The State of Ten Thousand Lakes: the effect of small bodies of water on climate change
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| Jean Pengra and Ordway crew row across Pratt Pond to check temperature sensors. |
Understanding and responding to climate change will define our generation’s contribution to the future.
Earth day
I was walking around Macalester on Earth Day, appreciating the weather. In light of the 50th anniversary of Earth Day, it was interesting to reflect on our collective contribution to climate change. Each day, our actions as a campus are releasing greenhouse gases which rise into the atmosphere and cause the Earth to warm.
The most common greenhouse gas is carbon dioxide, which is released into the atmosphere as a byproduct of making energy. Everything we do from heating our homes to driving our cars to growing our food requires energy which releases carbon dioxide. Although carbon dioxide is by far the greenhouse gas being released in the greatest quantity, other gases which are much more potent are released in smaller quantities but still contribute significantly to climate change.
One of these gasses is methane. Methane is not as stable as carbon dioxide in the atmosphere. Where carbon dioxide will last in the atmosphere and warm the earth for more than a century, methane is released to the atmosphere, warms the Earth, and breaks down and is recycled in about a decade. However, while it is in the atmosphere, methane has about 23 times more warming power than carbon dioxide.
Methane is produced by both natural and human sources. It is the natural gas that we burn to heat our homes, and which powers gas-top stoves. It is a cheap and fairly clean source of energy, which produces only water and carbon dioxide when fully burned. Because of this it has become popular as a form of clean energy. However, when a pipe which carries methane from drilling facilities to our houses leaks, it emits large amounts of the very potent methane to the atmosphere, where it will persist and warm the Earth for years.
Methane is also produced naturally by bacteria in intestinal systems. On campus, the student flatulence from burrito day in Cafe Mac releases up to 120mL per student of methane. It might not smell great, however, in the grand scheme of things, this amount is dwarfed by other contributors.
Wetlands and soil also produce methane. Bacteria which break down carbon rich food and produce methane as a waste product live in ponds, lakes, and the soil. Methane production is only possible in areas which are not exposed to oxygen. This is why areas that are sealed off from the air like the intestines and the bottom of a pond are prime methane production areas.
Small ponds emit large amounts of greenhouse gases, but predicting these emissions is not well understood. Pond emissions are an active area of scientific research contributing to climate change predictions.
During my time at Macalester, I have had the incredible opportunity to work on biology research the last two summers working at Ordway, the Macalester Field Study Area. Ordway has a prairie, an oak forest, and a large lake which is connected to the Mississippi River. At Ordway we have several ponds which produce methane.
Last summer, I worked with Professor Dan Hornbach to measure many aspects of Macalester’s three ponds, particularly their temperatures over the course of the spring, summer, and fall. To measure the temperature of the pond at different depths, we installed a pole with special monitors at different depths into the deepest part of each pond. Every week we waded out in waders or paddled out in a canoe to collect the temperature data and clean the sensors so they didn’t become overgrown with algae.
Many different aspects of a pond, including how deep or large it is, if it gets direct sunshine or is protected by trees, the air temperature, rain, and weather affect how the water moves in the pond and how much gas is produced by bacteria and released to the atmosphere. Because there are so many factors that affect ponds, different studies look at particular factors.
Scientists study different aspects of ponds, including their methane production. Capturing gasses emitted from ponds, and measuring and identifying the different gases is a complex task. Scientists Bansal, Tangen, and Finocchiaro performed a study on ponds similar to the ones at Ordway in northern Wisconsin and Sweden. Both of these areas have ponds that were formed from glaciers melting in the last ice age, meaning they have many characteristics in common. Bansal, Tangen, and Finocchiaro compared gas emissions between these ponds to see if they could find relationships between pond size and temperature and gas emissions.
Using the actual gas emissions, areas, depths, and temperatures of the ponds they measured, these scientists made a model that predicts the amount of methane that would be produced by a similar type of pond. I looked at one model produced by Bansal, Tangen, and Finocchiaro, and two models produced by Bastviken, Cole, Pace, and Tranvik studying similar ponds, and used these models to predict methane emissions from Ordway’s ponds every year.
According to the models, it is likely that the three ponds at Ordway that we studied are emitting between 124,559 nd 6,360,153 grams of methane every year. Although this is small compared to other methane sources, all small ponds together emit 8% of naturally produced methane. Because we know little about what makes a pond produce more or less methane, it is an important area of study to climate change. All of the models have large amounts of uncertainty, so it is important to continue researching ponds so we can make models more accurate. Most of this is being emitted by the biggest pond, Pratt Pond. In my models, as temperature goes up, methane emissions go up.
