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Climate change dangers in Northeast Ohio

Climate change is a growing concern of managers of natural areas in Northeast Ohio. They worry that their hard work to protect rare habitats will be undone as the warming climate makes it impossible for species to survive where they have been adapted for thousands of years. Below is a perspective from Holden Arboretum, one of the region's most important natural areas and one of the largest arboretums in the U.S. 

Threatened habitat<br />The cool, beech-maple habitat of Holden Arboretum's Pierson Creek valley may be a casualty of global warming.

By Brian Parsons, Director of Planning and Special Projects, Holden Arboretum

Global warming and climate change represent real and present dangers to The Holden Arboretum and the region. This is not an opinion; this is an accepted scientific fact. The questions that remain are “how great a danger is climate change?” and “how will the impact manifest itself on the natural landscape?”

How does climate change? The short answer is that greenhouse gasses in the atmosphere — most notably atmospheric carbon dioxide, methane, nitrous oxide and water vapor — have created a thermal blanket that traps the heat over the entire planet. Where do these gases come from? Again, the short answer is that an increasing amount of these gases are generated by burning of fossil fuels for heat, electricity, transportation, land management and mining.

What are the dangers of climate change? It threatens the basic ecosystem functions that plants provide. Plants are the base of the food pyramid for all terrestrial and most marine ecosystems upon which we and all other animals depend.

Plants provide all our food as well as many of the medicines and other materials we use each day. Plants produce the oxygen we breathe. Actively growing plants help to remove some portion of the carbon dioxide produced by the burning of fossil fuels. If we protect, maintain or increase forest cover, then more carbon dioxide is made unavailable as atmospheric carbon dioxide.

Plants help to create, stabilize and protect the soils we depend upon for agriculture, which are the greatest pools of organic carbon in terrestrial ecosystems. Plants help to create, define, and protect watersheds; filter water; slow down precipitation run-off; and allow surface water to infiltrate the ground water as a clean water resource. A changing climate directly affects all the plants that produce these healthy ecosystem functions. As a consequence, it threatens the biodiversity that contributes to the quality of life we enjoy.

Climate change is already happening in the greater Cleveland region. The average annual temperatures in the region are increasing; extreme heat events are occurring more frequently; heavy precipitation events are becoming more frequent; and winters are becoming shorter.

Impacts of warming

What are the projected consequences if this trajectory of climate change is not altered by human mitigated intervention? Based on 100 years of climatic data and current climate change models, by the end of the century Ohio temperatures are projected to rise 7–12 degrees F in the winter and 6–14 degrees F in the summer. This is about the same amount of warming that has occurred since glaciers left Ohio 12,000 years ago. In general, extreme heat events will be more frequent and longer. The amount of precipitation in our region may not change, but the times of year when the precipitation falls likely will change. It is predicted that Ohio will receive more precipitation in the form of rain during the winter months and less in the summer, producing regional droughts. Likewise, the models predict an increase in 24-hour and multiple-day rain events, increasing the likelihood of local flooding.

From an economic perspective, with about 50 percent of Ohio’s lands in agricultural production, it is projected that farm lands will be wetter during the spring planting and fall harvest seasons, and more subject to drought during the growing season, reducing productivity of these lands.

Increasing summer temperatures will continue to lower Lake Erie water levels. Increased water temperature will change the distribution and species of fish present in the lake and increase the summer stratification events that deprive the lower levels of lakes of oxygen and produce “dead zones,” and large fish kills. The Great Lakes are the largest fresh water resource in the world. It is inevitable that pressure will increase to share this resource with the rest of the world.

Within the urban environment, the projected increase in the frequency and duration of extreme rain events will continue, producing more flooding and property damage, requiring all cities to expand their storm water handling infrastructure, and placing an even greater burden on emergency management systems. Continued urban sprawl will further fragment our already fragmented natural areas and decrease the capacity of natural areas to absorb ground water; increase the amount of impervious surfaces; increase the speed of surface water run off, which increases erosion in streams and rivers; contribute to the degradation of the remaining wetlands; and result in increased competition of municipalities for increasingly precious, clean, ground water resources.

Much of Ohio is bordered by Lake Erie to the north, a formidable barrier to plant migration. As the climate in Ohio continues to warm, we can expect the diversity of plant species and species composition of our forests to change and favor tree species that are able to survive warmer climates and drier soils. Species that prefer cool soils like Eastern hemlock will find fewer and fewer suitable locations to survive. The overall distribution of these “northern” species will be forced to shrink northward in order to survive.

Faster change this time

This is not the first time Ohio’s forests have been challenged. Ohio has experienced at least four periods of glaciations, with the advancing glaciers forcing plants southward, and the retreating glaciers allowing a northward migration. Approximately 4,000-8,000 years ago, temperatures rose approximately 3-4 degrees F., and Ohio’s forests were forced to retreat east and northward to survive. Deep rooted prairie grasses and forbs that were more able to survive drought moved eastward and brought prairies into Ohio.

