Loss of Amazon rainforest resilience since the early 2000s

2021 ◽  
Author(s):  
Chris Boulton ◽  
Timothy Lenton ◽  
Niklas Boers
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Land Use Change ◽  
Carbon Cycle ◽  
Optical Depth ◽  
Tipping Point ◽  
Amazon Rainforest ◽  
Statistical Characteristics ◽  
Annual Rainfall ◽  
Action Science

<p>The resilience of the Amazon rainforest to both climate and land use change is of critical importance for biodiversity, regional climate, and the global carbon cycle. Some models project future climate-driven Amazon rainforest dieback (Cox et al. 2000) and others argue that land-use and climate change have already pushed the Amazon close to a tipping point of rainforest dieback and transition to savanna (Lovejoy & Nobre 2018, 2019). But competing effects between rising temperatures, changing precipitation patterns, and CO<sub>2</sub> fertilization, make the future of the Amazon uncertain. An alternative approach is to look for direct observational signals of changing rainforest resilience from timeseries analysis - here of remotely-sensed vegetation optical depth (VOD) (Moesinger et al. 2018), which correlates well with changes in broadleaf tree fraction coverage. Our results indicate that the Amazon rainforest has been losing resilience since the early 2000s, with statistical characteristics evolving consistently with critical slowing down on the way to a bifurcation-induced transition. Specifically, changes in lag-1 autocorrelation of VOD show that resilience is lost faster in regions with less mean annual rainfall. Parts of the rainforest that are closer to human activity are also losing resilience more quickly. Given observed increases in dry-season length, and expanding areas of land use change, the loss of Amazon rainforest resilience is likely to continue. Our results provide direct empirical evidence that the Amazon rainforest is losing stability, risking a sudden dieback that would have profound implications for biodiversity, carbon storage and climate change.</p><p> </p><p>References</p><p>Cox, P. M., Betts, R. A., Jones, C. D., Spall, S. A. & Totterdell, I. J. Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model. Nature 408, 184-187, doi:10.1038/35041539 (2000).</p><p>Lovejoy, T. E. & Nobre, C. Amazon Tipping Point. Science Advances 4, eaat2340, doi:10.1126/sciadv.aat2340 (2018).</p><p>Lovejoy, T. E. & Nobre, C. Amazon tipping point: Last chance for action. Science Advances 5, eaba2949, doi:10.1126/sciadv.aba2949 (2019).</p><p>Moesinger, L. et al. The global long-term microwave Vegetation Optical Depth Climate Archive (VODCA). Earth System Science Data 12, 177-196, doi:10.5194/essd-12-177-2020 (2020).</p><p> </p><p>This work was funded by the Volkswagen foundation and the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 820970.</p>

scholarly journals Global soil organic carbon removal by water erosion under climate change and land use change during 1850–2005 AD

2018 ◽  
Author(s):  
Victoria Naipal ◽  
Philippe Ciais ◽  
Yilong Wang ◽  
Ronny Lauerwald ◽  
Bertrand Guenet ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Soil Erosion ◽  
Organic Carbon ◽  
Land Use Change ◽  
Soil Organic Carbon ◽  
Climate Variability ◽  
Carbon Cycle ◽  
Atmospheric Co2 ◽  
Terrestrial Carbon

Abstract. The onset and expansion of agriculture has accelerated soil erosion by rainfall and runoff substantially, mobilizing vast quantities of soil organic carbon (SOC) globally. Studies show that at timescales of decennia to millennia this mobilized SOC can significantly alter previously estimated carbon emissions from land use change (LUC). However, a full understanding of the impact of erosion on land-atmosphere carbon exchange is still missing. The aim of our study is to better constrain the terrestrial carbon fluxes by developing methods compatible with Earth System Models (ESMs) in order to explicitly represent the links between soil erosion by rainfall and runoff and carbon dynamics. For this we use an emulator that represents the carbon cycle of a land surface model, in combination with the Revised Universal Soil Loss Equation model. We applied this modeling framework at the global scale to evaluate the effects of potential soil erosion (soil removal only) in the presence of other perturbations of the carbon cycle: elevated atmospheric CO2, climate variability, and LUC. We found that over the period 1850–2005 AD acceleration of soil erosion leads to a total potential SOC removal flux of 100 Pg C of which 80 % occurs on agricultural, pasture and natural grass lands. Including soil erosion in the SOC-dynamics scheme results in a doubling of the cumulative loss of SOC over 1850–2005 due to the combined effects of climate variability, increasing atmospheric CO2 and LUC. This additional erosional loss decreases the cumulative global carbon sink on land by 5 Pg for this specific period, with the largest effects found for the tropics, where deforestation and agricultural expansion increased soil erosion rates significantly. We also show that the potential effects of soil erosion on the global SOC stocks cannot be ignored when compared to the effects of climate change or land use change on the carbon cycle. We conclude that it is necessary to include soil erosion in assessments of LUC and evaluations of the terrestrial carbon cycle.

scholarly journals Pronounced loss of Amazon rainforest resilience since the early 2000s

2021 ◽  
Author(s):  
Chris Boulton ◽  
Timothy Lenton ◽  
Niklas Boers
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Land Use Change ◽  
Regional Climate ◽  
Global Scale ◽  
Dry Season ◽  
Amazon Rainforest ◽  
Critical Threshold ◽  
Broadleaf Tree ◽  
Tree Coverage

