Ecology, Climate Change and Related News

Conservation Science for a Healthy Planet

Tag Archive: land use

  1. Insectageddon: farming can be more catastrophic than climate breakdown

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    George Monbiot Friday 20 October 2017

    …two other issues have such huge and immediate impacts that they push even this great predicament [of global warming] into third place.One is industrial fishing, which, all over the blue planet, is now causing systemic ecological collapse. The other is the erasure of non-human life from the land by farming.

    And perhaps not only non-human life. According to the UN Food and Agriculture Organisation, at current rates of soil loss, driven largely by poor farming practice, we have just 60 years of harvests left. And this is before the Global Land Outlook report, published in September, found that productivity is already declining on 20% of the world’s cropland.

    The impact on wildlife of changes in farming practice (and the expansion of the farmed area) is so rapid and severe that it is hard to get your head round the scale of what is happening. A study published this week in the journal Plos One reveals that flying insects surveyed on nature reserves in Germany have declined by 76% in 27 years. The most likely cause of this Insectageddon is that the land surrounding those reserves has become hostile to them: the volume of pesticides and the destruction of habitat have turned farmland into a wildlife desert….

  2. Why Hurricane Irma Could Hurt, a Lot: increase in coastal development leaves much in harm’s way

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    By BRAD PLUMER Read full NYTimes article here SEPT. 7, 2017

    ….Central and South Florida have grown at a breathtaking pace since 1990, adding more than 6 million people. Glittering high-rises and condominiums keep sprouting up along Miami Beach and other coastal areas. A lot more valuable property now sits in harm’s way….

    …But half of the expected rise in hurricane costs is the result of expected increases in coastal development. Today, according to the C.B.O., roughly 1.2 million Americans live in coastal areas at risk of “substantial damage” from hurricanes — defined as damage of at least 5 percent of average income. By 2075, that number is forecast to rise to 10 million.

    Population growth can also increase hurricane risks by adding newcomers who are unfamiliar with big storms or by clogging roads during evacuations, experts said.

    ….As of Wednesday, forecasters were still unsure where Irma might make landfall in Florida or how strong it will be when it does. But in almost any conceivable scenario, a hurricane today is likely to do more damage than a comparable storm in the past, if only because of increased development….

  3. Deforestation has double the effect on global warming than previously thought

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    • Even if all fossil fuel emissions are eradicated, if current rates of deforestation in the tropics continue through to 2100 then there will still be a 1.5 degree Celsius increase in global temperature
    • While carbon dioxide emissions from energy use must be the primary target of climate change mitigation efforts, land use and land cover change (LULCC) also represent an important source of climate forcing.
    • Tackling deforestation should be higher on the climate change agenda.

    By

    In the fight against climate change, much of the focus rests on reducing our dependence on fossil fuels and developing alternative energy sources. However, the results of a new study suggest that far more attention should be paid to deforestation and how the land is used subsequently – the effects of which make a bigger contribution to climate change than previously thought.

    The research, conducted by Cornell University and published in the journal Environmental Research Letters,shows just how much this impact has been underestimated. Even if all fossil fuel emissions are eradicated, if current rates of deforestation in the tropics continue through to 2100 then there will still be a 1.5 degree Celsius increase in global temperature….

    Natalie M Mahowald et al. Are the impacts of land use on warming underestimated in climate policy? Environmental Research Letters. August 2017. DOI: 10.1088/1748-9326/aa836d

    Abstract: While carbon dioxide emissions from energy use must be the primary target of climate change mitigation efforts, land use and land cover change (LULCC) also represent an important source of climate forcing. In this study we compute time series of global surface temperature change separately for LULCC and non-LULCC sources (primarily fossil fuel burning), and show that because of the extra warming associated with the co-emission of methane and nitrous oxide with LULCC carbon dioxide emissions, and a co-emission of cooling aerosols with non-LULCC emissions of carbon dioxide, the linear relationship between cumulative carbon dioxide emissions and temperature has a two-fold higher slope for LULCC than for non-LULCC activities. Moreover, projections used in the Intergovernmental Panel on Climate Change (IPCC) for the rate of tropical land conversion in the future are relatively low compared to contemporary observations, suggesting that the future projections of land conversion used in the IPCC may underestimate potential impacts of LULCC. By including a “business as usual” future LULCC scenario for tropical deforestation, we find that even if all non-LULCC emissions are switched off in 2015, it is likely that 1.5°C of warming relative to the preindustrial era will occur by 2100. Thus, policies to reduce LULCC emissions must remain a high priority if we are to achieve the low to medium temperature change targets proposed as a part of the Paris Agreement. Future studies using integrated assessment models and other climate simulations should include more realistic deforestation rates and the integration of policy that would reduce LULCC emissions.

