a successful day out on the water requires all the standard equipment — sunscreen, snacks and a literal boatload of mangrove saplings and fossilized shells.  

the sanibel-captiva conservation foundation (sccf), based on sanibel island, florida, has led regular trips to restore benedict key — a tiny uninhabited island in pine island sound — since early 2021. benedict’s canopy of coastal mangrove trees, which provide habitat for heron, osprey, ibis and egret birds, is gradually recovering after sustaining severe damage from hurricane charley in 2004. volunteers are helping accelerate the process by planting mangrove seedlings and saplings to promote regrowth. they are also depositing fossilized shells that provide a foundation for oyster attachment, aiming to build up an oyster reef to shield the fledgling mangroves from destructive waves. 

“the mangroves that we planted at the beginning of the restoration effort are, for the most part, still there and thriving,” said kealy mcneal, the conservation initiative coordinator at sccf. “so it’s a very good sign that we’re going to be successful with the restoration of benedict.”

elsewhere on sanibel island, however, mangrove restoration requires addressing systemic hydrological issues. high levels of nutrients in the water and developments that have altered the way water moves among the trees are threatening the health of mangrove forests and their ability to respond to climate stressors. researchers at the j.n. “ding” darling national wildlife refuge on sanibel island are analyzing the impacts of water quality and flow on the island’s mangroves to inform restoration projects and adaptation efforts.

the ecosystem services of the mangrove tree are as plentiful and intertwined as the network of roots at its base. these roots, which extend underwater, serve as a nursery for fish, while the branches provide a nesting site for birds. by supporting wildlife, the mangrove canopy at the j.n. “ding” darling national wildlife refuge is estimated to generate an average of $85 million per year in recreational viewing and fishing revenue, according to a provisional united states geological survey (usgs) ecosystem services assessment.

and by storing carbon dioxide, absorbed through photosynthesis, in their roots and trapping carbon-containing matter in their soil, mangroves are a highly productive carbon sequestration system. the approximately 2,500 acres of mangrove at “ding” darling store an estimated average of 364,000 metric tons of carbon, according to a 2021 study. that’s equivalent to the amount of carbon dioxide emitted from the gas tanks of almost 5,000 tanker trunks. maintaining this carbon stock yields an estimated economic value of over $55 million, according to the usgs assessment.  

mangroves can also form a buffer that protects the coast from surging water during storms. but as hurricane charley revealed, mangroves themselves can take a beating from the heavy winds. in the 2021 study, researchers analyzed the “ding” darling mangrove canopy and found that the trees that have not recovered from the hurricane are located in a tidally restricted area of the refuge.

in the 1960s, a dike was constructed on the refuge to concentrate standing water for mosquito control and was later used to manipulate the water level to create habitat for migratory waterfowl. despite these advantages, the disruption to the refuge’s natural hydrology has detrimentally impacted mangroves in “impounded” areas that are disconnected from the surrounding waterways. 

water exchange from incoming and outgoing tides is critical for healthy water quality — and mangroves. when bacteria break down algae and other organic matter in the water, they consume oxygen. if the oxygen level of the water drops too low, other bacteria use sulfur compounds instead of oxygen, producing hydrogen sulfide in the process. mangroves in impounded areas don’t experience sufficient tidal flushing, which can lead to a buildup of hydrogen sulfide that stresses the trees. 

“we’ve seen this all over southwest florida, where even small changes in the tidal hydrology that was original to the system can cause long-term stress,” said ken krauss, an ecologist at usgs. 

due to this stress, mangroves in impounded areas of the refuge struggle to produce seedlings. they also receive fewer seedlings from trees outside the impoundment, which are delivered through tidal flushing.  collectively, these factors can impede the regeneration of tidally restricted mangroves after a hurricane. 

tunnel-like culverts have been constructed to reconnect some of the water flow between the two sides of the dike, but they don’t fully restore the refuge’s natural hydrology. “it’s like breathing through a straw,” said jeremy conrad, an ecologist at the united states fish and wildlife service.

the dike is not the only example of altered hydrology on sanibel island. in a waterfront residential area, mangroves were cut off from tidal flushing by the construction of a road, which requires regular maintenance as the rising sea laps at its edges. debris from the roadwork combined with organic material to form a hard deposit along the coastal side of the canopy, further restricting water flow. 

