Temperature Rise Threshold Target

The Paris Agreement in 2015 calls for concerted action to hold the increase in global average temperature to less than 2 degrees Celcius (C), and the more ambitious target, to 1.5 degrees C—above the pre-industrial levels[1]—and net-zero greenhouse gas (GHG) emissions by 2050. The temperature-limit  threshold refers to the Assessment Report 5 (AR 5) of the Intergovernmental Panel on Climate Change (IPCC) which stated with medium confidence that precise levels which can trigger a tipping point— dramatic, irreversible changes of the Earths’ climate. While the option of the more ambitious temperature limiting target has been advocated by climatologists, and also by Frank Bainimaram, the Prime Minister of Fiji, who stated that scientific research is revealing climate that is changing at a faster rate than was believed in the Paris Agreement. The temperature threshold target issue has further been complicated by assessments made on its feasibility[2]. While temperature threshold target has become a contentious issue, pledges and efforts thus far are still on the trajectory of putting the Earth’s temperature rise of 3C degree or more, thus the urgency of immediate action (United Nations Framework Convention on Climate Change).

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[1] Carbonbrief has provided an overview on the difference of 1.5 versus 2 degrees rise in the average global temperature which compares the differences in heatwave duration, freshwater availability , increases in rainfall  intensities, crop yield increases and decreases, sea level rises, and coral bleaching.

[2] A draft "special report" by the UN climate science panel to be unveiled in October, obtained by AFP, concludes that "holding warming at 1.5C by the end of the 21st century (is) extremely unlikely" (phys.org). However, "We can still keep temperatures well below 2 degrees," said Myles Allen, a professor of geosystem science at the University of Oxford a co-author on several of the studies. But doing so requires that "we start now and reduce emissions steadily to zero in the second half of the century," (phys.org). Nevertheless a study in Nature Geoscience finds that holding the rise of global temperature to 1.5 degree Celcius is possible although very challenging (Millar et al., 2017).