Volcanic eruptions alter worldwide climate by injecting ash and gases into the atmosphere, which reduce the amount of sunlight reaching the Earth, often causing cold weather and crop failures. The Huaynaputina eruption decreased the amount on solar energy reaching Earth by about The summer of 1601 was among the coldest in the northern hemisphere during the last six centuries, and the impact may have been comparable to that of the 1815 Tambora, 1453 Kuwae, 1257 Samalas and 536 Ilopango eruptions. Other volcanoes may have erupted alongside Huaynaputina and also contributed to the weather anomalies; a number of large volcanic eruptions took place in the decades preceding and following the Huaynaputina eruption.