Lakes and reservoirs as regulators of carbon cycling and climate
Uppsala University1, Iowa State University2, University of Minnesota3, University of Siena4, United States Geological Survey5, Trent University6, University of Regina7, University of North Carolina at Chapel Hill8, Miami University9, Finnish Environment Institute10, Marine Institute of Memorial University of Newfoundland11, University of Oslo12, Université du Québec13, Virginia Commonwealth University14, University of Colorado Boulder15, University of California, Santa Barbara16, University of the Sciences17, Université du Québec à Montréal18, Universidade Federal de Juiz de Fora19, Commonwealth Scientific and Industrial Research Organisation20, University of Alberta21, ETH Zurich22, Hydro-Québec23
TL;DR: The role of lakes in carbon cycling and global climate, examine the mechanisms influencing carbon pools and transformations in lakes, and discuss how the metabolism of carbon in the inland waters is likely to change in response to climate.
Abstract: We explore the role of lakes in carbon cycling and global climate, examine the mechanisms influencing carbon pools and transformations in lakes, and discuss how the metabolism of carbon in the inland waters is likely to change in response to climate. Furthermore, we project changes as global climate change in the abundance and spatial distribution of lakes in the biosphere, and we revise the estimate for the global extent of carbon transformation in inland waters. This synthesis demonstrates that the global annual emissions of carbon dioxide from inland waters to the atmosphere are similar in magnitude to the carbon dioxide uptake by the oceans and that the global burial of organic carbon in inland water sediments exceeds organic carbon sequestration on the ocean floor. The role of inland waters in global carbon cycling and climate forcing may be changed by human activities, including construction of impoundments, which accumulate large amounts of carbon in sediments and emit large amounts of methane to the atmosphere. Methane emissions are also expected from lakes on melting permafrost. The synthesis presented here indicates that (1) inland waters constitute a significant component of the global carbon cycle, (2) their contribution to this cycle has significantly changed as a result of human activities, and (3) they will continue to change in response to future climate change causing decreased as well as increased abundance of lakes as well as increases in the number of aquatic impoundments.
Citations
More filters
01 Jan 2014
TL;DR: For base year 2010, anthropogenic activities created ~210 (190 to 230) TgN of reactive nitrogen Nr from N2 as discussed by the authors, which is at least 2 times larger than the rate of natural terrestrial creation of ~58 Tg N (50 to 100 Tg nr yr−1) (Table 6.9, Section 1a).
Abstract: For base year 2010, anthropogenic activities created ~210 (190 to 230) TgN of reactive nitrogen Nr from N2. This human-caused creation of reactive nitrogen in 2010 is at least 2 times larger than the rate of natural terrestrial creation of ~58 TgN (50 to 100 TgN yr−1) (Table 6.9, Section 1a). Note that the estimate of natural terrestrial biological fixation (58 TgN yr−1) is lower than former estimates (100 TgN yr−1, Galloway et al., 2004), but the ranges overlap, 50 to 100 TgN yr−1 vs. 90 to 120 TgN yr−1, respectively). Of this created reactive nitrogen, NOx and NH3 emissions from anthropogenic sources are about fourfold greater than natural emissions (Table 6.9, Section 1b). A greater portion of the NH3 emissions is deposited to the continents rather than to the oceans, relative to the deposition of NOy, due to the longer atmospheric residence time of the latter. These deposition estimates are lower limits, as they do not include organic nitrogen species. New model and measurement information (Kanakidou et al., 2012) suggests that incomplete inclusion of emissions and atmospheric chemistry of reduced and oxidized organic nitrogen components in current models may lead to systematic underestimates of total global reactive nitrogen deposition by up to 35% (Table 6.9, Section 1c). Discharge of reactive nitrogen to the coastal oceans is ~45 TgN yr−1 (Table 6.9, Section 1d). Denitrification converts Nr back to atmospheric N2. The current estimate for the production of atmospheric N2 is 110 TgN yr−1 (Bouwman et al., 2013).
