What cities are likely to experience
Global warming is likely to reach 1.5°C between 2030 and 2052, and approximately 3°C in 2100 based on current national government commitments. This will have disastrous impacts on cities. In their last report on the impact of a 1.5°C change IPCC scientists warned that “Every half degree increase in temperature will matter”.
Risks of heavy precipitations, storms, hurricanes, floods are projected to be higher at 2°C compared to 1.5°C global warming. Robust adaptation will be needed along likely scenarios of temperature increase.
Extremely hot days will become more severe and common, leading to detrimental health impacts. With a 1.5°C increase, 14% of the population will be exposed to severe heat every 5 years. With a 2°C increase, 37% of the population will be exposed and at least twice as megacities could become heat stressed exposing more than 350 million people to deadly heat by 2050. Green planning and robust resilience strategies are needed.
In vulnerable regions, the amount of freshwater in rivers, lakes and aquifers is likely to decrease directly affecting cities. With a 1.5°C increase, 350 million people exposed to severe drought and with a 2°C increase 410 million people will be affected. Water conservation and management strategies and ecosystem-based solutions need to be put in place in cities likely to suffer from water stress.
Half a degree increase will flood out coastal settlements affecting 10 million more people. With a 1.5°C increase, 69 million people will be affected by sea level rise. With a 2°C increase, 79 million people will be affected. At least 136 megacities – the port cities (with +1 million people in 2005) will be affected by flood in the next two decades. Preparedness and city resilience strategies are essential.
Already around 7 million people worldwide die prematurely each year from air pollution related diseases. Keeping warming below 1.5°C is impossible without reducing short-live climate pollutants that can also prevent 2.5 million premature deaths from air pollution each year.
Cities will be affected by declining food supply. Agricultural yields are likely to fall rapidly as temperatures rise from 1.5°C to 2°C. Tropical regions will be more affected, with up to 45% reduction at 1.5°C increase and 65% reduction at 2°C (West Africa).
Informal Settlements at risk
Limiting global warming to 1.5°C could reduce the number of people both exposed to climate-related risks and susceptible to poverty by up to several hundred million by 2050. The urban poor, those living in informal settlements - currently 1 in 7 of the world’s urban population – will be increasingly and severely affected by climate change. Pro-poor climate action is essential to address the exposure to such risks.
Livelihoods will be under threat in urban areas in both developed and developing countries. The intensity and frequency of climatic shocks will make communities more vulnerable through significant negative wealth reduction by 2050, unless stringent emissions cuts are realized. The impacts of 1.5°C could disproportionately affect disadvantaged and vulnerable populations through lost livelihood opportunities.
Housing at risk
With extreme weather and sea level rise, homes will increasingly be at risk, endangering people lives. A 2°C warming will exacerbate property loss and the vulnerability of structures located on areas prone to land slides and erosion. Housing market shifts will affect access to homes.
Infrastructures at risk
Extreme weather episodes will have a heavy toll on urban infrastructures affecting access to basic services. The increasing needs for robust infrastructures will require huge investments to cope with the growing demand. Estimates of the net value of low-carbon investments in cities are as high as $16.6 trillion by 2050 (Coalition for Urban Transitions).
Unprepared migrations to cities
Extreme weather, flooding, heat and water stress will cause unprepared migrations to cities to likely increase. Already 60 % of global refugees are hosted in cities. The flow of new migrants in already stressed cities will add to the complexity of urban development.