Increases In Atmospheric Greenhouse Gases Research Articles

Predicting soil organic carbon stocks under future land use and climate change conditions in Northeast China

There are large uncertainties in predicting soil organic carbon (SOC) in response of future changing climate and human activities. This study estimates SOC stocks under future changing land use and climate conditions in Northeast China using a state-of-the-art digital soil mapping technique. A total of 487 soil samples and 12 environmental variables from 37 landscape units (derived from soil, topography, climate, and human activity data) combined with boosted regression trees (BRT) and random forest (RF) models are first used to map the topsoil (0–20 cm) SOC stocks in Northeast China in 2015. The primary environmental variables influencing the variability of SOC stocks are mean annual temperature, elevation, mean annual precipitation, and land use. We then applied the space-for-time substitution method in conjunction with the BRT model to predict the spatial distribution of SOC stocks under future (the 2050s and 2090s) climate and land use scenarios. SOC stocks under the scenarios of shared socioeconomic pathways (SSP245) and SSP585 (average and upper estimate of the increase in atmospheric greenhouse gases for that time) decreased by 1.5% and 4.5% in the 2050s, respectively, compared with 2015 (5293 Tg C). For the 2090s, the SOC stocks under the SSP245 scenario increased by 1.9%, and those under the SSP585 scenario decreased by 0.4%. The SOC stocks in both future periods are mainly stored in farmlands and forests, accounting for 90% and 92% of the total SOC stocks, respectively. Our high-resolution estimated SOC maps provide a scientific basis for optimizing ecological management in Northeast China.

Holocene temperature variability in China

The patterns and mechanisms of Holocene temperature variability in China remain highly controversial, possibly due to the lack of sufficient high-resolution records and few systematic compilations and reviews of published records. Here, we used branched glycerol dialkyl glycerol tetraethers (brGDGTs) to generate a Holocene mean annual air temperature (MAAT) record from Lake Yangzonghai (YZH) in southwest (SW) China. Our record, largely ruling out the effect of seasonal bias, displays a long-term cooling of ∼1.5 °C since 10 cal ka BP, indicating that the discrepancy of Holocene temperature records (such as long-term cooling vs warming trends) in China cannot be attributed to the seasonal bias in temperature proxies. We compiled 67 published Holocene temperature records from China. These temperature records exhibit a mathematically consistent pattern with a relatively warmer mid-Holocene and colder late Holocene in the Asian summer monsoon (ASM) domain, whilst records show a relatively colder mid-Holocene and warmer late Holocene in the westerlies domain. This spatial heterogeneity of Holocene temperature variability is attributed to the modulation of monsoon systems, including the warming effect of ASM and the cooling effect of the East Asian winter monsoon (EAWM). In the ASM domain, the dominant pattern with the relatively warmer mid-Holocene and colder late Holocene is primarily controlled by the persistent weakening of the warming effect of the ASM and the concurrent strengthening of the cooling effect of the EAWM during the mid-to-late Holocene. In the westerlies domain, the warming effect of the ASM disappears, the cooling effect of the EAWM is confined to the north of the Tibetan Plateau due to the blocking effect of the Tibetan Plateau. This dominant pattern with the relatively colder mid-Holocene and warmer late Holocene is driven by the increases in atmospheric greenhouse gases (GHG) radiative forcing and Northern Hemisphere Annual Insolation (NHAI) forcing during the mid-to-late Holocene.

Differentiable programming for Earth system modeling

Abstract. Earth system models (ESMs) are the primary tools for investigating future Earth system states at timescales from decades to centuries, especially in response to anthropogenic greenhouse gas release. State-of-the-art ESMs can reproduce the observational global mean temperature anomalies of the last 150 years. Nevertheless, ESMs need further improvements, most importantly regarding (i) the large spread in their estimates of climate sensitivity, i.e., the temperature response to increases in atmospheric greenhouse gases; (ii) the modeled spatial patterns of key variables such as temperature and precipitation; (iii) their representation of extreme weather events; and (iv) their representation of multistable Earth system components and the ability to predict associated abrupt transitions. Here, we argue that making ESMs automatically differentiable has a huge potential to advance ESMs, especially with respect to these key shortcomings. First, automatic differentiability would allow objective calibration of ESMs, i.e., the selection of optimal values with respect to a cost function for a large number of free parameters, which are currently tuned mostly manually. Second, recent advances in machine learning (ML) and in the number, accuracy, and resolution of observational data promise to be helpful with at least some of the above aspects because ML may be used to incorporate additional information from observations into ESMs. Automatic differentiability is an essential ingredient in the construction of such hybrid models, combining process-based ESMs with ML components. We document recent work showcasing the potential of automatic differentiation for a new generation of substantially improved, data-informed ESMs.

