The physical properties of the ice and of material trapped in it can be used to reconstruct the climate over the age range of the core.
The proportions of different oxygen and hydrogen isotopes provide information about ancient temperatures, and the air trapped in tiny bubbles can be analysed to determine the level of atmospheric gases such as carbon dioxide.
Christiane Amanpour spoke with Sinclair about a book which features her photographs called, "Questions without Answers: The World in Pictures by the Photographers of VII." Faiz, 40, and Ghulam, 11, sit in her home prior to their wedding in the rural Afghnanistan on Sept. " data-medium-file="https://cnniamanpour.files.wordpress.com/2012/08/stephaniesinclair_025a1.jpg? w=300" data-large-file="https://cnniamanpour.files.wordpress.com/2012/08/stephaniesinclair_025a1.jpg? w=310" class=" wp-image-3801 " style="border:2px solid black;" title="Afghanistan" alt="Faiz, 40, and Ghulam, 11, sit in her home prior to their wedding in the rural Afghnanistan on Sept. The young wife posed for this portrait with former classmate Ghada, also a child bride, outside their mountain home in Hajjah. w=300&h=193 300w, sizes="(max-width: 313px) 100vw, 313px" /"Whenever I saw him, I hid.
" data-medium-file="https://cnniamanpour.files.wordpress.com/2012/08/stephaniesinclair_040a1.jpg? w=300" data-large-file="https://cnniamanpour.files.wordpress.com/2012/08/stephaniesinclair_040a1.jpg? w=346" class=" wp-image-3809 " style="border:3px solid black;" title="Stephanie Sinclair_040a" alt="Nujoud Ali, two years after her divorce - when she was only eight years old - from her husband, more than 20 years her senior." src=" “It's definitely rare and Nujood became kind of an international symbol of child marriage, because she was able to do this.And it's not just Muslims; it happens across many cultures and regions. Sinclair has been working on the project for nearly a decade.Photographer Stephanie Sinclair has traveled the world taking pictures, like the one of the Afghan couple, to document the phenomenon. She goes into the areas with help from people in these communities who want the practice to stop, because they see the harmful repercussions. I hated to see him," Tahani (in pink) recalls of the early days of her marriage to Majed, when she was 6 and he was 25.Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper, and an ice core contains ice formed over a range of years.Cores are drilled with hand augers (for shallow holes) or powered drills; they can reach depths of over two miles (3.2 km), and contain ice up to 800,000 years old.