Dec 7, 2012 12:24 Pat Shingleton for Nov. 14, 2012 Pat Shingleton for Nov. 14, 2012 Advocate story Dec. 07, 2012 Comments Based upon warming and carbon dioxide, scientists believe the Arctic is the leading indicator of global warming. Ice-core samplings have recognized it as the fastest-warming region of Earth. Before the Industrial Age, CO2 levels registered 275 parts per million. For the first time in 800,000 years, the Arctic has climbed to 400 ppm. On Sept. 19, the National Snow and Ice Data Center reported the area has receded to levels not previously known. The Nature Climate Change recently forecast the effect of climate change on Northern Hemisphere snowpack through the 21st century in the western United States, Alpine Europe, Central Asia, the Himalayas and Tibetan Plateau. California, the largest agricultural producer in the country, and the sixth largest in the world, will be affected. Fastcast: Cold.