Student Blogpost: Coastal and marine implications of a 1.5˚C increase in warming: Implications of the Paris Agreement

ECE 2018/19 Student Toby Miller reports on the first coastal seminar of this term, a SMMI workshop on  “Coastal and marine implications of a 1.5˚C increase in warming: Implications of the Paris Agreement”. The workshop featured presentations by, and discussion with a team of experts from the University, including Dr Sally Brown, lead author on one of the chapters of the special IPCC report, Dr Ivan Haigh, Dr Phil Goodwin and Prof Robert Nicholls:

The expert panel (L to R: Ivan haigh, Phil Goodwin, Sally Brown, Robert Nicholls)

On the 8th of October 2018 a special IPCC report was released showing how important it will be to restrict global warming to only 1.5˚C before pre-industrial times, and possible implications if this cannot be achieved. This report stems from the Paris agreement; which aims to strengthen the global response the threat of climate change by keeping global temperature rise below a critical values of 2˚C. Although the Paris agreement is very important, this agreement does not look at the effect of sea level rise and the consequences this may have on a large number of people and ecosystems.

Since the 1st reading in 1850, Global temperatures have increased by 1˚C. Graphs show that global temperatures are rising linearly; meaning that global temperatures are likely to reach 1.5˚C bu 2030 to 2052. The only way in which a maximum global temperature rise of 1.5˚C is attained requires starting heavy mitigation now. Studies show that in order to keep temperatures to this level, we must be a carbon neutral society by 2050. To keep global temperatures below 2˚C, we must be a neutral carbon society by 2075. Carbon dioxide is not the only greenhouse gas which is causing this rise in temperature. Methane and Nitrous Oxide must also be limited in order to reduce global temperatures. However, these do not need to be reduced to 0 as they are released from the atmosphere much faster than CO2.

Goodwin et al. 2018 doi: 10.1038/s41561-017-0054-8


If society were to become a carbon neutral society by 2050 and global temperatures were limited to 1.5˚C, sea levels will still continue to rise. This is due to inertia in the system and the fact that so far only the surface water has been heated; it will take hundreds and maybe thousands of years for this heat to dissipate over all the oceans. Depending on the level of mitigation, sea levels are project to rise by 0.4m (severe mitigation) to 0.8m (no mitigation). This shows how mitigation can reduce and help stabilise the rate of sea level rise. By 2300 1.5% to 5.4% of the worlds population may be exposed to flooding. Other factors such as Ocean acidification will have severe effects on corals and organisms, ecosystems and population who rely on them. Coral reefs may be completely wiped out by 2100 if little mitigation takes place.

Rising sea levels will have a particularly drastic impact on small islands such as the Maldives. Although mitigation is very important, by 2030, most of the Maldives could be flooded due to rising sea levels after mitigation. The main cause of concern is urban areas on islands such as the Maldives as there is a large number of people in a small area. This means that people will either need to relocate, or adapt. Adapting includes planned retreat, accommodating (e.g. building houses on stilts), protecting (though hard and/or soft engineering and defences) or even advancing the line. While economic and technological barriers exist, the major barriers to adaptation to sea level rise include financial limits and social conflict. Beside small islands, the major areas which are vulnerable to sea level rise include deltas, which are historically very populated. 500 million people live on Deltas mainly in Asia such as in Bangladesh. Strong mitigation and protection is required to protect people living in this environment however, protection schemes now have to limit negative effects to nature and surrounding ecosystems, as well as these projects being very expensive. This causes problems as investors need to be found, and in many cases, these investors will also need to see benefits which makes these projects hard to sell.


Male , The Maldives

Overall it is clear that reducing our carbon footprint and becoming a carbon neutral society as fast as possible is very important in order to limit the negative effects of climate change. This, however, is easier said than done and is looking unachievable due to limits in technology and how peoples lifestyles have changed. Also even with strong mitigation on CO2 production, sea levels will continue to rise past 2300 meaning that other forms of mitigation will have to be put in place in order to limit this effect.

By Toby Miller


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