Exploring
the Estuary & Climate Change Connection

How does the Estuaries 101 Curriculum explore the topic of climate change in the activities?

One of the most pressing issue facing estuaries today is climate change. Climate extensions have been woven throughout the curriculum to help students understand why and how climate change is impacting estuaries, as well as ways students can help reduce the impacts of climate change. A climate extension is added to one activity from each principle for a total of six climate extensions.

This interactive provides critical background information to support the teaching of this curriculum. To gain more information on climate change in estuaries use the three diagrams to learn why estuaries are vulnerable to climate change, some of the indicators of climate change in estuaries, as well as the impacts.

See the box on the right for more information about the climate extensions and a direct link to the activities.

While climate change impacts vary regionally, coastal communities and estuaries are clearly on the front lines of climate change. Coastal ecosystems, especially estuaries, are particularly vulnerable to the impacts of global climate change for three major reasons:

1) Estuaries are influenced by both upland and coastal environmental factors. Since estuaries are where two distinct bodies of water meet and mix, each body of water brings its own unique climate sensitivities causing estuaries to have more climate impacts than many other ecosystems. For example, an estuary would feel the impact of both a reduced water levels caused by a climate related drought and climate induced changes in ocean currents. since estuaries lie at the interface of terrestrial and marine environments.

2) Estuaries are highly productive ecosystems because they are shallow, nutrient-rich, protected waters. However, being comprised of shallow waters mean that estuaries do not have a buffer to absorb changes in the environmental associated with climate change, such as sea level rise or changes in water temperature.

3) Many estuaries are already experiencing the stresses of coastal development. The coastal lands of the contiguous U.S. represents 17% of the nation’s continental land area, yet is inhabited by over half of the U.S. population. Climate change will interact with existing stresses from coastal development, intensifying their negative impacts on estuaries.

There are several environmental factors that drive estuaries that are expected to play a role in global climate change. These factors effectively work as signals of climate change in estuaries and include changes in water temperature, air temperature, precipitation, sea level, freshwater inflow (i.e. fresh water entering into estuaries and the associated nutrients from the land), coastal storms (i.e. changes to the intensity and frequency of storms) and coastal currents.

Coastal currents are intricately tied to winds, waves, and land formations. With climate change there may be an effect on coastal circulation due to changes in the distribution of heat in the atmosphere and the oceans. These changes would affect winds and currents that move along the nation’s coasts, changing the location, timing, and velocity of some major coastal currents. An increase or decrease in wind-driven upwelling of deeper ocean water could have important implications for the survival of particular estuary and marine life.

Climate change and its associated impacts are being increasingly felt in coastal areas. The impacts range from changes to the basic functions of an estuary to changes to the coastal communities relying on estuaries. Both water quality and nutrient cycling within an estuary will likely see dramatic climate-driven impacts. For example, a decrease in precipitation could cause the salinity of the estuary to increase and change how nutrients are flushed from rivers into the estuary. Biological communities of an estuary will also be impacted with local and regional changes in habitat, species range and food web interactions. For example, change in a decrease in the amount of freshwater inflow and associated nutrients in the water would likely result in changes in the amount of area a salt marsh covers, as well a change in the abundance and types of plants that make up the salt marsh community. Climate-driven changes in estuary system will also result in changes in the overall range of species, favoring some and driving other toward extinction

The changes are also likely to impact human communities. For example, there are likely to be changes in coastal economies (i.e. fishing, shipping and tourism). Increases in sea level, storm frequency and coastal currents could result in flooding and erosion of man-made infrastructure, like roads, airports, shoreline housing developments and recreation areas. Freshwater estuaries are expected to show a decline in water levels, as the Great Lakes are predicted to lower in water levels overall with climate change. On the Great Lakes, the shipping industry will be highly impacted as these levels lower, possibly leaving coastal infrastructure high and dry.

Although coastal communities will be impacted by climate change, we also have the power to can take actions to reduce climate change impacts and adapt to the impacts that we can’t avoid.