As both the partial pressure of CO2 in the air and the concrete temperature rises due to climate change, the depth of carbonatation (the process that lowers pH and initiates rebar corrosion) is expected to increase by 45% by 2100 under the A1FI "business as usual" emission scenario. So expect to hear more about this problem in the future.

http://www.cipremier.com/e107_files/downloads/Papers/100/37/...