Late Holocene temperature and precipitation variations in an alpine region of the northeastern Tibetan Plateau and their response to global climate change

Knowledge of temperature and precipitation variations on the northeastern Tibetan Plateau (NETP) during the recent past can improve our understanding of late Holocene regional climate change and its response to global climate change, in the past and potentially the future. Based on records of multiple geochemical indicators and branched glycerol dialkyl glycerol tetraethers from the sediments of alpine Lake Bihu on the NETP, we reconstructed high-resolution precipitation sequences and quantified the variation of the mean air temperature of months above freezing (MAF, between May and October) over the past ∼3500 years. The MAF reconstruction shows obvious fluctuations on decadal to centennial timescales, and the absolute values of the reconstructed temperature range from 0.70 to 3.98 °C, with an average of 2.19 °C. The precipitation record reflects the high-frequency variability of the East Asian summer monsoon (EASM). The maximum precipitation and temperature on the NETP occurred during the Medieval Warm Period (MWP, ∼800–1400 CE), rather than during the Current Warm Period (CWP, the last 150 years). We also observed broadly similar patterns of warm–wet and cold–dry climatic variations over the NETP and the broader EASM region; moreover, the decadal to centennial temperature fluctuations were consistent on a large spatial scale. Our results indicate that temperature variability during the late Holocene was primarily controlled by solar radiation, interrupted by multiple decades of successive volcanic eruptions. In addition, anomalous and rapid warming during the CWP may also be related to the unprecedented increase in atmospheric greenhouse gases. Precipitation variability in this region, driven by changes in the EASM, may have been primarily a response to changes in total solar irradiance and associated changes in atmospheric–oceanic modes (e.g., the El Niño–Southern Oscillation, Intertropical Convergence Zone, and Western Pacific Subtropical High). Overall, our results provide robust evidence for global climate teleconnections between different regions, especially in high mountains, in the past, present, and potentially in the future.

Comprehensive Analysis of Ocean Current and Sea Surface Temperature Trend under Global Warming Hiatus of Kuroshio Extent Delineated Using a Combination of Spatial Domain Filters

The effect of climate prevails on a diverse time scale from days to seasons and decades. Between 1993 and 2013, global warming appeared to have paused even though there was an increase in atmospheric greenhouse gases. The variations in oceanographic variables, like current speed and sea surface temperature (SST), under the influence of the global warming hiatus (1993–2013), have drawn the attention of the global research community. However, the magnitude of ocean current and SST characteristics oscillates and varies with their geographic locations. Consequently, investigating the spatio-temporal changing aspects of oceanographic parameters in the backdrop of climate change is essential, specifically in coastal regions along Kuroshio current (KC), where fisheries are predominant. This study analyzes the trend of ocean current and SST induced mainly during the global warming hiatus, before and till the recent time based on the daily ocean current data from 1993 to 2020 and SST between 1982 and 2020. The Kuroshio extent is delineated from its surrounding water masses using an aggregation of raster classification, stretching, equalization, and spatial filters such as edge detection, convolution, and Laplacian. Finally, on the extracted Kuroshio extent, analyses such as time series decomposition (additive) and statistical trend computation methods (Yue and Wang trend test and Theil–Sen’s slope estimator) were applied to dissect and investigate the situations. An interesting downward trend is observed in the KC between the East coast of Taiwan and Tokara Strait (Tau = −0.05, S = −2430, Sen’s slope = −5.19 × 10−5, and Z = −2.61), whereas an upward trend from Tokara Strait to Nagoya (Tau = 0.89, S = 4344, Sen’s slope = 8.4 × 10−5, and Z = 2.56). In contrast, a consistent increasing SST in trend is visualized in the southern and mid-KC sections but with varying magnitude.

Modeling of Valeriana wallichii Habitat Suitability and Niche Dynamics in the Himalayan Region under Anticipated Climate Change.

