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A Conversation with Dr. Meg Lowman |
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| Energy from the sun drives the earth’s weather and climate. Atmospheric greenhouse gases (water vapor, carbon dioxide, methane and nitrous oxides) trap some of the energy from the sun, creating a natural “greenhouse effect.” Without this effect, the planet would be too cold to support life as we know it. Instead, the earth’s average temperature remains a more hospitable 60° F. However, problems arise when the heat-trapping greenhouse effect is accelerated by human-generated emissions of greenhouse gases as it is today. Since the pre-industrial era, atmospheric concentrations of carbon dioxide have increased about 35%, methane concentrations have more than doubled, and nitrous oxides have risen by about 15%. Global warming would do more than add a few degrees to today’s average temperatures. Cold spells would still occur in winter, but heat waves would be more common. Some places would be drier, others wetter. Perhaps more important, severe weather, including tropical storms and hurricanes, is expected to intensify, with precipitation coming in short, intense bursts resulting in higher storm surges and more flooding. Sea levels will be higher than without global warming, although actual changes will vary from place to place because coastal lands are themselves sinking or rising. Source: EPA |
A: Concentrations of carbon dioxide, or CO2, (the predominant greenhouse gas) have increased from 280 parts-per-million (ppm) to 383 ppm over the last 150 years. Evidence suggests that the recent increase in greenhouse gases that is continuing and even accelerating today is the direct result of human activities. To compound the issue, CO2 stays in the air for several decades or even centuries. Methane and nitrous oxide, two other important greenhouse gases, have also showed marked increases over the same timeframe. Furthermore, ancient bubbles of air preserved in polar ice tell us that today’s level of CO2 is remarkably higher than anything observed in the last 650,000 years, and probably much earlier. Many point out that the planet has experienced fluctuations in greenhouse gases in the distant past. However, these changes tend to occur over thousands of years. The question is: will organisms and ecosystems, and communities be able to adapt to the rapid changes occurring today?
Water vapor, although not man-made, is sometimes thought of as a greenhouse gas because it traps heat in the same way as CO2. In fact, water in our atmosphere has a much more powerful effect on global warming than anything else. Many skeptics use this fact to refute the urgency of rising CO2, claiming that water-vapor has been neglected by scientists and policy makers while the less-consequential CO2 takes the spotlight. However, the truth is that experts are well aware of water-vapor’s warming potential and it forms the basis of any legitimate theory or model of the Earth’s climate. Here’s how it works: CO2 and water vapor are tied together in a feedback cycle that drives global warming. Since water rains out of the atmosphere in a matter of days, the amount of water in our atmosphere contributing to warming is really dependent on temperature. When the Earth’s temperature rises, more water will evaporate into the atmosphere where it can trap additional heat. So, while the additional input of CO2 may only produce small warming potential at first, it adds more water to the atmosphere that leads to further warming. Even a small temperature increase from CO2 can provide the initial change leading to more water evaporation, and in turn, a much larger heat-trapping effect.
Q: Is the climate warming at an unprecedented rate, and can observed changes be explained by natural variation alone?
A: The Earth’s climate has always experienced large natural changes throughout history. Like CO2, ice records give us thousands of years of precise temperature data that show how Earth’s climate swings back and forth between ice ages and warm periods like today. Many factors may contribute to these changes including variations in the Earth’s orbit around the sun, dust particles in the atmosphere and greenhouse gases. Sometimes it might be a combination of these factors. The biggest challenge for climatologists is to discover how and why these factors cause shifts and variations in the earth’s climate. Temperature records have shown that the Earth’s climate was in a relatively stable warm period for the last few millennia. However, temperatures have begun to increase over the last century, exceeding the normal fluctuations of this relatively stable period. The most consistent, plausible explanation to account for this anomalous recent warming is the increase of greenhouse gases. Scientists have investigated alternative causes for recent warming, such as increased solar output, but studies consistently show that solar variation and other factors only account for a small effect on the Earth’s climate, with greenhouse gases being the largest contributor. To say that today’s climate warming is unprecedented is a little misleading because the Earth may have been warmer than this in the past and may have experienced relatively rapid warming events. However, it is very likely that the recent warming is unprecedented during the existence of human civilization. Furthermore, the warming events of the past have only occurred in response to natural climate variations, but today’s warming is in response to CO2 levels that exceed natural variability. Humanity is unwittingly conducting a global experiment on the planet by raising CO2 levels in its atmosphere. The consequences of this experiment have already begun to change life as we know it, in ways never before seen in human history.
Q: Are we seeing early signs of warming in Florida?
A: Climate change is a global event and its local effects can be hard to predict. However some consequences of these global changes already appear to be evident in Florida. Professor Jack Putz at the University of Florida has measured dieback of coastal palm trees which seem to be linked to tidal flooding and salinity induced by sea level rise. Changing global weather patterns and temperatures have almost certainly magnified the large-scale droughts and fires that have dominated Florida news in the last decade. Some evidence shows that coral bleaching, algal blooms, dead zones, and other marine events could be associated with warming waters and storm activities. Perhaps even more insidious is the predicted increase in tropical disease vectors, insect pests, invasive species, and other ecological changes that are difficult to measure in their early stages.
