{"id":2105,"date":"2017-12-18T15:01:09","date_gmt":"2017-12-18T15:01:09","guid":{"rendered":"http:\/\/generic.wordpress.soton.ac.uk\/deccma\/?p=2105"},"modified":"2017-12-18T15:01:09","modified_gmt":"2017-12-18T15:01:09","slug":"what-does-a-1-5%e2%81%b0c-increase-in-global-temperature-mean-for-deltas","status":"publish","type":"post","link":"https:\/\/generic.wordpress.soton.ac.uk\/deccma\/2017\/12\/18\/what-does-a-1-5%e2%81%b0c-increase-in-global-temperature-mean-for-deltas\/","title":{"rendered":"What does a 1.5\u2070C increase in global temperature mean for deltas?"},"content":{"rendered":"

by Robert Nicholls<\/em><\/p>\n

Deltas are a climate change hotspot, where the effects of climate change coincide with large numbers of people. Sea level rise is a major threat to deltas, bringing risks of flooding and erosion. As the world tries to limit the global temperature increase to 1.5\u2070C, the DEltas, vulnerability and Climate Change: Migration and Adaptation (DECCMA) project has been looking at how deltas will be affected by increases in temperature of 1.5\u2070C, 2\u2070C or 3\u2070C.<\/p>\n

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Volta delta mangroves (photo by Klaus Wohlmann)<\/p><\/div>\n

Following the historic Paris Agreement, 1.5 \u2070C has become a hot topic.\u00a0 The Paris Agreement commits developed and developing countries to global temperature increase to 2\u2070C, with the aspiration to limit to 1.5\u2070C.\u00a0 These numbers are widely believed to be critical thresholds beyond which significant changes in the natural environment would be experienced (known as planetary boundaries).<\/p>\n

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The issue of 1.5\u2070C has recently been high on the political agenda again, as the 23rd Conference of the Parties to the UNFCCC met in Bonn to discuss a framework for reporting climate action to monitor the commitments made under the agreement.\u00a0 Knowing the implications of a 1.5\u2070C increase informs the \u201cambition mechanism\u201d, whereby stocktakes of progress are due to be taken every 5 years, with a view to then revising and updating mitigation and adaptation commitments.\u00a0 Improvements in science play a key input to ensuring that these commitments remain ambitious and on target to limit the damaging effects of climate change.<\/p>\n

Deltas are home to 500 million people worldwide, as well as being natural environments that generate livelihoods, income and essential ecosystem services.\u00a0 DECCMA has been investigating the effects of climate change in four study sites across three deltas across Africa and Asia: the Ganges-Brahmaputra-Meghna (GBM) megadelta in Bangladesh and the Indian Bengal component in India; and the smaller deltas of Mahanadi in India and Volta in Ghana.<\/p>\n

Given the interest in 1.5\u2070C, we have used our customised integrated assessment model \u2013the Delta Dynamic Integrated Emulator Model \u2013 to look at the likely changes in flooding (in terms of depth of flood and area affected) and the impacts on population in the GBM in Bangladesh under three different scales of temperature increase: 1.5\u00b0C, 2.0\u00b0C and 3.0\u00b0C.<\/p>\n

If we continue with relatively high rates of greenhouse gas emissions, models show that a 1.5\u00b0C increase could occur from 2011 to 2033.\u00a0 Rates of temperature increase have already been significant and rapid.\u00a0 Observed changes in temperature over the 20th century showed an increase in 0.7\u2070C.\u00a0 In comparison, in the readjustment period since the last ice age global temperatures have only increased by between 4-7c over 5000 years.<\/p>\n

Sea level rise of 5-14cm is associated with an increase in global temperature of 1.5\u2070C.\u00a0 This may not seem a lot, and it is particularly difficult to find a reference period because sea levels have varied significantly over the last 20,000 years, reflecting glacial periods and the readjustment of land masses.\u00a0 But, as an indication, sea levels rose by less than 2mm over the 20th century, so the projected increase is over 20 times more than that.<\/p>\n

Until 2040 the differences that are likely from a 1.5\u2070C increase and a 2\u2070C increase are indistinguishable largely due to the year on year variability that is already characteristic of deltas.<\/p>\n

If the temperature increase reaches 3\u2070C, some of consequences more than double.\u00a0 The area flooded under 3\u2070C is more than 2.5 times that under 1.5\u2070C of such sea level rise, for example.\u00a0 Those at greatest risk are in the central regions and northeast, where there are fewer polders to protect the land.<\/p>\n

The good news is that there is still time to implement adaptation \u2013 if we act now.\u00a0 Our team has investigated adaptation and found 93 documented examples in our study deltas spanning agriculture, water management and disaster risk reduction.\u00a0 We are now in the process of developing an integrated assessment model that will give us insights into adaptation needs and options under various future scenarios.<\/p>\n

For more information, see:<\/p>\n

Brown Sally, Nicholls Robert J, L\u00e1z\u00e1r Attila, Hazra Sugata, Appeaning Addo Kwasi, Hornby Duncan D, Hill Chris, Haque Anisul, Caesar John and Tompkins Emma, What are the implications of sea-level rise for a 1.5\u00b0C, 2\u00b0C and 3\u00b0C rise in global mean temperatures in vulnerable deltas? Submitted to Regional Environmental Change.<\/p>\n

(This blog is also published in the December edition of the CARIAA newsletter<\/a>)<\/p>\n

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by Robert Nicholls Deltas are a climate change hotspot, where the effects of climate change coincide with large numbers of people. Sea level rise is a major threat to deltas, bringing risks of flooding and erosion. As the world tries to limit the global temperature increase to 1.5\u2070C, the DEltas, vulnerability and Climate Change: Migration […]<\/p>\n","protected":false},"author":2570,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17,44],"tags":[70,60,68,71,69],"class_list":["post-2105","post","type-post","status-publish","format-standard","hentry","category-delta","category-media","tag-adaptation","tag-bangladesh","tag-delta","tag-ghana","tag-sea-level-rise"],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/generic.wordpress.soton.ac.uk\/deccma\/wp-json\/wp\/v2\/posts\/2105","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/generic.wordpress.soton.ac.uk\/deccma\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/generic.wordpress.soton.ac.uk\/deccma\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/generic.wordpress.soton.ac.uk\/deccma\/wp-json\/wp\/v2\/users\/2570"}],"replies":[{"embeddable":true,"href":"https:\/\/generic.wordpress.soton.ac.uk\/deccma\/wp-json\/wp\/v2\/comments?post=2105"}],"version-history":[{"count":1,"href":"https:\/\/generic.wordpress.soton.ac.uk\/deccma\/wp-json\/wp\/v2\/posts\/2105\/revisions"}],"predecessor-version":[{"id":2107,"href":"https:\/\/generic.wordpress.soton.ac.uk\/deccma\/wp-json\/wp\/v2\/posts\/2105\/revisions\/2107"}],"wp:attachment":[{"href":"https:\/\/generic.wordpress.soton.ac.uk\/deccma\/wp-json\/wp\/v2\/media?parent=2105"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/generic.wordpress.soton.ac.uk\/deccma\/wp-json\/wp\/v2\/categories?post=2105"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/generic.wordpress.soton.ac.uk\/deccma\/wp-json\/wp\/v2\/tags?post=2105"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}