the forest die-off was a case of “mangrove heart attack” — a seemingly overnight manifestation of underlying issues caused by reduced tidal flushing. the death of the mangroves has exacerbated shoreline erosion on this vulnerable part of the island, said bob gerwig, a wildlife refuge specialist at “ding” darling. “when these mangroves die off, all that root structure decays, and the soil subsides and it collapses. so then we’re losing that resiliency to sea level rise and climate change,” he said.

for mangroves growing in smaller bodies of water, simple concrete culverts have made a big difference in restoring hydrological connection. since a culvert linking a mosquito control ditch to the island’s tarpon bay was repaired three years ago, its mangroves have begun to show signs of recovery. “you may be breathing through a straw, but you’re breathing,” gerwig said. 

gerwig hopes to help larger swaths of impounded mangrove in the refuge breathe through bigger “straws” by breaking up the dike with raised boardwalks and bridges. “mangroves are a very slow grower and they respond to stressors and reliefs in a very slow manner. so these restorative actions are going to take time,” he said. “it’s so easy to break something, and it takes decades to put it back together.”

unfortunately, mangroves might be impacted by another anthropogenic factor: eutrophication, or the enrichment of nutrients such as nitrogen and phosphorous in the water. the water bodies surrounding sanibel island receive large amounts of agricultural and wastewater nutrients from discharges from lake okeechobee and the caloosahatchee river. “sanibel is right at the dumping point where everything flows right toward us, and it very much influences what happens on the ‘ding’ darling wildlife refuge,” said avery renshaw, a biological science technician at the refuge. 

just as nutrients in fertilizer help plants in a garden grow, nitrogen and phosphorous supplied by tidal flushing benefit mangroves in low-nutrient environments. “but what we’re finding is that when the system is under a high level of fertilization or eutrophication for long periods of time, it can actually become a detriment to the system,” conrad said.

to adapt to sea level rise, mangroves gain vertical elevation by accumulating leaf litter and sediment and growing their roots. when they are exposed to low levels of nutrients, mangroves develop extended root systems to forage for nitrogen and phosphorous, helping them build vertical elevation. but mangroves that are bombarded with nutrients may shift their energy to growing the aboveground portion of the tree at the expense of the roots, which could hinder the elevation process.

to evaluate the impact of nutrient loading on the mangroves at “ding” darling, conrad fertilized the soil with nitrogen or phosphorous and measured the growth of the tree above and below ground and any changes in the elevation of the soil over four years. while he observed some growth and metabolic shifts that hinted at adaptations to eutrophication, he did not find a significant difference in the soil elevation change in the phosphorous- or nitrogen-treated mangroves compared to the control plots. the minimal effect might be because “what we put in the ground was a drop in the bucket compared to what was already in the system,” conrad said. it’s also possible that the influence of the additional nitrogen and phosphorous could take more time to appear in a high-nutrient environment, krauss said.

with some experimental optimization, the team aims to incorporate the results into a model to forecast the effect of sea level rise on mangrove cover at the refuge over time. “in perpetuity, as we continue to get more data and a better understanding, we can begin to model and project what elevations look like in the forest versus what the elevations of the oceans are doing,” conrad said. “and then that gives us a model to predict what our lands will look like 30, 40, 50 years from now under these accelerated rates of sea level rise.” 

krauss hopes the project will help mangrove managers at the refuge and beyond prepare for and respond to climate-related disturbances. “this is a changing world, and we have to figure out how to adapt properly to it,” he said. 

although farmer steve stierwalt grows crops in the tiny town of sadorus, illinois — with a population of barely 350 — the agricultural practices he employs have environmental implications that stretch from midwestern cornfields to central american seas. 

fertilizer-polluted waterways in champaign county, where stierwalt farms, converge into the mississippi river, emptying toxins into the gulf of mexico — where a 2,000-square-mile, pollutant-induced hypoxic zone makes aquatic life nearly impossible.   

one cause of deoxygenated water in the gulf? water that falls from the sky. 

