Centuries-old records from Japanese priests and European shipping merchants are helping scientists confirm that the earth has warmed substantially — and freshwater ice formation significantly decreased — since the Industrial Revolution.
These early record keepers tracked annual freeze dates and the breakup of ice each spring on lakes and rivers for hundreds of years, beginning in the 1440s in Japan and 1690s in Finland. The data represents the oldest known inland ice records. An international team of scientists published a study this week in Nature Scientific Reports examining how ice behavior changed over the records’ years. They found that from 1443 to 1683, for example, the annual freeze date of Lake Suwa in Japan moved back 0.19 days per decade. From the start of the Industrial Revolution, however, that trend grew 24 times faster, pushing back the date of ice formation on the lake by 4.6 days per decade.