Global Warming Limit
Ethan Huang '27
The effects of climate change are becoming more pronounced with each coming year. 2023 was the hottest year on record,1.18°C over the average temperature of before humans began burning fossil fuels. This record inches us closer to surpassing the 1.5°C limit of global warming pronounced by the Paris Agreement. The Paris Agreement was a significant treaty signed by 195 countries who promised to limit warming to within the set threshold of 1.5°C.
https://www.ncei.noaa.gov/access/monitoring/monthly-report/global/202313
How far have we come?
There have been many international conventions and treaties regarding climate changing and managing emissions. The first international treaty regarding climate change, UN Framework Convention on Climate Change, was signed in 1992 and called for a decrease in greenhouse gas emissions. In 1997, the Kyoto Protocol aimed to have industrialized countries meet emission targets in order to hold back global warming. Thirteen years later, countries signed another treaty, the Cancun Agreement, that aimed to hold global temperatures below 2.0°C. However, in 2015, 195 nations came together at COP21 and signed the Paris Agreement, which stated that all signatories would “hold the increase in the global average temperature to well below 2°C above pre-industrial levels and pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels.” However, regardless of the agreements, countries have delayed or put off implementing policies curbing carbon emissions which have led to increasing temperatures as humans pump larger amounts of greenhouse gasses into the atmosphere. If the world had began to limit carbon emissions in 1992, they would have had nearly 100 years to eliminate carbon emissions in order to keep warming below 1.5°C. Now, due to the sheer amount of greenhouse gases and procrastination on states’ part, humans are left with 12 years to completely eliminate carbon emissions in order to limit global warming below 1.5°C.
Source: https://www.nature.com/immersive/d41586-023-03601-6/index.html
Where we are
At the current rate, warming is increasing by around 0.2°C per decade. In 2015, average global temperatures surpassed the preindustrial levels by 1.0°C for the first time since humans began recording the climate. Then, 2023 became the first year where all days had global temperatures break the 1.0°C point. During a 12-month period from 2023 to 2024, the Earth surpassed 1.5°C of global warming. Although the Paris Agreement aims to keep global temperatures down in the long term, this brief jump is veering dangerously close to the limit. If we continue at this rate, mean global temperatures could very well break 1.5°C in the next decade or so.
Why is 1.5°C? what will happen Global Warming of 1.5 ºC —
Well, of course the mean surface temperature of the earth would get 1.5C warmer; however, not all regions of the world will warm the same. The arctic may warm to nearly 3°C while landmasses may warm anywhere from 1.5-3°C. Therefore, even though the number only indicates a minor change in average temperature, specific places are likely to experience extreme heat. Additionally, precipitation may drastically increase in some areas, especially the polar regions and central Pacific Ocean, but decrease in others, such as the Mediterranean and Central America. It’s possible for some areas to receive 30% more rainfall while others struggle with 20% less. Places that may have more adverse impacts will include small island nations and Subsaharan African, regions of the world’s least developed countries. Due to the extreme abnormality in precipitation, many island nations will flood more easily and be more susceptible to storm damage as the rising sea level eats up the limited land they have. For example, Southeast Asia is expected to see more coastal flooding and heavy precipitation as sea levels rise, which will result in 1/3rd decline in crop yield per capita. The tropics will see substantial increase in the number of hot days & nights and more heatwaves, leading to decreased crop yields as well. Of note is Subsaharan Africa, which will see temperature increases higher than the global average and more frequent heatwaves. There will be the risk of less rainfall to the region, especially the Sahel, leaving it vulnerable to droughts and food shortages. The Arctic circle may suffer even more adverse effects. If human surpass 1.5°C of warming, the IPCC (Intergovernmental Panel on Climate Change) estimates that the risk for an ice-free arctic during the summer would be 50% or greater. This would lead to large number of habitat loss for Arctic wildlife as ice melts away.
Some notes:
Ipcc - warming is increasing at 0.2C per decade, earth will reach 1.5 C average between 2030-2052
If global temperatures reach 1.5C
https://www.ipcc.ch/sr15/chapter/chapter-3/
Climate Change: Global Temperature
https://climate.nasa.gov/vital-signs/arctic-sea-ice/?intent=121
What's in a number? The meaning of the 1.5-C climate threshold.
https://www.washingtonpost.com/climate-environment/2024/02/08/1-5-celsius-global-warming-record/
Explained: The 1.5 C climate benchmark | MIT News | Massachusetts Institute of Technology
https://www.nature.com/immersive/d41586-023-03601-6/index.html