Simple SummaryIn the modern era of the anthropocene, an increase in the accumulation of greenhouse gases in the atmosphere has resulted in the global rise of the Earth’s temperature. This has resulted in the habitat shift of various plant and animal species. Plant species that are endemic show a narrow distribution range and inhabit higher elevations are highly susceptible to the impacts of global warming. The present study discusses the habitat distribution of Valeriana wallichi, an endangered medicinal herb. We also predicted the impact of climate change on its distribution range and niche dynamics. Results reveal significant contraction in the possible habitats of this herb under future climatic scenarios, with RCP 8.5 for 2070 showing the highest habitat loss. Niche equivalency and similarity tests describe that the habitats could be compared but not identical between current and future climatic scenarios. From the current study, we conclude that the habitats of Valeriana wallichii are highly vulnerable to climate shifts. This study can not only be used to alleviate the threat to this plant by documenting the unexplored populations, restoring the degraded habitats through rewilding and launching species recovery plans in the natural habitats but could also be used by various conservation biologists to recover the declining status of various highly valued species across the globe.An increase in atmospheric greenhouse gases necessitates the use of species distribution models (SDMs) in modeling suitable habitats and projecting the impact of climate change on the future range shifts of the species. The present study is based on the BIOMOD ensemble approach to map the currently suitable habitats and predict the impact of climate change on the niche shift of Valeriana wallichii. We also studied its niche dynamics using the ecospat package in R software. Values of the area under curve (AUC) and true skill statistics (TSS) were highly significant (>0.9), which shows that the model has run better. From 19 different bioclimatic variables, only 8 were retained after correlation, among which bio_17 (precipitation of driest quarter), bio_1 (annual mean temperature), and bio_12 (annual mean precipitation) received the highest gain. Under future climate change, the suitable habitats will be significantly contracted by −94% (under representative concentration pathway RCP 8.5 for 2070) and −80.22% (under RCP 8.5 for 2050). There is a slight increase in habitat suitability by +16.69% (RCP 4.5 for 2050) and +8.9% (RCP 8.5 for 2050) under future climate change scenarios. The equivalency and similarity tests of niche dynamics show that the habitat suitability for current and future climatic scenarios is comparable but not identical. Principal Component Analysis (PCA) analysis shows that climatic conditions will be severely affected between current and future scenarios. From this study, we conclude that the habitats of Valeriana wallichii are highly vulnerable to climate shifts. This study can be used to alleviate the threat to this plant by documenting the unexplored populations, restoring the degraded habitats through rewilding, and launching species recovery plans in the natural habitats.

Case Studies on the Impacts of Climate Change on Historical Buildings in Northern Cyprus

The changing in climatic conditions is one of the most significant issues in the twenty-first century. The literature suggests various approaches for the understanding of the harmful influences of climate change. Climate change is caused by increases in atmospheric greenhouse gases, deforestation, altering watercourses and human actions with tragic effect on the environment has turned into certainty, as that the procedure may not be over in a short period or medium period. Climate observations showed that climate change occurrence had unfavorable impacts on society and mostly on built environment. The most vulnerable buildings are the historical buildings. The impact of climate change on historical buildings should be studied very carefully to determine the meteorological parameters and changes which are the most critical for the protection of the cultural heritage. Prediction of the effects of climate change on built cultural heritage for the next 100 years is necessary to take every step to protect the historical buildings that are likely to be worst affected by climate change effects. Against this background, this paper reviews the physical and chemical deteriorations of historical buildings and changing energy consumption of historic buildings. The research exposed the risk to lose cultural heritage and rising energy demand in the Northern part of Cyprus as a case study. Structural engineers and architects should consider the dominant forces of climate change to protect the historical buildings but also to construct sustainable, feasible and durable buildings for future projects.

Climate Change Impact on Water Resources in Mehedinţi County - Case Study

The increase of atmospheric greenhouse gases results in climate changes which cause the rise of sea level and an increased frequency of extreme climatic events including intense storms, heavy rainfall and droughts. There is a lower consensus on the magnitude of changes in climate variables, but several studies show that climate change has an impact on the availability and demand for water resources. Major rivers worldwide have experienced dramatic changes in flow, reducing their natural ability to adjust to and absorb disturbances. Given expected changes in global climate and water needs, this may create serious problems, including loss of native biodiversity and risks to ecosystems and humans from increased flooding or water shortages. This document analyzes the potential impact of climate change on water resources in Romania, Mehedinți County. The work ends with quantitative assessments of the effects of climate change on hydrology for a part of the Mehedinți County basins.