“it’s pretty amazing the amount of energy each single raindrop has,” stierwalt said. “when it hits bare soil, it’s like a miniature explosion. it displaces soil particles. anytime that soil gets into surface water, it’s carrying nutrients with it. the nutrients, as we know, contribute to the hypoxic zone.” 

to reduce soil erosion that illinois rivers carry to the gulf, stierwalt has decreased fertilizer use and adopted conservation practices, like nutrient management tools that measure cost-effective and environmentally conscious amounts of nitrogen to apply to corn. 

sustainable agriculture practices — like rotating crops, planting cover crops, and eliminating tillage — allow stierwalt to adapt to heavy rainfall, a form of extreme weather intensifying in illinois. indeed, science confirms stierwalt’s observations: a major assessment released by the nature conservancy in april outlines how climate change will escalate periods of extreme heat, increased precipitation, and more intense storms in illinois. 

on farms, for instance, heavy rain and conventional tillage — ploughing, harrowing, and removing plant residue to prepare seedbeds — can trigger a chain reaction of climatic damage, contributing to soil erosion, and phosphate- and nitrate-infested run-off, resulting in pollution of the gulf. these processes are already transforming illinois, and no domain — from urban infrastructure to human health to plant biodiversity — will remain unaffected. 

the report drew on the expertise of 45 researchers, scientists, climatologists, and policy-makers in illinois, all of whom contributed to its stark findings.  

“climate change can seem like an overall threat that we don’t have any ability to change,” said michelle carr, illinois state director at the nature conservancy. “when we look at state-specific data, and how it affects different industries that are prominent in our state, it allows those players to do more, because they’re seeing the specificity to their own geography.”  

45 authors, one report

co-led by climatologist donald wuebbles, former illinois state climatologist james angel, climate change project manager at the nature conservancy karen petersen and director of conservation science at the nature conservancy maria lemke, the 197-page report contains contributions from 45 specialists and covers the impacts of climate change on illinois hydrology, agriculture, public health, and ecosystems. the statistics alone illustrate the projected scope of environmental transformation.

accompanied by longer growing seasons and less severe extreme cold, temperatures will likely warm by 4 to 9 degrees f under a lower scenario and 8 to 14 degrees f under a higher scenario by the end of the 21st century. longer growing seasons may sound like a bonus — but extremely long seasons can devastate, limiting crop diversity, encouraging invasive plant growth and straining water supplies. 

the report also projects more rainy days and fewer snowy days by the century’s end, trends on the heels of a 5% to 20% increase in mean precipitation over the past 120 years. according to projections, severe weather will contribute to short-term droughts, as well as intense rain and flooding. far from functioning as a minor inconvenience, flooding can delay planting, wash away fields of seedlings and destroy exposed crops. 

illinois residents can expect extreme heat by the century’s close, too. in southern illinois, for instance, scientists project the annual hottest 5-day maximum temperature to increase from 96 degrees to 100-107 degrees f under a lower scenario and 102 to 114 degrees f under a higher scenario.

“you see reports about fires in california or sea level rise in florida, and you think it’s more of a coastal problem,” petersen said. “we hope this report will help make some of those future impacts tangible, and for people to realize that climate change will have serious impacts in illinois, and we can still do something about it.”

wuebbles said land use and greenhouse gas emissions have remained the most significant contributors to climate change since the mid-1900s. heavy emissions, he added, are unsustainable: the report projects that continued fossil fuel use will produce the most dramatic transformations, while a switch to renewable energy will net less extreme changes. a third scenario — which wuebbles called “negative emissions” — will require scientists to harness technology to remove greenhouse gases from the atmosphere. 

regardless of the scenario, human activity will drive transformations in northern, central, and southern illinois, said wuebbles, a university of illinois at urbana-champaign professor who has contributed to several united nations intergovernmental panel on climate change reports.

“illinois’ climate is expected to continue to change over the century, with significant impacts on urban and rural communities and sectors,” he said.

from farming to flooding 

consistent with the report’s predictions, stierwalt has observed — and adapted to — extreme weather events. to protect soil, waterways, and farmland, stierwalt practices no-till, strip-till, and cover crop farming — practices that sequester carbon in his soil while reducing nutrient pollution and soil erosion. 

currently the president of the association of illinois soil and water conservation districts, stierwalt also serves on the steering committee for s.t.a.r., a nationwide program dedicated to “saving tomorrow’s agriculture resources” by helping farmers adopt conservation-based practices. 

