If greenhouse gas emissions are not cut drastically and rapidly, between 2030-52, Earth’s global average temperatures could rise by 1.5 degree above pre-industrial era levels, leading to widespread climate change impacts. This is the crux of the UN climate change science panel report that all the countries accepted on Saturday after a contentious and strenuous meeting between scientists and diplomats in Korea.
On a jarring note, the US announced that it accepted the report - in effect stopped short of vetoing it - but it did not endorse the content and the findings in the report. It also reasserted that it was determined to step out of the Paris Agreement on the first given opportunity.
Before it did so, the US made a belligerent attempt to dilute the contents of the report along the lines it had planned. This included a push to drop references to how historically accumulated emissions in the atmosphere, and not just the current flow of emissions, have caused climate change. It also objected to references to the emissions being reduced in keeping with the principle of equity and fairness.
The larger import of the finalised report’s findings was not much different from that of the drafts that had leaked out earlier, though the negotiations between government representatives and scientists did end up substantially altering how much confidence the governments placed on different findings based on the scientific evidence underlying the summarised take-aways.
The report reads, “Human activities are estimated to have caused approximately 1.0 degree Celsius of global warming above pre-industrial levels, with a likely range of 0.8 degree celsius to 1.2 degree celsius. Global warming is likely to reach 1.5 degree Celsius between 2030 and 2052 if it continues to increase at the current rate.”
The scientists summarised that the already recorded rise of 1 degree in global average temperatures has led to substantial impacts. “Impacts on natural and human systems from global warming have already been observed (high confidence). Many land and ocean ecosystems and some of the services they provide have already changed due to global warming (high confidence).”
Confidence levels in the brackets refer to how emphatic the scientific research is in helping make these headline statements.
A rise in global temperatures by another 0.5 degree Celsius would increase, deepen and spread the impacts wider, the scientists concluded. “Several regional changes in climate are assessed to occur with global warming up to 1.5 degree Celsius compared to pre-industrial levels, including warming of extreme temperatures in many regions (high confidence), increases in frequency, intensity, and/or amount of heavy precipitation in several regions (high confidence), and an increase in intensity or frequency of droughts in some regions (medium confidence).”
The report laid out how the changes to climate, environment and human life would be less devastating and dangerous if the global temperature rise is contained at below 1.5 degree instead of 2 degree Celsius - the existing primary goal of the Paris Agreement.
Several countries have advocated at the negotiations to implement the Paris Agreement that the goal should be shifted to keeping temperature rise below 1.5 degree Celsius. This would require all countries to enhance their existing emission reduction targets under the agreement for the period starting 2020. It would also require developed countries to contribute more to global finance flows and technology sharing for poor countries to achieve these enhanced targets.
The tricky bit for countries remains to figure out what set of actions could keep the global temperature rise below 1.5 degree Celsius. Different set of actions lead to varying costs of action, impacts for different countries. Scientists acknowledged that some set of actions could require a trade-off with sustainable development (a proxy word used for sustainable growth, poverty eradication and better living standards for the poor).
Not acting to keep the temperatures under check would have many damaging consequences the scientists noted. But, these actions also require a significant effort. “These systems transitions are unprecedented in terms of scale...and imply deep emissions reductions in all sectors, a wide portfolio of mitigation options and a significant upscaling of investments in those options.”
The scientists concluded that the “Total annual average energy -related mitigation investment for the period 2015 to 2050 in pathways limiting warming to 1.5 degree Celsius is estimated to be around $900 billion at 2015 prices.
The final report made a more nuanced assessment of the costs than the drafts had suggested. It said the discounted marginal abatement cost through the 21st century would be 3-4 times higher than that for keeping temperatures rise up to 2 degree Celsius. It acknowledged that the full cost and benefits to the economy of keeping temperature rise to 1.5 degree Celsius had not been estimated.
But, the scientists also warned that the existing emission reduction targets for the period between 2020-2030 under the Paris Agreement had to be enhanced. The global temperature rise would not be contained at 1.5 degree Celsius if the countries enhance their targets only for the period after 2030.