Influence of the Atlantic Meridional Overturning Circulation on the Tropical Climate Response to CO2 Forcing

AbstractThe increase of atmospheric greenhouse gases is expected to affect the hydrological cycle and large‐scale precipitation patterns. In parallel, unforced natural variability on decadal‐to‐multidecadal timescales can also modulate forced changes at the regional scales. Based on multimember ensembles from a coupled General Circulation Model, we investigate the sensitivity of CO2‐forced changes in tropical precipitation and atmospheric circulation to fluctuations of the Atlantic Multidecadal Overturning Circulation (AMOC). We show that contrasted AMOC states yield considerable differences in equatorial Pacific precipitation forced changes, by impacting the direct (within a year) CO2‐induced weakening of the Walker circulation. We use global atmospheric energetics, as a theoretical backdrop, to explain the relationship between the tropical atmospheric circulation and the AMOC state. A physical mechanism is then proposed, relating the direct CO2‐forced weakening of the atmospheric tropical circulation to its climatological strength in unperturbed climate and indirectly to the AMOC state.

Modelling climate change impacts on nutrients and primary production in coastal waters

There is high confidence that the anthropogenic increase of atmospheric greenhouse gases (GHGs) is causing modifications in the Earth's climate. Coastal waterbodies such as estuaries, bays and lagoons are among those most affected by the ongoing changes in climate. Being located at the land-sea interface, such waterbodies are subjected to the combined changes in the physical-chemical processes of atmosphere, upstream land and coastal waters. Particularly, climate change is expected to alter phytoplankton communities by changing their environmental drivers (especially climate-related), thus exacerbating the symptoms of eutrophication events, such as hypoxia, harmful algal blooms (HAB) and loss of habitat. A better understanding of the links between climate-related drivers and phytoplankton is therefore necessary for projecting climate change impacts on aquatic ecosystems.Here we present the case study of the Zero river basin in Italy, one of the main contributors of freshwater and nutrient to the salt-marsh Palude di Cona, a coastal waterbody belonging to the lagoon of Venice. To project the impacts of climate change on freshwater inputs, nutrient loadings and their effects on the phytoplankton community of the receiving waterbody, we formulated and applied an integrated modelling approach made of: climate simulations derived by coupling a General Circulation Model (GCM) and a Regional Climate Model (RCM) under alternative emission scenarios, the hydrological model Soil and Water Assessment Tool (SWAT) and the ecological model AQUATOX. Climate projections point out an increase of precipitations in the winter period and a decrease in the summer months, while temperature shows a significant increase over the whole year. Water discharge and nutrient loads simulated by SWAT show a tendency to increase (decrease) in the winter (summer) period. AQUATOX projects changes in the concentration of nutrients in the salt-marsh Palude di Cona, and variations in the biomass and species of the phytoplankton community.

Arctic cryosphere and Milankovitch forcing of Great Basin paleoclimate

Although Great Basin paleoclimate history has been examined for more than a century, the orbital-scale paleoclimate forcings remain poorly understood. Here we show – by a detailed phasing analysis of a well-dated stalagmite δ18O time series – that Great Basin paleoclimate is linearly related to, but lagged, the 23,000 yr precession cycle in northern hemisphere summer insolation by an average of 3240 years (−900 to 6600 yr range) over the last two glacial cycles. We interpret these lags as indicating that Great Basin climate is sensitive to and indirectly forced by changes in the cryosphere, as evidenced by fast and strong linkages to global ice volume and Arctic paleoclimate indicators. Mid-latitude atmospheric circulation was likely impacted by a northward shifted storm track and higher pressure over the region arising from decreased sea ice and snow cover. Because anthropogenic warming is expected to reduce northern hemisphere snow and ice cover, continued increase in atmospheric greenhouse gases is likely to result in warming and drying over coming centuries that will amplify a warming trend that began ~2400 years ago.

On determining the point of no return in climate change

Abstract. Earth's global mean surface temperature has increased by about 1.0 °C over the period 1880–2015. One of the main causes is thought to be the increase in atmospheric greenhouse gases. If greenhouse gas emissions are not substantially decreased, several studies indicate that there will be a dangerous anthropogenic interference with climate by the end of this century. However, there is no good quantitative measure to determine when it is too late to start reducing greenhouse gas emissions in order to avoid such dangerous interference. In this study, we develop a method for determining a so-called point of no return for several greenhouse gas emission scenarios. The method is based on a combination of aspects of stochastic viability theory and linear response theory; the latter is used to estimate the probability density function of the global mean surface temperature. The innovative element in this approach is the applicability to high-dimensional climate models as demonstrated by the results obtained with the PlaSim model.

