The 1.5°C Global Warming Threshold

Source-This post on the 1.5°C Global Warming Threshold has been created based on the article “‘One point five degrees’: Has global warming exceeded the much-feared tipping point?” published in “Down to Earth” on 27 July 2024.

UPSC Syllabus– GS Paper 3 – Conservation, Environmental Pollution and Degradation, Environmental Impact Assessment.

Context– A recent paper by climatologist Malcolm T. McCulloch, published in Nature Climate Change, has sparked debate by claiming that global warming has already exceeded the critical 1.5°C threshold above pre-industrial levels.

The Paris Climate Agreement, signed in 2016 by nearly 200 nations, aims to keep global temperature rise below 2°C and ideally within 1.5°C. Exceeding the 1.5°C limit could cause severe damage, such as destroying coral reefs, melting Arctic Sea ice, and thawing permafrost.

What are the issues with the recent publication of a paper on Nature Climate Change?

1) Disagreements in the Scientific Community- The Paris Climate Agreement doesn’t specify a clear baseline for temperature changes. McCulloch’s research, which compares today’s temperatures to those from 1700-1860, 1.5°C threshold is breached. However, most climate scientists prefer using the 1850-1900 average for comparison.

Read More- Climate Change Negotiations after Bonn Climate Meet

2) Calculation methods- The Paris Agreement also does not specify the process of calculating the increase in temperature. For ex- using the 1850-1900 average as a baseline shows that last year’s global average temperature was 1.5°C higher. However, experts argue this doesn’t necessarily indicate a permanent breach of the 1.5°C threshold.

3) Temperature Measurement – To account for annual temperature fluctuations like those from El Niño, scientists use a 20-year average, combining the past 10 years with projections for the next 10 years. This method shows the current average temperature increase is about 1.3°C.

Way forward– Despite these disagreements among scientists, the IPCC projects that 1.5°C threshold will be breached by 2040. This highlights the urgent need for immediate climate action and global cooperation to avoid the worst impacts.

Question for practice

What are the issues with the recent publication of a paper on Nature Climate Change?