Econintersect: At the end of September 2013 Working Group I of the IPCC (Intergovernmental Panel on Climate Change) released their fifth assessment of climate change physical science research. This was assembled six years after the fourth assessment in 2007. Among the most significant parts of the new report are analysis and assessment attempts to understand the apparent slowing of global warming over the last decade.
Climate and natural resources economist Sig Silber (who is a contributor to Global Economic Interchange) has provided the following list of what he considers the most signficant aspects of the new report:
It provides a clear picture of how Climate Change is likely to evolve over time.
It does a pretty good job of explaining Internal Variability which is the variation in climate that is unrelated to anthropogenic Climate Change but is the natural rhythms of climate. Of course these rhythms may themselves be influenced over time by Climate Change. This is probably the most misunderstood aspect of Climate Change by those who write about it without adequately studying the IPCC Reports.
It provides the bases for continuing debate as to what is the impact of man’s activities versus what is simply these natural rhythms.
- By and large it establishes that the worst impacts (what is called Catastrophic Climate Change) , those described in the popular media, are likely to be avoided until the next Century or the latter part of this one. It is more like the frog in water that is being heated than a sudden boiling of the water.
- But it is also a process that is essentially inexorable or perhaps not…since the Report of Working Group III has not yet been released. We have to wait for that to know what the possible mitigations are.
There are many possible scenarios modeled in the report, some of which are reported in the following table.
Table TS.1: Projected change in global mean surface air temperature and global mean sea level rise for the mid- and late 21st century.
The various scenarios cover an extended range of possible outcomes. For example the potential outcomes shown cover a range of temperature increases by 2100 from 0.3 to 4.8 degrees Celcius (0.5 to 8.6 degress Fahrenheit). The possible range of sea level rises by 2100 range from 0.26 to 0.81 meters (10 inches to 2 feet 8 inches). As much as the scientists are quite certain that warming will occur in the current century the extent and effects are quite uncertain.
Tthe results of Working Group I will not constitute the full report of the IPCC until they are integrated with the WPGII and WPGIII Reports and a Synthesis Report summary (SYR) is produced in the second half of 2014.
The additional six years of research included since the last report makes this a significant document in the assessment of what we know about climate change and global warming. The working group had 259 authors from 39 countries and reviewed 54,677 comments on their work.
Note: Sigmund Silber is currently researching and writing a book on the global long-term economic and geopolitical impacts of climate change, which to some extent will include analysis of the Working Group II Report when it is issued. He also serves on the American Society of Civil Engineers Weather Modification Standards Committee.
Sources:
Working Group I Summary for Policy Makers (IPCC, 27 September 2013)
Climate Change 2013: The Physical Science Basis (IPCC, September 2013)