There are several evidence that show rise in global temperature.
Explanation:
Thermometerreadings
Ongoing temperature recordings using thermometers are showing a clear warming of the earth's temperature over past few decades.
Glacierretreat
Over the past 50 to 100 years, photographic evidence has shown that the world's glaciers have been melting, which has caused them to retreat. The increase in global temperatures is causing glaciers to disappear and is increasing the melting of sea ice in artic.
Ice cores
scientists often use ice cores to detect changes in temperatures. When snow falls it traps air into the ice. When scientists take a sample of ice it reveals the atmospheric gas concentrations at the time the snow fell. This is used to calculate temperature of each year.
Early springandRisingsealevelsarealsothe evidenceofglobalwarming.
probably stamps cuz ya know they're real tiny and they probably thought that in like 30 years no one would be sending a letter so they're like 'yea ok they're just sticky pieces of paper no one cares'