4 Risks & Coastal Urbanization F22.pdf

Where the City Meets the Sea Studies in Coastal Urban Environments DEVELOPING FOR DISASTER: RISKS ASSOCIATED WITH COASTAL DEVELOPMENT  UN population projections  Regional Growth Rates Human populations continue increasing and becoming more urban Hallegatte & Corfee-Morlot...

Where the City Meets the Sea Studies in Coastal Urban Environments DEVELOPING FOR DISASTER: RISKS ASSOCIATED WITH COASTAL DEVELOPMENT  UN population projections  Regional Growth Rates Human populations continue increasing and becoming more urban Hallegatte & Corfee-Morlot 2011 Climactic Change  Coastal mega-cities (>8 million) 1950: 2 mega-cities 1990: 13 mega-cities 2010: 20 mega-cities Nicholls 1995 GeoJournal  Growth of the number of coastal cities has slowed  But the population size of these coastal cities continues to increase exponentially Nicholls 1995 GeoJournal Barragan et al. 2015 Oceans & Coastal Management People live near water for historical and contemporary reasons, but this puts them at risk Climate Vs Weather  Weather  Conditions over the short-term (~days)  Climate  Long term average weather in an area (≥ 30 yr)  Climate variability  Variation from the average climate on larger spatial or temporal scales (~ months to a year)  Climate change  Change in the long-term average weather (years) The Atmosphere Lutgens & Tarbuck 8th Edition Greenhouse Gases IPCC Climate Change 2007 Report; US-EPA Atmospheric CO2 Concentration (ppm) 420.8 ppm May 2022 Paris Agreement Copenhagen Accord Earth Summit NOAA-ESRL 2013; Scripps CO2 Program Previous 800,000 years Since industrial revolution (most after 1950) Scripps CO2 Program  Who are the main polluters?  The Human-Enhanced Greenhouse Effect  Anthropogenic greenhouse gases have led to a >1 °C increase in global temperatures since the Industrial Revolution National Park Service  Climate change due largely to human activities  Mainly burning of fossil fuels and agriculture  Net positive effect on global temperature IPCC Climate Change 2007 Report  The six warmest years on record have occurred since 2010!  2015, 16,17, 18, 19, 20 and 21 were the seven warmest years on record since the dawn of human civilization (and much earlier!)  2016 was the warmest year ever recorded (remember coral bleaching in the media?), while 2020 was second (and very close) UK Met Office In 2021 the earth was 1.1 C warmer than the long-term average Sea Surface Temperature Anomalies NOAA-ERSST V3  Risk 1: Sea Level Rise  Sea levels are rising as a result of climate change  Mainly due to thermal expansion and melt of land-based ice  SLR has averaged 1.8 mm/yr in 20th century  Since early 1990s rate has accelerated to 3.1 mm/yr  Sea level has increased by 0.18 m in 20th century  SLR rate expected to accelerate to 4 mm/yr by end of century IPCC Climate Change 2007 Report   What will happen in the future?  Four families of emission scenarios: IPCC Climate Change 2007 Report  Note: Actual emissions since 2000 have slightly exceeded the most fossil-fuel intensive A1FI scenario! IPCC Climate Change 2007 Report; Raupach et al 2007 Proc. Nat. Acad. Sci.  Why is climate-induced sea-level rise so important?  LECZ represents just 2% of land  But contain 10% of world population and 13% of its urban population  Higher in developing countries (21% of pop) Vs developed (11%) LECZ = low elevation coastal zone (