Potential and Actual impacts of deforestation and afforestation on land surface temperature

Forests are undergoing significant changes throughout the globe. These changes can modify water, energy, and carbon balance of the land surface, which can ultimately affect climate. We utilize satellite data to quantify the potential and actual impacts of forest change on land surface temperature (LST) from 2003 to 2013. The potential effect of forest change on temperature is calculated by the LST difference between forest and nearby nonforest land, whereas the actual impact on temperature is quantified by the LST trend difference between deforested (afforested) and nearby unchanged forest (nonforest land) over several years. The good agreement found between potential and actual impacts both at annual and seasonal levels indicates that forest change can have detectable impacts on surface temperature trends. That impact, however, is different for maximum and minimum temperatures. Overall, deforestation caused a significant warming up to 0.28 K/decade on average temperature trends in tropical regions, a cooling up to -0.55 K/decade in boreal regions, a weak impact in the northern temperate regions, and strong warming (up to 0.32 K/decade) in the southern temperate regions. Afforestation induced an opposite impact on temperature trends. The magnitude of the estimated temperature impacts depends on both the threshold and the data set (Moderate Resolution Imaging Spectroradiometer and Landsat) by which forest cover change is defined. Such a latitudinal pattern in temperature impact is mainly caused by the competing effects of albedo and evapotranspiration on temperature. The methodology developed here can be used to evaluate the temperature change induced by forest cover change around the globe.Maryland Council on the Environment [1357928]; National Natural Science Foundation of China [41371096, 41130534]; China Scholar Council fellowship [201306010169]; National Socio-Environmental Synthesis Center-NSF [DBI-1052875]SCI(E)[email protected]

The failure of Integrated Assessment Models as a response to ‘climate emergency’ and ecological breakdown: the Emperor has no clothes

In this brief commentary we provide some parallel points to complement Steve Keen’s paper in the recent Globalization’s special forum on ‘Economics and Climate Emergency’. Keen’s critique of climate and economy Integrated Assessment Models (IAMs) is wide-ranging, but there is still scope to bring to the fore the general issues that help to make sense of the critique. Accordingly, we set out six key inadequacies of IAMs and argue towards the need for a different approach that is more realistic regarding the limits to growth

Modeling sustainability : Population, inequality, consumption, and bidirectional coupling of the Earth and human systems

Over the last two centuries, the impact of the Human System has grown dramatically, becoming strongly dominant within the Earth System in many different ways. Consumption, inequality, and population have increased extremely fast, especially since about 1950, threatening to overwhelm the many critical functions and ecosystems of the Earth System. Changes in the Earth System, in turn, have important feedback effects on the Human System, with costly and potentially serious consequences. However, current models do not incorporate these critical feedbacks. We argue that in order to understand the dynamics of either system, Earth SystemModels must be coupled with Human SystemModels through bidirectional couplings representing the positive, negative, and delayed feedbacks that exist in the real systems. In particular, key Human System variables, such as demographics, inequality, economic growth, and migration, are not coupled with the Earth System but are instead driven by exogenous estimates, such as United Nations population projections.This makes current models likely to miss important feedbacks in the real Earth-Human system, especially those that may result in unexpected or counterintuitive outcomes, and thus requiring different policy interventions from current models.The importance and imminence of sustainability challenges, the dominant role of the Human System in the Earth System, and the essential roles the Earth System plays for the Human System, all call for collaboration of natural scientists, social scientists, and engineers in multidisciplinary research and modeling to develop coupled Earth-Human system models for devising effective science-based policies and measures to benefit current and future generations

Emergence and Evolution of Cooperation Under Resource Pressure

We study the influence that resource availability has on cooperation in the context of hunter-gatherer societies. This paper proposes a model based on archaeological and ethnographic research on resource stress episodes, which exposes three different cooperative regimes according to the relationship between resource availability in the environment and population size. The most interesting regime represents moderate survival stress in which individuals coordinate in an evolutionary way to increase the probabilities of survival and reduce the risk of failing to meet the minimum needs for survival. Populations self-organise in an indirect reciprocity system in which the norm that emerges is to share the part of the resource that is not strictly necessary for survival, thereby collectively lowering the chances of starving. Our findings shed further light on the emergence and evolution of cooperation in hunter-gatherer societies.Spanish Ministry of Science and Innovation Project CSD2010-00034 (SimulPast CONSOLIDER-INGENIO 2010) and HAR2009-06996; from the Argentine National Scientific and Technical Research Council (CONICET): Project PIP-0706; from the Wenner-Gren Foundation for Anthropological Research: Project GR7846; and from the project H2020 FET OPEN RIA IBSEN/66272

An ecological theory of changing human population dynamics

International audienceThe dependence of humans on nature has come into focus as the human popula‐tion continues to grow, resources diminish and production technology stagnates – threatening human well‐being on a global scale. Numerous previous models de‐scribe human population dynamics, in relation to a multitude of different factors. However, there are no consistent driving factors of human demography through history, which makes predicting future changes more challenging. Here, we review the literature on human population growth from empirical data and previous models, which allows us to highlight key trends in demography and land cover changes.. We then establish an ecologically driven theory of demographic change that uses resource accessibility as a proxy for socio‐economic factors. The theory combines multiple concepts to represent 12 millennia of past population dynamics through simple human–nature relationships.. Furthermore, the model allows us to compare different scenarios related to tech‐nological progress and land cover change, for which we find that the peak human population is highly dependent on whether technological developments continue at an exponential growth rate, or if and when there is a saturation point. Likewise, agriculture is shown to be helpful for growing the population, but nature is ulti‐mately needed to maintain the human population