  4. Soil carbon debt from 12,000 years of human land use

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    • global carbon debt due to agriculture of 133 Pg C [133 Gt (billion metric tons of C) or 488 Gt CO2e] for the top 2 m of soil, with the rate of loss increasing dramatically in the past 200 years
    • assuming soil organic carbon (SOM) reaches a new steady state in 20 y (35, 44), this calculation suggests that 8 Pg C to 28 Pg C [up to 28 Gt (billion metric tons of C) or 103 Gt CO2e] or can be recaptured
    • there are identifiable regions which can be targeted for SOC (soil organic carbon) restoration efforts
    • [Note: Hansen et al 2017 calls for 150 Pg C or ~550 Gt CO2e extraction from atmosphere globally with massive greenhouse emissions reductions of 6%/year starting in 2021 to return to 350 PPM CO2 in atmosphere and to secure a safe climate (Holocene) for human civilization by 2100]
      • [Sanderman high end scenario would be 19% of CO2e extraction needed to secure safe climate by 2100 per Hansen above]

    Jonathan Sanderman, Tomislav Hengl and Gregory J. Fiske. Soil carbon debt of 12,000 years of human land use. PNAS September 5, 2017 vol. 114 no. 36 9575-9580

    Abstract: Human appropriation of land for agriculture has greatly altered the terrestrial carbon balance, creating a large but uncertain carbon debt in soils. Estimating the size and spatial distribution of soil organic carbon (SOC) loss due to land use and land cover change has been difficult but is a critical step in understanding whether SOC sequestration can be an effective climate mitigation strategy. In this study, a machine learning-based model was fitted using a global compilation of SOC data and the History Database of the Global Environment (HYDE) land use data in combination with climatic, landform and lithology covariates. Model results compared favorably with a global compilation of paired plot studies. Projection of this model onto a world without agriculture indicated a global carbon debt due to agriculture of 133 Pg C for the top 2 m of soil, with the rate of loss increasing dramatically in the past 200 years. The HYDE classes “grazing” and “cropland” contributed nearly equally to the loss of SOC. There were higher percent SOC losses on cropland but since more than twice as much land is grazed, slightly higher total losses were found from grazing land. Important spatial patterns of SOC loss were found: Hotspots of SOC loss coincided
    with some major cropping regions as well as semiarid grazing regions, while other major agricultural zones showed small losses and even net gains in SOC. This analysis has demonstrated that there are identifiable regions which can be targeted for SOC restoration efforts.

    Implications: This analysis indicates that the majority of the used portions of planet Earth have lost SOC, resulting in a cumulative loss of ∼133 Pg C due to agricultural land use. These SOC losses are on par with estimates of carbon lost from living vegetation primarily due to deforestation (40) and are nearly 100 Pg C higher than earlier estimates of land use and land use change-driven losses of SOC (41). Importantly, as Fig. 1 demonstrates, there are hotspots of SOC loss, associated with extensive cropping regions but also with highly degraded grazing land (SI Appendix, Fig. S9), suggesting that there are identifiable regions which should be targets for SOC restoration efforts.

    The potential to recover lost SOC may be more limited than is often assumed. The amount of SOC that has been lost historically can be thought of as the carbon sink potential of the soil (42). Our analysis has found that this sink potential is ∼133 Pg C (SI Appendix, Table S3). A widely repeated figure is that, with adoption of best management practices, two thirds of lost SOC can be recovered (42). If the two-thirds figure is accurate, then SOC sequestration has the potential to offset 88 Pg C (322 Pg CO2) of emissions. However, bottom-up estimates of the maximum biophysical potential for carbon sequestration on cropping and grazing land range from 0.4 Pg Cy−1 to 1.4 Pg Cy−1 (20, 43). Assuming SOC reaches a new steady state in 20 y (35, 44), this calculation suggests that 8 Pg C to 28 Pg C can be recaptured. Even the range of 8 Pg C to 28 Pg C is likely overly ambitious given the various social, economic, and technical constraints on universal adoption of best management practices (45), suggesting that the amount of the carbon sink that can be filled is on the order of, at best, 10 to 30% globally and may well be <10%.