1,967 citations
Yale University1, Université libre de Bruxelles2, University of Hamburg3, Uppsala University4, Wisconsin Department of Natural Resources5, United States Geological Survey6, University of Washington7, Stockholm University8, Finnish Environment Institute9, University of Waterloo10, Pierre-and-Marie-Curie University11, United States Naval Academy12
TL;DR: In this article, the authors report regional variations in global inland water surface area, dissolved CO2 and gas transfer velocity, and obtain global CO2 evasion rates of 1.8(-0.25) and 0.52 Pg C yr(-1) from lakes and reservoirs, where the upper and lower limits are respectively the 5th and 95th confidence interval percentiles.
Abstract: Carbon dioxide (CO2) transfer from inland waters to the atmosphere, known as CO2 evasion, is a component of the global carbon cycle. Global estimates of CO2 evasion have been hampered, however, by the lack of a framework for estimating the inland water surface area and gas transfer velocity and by the absence of a global CO2 database. Here we report regional variations in global inland water surface area, dissolved CO2 and gas transfer velocity. We obtain global CO2 evasion rates of 1.8(-0.25)(+0.25) petagrams of carbon (Pg C) per year from streams and rivers and 0.32(-0.26)(+0.52) Pg C yr(-1) from lakes and reservoirs, where the upper and lower limits are respectively the 5th and 95th confidence interval percentiles. The resulting global evasion rate of 2.1 Pg C yr(-1) is higher than previous estimates owing to a larger stream and river evasion rate. Our analysis predicts global hotspots in stream and river evasion, with about 70 per cent of the flux occurring over just 20 per cent of the land surface. The source of inland water CO2 is still not known with certainty and new studies are needed to research the mechanisms controlling CO2 evasion globally.
1,696 citations
Leibniz Association1, Bard College2, Stony Brook University3, University of Oslo4, Ontario Ministry of the Environment5, Swiss Federal Institute of Aquatic Science and Technology6, University of Innsbruck7, University of Konstanz8, Swedish University of Agricultural Sciences9, University of California, Davis10
TL;DR: This work has identified the key response variables within a lake that act as indicators of the effects of climate change on both the lake and the catchment, which reflect a wide range of physical, chemical, and biological responses to climate.
Abstract: While there is a general sense that lakes can act as sentinels of climate change, their efficacy has not been thoroughly analyzed. We identified the key response variables within a lake that act as indicators of the effects of climate change on both the lake and the catchment. These variables reflect a wide range of physical, chemical, and biological responses to climate. However, the efficacy of the different indicators is affected by regional response to climate change, characteristics of the catchment, and lake mixing regimes. Thus, particular indicators or combinations of indicators are more effective for different lake types and geographic regions. The extraction of climate signals can be further complicated by the influence of other environmental changes, such as eutrophication or acidification, and the equivalent reverse phenomena, in addition to other land-use influences. In many cases, however, confounding factors can be addressed through analytical tools such as detrending or filtering. Lakes are effective sentinels for climate change because they are sensitive to climate, respond rapidly to change, and integrate information about changes in the catchment.
1,353 citations
TL;DR: The continental GHG sink may be considerably overestimated, and freshwaters need to be recognized as important in the global carbon cycle.
Abstract: Inland waters (lakes, reservoirs, streams, and rivers) are often substantial methane (CH4) sources in the terrestrial landscape. They are, however, not yet well integrated in global greenhouse gas (GHG) budgets. Data from 474 freshwater ecosystems and the most recent global water area estimates indicate that freshwaters emit at least 103 teragrams of CH4 year−1, corresponding to 0.65 petagrams of C as carbon dioxide (CO2) equivalents year−1, offsetting 25% of the estimated land carbon sink. Thus, the continental GHG sink may be considerably overestimated, and freshwaters need to be recognized as important in the global carbon cycle.
1,208 citations
TL;DR: The abundance and size distribution of lakes is critical to quantifying limnetic contributions to the global carbon cycle as discussed by the authors, however, estimates of global lake abundance are not accurate and are unreliable.
