A record of the historical amounts of greenhouse gases in the atmosphere and a record of ancient temperatures can be obtained from examining chemicals trapped in the layers of ice in major glaciers. These data indicate that global temperature and greenhouse gas amounts are closely related. Within the last 100 years the amounts of greenhouse gases have increased and the global temperature has increased by about 0.60 ºC (1 ºF). Computer models predict that by 2060, with the expected increases in greenhouse gases, global temperatures will rise 1.50-4.50 ºC (2-8 ºF).