Because accurately estimating methane emissions for ponds is difficult, methane emissions are often left out of climate change models. In addition, rise in global temperature could cause increased methane emissions from ponds, because increases in temperature correspond to increases in methane emissions. It is important to continue research to improve modeling to make more accurate climate change predictions and to better understand how these ponds will respond to climate change.
The most common greenhouse gas is carbon dioxide, which is released into the atmosphere as a byproduct of making energy. Everything we do from heating our homes to driving our cars to growing our food requires energy which releases carbon dioxide. Although carbon dioxide is by far the greenhouse gas being released in the greatest quantity, other gases which are much more potent are released in smaller quantities but still contribute significantly to climate change.
One of these gasses is methane. Methane is not as stable as carbon dioxide in the atmosphere. Where carbon dioxide will last in the atmosphere and warm the earth for more than a century, methane is released to the atmosphere, warms the Earth, and breaks down and is recycled in about a decade. However, while it is in the atmosphere, methane has about 23 times more warming power than carbon dioxide.
Methane is produced by both natural and human sources. It is the natural gas that we burn to heat our homes, and which powers gas-top stoves. It is a cheap and fairly clean source of energy, which produces only water and carbon dioxide when fully burned. Because of this it has become popular as a form of clean energy. However, when a pipe which carries methane from drilling facilities to our houses leaks, it emits large amounts of the very potent methane to the atmosphere, where it will persist and warm the Earth for years.
Methane is also produced naturally by bacteria in intestinal systems. On campus, the student flatulence from burrito day in Cafe Mac releases up to 120mL per student of methane. It might not smell great, however, in the grand scheme of things, this amount is dwarfed by other contributors.
Wetlands and soil also produce methane. Bacteria which break down carbon rich food and produce methane as a waste product live in ponds, lakes, and the soil. Methane production is only possible in areas which are not exposed to oxygen. This is why areas that are sealed off from the air like the intestines and the bottom of a pond are prime methane production areas.
Small ponds emit large amounts of greenhouse gases, but predicting these emissions is not well understood. Pond emissions are an active area of scientific research contributing to climate change predictions.
During my time at Macalester, I have had the incredible opportunity to work on biology research the last two summers working at Ordway, the Macalester Field Study Area. Ordway has a prairie, an oak forest, and a large lake which is connected to the Mississippi River. At Ordway we have several ponds which produce methane.
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| Macalester’s prairie and Prairie Pond at Ordway. |
Last summer, I worked with Professor Dan Hornbach to measure many aspects of Macalester’s three ponds, particularly their temperatures over the course of the spring, summer, and fall. To measure the temperature of the pond at different depths, we installed a pole with special monitors at different depths into the deepest part of each pond. Every week we waded out in waders or paddled out in a canoe to collect the temperature data and clean the sensors so they didn’t become overgrown with algae.
Many different aspects of a pond, including how deep or large it is, if it gets direct sunshine or is protected by trees, the air temperature, rain, and weather affect how the water moves in the pond and how much gas is produced by bacteria and released to the atmosphere. Because there are so many factors that affect ponds, different studies look at particular factors.
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Macalester Professor Dan Hornbach and student Shannon Hahn wade into Eddies Pond to take measurements. |
Scientists study different aspects of ponds, including their methane production. Capturing gasses emitted from ponds, and measuring and identifying the different gases is a complex task. Scientists Bansal, Tangen, and Finocchiaro performed a study on ponds similar to the ones at Ordway in northern Wisconsin and Sweden. Both of these areas have ponds that were formed from glaciers melting in the last ice age, meaning they have many characteristics in common. Bansal, Tangen, and Finocchiaro compared gas emissions between these ponds to see if they could find relationships between pond size and temperature and gas emissions.
Using the actual gas emissions, areas, depths, and temperatures of the ponds they measured, these scientists made a model that predicts the amount of methane that would be produced by a similar type of pond. I looked at one model produced by Bansal, Tangen, and Finocchiaro, and two models produced by Bastviken, Cole, Pace, and Tranvik studying similar ponds, and used these models to predict methane emissions from Ordway’s ponds every year.
According to the models, it is likely that the three ponds at Ordway that we studied are emitting between 124,559 nd 6,360,153 grams of methane every year. Although this is small compared to other methane sources, all small ponds together emit 8% of naturally produced methane. Because we know little about what makes a pond produce more or less methane, it is an important area of study to climate change. All of the models have large amounts of uncertainty, so it is important to continue researching ponds so we can make models more accurate. Most of this is being emitted by the biggest pond, Pratt Pond. In my models, as temperature goes up, methane emissions go up.
Because accurately estimating methane emissions for ponds is difficult, methane emissions are often left out of climate change models. In addition, rise in global temperature could cause increased methane emissions from ponds, because increases in temperature correspond to increases in methane emissions. It is important to continue research to improve modeling to make more accurate climate change predictions and to better understand how these ponds will respond to climate change.