    Conclusions: Our data-driven statistical analysis confirms that agricultural land use is a significant driver of SOC levels. ….This analysis also demonstrated that not all land use is associated with large losses in SOC, particularly in regions with naturally infertile soils. These results provide a basis for national and international policies to target SOC restoration efforts but also suggest that more effort needs to be put into collecting, integrating, and using legacy soil profile data, especially historic data 50+ y old, so that even more reliable models of SOC dynamics can be produced.

     

  5. Urban land transformation and electricity production impact river ecosystems on much larger scale

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    • The results indicate that urban land transformation and electricity production together affect seven percent of U.S. streams, which influence habitats for more than 60 percent of all North American freshwater fish, mussel, and crayfish species.

    August 23, 20 DOE/Oak Ridge National Laboratory  Read full ScienceDaily article here

    New mapping methods can help urban planners minimize the environmental impacts of cities’ water and energy demands on surrounding stream ecologies.

    Using streamflow data from the U.S. Geological Survey, the researchers mapped changes to natural hydrology to assess how infrastructure development and competition over water resources affects the environment at a national scale.

    The results indicate that urban land transformation and electricity production together affect seven percent of U.S. streams, which influence habitats for more than 60 percent of all North American freshwater fish, mussel, and crayfish species.

    …In the five cities, urban land transformations negatively affected more stream length overall than any other factor considered, including electricity production. The introduction of roads, buildings, and other impervious surfaces alters the natural water cycle, displaces water supplies for downstream communities and can threaten the loss of rich and diverse aquatic species.

    …”Both the source and solution to global environmental challenges may lie in the hands of cities. Unfortunately, the changes we discuss are highly transformative, not cheap,” McManamay said. “Our goal here is to give cities a way to look at the big picture, so to speak, and to generate metrics that will help them move toward more environmentally sound policies as they continue to develop.

    Ryan A. McManamay et al. US cities can manage national hydrology and biodiversity using local infrastructure policy. Proceedings of the National Academy of Sciences, 2017; 201706201 DOI: 10.1073/pnas.1706201114

  6. Climate change and habitat conversion combine to homogenize nature- report on Costa Rican bird studies

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    • Land use change and drought favor the same species and threaten the same species so we may be losing biodiversity faster than we previously thought when we were studying these separately
    • Key strategies include protecting areas of wetter forests that expected to stay wet in the future; targetting conservation on wet-forest species that are particularly sensitive to habitat conversion and climate change; and incentivizing  landowners in wet regions to create or maintain patches of forests near or within their farms to better balance food production and biodiversity.

    August 18, 2017 University of California – Davis  Read full ScienceDaily article here

    Climate change and habitat conversion to agriculture are working together to homogenize nature, indicates a study in the journal Global Change Biology led by the University of California, Davis.

    In other words, the more things change, the more they are the same.

    While the individual impacts of climate change and habitat conversion on wildlife are well-recognized, little is known about how species respond to both stressors at once.

    In northwest Costa Rica, the study’s authors surveyed birds and plants at 120 sites that included rainforests, dry forests and farmland to determine how habitat conversion and climate-change-induced droughts affect tropical wildlife. They found that different bird species thrive in drier versus wetter areas of forests. In farmlands however, birds associated with dry sites were found everywhere, even in the wettest sites.


    Green-headed tanager (Tangara seledon). Credit: © Wilfred / Fotolia
    Across Central and South America, we are seeing large areas being converted from native forest to agriculture, and droughts are becoming more frequent,” said lead author Daniel Karp, an assistant professor in the UC Davis Department of Wildlife, Fish and Conservation Biology. “Both of these global pressures are favoring the same species and threatening the same species This means we may be losing biodiversity faster than we previously thought when we were studying climate change and habitat conversion individually.”
    most vulnerable birds at the study sites were those in the wet forests, which include tropical birds like tanagers, manakins, and woodcreepers. He noted that birds in the agricultural sites — such as blackbirds, doves, and sparrows — were more similar to those found in the dry forest, where there is less of a tree canopy and more grass cover….
    Daniel S. Karp, Luke O. Frishkoff, Alejandra Echeverri, Jim Zook, Pedro Juárez, Kai M. A. Chan. Agriculture erases climate-driven β-diversity in Neotropical bird communities. Global Change Biology, 2017; DOI: 10.1111/gcb.13821
  7. Positive Disruption: LIMITING GLOBAL TEMPERATURE RISE TO WELL BELOW 2 Cº; focus on energy, ag and land use

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    Positive Disruption: LIMITING GLOBAL TEMPERATURE RISE TO WELL BELOW 2 Cº

    BY MARSHALL ABRAMCZYK, MARTHA CAMPBELL, AMAN CHITKARA, MIA DIAWARA, AILEEN LERCH, AND JAMES NEWCOMB

    ROCKYMOUNTAIN INSTITUTE

    From the intro:

    Today, many experts doubt that energy systems can decarbonize fast enough to prevent this scenario. But this belief is both dangerous and wrong—dangerous because despair undercuts the will to act; and wrong because this view does not take into account events already taking place that indicate a possible pathway to a rapid energy transition.

