The intensity of summer algae blooms has increased over the past 3 decades according to the first ever global survey of dozens of large fresh water lakes.
Reports of algae blooms are growing. They are harmful in their intensity of their growth, or because they include populations of toxin producing phytoplankton. Before this recent study it was unclear if things were getting worse, or the degree to which human activity- agriculture, urbanization, and climate change was contributing.
Toxic algae blooms affect drinking water, agriculture, fishing, recreation , and tourism. Studies indicate that blooms in the USA result in a loss of $4 billion.
The study concludes the algae blooms really are getting more wide spread and more intense. The reasons for this increase can vary from lake to lake. One clear finding was that among the lakes that improved at any point over the 30 yr span looked at were the ones that experienced the least warming. The suggestion being that climate warming is playing a role.