Most Earth system models agree that land will continue to store carbon due to the physiological effects of rising CO
concentration and climatic changes favoring plant growth in temperature-limited ...regions. But they largely disagree on the amount of carbon uptake. The historical CO
increase has resulted in enhanced photosynthetic carbon fixation (Gross Primary Production, GPP), as can be evidenced from atmospheric CO
concentration and satellite leaf area index measurements. Here, we use leaf area sensitivity to ambient CO
from the past 36 years of satellite measurements to obtain an Emergent Constraint (EC) estimate of GPP enhancement in the northern high latitudes at two-times the pre-industrial CO
concentration (3.4 ± 0.2 Pg C yr
). We derive three independent comparable estimates from CO
measurements and atmospheric inversions. Our EC estimate is 60% larger than the conventionally used multi-model average (44% higher at the global scale). This suggests that most models largely underestimate photosynthetic carbon fixation and therefore likely overestimate future atmospheric CO
abundance and ensuing climate change, though not proportionately.
Northern peatlands have been a persistent natural carbon
sink since the Last Glacial Maximum. The continued growth and expansion of
these carbon-rich ecosystems could offset a large portion of ...anthropogenic
carbon emissions before the end of the present interglacial period. Here we
used an impeded drainage model and gridded data on the depth to bedrock and
the fraction of histosol-type soils to evaluate the limits to the growth
of northern peatland carbon stocks. Our results show that the potential
carbon stock in northern peatlands could reach a total of 875±125 Pg C
before the end of the present interglacial, which could, as a result, remove
330±200 Pg C of carbon from the atmosphere. We argue that northern
peatlands, together with the oceans, will potentially play an important role
in reducing the atmospheric carbon dioxide concentration over the next 5000 years.
The outputs of the Earth system models (ESM) provided by the sixth phase of the Coupled Models Intercomparison Project (CMIP6) reflect the current state of scientific knowledge on climate change and ...make it possible not only to draw conclusions about the adverse consequences of climate change but also to evaluate the certainty of such conclusions. This study is aimed to check if the CMIP6 model projections of mean annual air temperature (MAAT) allow us to make a robust conclusion about the possibility of adverse consequences of climate change in the northern part of Western Siberia. With this purpose in mind, we construct the weighted multi-model ensemble and find that it reproduces with 30% accuracy the observation-based MAAT anomalies over this region. Then, we use this weighted multi-model ensemble to predict MAAT changes and find that under the SSP5-8.5 scenario, MAAT will exceed 0 °C almost everywhere in the North of Western Siberia by the end of this century. Since permafrost occurs sporadically over the territories where MAAT is above − 2 °C, this result suggests that permafrost will not persist in Western Siberia under the SSP5-8.5 scenario.
We suggests that temperature response of plant productivity can be modeled by the Arrhenius function modified to describe the effect of temperature on enzyme activity:
G
A(
T)
=
2
f(
T)/(1
+
f
2(
...T)), where
f(
T)
=
exp(
E
a/
RT
opt
−
E
a/
RT),
R the universal gas constant,
E
a the activation energy and
T
opt is the optimal temperature. In common with other functions used for modeling the temperature response of plant productivity, the curve of function
G is almost symmetrical and bell-shaped. The special convenience of
G
A is that it relates the width of the “bell” to thermodynamic concepts, such as activation energy of chemical reactions converting carbon dioxide and water to carbohydrates.
The observed growth of a particular forest stand can be described by many models and explained by some of them. The forest growth models are also successfully applied for extrapolating the growth ...curve. However, the known models of forest growth are not “one-point” models. They are not designed to predict the future growth of a forest stand from its current state: the model parameters either are not directly measurable or cannot be measured with relevant accuracy. This article is an attempt to use Jørgensen–Svirezhev theory as a new clue to the choice of variables that determines forest growth. The postulates of this theory combined with the pipe theory of tree growth lead to conclusion that biomass of a stand should be proportional to the four-fifths power of its age. Empirical validation, however, disclosed that calendar age is rather approximate measure of ecosystem ontogeny. Delayed development or intensive thinning of a forest stand at the early stages leads to rejuvenation bias. Thus derived 4/5-law model approximates well-known Chapman–Richards model in the neighborhood of the inflection point, and is applicable to middle-aged forest stands.
The International Year of Forests, declared by the UN, is a good occasion to discuss approaches to reducing forest degradation in developing countries. The articles collected in Thematic Forest ...Series form a diversity of ideas which is essential for setting the levels below which the countries' reduced emissions could be measured and credited. This editorial calls attention to the use of Land-Use/Land-Cover Change models.
The dominant model of journal evaluation emerged at the time when there were no open-access journals, and nobody has assessed yet whether this model is able to cope with this modern reality. This ...commentary attempts to fill the gaps in the common understanding of the role that 'impact factor' should play in evaluation of open-access journals.
Understanding the relationship between the age of a forest stand and its biomass is essential for managing the forest component of the global carbon cycle. Since biomass increases with stand age, ...postponing harvesting to the age of biological maturity may result in the formation of a large carbon sink. This article quantifies the carbon sequestration capacity of forests by suggesting a default rule to link carbon stock and stand age.
The age dependence of forest biomass is shown to be a power-law monomial where the power of age is theoretically estimated to be 4/5. This theoretical estimate is close to the known empirical estimate; therefore, it provides a scientific basis for a quick and transparent assessment of the benefits of postponing the harvest, suggesting that the annual magnitude of the sink induced by delayed harvest lies in the range of 1-2% of the baseline carbon stock.
The results of this study imply that forest age could be used as an easily understood and scientifically sound measure of the progress in complying with national targets on the protection and enhancement of forest carbon sinks.
Background
The biosphere models of terrestrial productivity are essential for projecting climate change and assessing mitigation and adaptation options. Many of them have been developed in connection ...to the International Geosphere-Biosphere Program (IGBP) that backs the work of the Intergovernmental Panel on Climate Change (IPCC). In the end of 1990s, IGBP sponsored release of a data set summarizing the model outputs and setting certain norms for estimates of terrestrial productivity. Since a number of new models and new versions of old models were developed during the past decade, these normative data require updating.
Results
Here, we provide the series of updates that reflects evolution of biosphere models and demonstrates evolutional stability of the global and regional estimates of terrestrial productivity. Most of them fit well the long-living Miami model. At the same time we call attention to the emerging alternative: the global potential for net primary production of biomass may be as high as 70 PgC y
-1
, the productivity of larch forest zone may be comparable to the productivity of taiga zone, and the productivity of rain-green forest zone may be comparable to the productivity of tropical rainforest zone.
Conclusion
The departure from Miami model's worldview mentioned above cannot be simply ignored. It requires thorough examination using modern observational tools and techniques for model-data fusion. Stability of normative knowledge is not its ultimate goal – the norms for estimates of terrestrial productivity must be evidence-based.
First scientific journals were simply a way of informing colleagues about new research findings. In due course, they started filtering out unreasonable claims, and introduced a peer-review system. ...The purpose of peer reviewing changed with time. Since the middle of the past century, commercial publishers have owned a large number of scientific journals and as a result, the marketable value of a submitted manuscript has become an increasingly important factor in publishing decisions. Recently some publishers have developed business schemes which may stop this tendency. In the case of an open-access publication, the marketable value of a manuscript is not the primary consideration, since access to the research is not being sold. This innovation challenges scientists to re-consider the purpose of peer review. This editorial indicates some of the commonly used criteria for publication that consequently should receive less or little emphasis under the open-access model.
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