Toxic Alga Blooms: Our Changing Climate A Missing Part of the Story

In the recent weeks there have been a number of news stories reporting on toxic alga blooms in Skaneateles Lake – a source of water for Onondaga County. Toxic alga blooms with toxicity at levels that can cause death to animals and harm to humans. The role of climate change is important to understand.

“A recent study from Tufts University (see below) stated toxic alga blooms are projected to increase especially in the Northeast because of climate change” said Pete Wirth, a spokesperson for Climate Change Awareness and Action.

According to * Dr. Boyer the following factors are key to the formation of toxic alga blooms:

* Increasing rainfall associated with climate change means more nutrients from agricultural and  municipal runoff  to support the formation  of toxic alga blooms.

* Warmer temperatures tend to be more favorable to blue-green algal blooms over many other algal species.

* A stable water column –  earlier ice out and stratification, and later ice in and fall turnover –  gives the toxic alga blooms a longer growing period.  This tends to make for more blooms later in the season.

Dr. Boyer said, “lakes are freezing later and melting sooner and water temperatures and extreme precipitation events are increasing leading to conditions that increase the chances of toxic alga blooms formation.”

A 2014 National Climate Assessment Report stated, “between 1895 and 2011, temperatures in the Northeast increased by almost 2˚F and precipitation increased by approximately five inches.”

According to the Environmental Protection Agency web site ‘between 1958 and 2012, the Northeast saw more than a 70% increase in the amount of rainfall measured during heavy precipitation events, more than in any other region in the United States.”

“It is important for Central Yorkers to understand the role we play in this process,” said Peter Wirth. “We can expect to see an increase in toxic alga blooms in CNY due to climate change as long as  we continue to increase the concentrations of greenhouse gases in the atmosphere, primarily due from the burning of fossil fuels.”

Climate Change Awareness & Action is a local organization whose mission is to help Central New Yorkers understand the impact of climate change and what we can do to address it. For more information go to

Editor’s Note: The following is an Action Steps List (Political). These are the people you need to contact in order to make a difference.

Climate change projected to significantly increase harmful algal blooms in US fresh waters

Summary: Harmful algal blooms known to pose risks to human and environmental health in large freshwater reservoirs and lakes are projected to increase because of climate change.

This is cyanobacterial bloom in Pamlico River, NC. (Hans W. Paerl, Ph.D., a study co-author/University of North Carolina).Credit: Hans W. Paerl, Ph.D a study co-author/University of North Carolina

Harmful algal blooms known to pose risks to human and environmental health in large freshwater reservoirs and lakes are projected to increase because of climate change, according to a team of researchers led by a Tufts University scientist.

The team developed a modeling framework that predicts that the largest increase in cyanobacterial harmful algal blooms (CyanoHABs) would occur in the Northeast region of the United States, but the biggest economic harm would be felt by recreation areas in the Southeast.

The research, which is published in print today in the journal Environmental Science & Technology, is part of larger, ongoing efforts among scientists to quantify and monetize the degree to which climate change will impact and damage various U.S. sectors.

“Some of the biggest CyanoHAB impacts will occur in more rural regions, such as those in the Southeast and Midwest — areas that don’t often come up in conversation about unavoidable effects of climate change,” said Steven C. Chapra, Ph.D., lead author and Louis Berger Chair of Civil and Environmental Engineering in the School of Engineering at Tufts. “The impact of climate change goes way beyond warmer air temperatures, rising sea levels and melting glaciers.”

“Our study shows that higher water temperature, changes in rainfall, and increased nutrient inputs will combine to cause more frequent occurrence of harmful algal blooms in the future,” he added.

Cyanobacteria are the earth’s oldest oxygenic photosynthetic organisms. Throughout their 3.5 billion-year-old evolutionary history, these organisms have proven resilient and adaptable to a wide range of climates. Consequently, many cyanobacteria exhibit optimal growth and bloom potentials at high water temperatures relative to other aquatic plants. Therefore, global warming plays a key role in their expansion and persistence, said Chapra.

In order to capture the range of possible futures, the analysis used climate change projections from five general circulation models, two greenhouse gas emission scenarios, and two cyanobacterial growth scenarios. It is among the few studies to combine climate projections with a hydrologic/water quality network model of U.S. lakes and reservoirs. The modeling approach is unique in its practice of coupling climate, hydrologic, and water quality models into a unified computational framework that is applied on a national scale.

The model chain starts with projections of alternative future climates from General Circulation Models (GCMs). The GCM projections of temperature and precipitation are then entered into two other models:

How Algal Blooms are formed. (Skaneateles, has a protected water shed) This chart is for general purposes, not specific to the city of Syracuse water supply issue

a rainfall-runoff model to simulate monthly runoff in each of the 2,119 watersheds of the  continental U.S.; and a water demand model, which projects water requirements of each watershed’s municipal, industrial, and agriculture sectors. Given these runoff and demand projections, a water resources systems model produces a time series of reservoir storage, release, and demand allocations (e.g., agriculture, environmental flows, and hydropower).

Finally, these water flows and reservoir states are entered into a water quality model to simulate a number of water quality characteristics, including cyanobacteria concentrations, in each of the nation’s waterbodies. The end result is a framework that can predict the combined impact of climate, population growth, and other factors on future water quality for different U.S. regions.

It has been estimated that lakes and reservoirs serving as drinking water sources for 30 million to 48 million Americans may be contaminated periodically by algal toxins. Researchers cited an example in 2014, when nearly 500,000 residents of Toledo, Ohio, lost access to drinking water after water drawn from Lake Erie revealed the presence of cyanotoxins.

Beyond the human health effects, CyanoHABs have a variety of negative consequences for aquatic ecosystems, including the creation of unsightly surface scums and a reduction in recreational use and access to shorelines. Also, because most cyanobacteria are inedible by zooplankton and planktivorous fish, they represent a “dead end” in the aquatic food chain — a scenario that ultimately hurts both commercial and recreational fishing industries.

Chapra noted that the research indicates that as water temperatures increase, more stringent and costly nutrient controls would be necessary in order to maintain current water quality.

“The study provides a framework that offers insights on cause and effect linkages to help support planning, policy, and identify data gaps for future research,” said Chapra.

Story Source: 
Materials provided by Tufts University. Note: Content may be edited for style and length.

Journal Reference: 
Steven C. Chapra, Brent Boehlert, Charles Fant, Victor J. Bierman, Jim Henderson, David Mills, Diane M. L. Mas, Lisa Rennels, Lesley Jantarasami, Jeremy Martinich, Kenneth M. Strzepek, Hans W. Paerl. Climate Change Impacts on Harmful Algal Blooms in U.S. Freshwaters: A Screening-Level Assessment. Environmental Science & Technology, 2017; 51 (16): 8933 DOI: 10.1021/acs.est.7b01498

Cite This Page: 
Tufts University. “Climate change projected to significantly increase harmful algal blooms in US freshwaters.” ScienceDaily. ScienceDaily, 15 August 2017. <>.