We have just released a paper reviewing how the urban heat island will change with climate change and urban growth. The paper, 'The impact of urbanization and climate change on urban temperatures: a systematic review' is available here.
We found urban growth had a large impact on temperatures, of up to 5⁰C in some areas. Climate change and urban growth together had a larger temperature impact than when either factor was considered alone.
We also identified an increased need for further research in this area, as out of the1,574 papers we reviewed, only 8 looked at both climate change and urban growth.