An apparent hiatus in global warming?

AbstractGlobal warming first became evident beyond the bounds of natural variability in the 1970s, but increases in global mean surface temperatures have stalled in the 2000s. Increases in atmospheric greenhouse gases, notably carbon dioxide, create an energy imbalance at the top‐of‐atmosphere (TOA) even as the planet warms to adjust to this imbalance, which is estimated to be 0.5–1 W m−2 over the 2000s. Annual global fluctuations in TOA energy of up to 0.2 W m−2 occur from natural variations in clouds, aerosols, and changes in the Sun. At times of major volcanic eruptions the effects can be much larger. Yet global mean surface temperatures fluctuate much more than these can account for. An energy imbalance is manifested not just as surface atmospheric or ground warming but also as melting sea and land ice, and heating of the oceans. More than 90% of the heat goes into the oceans and, with melting land ice, causes sea level to rise. For the past decade, more than 30% of the heat has apparently penetrated below 700 m depth that is traceable to changes in surface winds mainly over the Pacific in association with a switch to a negative phase of the Pacific Decadal Oscillation (PDO) in 1999. Surface warming was much more in evidence during the 1976–1998 positive phase of the PDO, suggesting that natural decadal variability modulates the rate of change of global surface temperatures while sea‐level rise is more relentless. Global warming has not stopped; it is merely manifested in different ways.

Impacts of climate change on water resources in southern Africa: A review

The Intergovernmental Panel on Climate Change concluded that there is consensus that the increase of atmospheric greenhouse gases will result in climate change which will cause the sea level to rise, increased frequency of extreme climatic events including intense storms, heavy rainfall events and droughts. This will increase the frequency of climate-related hazards, causing loss of life, social disruption and economic hardships. There is less consensus on the magnitude of change of climatic variables, but several studies have shown that climate change will impact on the availability and demand for water resources. In southern Africa, climate change is likely to affect nearly every aspect of human well-being, from agricultural productivity and energy use to flood control, municipal and industrial water supply to wildlife management, since the region is characterised by highly spatial and temporally variable rainfall and, in some cases, scarce water resources. Vulnerability is exacerbated by the region’s low adaptive capacity, widespread poverty and low technology uptake. This paper reviews the potential impacts of climate change on water resources in southern Africa. The outcomes of this review include highlighting studies on detected climate changes particularly focusing on temperature and rainfall. Additionally, the impacts of climate change are highlighted, and respective studies on hydrological responses to climate change are examined. The review also discusses the challenges in climate change impact analysis, which inevitably represents existing research and knowledge gaps. Finally the paper concludes by outlining possible research areas in the realm of climate change impacts on water resources, particularly knowledge gaps in uncertainty analysis for both climate change and hydrological modelling.

Assessment of CO2 Emission Reduction in Road Construction Using Recycled Concrete Materials

Climatic change is a grave threat for human life. After the industrial revolution, the rapid increase in atmospheric greenhouse gases, most notably carbon dioxide (CO2), is primarily responsible for global warming over the past 50 years. Particularly, the high emission of CO2 in civil works becomes a critical issue for urban development and construction due to its high energy demand and fuel consumption. Therefore, it is important to make the effort to reduce the CO2 emission from each quality construction project. Based on product-category rules (PCR), two major road construction materials, asphalt concrete and cement concrete, were studied in this paper. Carbon footprints of the studied materials were examined through the cradle-to-gate life cycle assessment (LCA) from raw material mining and transportation to factory manufacturing. Our results showed that the primary factor controlling the CO2 emission factor of recycled concrete is the proportion of recycled materials in the mixture of cement and fine-grained aggregates. The amount of CO2 emission of road construction using recycled asphalt concrete was 4.533 kg CO2 less than those using normal asphalt concrete.

A commentary on the climate change issue

The climate is changing and the balance of scientific evidence indicates a human contribution through increases in atmospheric greenhouse gases, continued emissions of which will lead to further climate change. Hence, there is an issue to manage through both reducing net greenhouse gas emissions and implementing adaptation strategies. This is not about scientific certainty but probability and risk management. Timely responses to this challenge are somewhat thwarted; first, because policy developers receive relevant knowledge about climate change largely through ad hoc processes open to unintended barriers and manipulation and, second, because behavioural characteristics such as subjectiveness, short-sightedness and irrationality are barriers to the acceptance of a need for action. Businesses that see future opportunities in a low-carbon society, or have an ethos of sustainability, might consider the value of being early starters; strategic and flexible; using expert knowledge and building technological skill; and spreading risk through a portfolio approach. Climate change reflects the way we are as individuals, our expectations, culture, history, education, and our institutional structures, market economy, governance, shared behavioural norms and legal frameworks. There is a need to reassess the foundation of these characteristics in light of the climate change issue.

