How Everglades Restoration Can Mitigate Some Effects of Sea Level Rise in South Florida By the Arthur R Marshall 2013 Interns: Sarah Denisen, Casey Hickcox, Jessica James, Tomena Scholze, and Kelsie Timpe

Climate Change and Sea Level Rise May 9, 2013: Mauna Loa above 400 ppm Pre 1870s: 180-280 ppm Greenhouse gas (GHG) emissions have grown since before the 1870s. Over the last 150 years, carbon dioxide concentrations have increased from 280 parts per million (ppm) to more than 395 ppm 2012: Highest value measured for over the previous 800,000 years! Today’s rate of increase is more than 100 times faster than the increase that occurred the end of the last ice age. Fig 1: NOAA, Climate.gov

Climate Change and Sea Level Rise The net effect of human activities has been one of warming with radiative forcing of +1.6 W/m^2. (IPCC 2007) The increase in GHGs has altered the outgoing solar energy from the Earth-Atmosphere system, causing average global temperatures to increase. Fig 2: IPCC 2007

Warming surface temperatures has caused sea level rise via thermal expansion of the oceans, and glacial and ice sheet melting in the poles. Fig 3: NOAA 2012

Climate Change and Sea Level Rise IPCC 2007 Report predicts a sea level rise rate of 1.9 mm/yr. However, the report doesn’t take into account the contribution from melting continental ice sheets in Greenland and Antarctica. Predictions taking into account the melting of ice sheets range from a rate of 3 to 3.5 mm/yr of sea level rise (Rahmstorf 2007). The US National Climate Assessment predicts with high confidence that the sea will rise at least 0.2 m (8 inches) and no more than 2 m (6.6 ft) by 2100 (NOAA 2012). Table 1: NOAA 2012 The US National Climate Assessment predicts with high confidence that the sea will rise at least 0.2 m (8 inches) and no more than 2 m (6.6 ft) by 2100 (NOAA 2012).

Sea Level Rise: The Future of Florida

History of Everglades Restoration 1920s and 1940s: Destructive hurricanes caused massive flooding damage 1948: Central & Southern Florida Project (C&SF) was put into place Project managed water flow by putting in system of canals and levees Damaged overall Everglades system 2000: Central Everglades Restoration Plan (CERP) approved in Water Resources Development Act (WRDA) Historic Flow Current Flow CERP Future Plan Flow

Outline of Sea Level Rise Threats Threats to the urban environment Saltwater Intrusion Increased flooding Infrastructure damage Threats to the natural environment Storm Surge Saltwater Inundation Mangrove Destruction Habitat Conversion Trophic Disruption

Threats to the Natural Environment: Storm Surge Physical Erosion Sediment removal Mangrove destruction and removal Soil subsidence Chemical Erosion Saltwater inundation Wetland Destruction Almost 3100 acres in S.Fla due to Hurricane Wilma Almost 50k acres lost in Louisiana due to Hurricane Katrina (1 acre = almost 1 football field) Storm surges from 15-22 ft were common during Hurricane Katrina http://www.disaster.qld.gov.au/getready/images/storm-surge.png

Healthy Ecosystems Provide Natural Protection Mangroves - 'Natural wall' Create peat dam Increases drag on water motion Absorbs wave energy Decreases fetch in wave action Inland plants Prevent creation of waves Holds sediment in place inland “riparian” forests offer no significant storm surge protection storm surge reduced by 4.7 cm km^-1 by marshes during Andrew - C1 Wind speed shown to increase damages while marshes shown to decrease - C1

Mangrove Wave Attenuation During Storm Surge:

Threats to the Natural Environment: Saltwater Inundation Peat decomposition Oxidative destruction Nutrient Enrichment Phosphorus Salinity increase 24% of total global C in peat Seawater Okeechobee Everglades Goal

Threats to the Natural Environment: Mangrove Destruction Mangrove Threats Soil Erosion Too fine sediment Hypersalinity Migration Capacity Limited SLR <9 cm/yr - Acceptable SLR 9-12 cm/yr - Stressed SLR >12 cm/yr - Threatened As sea level rises, mangrove seedlings will propagate inland, thus moving the forest away from shore Migration will only occur if sea rises slow enough Mangrove forests will not be able to migrate if sea rises faster than 12 cm per decade

Mangrove Migration

Threats to the Natural Environment: Habitat Conversion Salinity increases and reduced freshwater -> vegetation community shifts aquatic vegetation regime shifts tidal marsh shifts and submergence buttonwood/coastal hammock loss Differing rates of migration -> elimination of some habitats 1. clear water, SAV to turbid water, phytoplankton dominance 2. risk of conversion to salt marsh, loss of marsh by submergence, accelerated decomp by saltwater intrusion/innundation 3. shift from glycophytes (buttonwoods) to halophytes(mangroves); complete collapse with loss of intermediate-salinity niche increased rates of migration due to rapidly changing environmental conditions, including stress related to saltwater inundation and drought; coastal, saline-tolerant systems such as mangroves, salt marshes, and intertidal mudflats may migrate inland faster than intermediate- and low- salinity systems such as buttonwoods, hardwood hammocks, and freshwater marshes