“healthy soils are more armored against these extreme weather events,” stierwalt said. “(without adapting), the danger is losing this asset that we can’t afford to lose. we lose that soil for future generations.”  

in conventional tillage, farmers use an implement to turn over soil, passing over the field multiple times and leaving barren soil behind. in no-till farming, farmers use planters or drills to cut a v-slot in the remains of previous crops, planting seeds within. benefits of no-till include increased infiltration and soil fertility, and decreased labor costs and soil erosion. 

adopting sustainable agricultural practices, like no-till and drought-resistant crops, will determine the extent to which “future generations” of farmers face smaller crop yields, increased livestock illnesses, and increased crop diseases. bill miller, a northwestern university engineering professor who contributed to the report, said “natural climate solutions” present promising ways to mitigate extreme weather. cover crops, for instance, prevent soil erosion while strengthening soil’s biological properties. “it can help build up the richness of the soil,” miller said. 

farming, though, is far from the only affected sector. changing precipitation patterns are causing flooding events in the majority of illinois’ gaged rivers and streams, exacerbating stress on urban drainage systems and increasing the incidence of combined sewer outflows. northwestern engineering professor aaron packman, who also serves as director of northwestern’s center for water research, worked on the report’s hydrology team. 

packman said chicago’s low-lying inland areas, particularly neighborhoods on the south and southwest side, are especially flood-prone. there, stormwater damage and inadequate infrastructure deplete property values, and chronic flooding carries waterborne illnesses. across the city, extreme weather exacerbates geographical inequalities.  

“the loop has more than a hundred years of engineering to keep everything from flooding,” packman said. “the lower-lying areas were settled later because they’re naturally more flood-prone, and they’re not as well protected by that centralized infrastructure.” 

the metropolitan water reclamation district of greater chicago treats wastewater and provides stormwater management for 5.25 million people in cook county, as well as a commercial and industrial equivalent of 4.5 million people. to mitigate the impacts of urban flooding and stormwater damage, mwrd has crafted stormwater management regulations for new developments, partnered with communities to better manage water and supported local green infrastructure projects. 

still, “policies, planning, tunnels and reservoirs cannot eliminate flooding alone,” mwrd public affairs staffer patrick thomas said. the report presents similar conclusions: packman said a combination of sustainable water management in agricultural sectors, flood-control measures in municipalities, state-wide policies and consistent data collection might mitigate the harm climate change poses to illinois’ water resources. 

no turning back 

prominent report contributors, including wuebbles, participated in a may 17 panel to discuss the report’s results. during the panel, elena grossman, the program manager of illinois’ building resilience against climate effects program, reminded audiences that projected extreme weather will significantly harm our physical and mental health. 

contaminated drinking water, tick- and mosquito-borne diseases and respiratory illnesses will all increase amid intensifying weather — so, too, will psychological and financial challenges.  

in the case of flooding, “there’s both the trauma of watching your home being flooded, of losing personal items, and then the financial stress of having to rebuild it or fix it,” grossman said. 

at its core, she added, the report is “about humans.” 

in the month since the report’s release, miller said authors have begun to discuss writing analyses that specifically address mitigation measures. as climate change continues to create extreme weather conditions in illinois, reimagining the state’s infrastructure, policies and economic practices becomes increasingly urgent, packman added. 

“climate change is a long-term process,” packman said. “but in the last four years, we’ve seen unprecedented things, things that historically never happened. so it’s not something far off in the future. it’s something happening now.”

***

q&a: farmer joe rothermel talks soil health, sustainability 

joe rothermel is a farmer who grew up in broadlands, illinois. he farms corn and soybeans on 1,000-acres in champaign county. in 1992, his father, also a farmer, switched from conventional tillage to conservation-driven no-till farming. 

conventional tillage requires farmers use an implement to turn over soil, leaving barren soil behind. in no-till farming, farmers use planters or drills to cut a v-slot in the remains of previous crops, planting seeds within. rothermel adopted no-till in 1995, and began supplementing this practice with cover crops in 2010. 

q: what are some of the advantages of farming with no-till and cover crops like alfalfa, rye, and clovers? 

a: one of the reasons we plant cover crops is to help increase our soil health. one of the things you’ll notice is soil structure is improved. the ground is firmer. you can drive on it sooner. we have a lot of heavy equipment nowadays, and in a conventional program it’s easy to compact the soil. conservation practices lend themselves to improving soil structure and holding up equipment so we don’t have as much compaction. 

one of the main reasons to plant cover crops or to no-till is to reduce soil erosion. through tillage, we’ve already lost half the organic matter that was originally in the prairie. other potential benefits are nutrient recycling. the more biological activity we have, the more nutrient recycling. the idea is to use less synthetic fertilizer, less inputs. if we can maintain the same output with reduced inputs, that’s more efficient for the farmer. 

