Breaching 1.5°C

Source: This post on Breaching 1.5°C has been created based on article “What breaching 1.5°C means ” published in Indian Express on 11^th January 2025.

UPSC Syllabus- GS Paper 3 – Environment

Context: The article discusses the significant milestone in climate change: the year 2024 became the first calendar year to breach the 1.5°C global warming threshold, marking a critical point in the planet’s warming trend. This breach, measured relative to pre-industrial temperatures (1850-1900 averages), is based on data from multiple global datasets, including the Copernicus Climate Change Service and the World Meteorological Organization (WMO).

What does breaching 1.5°C mean, and why is it significant?

1. Significance of 1.5°C: The 1.5°C mark, referenced in the 2015 Paris Agreement, is an arbitrary threshold indicating severe climate impacts as temperatures rise. It doesn’t signify an abrupt change but emphasizes worsening climate effects.
2. 2024 Breach: The year 2024 became the first calendar year to breach the 1.5°C warming threshold, with a global annual average temperature of 1.6°C above pre-industrial levels (1850-1900).
3. Paris Agreement Context: The 1.5°C target refers to long-term trends over decades, not individual years. Therefore, this breach does not imply the Paris Agreement has been violated yet.

What data confirms the breach?

1. Copernicus Climate Change Service: Recorded a 1.6°C rise above pre-industrial levels for 2024.
2. World Meteorological Organization (WMO): Using six datasets, WMO reported a warming of 1.55°C for 2024.
3. Historical Context: 2024 surpassed 2023 as the warmest year on record. For comparison, 2016, influenced by a strong El Niño, was 1.29°C warmer than pre-industrial levels.

Why did 2024 become the warmest year ever?

1. Contributing Factors:
   • Mild El Niño conditions during 2023-2024.
   • Other El Niño-like systems in different ocean regions.
   • The 2022 Tonga volcanic eruption, which altered atmospheric composition.
   • Reduced sulphur dioxide emissions from the shipping industry, which otherwise reflect solar radiation.
   • The Sun’s solar maximum phase during 2024, increasing solar energy reaching Earth.
2. No Single Cause: ECMWF notes that warming resulted from a combination of factors, and further analysis is required.

How do 2023 and 2024 compare to previous years?

Exceptionally Warm Years:

1. 2023: 1.45°C above pre-industrial levels.
2. 2024: 1.6°C above pre-industrial levels, breaking the previous record.
3. Monthly Trends: Every month since July 2023, except July 2024, was over 1.5°C warmer than pre-industrial averages.

Does this breach mean the 1.5°C target is unachievable?

1. Not Yet: A single-year breach does not mean the Paris Agreement target is unattainable. The focus is on multi-decade trends.
2. Future Outlook: With global warming rates exceeding 0.2°C per decade, breaching the 1.5°C target within the 2030s is highly likely.

What are the long-term implications of the 2024 breach?

1. Global Emissions: Emissions are still rising, and 2030 emission cut targets are unlikely to be met. This increases the probability of 1.5°C breaches becoming the norm.
2. Projections: According to the WMO, annual temperatures could reach 1.9°C above pre-industrial levels before 2028. There’s a 50% chance of the five-year average exceeding the 1.5°C mark by 2028.

What does 2025 and beyond look like?

1. 2025 Forecast:
   1. Not expected to surpass 2024 as the warmest year.
   2. Likely to remain in the 1.1°C to 1.4°C range above pre-industrial levels, consistent with the past decade.
2. Long-term Trends: The UK Met Office predicts 2025 might be the third warmest year ever, after 2024 and 2023.