    This paper describes scenarios for transitions in energy, agriculture, and land use that together are sufficient to limit global average temperature increase to 1.5–2 C°. Unlike conventional modeling approaches, these scenarios entail patterns of disruption, innovation, and nonlinear change, harnessed at global scale, that mirror the episodic and disruptive ways that individual industries and the economy as a whole have changed historically. The great transitions in the economy, such as the Industrial Revolution, have been driven by such self-reinforcing patterns of change. Their signs are all around us….

  8. Deforestation and climate change amplifying droughts in the Amazon

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    • Study finds human-driven changes in climate and land-use in Amazon’s 3rd “1-in-100 year” drought since 2005
    • man-made warming is accelerating the movement of water through the ecosystem, which can cause drought even if precipitation does not decrease. Warming also causes changes in the large-scale patterns of air motion (atmospheric circulation) that reduces rainfall in this region

    By John Abraham 3 August 2017 see full article in theGuardianUK

    If you are like me, you picture the Amazon region as an ever lush, wet, tropical region filled with numerous plant and animal species. Who would imagine the Amazon experiencing drought?……[there was a] very interesting paper recently published in Scientific Reports, entitled Unprecedented drought over tropical South America in 2016: significantly under-predicted by tropical SST[sea surface temperature]. So, what did this paper show?

    …the Amazon region does encounter periodic droughts. There was one in 2005, another in 2010, both of which were 100-year events, and the most recent one in 2015-2016.

    [The authors] quantified the precipitation deficits and water storage on the ground. They also used two different vegetation measures of drought. The results showed that the most recent drought was unprecedented in severity. ……

    …the authors found that the relationship between water temperatures and drought worked well for prior droughts (the 2005 and 2010 droughts as well as 1983 and 1998 droughts, also El Niño years) but fell apart in 2015-2016.

    …the predicted 2015-2016 drought should not have been nearly as severe or as large as it was. The paper also reports that the 2015-2016 drought clearly exceeded that of the 100-year events in 2005 and 2010. So, in approximately one decade, this zone has had three 100-year events. Quite astonishing…

    why was SST unable to explain the 2015-2016 drought, like it had for past events? Part of it has to do with land-use changes. That is, human changes to the land surface such as deforestation. Another part is related to warming from greenhouse gases…land-use changes can affect drought. As farmers deforest, for instance, they convert woodlands and forests into agricultural land. This changes not only the darkness (reflectivity) of the land, but it also impacts the transfer of water to and from the atmosphere (evapotranspiration). 

    how [does] warming affects droughts… As air temperatures increase, air is able to evaporate water more rapidly and dry out surfaces. At the same time, air can contain more water vapor so that when rain does occur, it is more often in heavy downpours. These two changes underlie what is referred to as an accelerated hydrological cycle. Simply put, man-made warming is accelerating the movement of water through the ecosystem, which can cause drought even if precipitation does not decrease. Warming also causes changes in the large-scale patterns of air motion (atmospheric circulation) that reduces rainfall in this region.

    Dr. Wang, who told me:

    Since oceanic forcing could not fully explain the severity of the latest drought, one will have to account for the roles of greenhouse gas warming, land use land cover changes, and/or dynamic ecosystem feedback in order to advance the understanding, attribution and prediction of extreme droughts in this region. The frequent recurrence of severe droughts in the recent decade may be a precursor of what the future might have in store for this regional climate and ecosystem.

    droughts in this part of the world create an increased risk for desertification and fire occurrence and hurt the region’s ecosystem, harm trees, and accelerate the release of carbon dioxide…

    A Erfanian et al. Unprecedented drought over tropical South America in 2016: significantly under-predicted by tropical SST. Sci Rep. 2017; 7: 5811. Published online 2017 Jul 19. doi:  10.1038/s41598-017-05373-2

     

  9. Increasing climate and land use change overlap in arid lands– potential to affect 36% of world’s population

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    • Increasing aridity and land-use overlap have potential to cause social and economic conflict in dryland areas
    • scenario framework used to estimate how climate and land uses influence ecosystems and landscapes

    May 23, 2017 Northern Arizona University  see here for ScienceDaily article

    Drylands are of environmental concern because broad-scale changes in these systems have the potential to affect 36 percent of the world’s human population, suggests new research.

