In my
first post, I briefly touched upon the widely debated link between conflict,
migration and climate change. However, there are other seemingly less complex,
and certainly less controversial, cause-and-effect relationships between
climate change and population displacement. For example, it has been estimated that sea-level rise will displace 150 million by 2100, either as result
of submerged land or chronic flooding.
Reconstructions
of past sea level show that considerable fluctuations have occurred throughout
geological time, but conditions seem to have remained relatively stable
for the past 6000 years. This however, appears to have changed within the
last 100-150 years; studies suggest that sea level has risen at a rate of approximately
1.74 mm per year over this period of time.
Sea level measurements from 23 tide gauge records in geologically
stable environments during the 20th century (Douglas, 1997).
Two of
the main contributing factors to this sea level rise are:
- Thermosteric change: An increase in atmospheric temperature contributes to the warming of the surface ocean. This leads to an expansion in the overall volume of water and is thought to have contributed to approximately 2.5 cm of the sea level rise observed in the last 100 years.
- Melting ice sheets: In Antarctica, rapid shelf loss is already being witnessed at the Antarctic Peninsular and new research highlights a number of other ice shelves which may collapse completely within the next century, assuming similar emissions. The Greenland ice sheet is also vulnerable. Were the entire sheet to disappear, it would contribute to 7 m of global sea level rise.
Using the
IPCC’s 6 different radiative forcing scenarios, a sea level rise of between 0.6
and 1.6 m is predicted to occur by
end of the century. Putting this into perspective, a 0.8 - 2.0 m rise would be
enough to drown many U.S. East Coast cities, and some low lying Pacific islands
may be lost completely. Surges and flooding will also be greatly exacerbated
during storm events. Consequently, it is thought that rising sea levels could
result in loss and damages that are equivalent to ten percent of yearly global GDP by 2100.
Whilst there are discrepancies as to the scale of change, there is an
overwhelming consensus that sea levels will continue rise. It would however, be
too simplistic just to get a map, cross out the the areas that would be
expected to disappear or encounter extreme flooding, and assume that all of the
people living there will move. For the people who do move, it is also not
possible to isolate sea level rise as the direct reason for this, with many
other factors likely to be influential. Therefore, in my next few posts I will
aim to look at a range of case studies, comparing the predicted impacts and
potential responses between contrasting countries.
I saw a Ted Talk by Mary Robinson where she mentioned that the President of Republic of Kiribati, a small island country, was buying land on Fiji for his people in case they need to emigrate. Do you expect many other island nations to adopt similar strategies?
ReplyDeleteThanks Darcy, I’m actually going to look at Kiribati as a case study in my next post, but this is a really interesting question to consider. I know that Maldives looked at purchasing land in Australia a couple of years ago for a similar purpose, but I can’t see anywhere which suggests whether or not this actually went through. However, I think it is difficult to see how this is likely to be a practical or financially viable option for all islands in this situation. For places such as the Maldives, Kiribati and Tuvalu, the cost of protecting against and adapting to climate change, as a percentage of national income, is amongst the highest in the world. This is something that is only going to be exacerbated in the coming years as the tourism (particularly so for the Maldives) and agricultural industries are further damaged by rising tides.
ReplyDeleteI think this links into the issue of ‘climate change compensation’; given that these particular countries are disproportionately affected by climate change, should they have to foot the bill for an adaptive strategy, when their individual impact upon the issue has been minimal? There was a recent article in the Guardian which voiced the pleas of the Pacific islanders for assistance from wealthier nations with a future adaption and migration strategy and it will be really interesting to see how this is discussed in Paris. From the article, it appears that they are predominately aiming for external assistance to mitigate against the effects of rising sea levels and to stay as they are for as long as possible, with the expectation that some migration will be necessary. I think the extent to which they manage to achieve ‘compensation’, will have vast implications for the adaptive strategies that they choose to adopt in the future. I’m planning to cover this topic a little more extensively throughout the course of the blog, but hopefully this has answered your question to some extent!
Nice post Katherine. How does the Fig presented above on SLR by Douglas (1997) compare with more recent model forecasts, which (even after the last IPCC report) may be a strong under-estimation?
ReplyDeleteThanks Anson. The Douglas (1997) observations of sea level rise that I used in the post are indeed significantly lower than the recent IPCC projections. The initial tide gauge measurements presented an approximate 0.18 m sea level rise in the 100 years prior to the publication of the paper. The IPCC however has predicted that even assuming a best case scenario, by 2081-2100 there would be a 0.40 m (0.26-0.55) increase in global mean sea level rise from observed 1986-2005 values. For the worst case of the IPCCs six future scenarios, this value increases to 0.63 m (0.45-0.82).
DeleteHowever as you said, this value was heavily criticised for being too conservative. This disagreement generally appears to revolve around the type of model used; process-based models as used by the IPCC generate much lower value than semi-empirical models. Although the latter are thought to be less reliable by many, there are others who argue that the information should not be ignored completely. Rahmstorf (2014), who seems to be a keen supporter of this method, suggested that a global mean sea level rise would increase by 0.7- 1.2 m by 2100, in a high emission scenario. It seems to be that most are able to agree that mean sea level will have increased by 2100 (and will increase at a greater rate than was evident in the last century), but there is still too much uncertainty in the modelling to generate a more universally accepted figure. It will be very interesting to see how the IPCC develop their methods in the future, particularly given that their most recent estimates were a significant revision on those presented in the Fourth Assessment.