Abstract: An accurate description of the abundance and size distribution of lakes is critical to quantifying limnetic contributions to the global carbon cycle. However, estimates of global lake abundance are ...
996 citations
References
More filters
01 Jan 2007
TL;DR: The first volume of the IPCC's Fourth Assessment Report as mentioned in this paper was published in 2007 and covers several topics including the extensive range of observations now available for the atmosphere and surface, changes in sea level, assesses the paleoclimatic perspective, climate change causes both natural and anthropogenic, and climate models for projections of global climate.
Abstract: This report is the first volume of the IPCC's Fourth Assessment Report. It covers several topics including the extensive range of observations now available for the atmosphere and surface, changes in sea level, assesses the paleoclimatic perspective, climate change causes both natural and anthropogenic, and climate models for projections of global climate.
32,826 citations
TL;DR: In this article, a review of available scientific evidence shows that human alterations of the nitrogen cycle have approximately doubled the rate of nitrogen input into the terrestrial nitrogen cycle, with these rates still increasing; increased concentrations of the potent greenhouse gas N 2O globally, and increased concentration of other oxides of nitrogen that drive the formation of photochemical smog over large regions of Earth.
Abstract: Nitrogen is a key element controlling the species composition, diversity, dynamics, and functioning of many terrestrial, freshwater, and marine ecosystems. Many of the original plant species living in these ecosystems are adapted to, and function optimally in, soils and solutions with low levels of available nitrogen. The growth and dynamics of herbivore populations, and ultimately those of their predators, also are affected by N. Agriculture, combustion of fossil fuels, and other human activities have altered the global cycle of N substantially, generally increasing both the availability and the mobility of N over large regions of Earth. The mobility of N means that while most deliberate applications of N occur locally, their influence spreads regionally and even globally. Moreover, many of the mobile forms of N themselves have environmental consequences. Although most nitrogen inputs serve human needs such as agricultural production, their environmental conse- quences are serious and long term. Based on our review of available scientific evidence, we are certain that human alterations of the nitrogen cycle have: 1) approximately doubled the rate of nitrogen input into the terrestrial nitrogen cycle, with these rates still increasing; 2) increased concentrations of the potent greenhouse gas N 2O globally, and increased concentrations of other oxides of nitrogen that drive the formation of photochemical smog over large regions of Earth; 3) caused losses of soil nutrients, such as calcium and potassium, that are essential for the long-term maintenance of soil fertility; 4) contributed substantially to the acidification of soils, streams, and lakes in several regions; and 5) greatly increased the transfer of nitrogen through rivers to estuaries and coastal oceans. In addition, based on our review of available scientific evidence we are confident that human alterations of the nitrogen cycle have: 6) increased the quantity of organic carbon stored within terrestrial ecosystems; 7) accelerated losses of biological diversity, especially losses of plants adapted to efficient use of nitrogen, and losses of the animals and microorganisms that depend on them; and 8) caused changes in the composition and functioning of estuarine and nearshore ecosystems, and contributed to long-term declines in coastal marine fisheries.
5,729 citations
TL;DR: In this paper, the role of inland water ecosystems in the global carbon cycle has been investigated and it is shown that roughly twice as much C enters inland aquatic systems from land as is exported from land to the sea, roughly equally as inorganic and organic carbon.
