National Geographic : 2013 Jul
NORTH AMERICA SOUTH AMERICA AUSTRALIA ASIA EQUATOR TROPIC OF CANCER TROPIC OF CAPRICORN INDIAN OCEAN PACIFIC OCEAN PACIFIC OCEAN ATLANTIC OCEAN NEXT Stormy History Determining climate change’s effects on hurricanes is a messy business. Globally, hurricane frequency doesn’t seem to be increasing, but the proportion of strongest storms is, according to senior research scientist Greg Holland of the National Center for Atmospheric Research. The North Atlantic region has seen increases in hurricane frequency and intensity since the 1970s, says atmospheric scientist Jim Kossin of the National Climatic Data Center. Human influences on climate are difficult to detect in historical data sets of hurricane activity due to natural variability and incomplete records. Before airplanes and satellites, people conveyed information about hurricanes using two-way radios, firsthand accounts, and the telegraph. —Jane J. Lee This map shows the seasonal intensity of hurricanes, typhoons, and tropical cyclones—all three names refer to the same phenomenon—since 1851 as recorded in NOAA’s public archives. Storms in the Atlantic have been recorded for a much longer period, and therefore appear denser. Only in recent decades has activity in the more tumultuous Pacific been reliably monitored. Hurricane detection over time by Saffir-Simpson scale Category 5 Category 4 Category 3 Category 2 Category 1 1851 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 This chart shows summaries of historical hurricane seasons, adding up recorded length in days of each storm and where storms rate on the Saffir-Simpson scale throughout their lifetimes, for a sense of overall activity.