Written by Sustainability Office student worker Shannon Hahn
Sources:
Bansal, S., Tangen, B., & Finocchiaro, R. Temperature and hydrology affect methane emissions from prairie pothole wetlands. Wetlands 36(2), 371-381(2016).
Bastviken, D., Cole, J., Pace, M., & Tranvik, L. Methane emissions from lakes: Dependence of lake characteristics, two regional assessments, and a global estimate. Global Biogeochemical Cycles, 18, GB4009(2004).
Bohn, T. J., Lettenmaier, D. P., Sathulur, K., Bowling, L. C., Podest, E., McDonald, K. C., & Friborg, T. Methane emissions from western siberian wetlands: heterogeneity and sensitivity to climate change. Environmental Research Letters 2, 045015 (2007).
Dove, A., Roulet, N., Crill, P., Chanton, J., & Bourbonniere, R. Methane dynamics of a northern boreal beaver pond. Écoscience, 6(4), 577-586 (1999).
Downing, J. A. Emerging global role of small lakes and ponds : Little things mean a lot. Limnetica, 29(1), 9-24 (2010).
Edwards, G., Dias, G., Thurtell, G., Kidd, G., Roulet, N., Kelly, C., & Halfpenny-Mitchell, L. Methane fluxes from a wetland using the flux-gradient technique: The measurement of methane flux from a natural wetland pond and adjacent vegetated wetlands using a TDL-based flux-gradient technique. Water, Air and Soil Pollution: Focus, 1, 447-454 (2001).
Holgerson, M. Drivers of carbon dioxide and methane supersaturation in small, temporary ponds. Biogeochemistry, (2015).
Holgerson, M. & Raymond, P. Large contribution to inland water CO2 and CH4 emissions from very small ponds. Nature Geoscience 9, 222-226 (2016).
IPCC. Climate Change 2013: The Physical Science Basis. Contribution of
Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press. (2013).
Natchimuthu, S., Selvam, B. P., & Bastviken, D. Influence of weather variables on methane and carbon dioxide flux from a shallow pond. Biogeochemistry, (2014).
Palma-Silva, C., Marinho, C. C., Albertoni, E. F., Giacomini, I. B., Figueiredo Barros, M. P., Furlanetto, L. M., & Esteves, F. d. A. Methane emissions in two small shallow neotropical lakes: The role of temperature and trophic level. Atmospheric Environment 81, 373-379(2013).
Sources:
Bansal, S., Tangen, B., & Finocchiaro, R. Temperature and hydrology affect methane emissions from prairie pothole wetlands. Wetlands 36(2), 371-381(2016).
Bastviken, D., Cole, J., Pace, M., & Tranvik, L. Methane emissions from lakes: Dependence of lake characteristics, two regional assessments, and a global estimate. Global Biogeochemical Cycles, 18, GB4009(2004).
Bohn, T. J., Lettenmaier, D. P., Sathulur, K., Bowling, L. C., Podest, E., McDonald, K. C., & Friborg, T. Methane emissions from western siberian wetlands: heterogeneity and sensitivity to climate change. Environmental Research Letters 2, 045015 (2007).
Dove, A., Roulet, N., Crill, P., Chanton, J., & Bourbonniere, R. Methane dynamics of a northern boreal beaver pond. Écoscience, 6(4), 577-586 (1999).
Downing, J. A. Emerging global role of small lakes and ponds : Little things mean a lot. Limnetica, 29(1), 9-24 (2010).
Edwards, G., Dias, G., Thurtell, G., Kidd, G., Roulet, N., Kelly, C., & Halfpenny-Mitchell, L. Methane fluxes from a wetland using the flux-gradient technique: The measurement of methane flux from a natural wetland pond and adjacent vegetated wetlands using a TDL-based flux-gradient technique. Water, Air and Soil Pollution: Focus, 1, 447-454 (2001).
Holgerson, M. Drivers of carbon dioxide and methane supersaturation in small, temporary ponds. Biogeochemistry, (2015).
Holgerson, M. & Raymond, P. Large contribution to inland water CO2 and CH4 emissions from very small ponds. Nature Geoscience 9, 222-226 (2016).
IPCC. Climate Change 2013: The Physical Science Basis. Contribution of
Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press. (2013).
Natchimuthu, S., Selvam, B. P., & Bastviken, D. Influence of weather variables on methane and carbon dioxide flux from a shallow pond. Biogeochemistry, (2014).
Palma-Silva, C., Marinho, C. C., Albertoni, E. F., Giacomini, I. B., Figueiredo Barros, M. P., Furlanetto, L. M., & Esteves, F. d. A. Methane emissions in two small shallow neotropical lakes: The role of temperature and trophic level. Atmospheric Environment 81, 373-379(2013).
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