What was done
The author examines the oft-repeated claim that malaria will become more widespread, expanding from the tropics into the mid- and upper-latitudes as a result of global warming.

What was learned
A historical analysis of malaria reveals that this disease was an important cause of illness and death in England during the Little Ice Age, when temperatures in Europe were much colder than at present.  Its transmission began to decline only in the 19th century and "cannot be attributed to climate change, for it occurred during a warming phase, when temperatures were already much higher than in the Little Ice Age."

What it means
Claims that malaria resurgence is due to CO2-induced global warming "ignore [other important factors] and disregard history."  If warmer temperatures are such a major factor in malaria transmission, as they are often stated to be, then why was this disease so prevalent during some of the coldest centuries in Europe this past millennium?  And why have we only recently witnessed malaria's widespread decline at a time when temperatures have been warming?  Clearly, there must be other factors that are more important than temperature.  And there are, as the author points out, including the quality of public health services, irrigation and agricultural activities, land use practices, civil strife, natural disasters, ecological change, population change, use of insecticides, and the movement of people.  Hence, it is clear that the role of temperature in the spread of malaria is insignificant in comparison to the roles played by other factors.