and then the big thing is carbon sequestration. by not tilling the soil and using cover crops, through photosynthesis that will put carbon into the soil. hopefully someday, that’ll be a source of revenue for farmers to help offset some of the costs of these conservation practices.

q: how have extreme weather events impacted soil erosion and health?

a: it seems to rain a lot. we used to get a half inch [in a single rainfall]. now, if we’re unlucky, we can get a two- or three-inch rain in a couple hours. i think we’ve cut down on some erosion; we still get some gullies. but compared to some of the other fields in the area, it’s significantly less. some of the other conventionally tilled fields will have a cascade of soil coming off the field into the ditch. we don’t have that anymore. 

it’s not perfect — but it does reduce erosion, especially if you have covers growing. we want the water to go down into the ground instead of running off, because when it runs off it takes topsoil with it. and then it takes nutrients with it. and then we have the hypoxia issue in the gulf of mexico. and so that’s another issue. another reason to reduce tillage and grow covers.

q: what percentage of illinois farmers are practicing conservation agriculture? 

a: in illinois, less than 6% of farmers are growing cover crops, so there’s a long way to go. 

farmers are very independent. older populations don’t like change. there’s peer pressure. there’s a risk of failure. there’s a whole host of reasons, but i’d say the number one is economics. 

q: how can conservation farming become more economically viable? 

a: conservation is not free. initially, somebody’s got to pay for it, and i’m not sure it should all be on the farmer. if we would get paid for carbon sequestration that would certainly help.

but until then, there’s cost share programs from places like the (u.s. department of agriculture) and (natural resources conservation service). there’s several other places that will offer cost share. a lot of the big food companies now are getting on board, because they want to be able to tell their customers that their food supply is grown sustainably, so they’re offering some incentives to farmers. 

so there are some sources of revenue, but it’s not a huge amount of money. over the long run, i think this way of farming will eventually be self-sufficient. in other words, the benefits will outweigh the costs, and there won’t be a cost to it. hopefully, it will become the mainstream way of farming.

a study published in the proceedings of the national academy of sciences on jan. 22 uses grace satellite data recorded between 2002 and 2014 to track water storage in 186 river basins around the world. lead author bridget scanlon, a senior research scientist at the university of texas at austin, and her coauthors compared satellite observations to seven models commonly used by scientists investigating the water cycle, a topic of growing importance as the climate changes and population grows.

“sometimes the models simulated the opposite trend” to what satellites observed, scanlon said. “if the satellites go over an area that’s getting wetter or flooding, then the gravitational attraction would increase, and the leading satellite would speed up. the distance between the two satellites would then increase,” scanlon said. “so these changes in distance between the satellites … provide an estimate of changes in water storage, from up in the atmosphere, to deep in the subsurface.”

scanlon found that the models underestimated large changes in water storage, both with declines mostly caused by human-driven depletion, and rises related to precipitation and climate variability.

the models she investigated are split into two categories. five of the seven were land models, components of global climate models, while the two others were expressly built to focus on human water use and predict scarcity in the future.

“most of the land surface models only simulate soil moisture storage, not surface water or groundwater storage. all of the models may not have sufficient storage capacity in the soil profile to accommodate the changes in water storage that we get from wet and dry periods,” scanlon said.

the grace data indicate there was a net increase in land water storage from 2002 to 2014, whereas all the models simulated a net decrease. from basin to basin, the grace observations vary: showing increasing storage in places like the amazon and decreasing storage in the ganges in india.

many of the models the researchers looked at estimated the ganges would gain water over the 12-year period, but grace observed a loss of 12 to 17 cubic kilometers per year. scanlon said the decline was likely caused by human extraction, something many land models don’t capture.

“the results suggest that past studies that have used models to estimate global-scale water storage could have underestimated the effects of humans and climate variability. it means the potential effects of human water use and climate change in the future could be worse than we thought for some regions of the globe,” said simon gosling, a climate risk professor at the university of nottingham who was not involved with the study.

one of scanlon’s coauthors, hannes müller schmied, a senior researcher at goethe university frankfurt, works on improving a global hydrological model that focuses on human alterations to the water cycle.

“the focus should now lay on the models themselves and bridget provides the basis for it,” he said.