Early Eocene Arctic climate sensitivity to pCO2 and basin geography

We present results from new early Eocene (∼55–45 Ma) climate modeling experiments with the NCAR Community Climate System Model. These experiments test the sensitivity of climate to a large increase in atmospheric greenhouse gases, such as may have occurred at the Paleocene‐Eocene (P‐E) boundary (∼55.5 Ma), and also allow us to explore the role of Arctic basin configuration on climate. Experiments were run with pCO2 at 560 and 2240 ppm, and a third experiment, at 2240 ppm, incorporates a passage to a neighboring ocean to explore the potential effect of the ocean on Arctic warming, were the Arctic not isolated. Quadrupling pCO2 warms the Arctic by ∼8°C in the annual average, doubles atmospheric moisture content in this region and eliminates Arctic sea ice, consistent with proxy estimates of warming at the P‐E boundary. Opening the Arctic Ocean warms mean annual sea surface temperature by an additional ∼4°C.

The significance of small things

The world may be largely indifferent to the presence of humanity, yet we have magnified our influence to global scales - above all, through the recent increase in atmospheric greenhouse gases.

On the Potential Change in Surface Water Vapor Deposition over the Continental United States due to Increases in Atmospheric Greenhouse Gases

Abstract Characteristics of surface water vapor deposition (WVD) over the continental United States under the present climate and a future climate scenario reflecting the mid-twenty-first-century increased greenhouse gas concentrations were evaluated by using a regional climate model forced by initial and lateral boundary conditions generated by a GCM. Simulated seasonal WVD frequency and daily amounts are presented and elaboration on their relation to potential surface dew/frost is also provided. The climate scenario showed in winter a noticeable decline in WVD frequency over snow-covered areas in the Midwest and over most of the elevated terrain in the western United States, contrasted by an overall increase in the eastern United States. In summer, a decline in frequency was simulated for most of the United States, particularly over the mountains in the west. A spatially mixed trend of change in the frequency was indicated in spring and fall. The trend of change in WVD amount resembled that of the frequency in summer, whereas a largely reversed relation was shown in winter. Quantitatively, changes in frequency and amount of WVD in the range of −30% to +30% generally were indicated for all locations and seasons, except for the western half of the United States, where the change was larger in summer. While areas passing a local statistical test on WVD changes ranged from 11% to 36% of land domain, the WVD differences as a whole field between present climate and future scenarios are significant.

Fluxes of CO 2, CH 4 and N 2O from drained coniferous forests on organic soils

Fluxes of CO 2, CH 4 and N 2O were measured during two to three years at four sites, located within an area of 9 km 2 in southern Sweden, using dark static chamber techniques. Three of the sites were drained coniferous forests on moist organic soils that differed in forest productivity and tree species. The fourth site was an undrained tall sedge mire. Although the drained sites were all moist, with average groundwater levels between 17 and 27 cm below the soil surface, the mean annual dark forest floor CO 2 release rate was significantly higher at the drained sites, (0.9–1.9 kg m −2 y −1) than at the undrained mire site (0.8 to 1.2 kg m −2 y −1). CH 4 emissions were significantly lower from the drained sites than from the undrained mire (0.0 to 1.6 g m −2 y −1, compared to 10.6 to 12.2 g m −2 y −1), while N 2O emissions were significantly lower from the undrained site than from the drained sites (20 to 30 mg m −2 y −1, compared to 30 to 90 mg m −2 y −1). There were no clear effects of site productivity or tree species on the soil fluxes of any of the gases. The annual net primary production of the forests was modeled. All drained sites were net sinks, while the undrained mire was a net source of greenhouse gases. The estimated net greenhouse gas exchange of the drained sites was correlated with productivity: the most productive site was the largest net sink and the least productive the smallest net sink for greenhouse gases. The results indicate that, to mitigate the increase of atmospheric greenhouse gases, drained forest sites, which have been unsuccessfully drained or rewetted due to subsidence, should be managed in a way that keeps the groundwater level at a steady state.