b'MUDD 25 - Urban Intensity l Urban Design - SydneyGlobal Challenges for Urban Development and DesignIncreasing urbanisation, population ageing and climate change are three important global challenges of the 21st century. How effectively these are addressed will largely shape the social, economic and physical nature of cities into the future. Though often dealt with individually within different disciplines of research, policy and practice, all three are inextricably linked and need to be addressed together. Urban development and urban design have an essential role in this endeavour. While the economics and technologies of city-making are important, it is the human focus that must always be of central concern since, Professorafter all, all built environments are a response to human needs, values and Bruce Judd aspirations.The agglomeration of people into cities has taken place at a staggering rate in the post WWII period. According to UN data, in 1950 there were around 1.02 billion people (33%) living in urban areas world-wide and twice that number (2.01 billion or 66%) in rural areas. By the turn of the century urban dwellers had more than doubled to 2.86 billion (47%) with 3.26 billion in rural areas (53.3%). Seven years later urban and rural populations reached parity - 3.35 billion each. In just one further decade, by 2017, urban population had increased to 4.13 billion (55%) and rural population to 3.4 billion (45%) making the 21st century the urban century (UN 2018a). This represents an enormous challenge to those involved in making and reshaping cities. At the same time, while the proportion of people living in urban slums has reduced in recent decades it still represents 30% of all urban dwellers (World Bank Group 2020). There is therefore much to be done in improving social equity in many urban areas.At the same time world populations are ageing, most advanced in Japan (28% 65+) and some European Countries (Italy 23%, Germany 22%, Spain 20%), compared to 16% in Australia, but with the fastest trajectories in developing countries. China, the worlds most populous country while estimated to be 12% 65+ in 2020 is on a steep growth path expected to reach 26% by 2050 and 32% (342 million) by the end of the century (UN2018b), just a few percentage points less than that of Japan at present. The implications of rapid population ageing are critical for cities, where with increasing urbanisation the majority of older people will live. These implications include the design of appropriate housing, public spaces and facilities, and urban infrastructureall important to the participation of older people in urban life which is critical to their health and wellbeing. The demands of this urban challenge were recognised by the World Health Organisation in 2007 when it launched the Age Friendly Cities program and the Global Network for Age Friendly Cities as part of its emphasis on the 10P1-20200229-FOLIO INTRO.indd 15 2020/3/8 11:19:32'