Abstract: Because freshwater covers such a small fraction of the Earth’s surface area, inland freshwater ecosystems (particularly lakes, rivers, and reservoirs) have rarely been considered as potentially important quantitative components of the carbon cycle at either global or regional scales. By taking published estimates of gas exchange, sediment accumulation, and carbon transport for a variety of aquatic systems, we have constructed a budget for the role of inland water ecosystems in the global carbon cycle. Our analysis conservatively estimates that inland waters annually receive, from a combination of background and anthropogenically altered sources, on the order of 1.9 Pg C y−1 from the terrestrial landscape, of which about 0.2 is buried in aquatic sediments, at least 0.8 (possibly much more) is returned to the atmosphere as gas exchange while the remaining 0.9 Pg y−1 is delivered to the oceans, roughly equally as inorganic and organic carbon. Thus, roughly twice as much C enters inland aquatic systems from land as is exported from land to the sea. Over prolonged time net carbon fluxes in aquatic systems tend to be greater per unit area than in much of the surrounding land. Although their area is small, these freshwater aquatic systems can affect regional C balances. Further, the inclusion of inland, freshwater ecosystems provides useful insight about the storage, oxidation and transport of terrestrial C, and may warrant a revision of how the modern net C sink on land is described.
3,179 citations
"Lakes and reservoirs as regulators ..." refers background in this paper
...Further, saline lakes, which, in spite of their large area (e.g., Caspian Sea, Aral Sea, Lake Chad), were not included in the work of Cole et al. (1994), contribute another 0.11–0.15 Pg C yr21 to the atmosphere (Duarte et al. 2008)....
[...]
...Cole et al. (1994) estimated that lakes emit about 0.14 Pg C yr21 (as CO2) to the atmosphere....
[...]
TL;DR: In this article, the authors summarize the recent literature about controls on dissolved organic matter (DOM) concentrations and fluxes in so-called "soil degraded organic matter" (SOCOM).
Abstract: Dissolved organic matter (DOM) in soils plays an important role in the biogeochemistry of carbon, nitrogen, and phosphorus, in pedogenesis, and in the transport of pollutants in soils. The aim of this review is to summarize the recent literature about controls on DOM concentrations and fluxes in soi
2,138 citations
"Lakes and reservoirs as regulators ..." refers background in this paper
...Changes in plant species influence litter fall and humus accumulation in forest ecosystems (Kalbitz et al. 2000)....
[...]
TL;DR: In this article, an analysis of 2,700 soil profiles, organized on a climate basis using the Holdridge life-zone classification system, indicates relationships between soil carbon density and climate, a major soil forming factor.
Abstract: Soil organic carbon in active exchange with the atmosphere constitutes approximately two-thirds of the carbon in terrestrial ecosystems1,2. The relatively large size and long residence time of this pool (of the order of 1,200 yr) make it a potentially important sink for carbon released to the atmosphere by fossil fuel combustion; however, in many cases, human disturbance has caused a decrease in soil carbon storage3,4. Various recent estimates place the global total of soil carbon between 700 (ref. 2) and 2,946 × 1015 g (ref. 5) with several intermediate estimates: 1,080 (ref. 1), 1,392 (ref. 6), 1,456 (ref. 3), and 2,070 × 1015g (ref. 7). Schlesinger's3 estimate seems to be based on the most extensive data base (∼200 observations, some of which are mean values derived from large studies in particular areas) and is widely cited in carbon cycle studies. In addition to estimating the world soil carbon pool, it is important to establish the relationships between the geographical distribution of soil carbon and climate, vegetation, human development and other factors as a basis for assessing the influence of changes in any of these factors on the global carbon cycle. Our analysis of 2,700 soil profiles, organized on a climate basis using the Holdridge life-zone classification system8, indicates relationships between soil carbon density and climate, a major soil forming factor. Soil carbon density generally increases with increasing precipitation, and there is an increase in soil carbon with decreasing temperature for any particular level of precipitation. When the potential evapotranspiration equals annual precipitation, soil carbon density9 is ∼10 kg m−2, exceptions to this being warm temperate and subtropical soils. Based on recent estimates of the areal extent of major ecosystem complexes9,10 which correspond well with climatic life zones, the global soil organic carbon pool is estimated to be ∼1,395 × 1015g.
2,122 citations
"Lakes and reservoirs as regulators ..." refers background in this paper
...Arctic regions—Carbon storage in high-latitude peatlands is estimated to represent one third or more of the global soil carbon pool (Post et al. 1982; Zimov et al. 2006)....
[...]