Abstract The resilience of the Amazon rainforest to climate and land-use change is of critical importance for biodiversity, regional climate, and the global carbon cycle. Some models project future climate-driven Amazon rainforest dieback and transition to savanna1. Deforestation and climate change, via increasing dry-season length2,3 and drought frequency – with three 1-in-100-year droughts since 20054-6 – may already have pushed the Amazon close to a critical threshold of rainforest dieback7,8. However, others argue that CO2 fertilization should make the forest more resilient9,10. Here we quantify Amazon resilience by applying established indicators11 to remotely-sensed vegetation data with focus on vegetation optical depth (1991-2016), which correlates well with broadleaf tree coverage. We find that the Amazon rainforest has been losing resilience since 2003, consistent with the approach to a critical transition. Resilience is being lost faster in regions with less rainfall, and in parts of the rainforest that are closer to human activity. Given observed increases in dry-season length2,3 and drought frequency4-6, and expanding areas of land use change, loss of resilience is likely to continue. We provide direct empirical evidence that the Amazon rainforest is losing stability, risking dieback with profound implications for biodiversity, carbon storage and climate change at a global scale.

scholarly journals Dynamics of soil organic carbon in the steppes of Russia and Kazakhstan under past and future climate and land use

2021 ◽  
Vol 21 (3) ◽  
Author(s):  
Susanne Rolinski ◽  
Alexander V. Prishchepov ◽  
Georg Guggenberger ◽  
Norbert Bischoff ◽  
Irina Kurganova ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Organic Carbon ◽  
Land Use Change ◽  
Soil Organic Carbon ◽  
Arable Land ◽  
Future Climate ◽  
Future Climate Change ◽  
Climate Scenarios ◽  
The Impact

AbstractChanges in land use and climate are the main drivers of change in soil organic matter contents. We investigated the impact of the largest policy-induced land conversion to arable land, the Virgin Lands Campaign (VLC), from 1954 to 1963, of the massive cropland abandonment after 1990 and of climate change on soil organic carbon (SOC) stocks in steppes of Russia and Kazakhstan. We simulated carbon budgets from the pre-VLC period (1900) until 2100 using a dynamic vegetation model to assess the impacts of observed land-use change as well as future climate and land-use change scenarios. The simulations suggest for the entire VLC region (266 million hectares) that the historic cropland expansion resulted in emissions of 1.6⋅ 1015 g (= 1.6 Pg) carbon between 1950 and 1965 compared to 0.6 Pg in a scenario without the expansion. From 1990 to 2100, climate change alone is projected to cause emissions of about 1.8 (± 1.1) Pg carbon. Hypothetical recultivation of the cropland that has been abandoned after the fall of the Soviet Union until 2050 may cause emissions of 3.5 (± 0.9) Pg carbon until 2100, whereas the abandonment of all cropland until 2050 would lead to sequestration of 1.8 (± 1.2) Pg carbon. For the climate scenarios based on SRES (Special Report on Emission Scenarios) emission pathways, SOC declined only moderately for constant land use but substantially with further cropland expansion. The variation of SOC in response to the climate scenarios was smaller than that in response to the land-use scenarios. This suggests that the effects of land-use change on SOC dynamics may become as relevant as those of future climate change in the Eurasian steppes.

Climate and land use change impacts on water resources in Sardinia (Italy)

2021 ◽  
Author(s):  
Dario Ruggiu ◽  
Salvatore Urru ◽  
Roberto Deidda ◽  
Francesco Viola
Keyword(s):  
Land Use ◽  
Water Resources ◽  
Land Use Change ◽  
Hydrological Cycle ◽  
Potential Evapotranspiration ◽  
Regional Scale ◽  
Annual Runoff ◽  
Annual Rainfall ◽  
Land Use Scenarios ◽  
Near Future

<p>The assessment of climate change and land use modifications effects on hydrological cycle is challenging. We propose an approach based on Budyko theory to investigate the relative importance of natural and anthropogenic drivers on water resources availability. As an example of application, the proposed approach is implemented in the island of Sardinia (Italy), which is affected by important processes of both climate and land use modifications. In details, the proposed methodology assumes the Fu’s equation to describe the mechanisms of water partitioning at regional scale and uses the probability distributions of annual runoff (Q) in a closed form. The latter is parametrized by considering simple long-term climatic info (namely first orders statistics of annual rainfall and potential evapotranspiration) and land use properties of basins.</p><p>In order to investigate the possible near future water availability of Sardinia, several climate and land use scenarios have been considered, referring to 2006-2050 and 2051-2100 periods. Climate scenarios have been generated considering fourteen bias corrected outputs of climatic models from EUROCORDEX’s project (RCP 8.5), while three land use scenarios have been created following the last century tendencies.</p><p>Results show that the distribution of annual runoff in Sardinia could be significantly affected by both climate and land use change. The near future distribution of Q generally displayed a decrease in mean and variance compared to the baseline.   </p><p>The reduction of  Q is more critical moving from 2006-2050 to 2051-2100 period, according with climatic trends, namely due to the reduction of annual rainfall and the increase of potential evapotranspiration. The effect of LU change on Q distribution is weaker than the climatic one, but not negligible.</p>

scholarly journals Governing the global commons: an ethical-legal framework

2017 ◽  
Vol 13 (1) ◽  
Author(s):  
Prue Taylor
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Land Use Change ◽  
Ocean Acidification ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Legal Framework ◽  
State System ◽  
Global Commons ◽  
Global Challenges

Governance of the Earth’s global ecological commons creates unprecedented challenges for humanity. Our traditional Westphalian state system was not designed to respond to these global challenges and thus far it has failed to transform. Climate change is the current headline issue; 30 years on and we still swing between hope and despair about our collective ability to radically reduce greenhouse gas emissions. Related issues are beginning to vie for our response: ocean acidification, mass species extinction, land use change and freshwater scarcity. 

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