Final answer:
The IPCC AR5 report suggested that the Arctic Ocean may be ice-free in summer by potentially as early as 2030, indicating a drastic shift in the climate system. the correct answer is (b) 2030,
Step-by-step explanation:
The question refers to the future status of the Arctic Ocean sea ice cover as projected in the IPCC AR5 report. The report and subsequent studies indicate rapid changes in Arctic conditions due to increasing global temperatures, with predictions of an ice-free Arctic Ocean during summers.
One of the most striking findings is that the possibility of having the first ice-free Arctic summer was once thought to occur by 2100, but this has been updated to possibly as early as 2030. Not only does this signify a drastic shift in the Earth's climate system, but it also contributes to positive feedback mechanisms that may accelerate climate change.
Given this information, the correct answer is (b) 2030, as the latest predictions suggest that the first summer with an ice-free Arctic Ocean could be possible around this time.