I awoke this morning to find notification of a tweet from Jan Pascal van Ypersele, the vice chairman of the IPCC. He had tweeted the image of a new graph from the Japanese Met Office suggesting something of a leap in global temperatures in 2014. I had pointed out that the long-term trend marked on the graph was, at just 0.7°C, hardly the stuff of nightmares.
At this point, our exchange was interrupted from a environmentalist who pointed to the current wildfires in South Australia and one to problems in the delta of Bangladesh. His point was somewhat obscure in relation to what van Ypersele and I had been discussing, so I ignored these contributions, but it seems that the great man felt that the Bangladesh point was worth a wider audience and he retweeted to his followers:
Here's the original:
@aDissentient @Sustainable2050 @JPvanYpersele You're probably not a Bangladeshi subsistence farmer. Conspiracy? http://t.co/jgurhF8Zzm
— David Hoyle (@VeteranDave) January 4, 2015
The link is to a story in the Sydney Morning Herald which tells of farmers being driven from their lands by rising seas and is based on a report from the Asian Development Bank. It's a familiar story.
It's worth recalling, however, that sea level rise is only one of several factors in play in the delta area of Bangladesh. The area of the delta is affected not only by rising seas, but also by the continual discharge of sediment from the rivers that feed it. I had thought that the simplistic story that the delta was disappearing had been killed by research published in 2008, which showed that the area of the delta has increased. Interestingly, one of the threats to this process is the advent of hydroelectric dams upstream in India. So the preference for renewables over fossil fuels may well be the real threat to the delta.
The authors of the SMH story also want you to believe that salinity issues are leading to a vast loss of agricultural land:
The proportion of arable land has fallen 7.3 per cent between 2000-2010, faster than South Asia's 2 per cent decline, with geography playing a large role.
The problem is that the World Bank's data finds that there has been no fall in the proportion of agricultural land. In fact there has been an almost uninterrupted increase in production of rice in Bangladesh and I think I'm right in saying that most of this comes from the delta.
This is not to say that there aren't salinity problems, but salinity is a complex issue with multiple factors at play - see overview here. Given what we know about the increase in size of the delta it's hard to imagine that sea level rise is a major factor. And given that the climatic contribution to sea level rise is at present nugatory, I think we can say that the SMH story is largely nonsense.