Salinity-induced vegetation shifts reduce ecosystem values example: tidal marshes - freshwater marshes have significantly higher productivity (biomass), nitrogen accumulation rates, biodiversity, and nitrification rates than saltwater marshes (Craft et al. 2009) example: freshwater marsh ($16,500/ac) -> saltwater marsh ($7,400/ac) -> intertidal mudflat ($5,200/ac) -> coastal Gulf of Mexico ($4600/ac) our study: see methods Total Ecosystem Valuation (TEV)

Total Ecosystem Value (TEV) Decreases as Habitats Shift TEV is $74 billion with no SLR effects in study area TEV decreases to $5 billion with 5 ft. of SLR Losses occur as ecosystems degrade to less valuable habitats through salinity changes C sequestration values decreased from $32 million to $490 k due to mangrove loss

Threats to the Natural Environment: Trophic Disruption Biological effects of physical changes caused by SLR and flow alterations disrupted trophic interactions productivity effects population/community structure changes Examples: coastal fish nurseries wading bird nesting/feeding periphyton composition

The Urban Side 2010 population along the lower east coast was approx. 5.6 million 2010 gross water demand of 1,775,000,000 gallons per day 2030 population projected to increase by 18% to approx. 6.6 million 2030 gross water demand for all uses is projected to increase by 213 million gallons per day (12%)

Climate Change Threatens Water Supply Warming will change in the rate of evapotranspiration Unpredictable weather patterns and rising temperatures may increase water demands Less frequent but more intense rainfall, with longer dry periods in between, may increase total annual rainfall but decrease total useable rainfall - more water may be lost to tide or runoff. This scenario increases the necessity for long term water storage for use during dry periods.

Salt Water Intrusion Threatens Water Supply The majority of public water supply is pumped from shallow wells Salt water contaminates shallow well fields, making them unusable Many coastal well fields are already experiencing salt water intrusion and must be abandoned Utilities at risk - Lake Worth, Lantana, Hillsboro Beach, Dania Beach, Hallendale Beach, Miami-Dade south wellfields, Florida City, Homestead, and the Florida Keys Aqueduct Authority.

The Aquifer Systems under South Florida Surficial Aquifer System (SAS) Floridan Aquifer System (FAS) SAS holds freshwater from surface level to about 200 ft in depth FAS holds brackish water in several layers Photo Credit: SFWMD

How Saltwater Intrusion Works When water is withdrawn faster than it is recharged, seawater moves in With SLR, pressure from the a growing ocean will push more saltwater inland. Photo Credit: USGS

Connection between Water Supply and the Greater Everglades Water from Lake Okeechobee, the Water Catchment Areas (WCAs) and the C&SF Canals recharge the SAS and Biscayne Aquifer Photo Credit: SFWMD Photo Credit: SFWMD

How can we meet future water supply demand? Diversify our water sources Increase surface water storage Use reclaimed water and rain for non-potable uses Increase water conservation Restore the Everglades Photo Credit Ken Kaye

Alternative Water Supply Options Temporary fix - move Biscayne and surficial aquifer system (SAS) wells inland. Desalinize brackish water from the Floridan Aquifer System (FAS). Desalinize saltwater from the ocean.

SAS and the Biscayne Aquifer Salt water intrusion necessitates abandoning wells or moving them further inland. Moving wells is costly - Earl King, assistant director of utilities for the City of Hallendale Beach, estimates moving a small wellfield inland will cost $8,500,000. Only a temporary fix. Relying exclusively on the SAS and the Biscayne is not a viable option to meet future water demand. Other water sources must be explored.

Floridan Aquifer System - FAS FAS is brackish – requires treatment (RO) Construction is costly. RO highly energy intensive. Deep injection wells (DIWs) are necessary

Seawater Desalinization Unlimited, drought-proof source of water RO is highly energy intensive and expensive Brine byproduct of RO can be damaging to marine ecosystems. Advances technology reducing cost Co-location of desal facilities and coastal power plants

SAS

Supplemental Sources and Conservation Measures Rainwater harvesting, use of reclaimed water and water conservation practices will help reduce water supply demands Photo Credit: EPA

Reclaimed Water Used for irrigation, agricultural and industrial uses Reduces pumping from groundwater Reduces quantity of wastewater disposed of via ocean outfalls and deep injection wells Reduces need for fertilizer Wastewater flows predicted to increase from 636 MGD in 2010 to 832 MDG by 2030 Is no more dirty than ocean water! Photo Credit: SunSentinel

Rainwater Harvesting Inexpensive Reduces stress on water supplies Reduces stormwater runoff, pollution and flooding Photo Credit: EcoFriend Photo Credit: SunSentinal

Everglades Restoration Will: Recharge the aquifers – extend the life of wellfields Increase surface water storage – reduce amount of water lost to tide Strengthen freshwater head – push back the salt water intrusion line Secure resource and water supply – ensure a bright future for the next generation. Photo Credit: Rodney Cammauf, USNPS

The Solution: Everglades Restoration More water in the Everglades ecosystem will: Help recharge the shallow Biscayne Aquifer Provide more surface water storage Prevent peat degradation Push back saltwater intrusion Reduce nutrient enrichment Maintain freshwater habitats for plants and wildlife. Maintain the coastal mangrove storm barriers

THANK YOU! Questions?