By Rajendra Paudel, Ph.D.
Would a little less rainfall each year or warmer temperatures impact South Florida and the Everglades? Should we be concerned? These are important questions that scientists are trying to address for many areas across the globe.
In fact, the Intergovernmental Panel on Climate Change (IPCC), the leading international body for the assessment of climate change, has said that global water resources are under increasing stress due to climate change. South Florida is among the most vulnerable regions in the United States, due to a large human population and a fragile Everglades ecosystem located on flat, low-lying and porous terrain. The predicted changes are likely to have a profound negative impact on the freshwater supply that is crucial to sustaining both the human and natural systems that we currently enjoy.
Unfortunately, the detrimental effects of climate change in South Florida will likely be compounded by rapid population growth and development. It is therefore critical to improve our understanding what the specific effects of climate change will be in South Florida and incorporate this information into our plans for restoration.
How Will Climate Change Affect Water Availability in South Florida?
The IPCC reported in 2013 that climate change will likely increase average surface temperatures as well as the magnitude, frequency, and duration of extreme weather events such as storm and droughts. A rise in surface temperature will increase the rate of evaporation from land and water to the atmosphere. As temperatures increase, the rate that plants release water into the air will also go up. As a result, irrigated farmlands and the Everglades will require more water. In South Florida, greater than 25 percent more water will be needed during the next half-century. Rainfall alone is unlikely to compensate for this lost water and increased demand. Further, as temperatures increase, the rate at which plants transpire water into the air will go up.
How Will Climate Change Affect Rainfall and Droughts in South Florida?
Climate change in South Florida is also likely to result in warmer temperatures and shifts in seasonal rainfall patterns. These changes will then contribute to an increase in the frequency and severity of both droughts and heavy rainfall events. South Florida has always been impacted by droughts and heavy rainfall, but because of its warm climate, these impacts are likely to increase substantially.
Heavy rainfall can stress the capacity of drainage systems and cause flooding, while prolonged droughts can reduce the availability of water for human use and the Everglades. These changes can shrink and degrade aquatic ecosystems.
Finally, increased fire and soil oxidation due to severe droughts will likely reduce ridge and slough habitats, critical for the wildlife found in the Everglades.
How Will Sea-level Rise Affect South Florida?
When it comes to sea level rise, South Florida has good reason to be concerned. According to the Unified Sea Level Rise Projection Southeast Florida report, sea level rise along South Florida’s coastline is projected to be from 31 to 81 inches by 2100. This amount of sea level rise could easily push sea water inland and flood coastal areas more frequently and for longer periods of time. The Biscayne Aquifer, which consists of highly permeable limestone rock and provides fresh drinking water to the 8 million residents of South Florida, lies at shallow depths making it particularly prone to saltwater intrusion.
Finally, as sea levels rise, saltwater will infiltrate into aquifers and canals pushing freshwater further inland, potentially changing the distribution of habitats in the Everglades and further reducing the supply of freshwater for people.
Implications of Climate Change on Everglades Restoration
The Comprehensive Everglades Restoration Plan (CERP), a multibillion dollar project authorized to “restore, preserve, and protect the South Florida ecosystem, while providing for other waterrelated needs of the region, including water supply and flood protection,” was planned with a much more limited understanding of climate change than we have today. CERP was based on the concept of climate “stationarity,” which assumes the climate will not change appreciably in the future. We now know that this is not a realistic or safe assumption. Current Everglades restoration plans, therefore, are likely inadequate for future conditions. As Everglades restoration continues to advance over the next few decades, the success of restoration and management efforts will increasingly depend on incorporating understanding of climate change into future planning, implementation and operation of projects.