However, in these previous migration events, climate change occurred gradually, allowing plants to slowly migrate and expand into more compatible habitats. Temperature increases projected to occur in the next 100 years equal all the previous temperature increases since the last glacier left Ohio. This compressed window of time, gives very little time for plant species to respond and become established in more friendly habitats and climate. Unfortunately, some plant species have no where to move. Plant species that occur within very specialized habitats do not always have a mechanism to move great distances and as a result have nowhere to immigrate. Which species will compose Ohio’s forests depends on many factors, many plant specific and many outside of our control.

Increased atmospheric carbon dioxide, on a short-term basis, can act as a fertilizer and accelerate plant growth. Early theories and models on climate change postulated that the increase in atmospheric carbon dioxide would increase forest growth. This accelerated plant growth would result in more carbon being stored in plant tissue and the soil, and reduce the concentration of atmospheric carbon dioxide. Reduced concentration in atmospheric carbon dioxide was projected to mitigate climate change and lower global temperatures. Unfortunately, the results of long-term studies in forest systems world wide have shown that forest growth does not match the early models, and in fact forest growth is decreasing in some forest systems.

Thus, the function of natural systems is truly complex and there are many other factors that need to be considered. The burning of fossil fuels has doubled the amount of nitrogen that is entering forest systems in both rain and snow, (acid rain). This nitrogen is taken up by below ground soil microorganisms and eventually made available to fertilize plant growth. Unfortunately, there are many limiting factors that prevent plants from utilizing all this nitrogen for plant growth. As a result, the excess nitrogen favors fast growing trees and invasive plant species.

Increasing levels of ozone within forests downwind from coal powered factories have been observed to damage the foliage of many tree species and in turn limit the capacity of many tree species to grow according to the models. Likewise, too much or too little ground water during the growing season can limit plant growth. The end result is plants aren’t following the models for plant growth and are not reducing the concentration of atmospheric carbon dioxide and lowering global temperatures.

By the end of the century the climate of Ohio will be similar to Arkansas in the summer and Virginia in the winter. Some people might appreciate the change; for those that don’t, they can move somewhere with a more desirable climate. But what about the plants, insects, birds, and other animals? If our forests change, so do the other biota within our forest ecosystems; the species composition and population size of birds, insects, and other animal species will change as the forests change.

Shortened winters will lead to earlier leaf out, flowering times, fruit production, and fruit availability. Like plant species, we can expect some bird species to follow their food sources and preferred cover, such as the hemlocks, and redistribute their ranges northward. In turn, we can expect southern and western bird species to follow their food sources and preferred cover and expand their ranges into Ohio. Change will happen within the natural landscapes of Ohio and at Holden. The extent of the change is full of variables that are hard to predict, but it is safe to say that the forests landscapes we enjoy now will not be the same at the end of the century.

Changing the trajectory

On Earth Day in 1970, Walt Kelly’s Pogo first warned us that; “We have met the enemy and he is us.” If the daily activities of the region’s residents are part of the problem, are we not also part of the solution? Are there actions that Holden, as an organization, and the region’s residents can take in an effort to change the trajectory of the projected impacts of climate change?

If burning fossil fuels for transportation and energy is one of the major factors for the increase of atmospheric carbon dioxide, it follows that limiting our energy consumption will reduce emission of major greenhouse gasses. Decreasing energy consumption is just one change needed. It will be necessary to modify patterns of urban and suburban development. Redevelopment of urban areas with existing infrastructure may be required instead of unabated development of natural lands outside of our urban centers. Water use will also have to change if clean water becomes a limited resource. In general, residents and institutions of the region will have to reduce the consumption of natural resources and learn to live with less or in a more sustainable fashion.

For Holden, conservation of natural resources and our changing climate will impact the plants we display, how we manage our natural areas, the vehicles we drive, the fuels we use, the buildings we build, the heating and cooling systems we utilize, and the amount of infrastructure needed to ensure clean water resources, as well as most every element of new construction. Sustainable land use and generally sustainable living is necessary if we are to ensure long-term conservation of our resources.

How we manage our fiscal and natural resources will be challenged. These are clear and present dangers, which can be viewed as hopeless or as opportunities for change and to give back to the greater Cleveland community. The 3,500 acres of land protected by Holden will continue to stabilize soils, act as a filter for clean water, store carbon and grow in value over time.

The challenges that face Holden will serve as lessons for sustainable horticulture and land management. It is incumbent upon all Holden employees and members to reflect upon their lifestyles and ask how they can become part of the solution and not continue to contribute to global warming and climate change. The opportunities we face will provide us all lessons on how we can reduce our global impact and how Holden, as an institution, can live up to our mission: “To connect people with nature for inspiration and enjoyment, foster learning, and promote conservation.” To live and personify our mission will be Holden’s greatest legacy.

Originally printed in Holden Arboretum's Leaves magazine, 2007.

What are the dangers of climate change? It threatens the basic ecosystem functions that plants provide. Plants are the base of the food pyramid for all terrestrial and most marine ecosystems upon which we and all other animals depend.
— Brian Parsons, Holden Arboretum

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