    Climate change combined with overlapping high-intensity land uses are likely to create conditions detrimental to the recreation economy, wildlife habitat, water availability and other resources in hyper-arid landscapes, or drylands, in the future, according to a paper published recently in Ecosphere. Drylands are of concern because broad-scale changes in these systems have the potential to affect 36 percent of the world’s human population…..

    …The research team examined the combined effects of climate change and human land use — agriculture, recreation, energy development, mining and population growth — on a range of ecosystem functions and landscape attributes. “Our approach offers a relatively simple method for scenario development that could be applied to a wide range of change agents, ecosystem services and regions,” said lead author Stella Copeland, NAU Merriam-Powell Center post-doctoral scholar. “Tools such as these can be used to inform natural resource planning and management efforts in the United States and elsewhere.”

    The study examined four scenarios to estimate how climate change and overlapping land uses may influence ecosystem functions and landscape attributes. Although outcomes varied by scenario and characteristic, the recreation economy had the highest impacts for all scenarios; followed by vegetation and wildlife habitat and cultural and spiritual values; water availability; soil productivity; and cropland productivity….

    Stella M. Copeland, John B. Bradford, Michael C. Duniway, Rudy M. Schuster. Potential impacts of overlapping land-use and climate in a sensitive dryland: a case study of the Colorado Plateau, USA. Ecosphere, 2017; 8 (5): e01823 DOI: 10.1002/ecs2.1823

    Abstract: The combination of co-occurring climate change and increasing land-use is likely to affect future environmental and socioeconomic conditions in drylands; these hyper-arid to sub-humid landscapes are limited by water resources and prone to land degradation. We characterized the potential for geographic overlap among land-use practices and between land-use and climate change on the Colorado Plateau—a dryland region experiencing rapid changes in land-use and facing aridification. We characterized spatial patterns and temporal trends in aridification, land-use, and recreation at the county and 10-km2 grid scales. Increasing trends and overlapping areas of high intensity for use, including oil and gas development and recreation, and climate drying, suggest areas with high potential to experience detrimental effects to the recreation economy, water availability, vegetation and wildlife habitat, and spiritual and cultural resources. Patterns of overlap in high-intensity land-use and climate drying differ from the past, indicating the potential for novel impacts and suggesting that land managers and planners may require new strategies to adapt to changing conditions. This analytical framework for assessing the potential impacts of overlapping land-use and climate change could be applied with other drivers of change or to other regions to create scenarios at various spatial scales in support of natural resource planning efforts.

  10. Diet and global climate change

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    Diet and global climate change

    Posted: 08 Mar 2017 12:44 PM PST

    Eating healthier food could reduce greenhouse gas emissions, suggests a new study. As it turns out, some relatively small diet tweaks could add up to significant inroads in addressing climate change….To create healthier model diets, the researchers altered the standard 2,000-calorie-a-day U.S. diet, changing the sources of about half of those calories. The different model diets progressively reduced the amount of red and processed meats, with the most stringent diet eliminating them completely. Fruit and vegetable intake was doubled, and peas and beans increased to replace the meat protein removed. Refined grains were partially replaced with whole grains. Added sugar, which Cleveland noted is a known health risk, was not reduced. Neither was dairy, eggs, fish or non-red meat.

    “This means our estimates are probably very conservative, both in terms of health and climate change implications,” Cleveland said. “Just changing half of the diet and including only some of the diseases associated with diets, we found a huge effect. “Food has a tremendous impact on the environment,” he added. “That means that there is enormous potential for our food choices to have positive effects on our environment as well on our health and our health care costs.”…. The food system contributes about 30 percent of total U.S. greenhouse gas emissions, with the largest proportion coming from animal-based food. In addition, the poor quality of the standard U.S. diet — including high levels of red and processed meat and low levels of fruits and vegetables — is a major factor in a number of preventable diseases. The U.S. spends $3 trillion on health care every year — 18 percent of the gross domestic product — much of it allocated to diseases associated with poor diets…

    Elinor Hallström, Quentin Gee, Peter Scarborough, David A. Cleveland. A healthier US diet could reduce greenhouse gas emissions from both the food and health care systems. Climatic Change, 2017; DOI: 10.1007/s10584-017-1912-5