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| Dr. Meg Lowman is the director of environmental initiatives at New College, the premier honors college for the State of Florida, with professorships in biology and environmental studies. Lowman is actively building a new department of environmental studies to focus on conservation outreach for students, create a subtropical field station for regional universities, and conduct conservation biology research in tropical ecosystems. Her expertise involves canopy ecology, particularly plant-insect relationships, and spans over 25 years in Australia, Peru, Africa, the Americas and the South Pacific. She has authored over 95 peer-reviewed publications and three books. Her latest book, Life in the Treetops, received a cover review in the New York Times Sunday Book Review. Another recent book, It’s a Jungle Up There, was co-authored with her son, Edward Burgess. She recently delivered a presentation on climate change to Florida leaders as part of Conversations on Climate Change, a series of Cabinet workshops exploring how Florida’s economy could be affected by climate changes and our state’s opportunities to expand renewable energy sources (www.floridaclimatechange.com). Before joining New College, Lowman served first as Director of Research and Conservation and then Chief Executive Officer of Selby Botanical Gardens, an institution that specializes in tropical plants, especially epiphytes. Prior to joining Selby, Lowman was a professor in Biology and Environmental Studies at Williams College, Massachusetts where she pioneered temperate forest canopy research and built the first canopy walkway in North America. Working in Australia on forest ecology, she was instrumental in determining the causes of the eucalypt dieback syndrome that destroyed millions of trees in rural Australia, assisted with conservation programs for tree regeneration, and ran a successful ecotourism business in the outback. For more information, visit www.canopymeg.com |
A: Changes in the frequency of tropical cyclones (hurricanes) are unclear and still under heavy discussion in the scientific community. Multi-decadal climate cycles like “El Niño” often obscure long-term changes in weather patterns from the normal fluctuations. Many uncertainties still exist with regard to weather patterns, especially untangling global and regional effects, but it is becoming increasingly apparent that recent events are beginning to exceed the natural variations even for multi-decadal cycles.
Despite uncertainties in frequency, however, we are more likely than not to see increases in future storm intensity resulting from two major effects of climate change: warmer oceans and more moisture in the atmosphere. This increase brings up important economic considerations for Floridians including beach renourishment, growth management, tourism, real estate values and home insurance.
Q: Can we project how sea levels will rise in Florida?
A: Geoscientists have produced models for sea level rise with estimates ranging from about 1-3 feet by the end of the century. Since Florida is in a low-lying area, even a small rise could significantly increase the damage from storm surge. Everyone remembers the pictures of flooding in New Orleans, another low-lying area, after Katrina. Had the initial water level been any higher, the damage would have been even more catastrophic.
To make matters worse, the model predictions often represent conservative estimates since there are many uncertainties in the future changes of melting ice-sheets. Time after time, predictions have been shown to underestimate the rate of ice melting in the Arctic. Such was the case with the once-frozen Northwest Passage, which opened for the first time in September 2007. When I heard the news, I was devastated and called my husband to report the tragedy. He was attending the Florida/Tennessee football game and couldn’t hear me above the 90,000 screaming fans. Ironically, as Florida rejoiced over its football victory, a largely overlooked ice-melt event took place that may put our children’s heritage at risk.
Q: What are the consequences for Florida’s coastal zones?
A: Florida will likely lose significant amounts of tidal marshes, seagrass beds, mangroves and other ecosystems that rely on a narrow band of delicate conditions for survival. Unfortunately there will be no possibility for the salt marshes to retreat inland, since much all of that area is occupied by development. If these coastal ecosystems are lost, shore bird and fish habitats will decline. And without natural storms buffers, coastal real estate will be greatly exposed to hurricane damage. Along with rising storm surges, the ability to renourish beaches will become more costly, and the real estate and tourism markets could suffer.
Q: How can Florida adapt and lead the way in addressing climate change?
A: First and foremost, Florida can minimize and mitigate its impact on greenhouse gas emissions. Recent actions by the governor — who has committed to develop a comprehensive greenhouse gas inventory and signed executive orders this summer calling for substantial reductions in greenhouse gases – represent giant steps in the right direction. Local governments should follow suit by establishing their own emissions targets and reductions. We need scientists and economists sitting at the table with regional government and business leaders to offer their advice in planning Florida’s future. And we should use this knowledge to adopt responsible land-use strategies that limit suburban sprawl and ecosystem degradation while improving transportation efficiency. On the energy front, we must conserve, promote energy-efficient technologies, and develop renewable energy sources – and create the incentives needed to spur broader utilization and economies of scale.
Florida also should develop a carbon sequestration plan, which would calculate the value of carbon storage in different vegetation types and land uses. For example, orange groves have a different carbon storage capacity from oak hammocks and turf grass. Developers need to understand these new land-use valuations (in terms of carbon storage per acre) and leverage it against carbon emissions. There are significant opportunities for economic development through land management for carbon mitigation and participation in carbon markets.
Secondly, Florida can begin to make changes in anticipation of the changes we can no longer prevent. This can be accomplished by limiting coastal development in high-risk areas; protecting natural storm buffers such as beaches, mangroves and wetlands, then educating the public about their value; and developing robust regional sea level rise models to inform future planning and development. Additionally, we must insure that regional governments are collecting ecological, as well as economic data, so that we can monitor environmental change and adapt as changes are measured. We also need a mechanism for statewide public education, something I call Climate Change 101 – a short course for policy-makers, environmental managers, teachers and then the public (in that order) to brief them on the key science behind climate change, and methods of adaptation and mitigation.
Finally, we must elect government officials who have solid action plans, not just pay vague lip service to the issues.
—Compiled by Dr. Meg Lowman, Professor of Biology and Environmental Studies, New College of Florida, and Edward Burgess, Research Fellow for Environmental Defense, NYC.