Parties (COP). Among the significant achievements in the international climate policy that are worth mentioning are the Kyoto Protocol at COP 3 in 1997, the Bali Roadmap at COP 13 in 2007, the Copenhagen Accord at COP 15 in 2009, and—above all—the Paris Agreement at COP 21 in 2015. The latest COP of the UNFCCC (COP 29) was held in Baku (Azerbaijan) from November 11 to 24, 2024, with the attendance of some 66,700 participants from approximately 200 states. The negotiations took much time, resulting in COP 29 terminating 2 days after the scheduled end of the conference. A new climate finance goal, which aims for developed countries to mobilize at least USD 300 billion annually by 2035 to assist developing countries in adaptation to climate change, can be regarded as one of the most significant steps forward.

Challenges faced by the Paris Agreement

The global average temperature in 2023 surpassed the previous record-high year, 2016, being 1.45°C ± 0.12°C higher than the 1850–1900 average, that is, close to the more ambitious Paris Agreement warming limit of 1.5°C above the pre-industrial level. The 2023 temperature record coincided with a warm (El Niño) phase of the ENSO cycle of climate variability over most of the year. The Oceanic Niño Index (ONI), based on a 3-month running mean, marked the warm (El Niño) phase, with ONI ≥ 0.5, from AMJ (April-May-June) 2023 to MAM (March-April-May) 2024 (https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf). The climate variability index ONI transgressed to the neutral state in AMJ 2024, and the climate system remained in the neutral state −0.5 < ONI < 0.5 for most of the year, moving to the cold phase (La Niña) toward the end of the year (3-month running mean from November 2024 to January 2025). Yet the year 2024 was by 1.55°C ± 0.13°C warmer than the 1850–1900 average (Figure 1A), being the first year in which the global temperature anomaly has exceeded the 1.5°C threshold. Each of the years from 2014 to 2024 belongs to 11 globally warmest years on record. The essential attribution statement given in the Sixth Assessment Report (AR6) of the IPCC1 attributes the warming of the atmosphere, ocean, and land to human influence in an unequivocal way. Climate change impacts are among the essential reasons for concern of humankind, and the transgression of tipping points would imply unbearable challenges to the affected societies and ecosystems.