The financial damage due to extreme weather events has been increasing since the 1940s, and evidence suggests that societal shifts are the predominate cause of this upward trend. For instance, increasing populations around hurricane-prone regions account for enormous increases in damages over the last several decades, and the continuation of these and other similar demographic trends is likely to bring about ever rising financial losses regardless of the added impact of climate change. As this article points out, identifying and understanding this societal vulnerability has great importance for understanding the nation's economy, in guiding governmental policies, and for planning for future mitigative activities including ways for society to adapt to the added impacts of a changing climate.

Spanning Boundaries: Aspen Global Change Institute Strategic Plan, 2020-2025 outlines how AGCI will build on the foundation of its first 30 years. The plan leverages AGCI’s key strengths and legacy as a convenor and collaborator, while also aligning future work with newly developing capacities that extend the Institute’s impact. In the following pages, we set forth five values, three goals, and three programs that embody AGCI’s mission and map a path to fulfilling it. In addition, we briefly describe key mechanisms for accomplishing this plan and make commitments to sustainability, broadly defined. Finally, we invite readers to join us by sharing your ideas, following our progress, offering partnership, or otherwise helping make this plan a reality.

This report utilizes California as a regional case study to categorize and visualize scientific uncertainties and assess the state of the art emission and climate models with an emphasis on the regional scale. The report addresses the following key questions: 1) What are the range of possible SRES scenarios; how likely are they; how can subjective probabilities be assigned, and at what levels of confidence; what methods are most promising in such estimation; and how vexing is the lack of subjective probabilities for regional analyses for the California case study? 2) How well do GCMs do at producing meteorological variables at regional scales, and which of the various strategies to improve GCMs provide the greatest direct aid in improving knowledge of and confidence in the California regional modeling efforts and assessment strategies? 3) Utilizing California as a regional case study, how can the assessment and eventual reduction of uncertainties upstream, combined with improved downscaling models, better inform regional decision-making and resource management, and what are the stakes? 4) What elements of integrated analyses are essentially unknowable? Can robust strategies (Lempert and Schlesinger, 2000) be developed in spite of those aspects of analysis?

Climate models used in the writing of the Intergovernmental Panel on Climate Change Second Assessment Report indicate that future weather extremes as a result of climate change are likely to include a greater frequency of extreme warm days, lower frequency of cold days, higher nighttime temperatures, increased precipitation intensity, as well as a range of other climate variations. Subsequent models have reconfirmed these predictions, but there remains disagreement in current models as to the impact of synoptic time and space scale processes, such as tropical cyclones, El Nino effects, and extratropical storms. This article summarizes the state of scientific knowledge of possible future changes in the statistical aspects of weather and climate extremes.

Human activity is threatening the existence of natural habitats and the existence of species to such a degree that potentially half of all the life forms on the planet could be lost in a single human lifetime. To address this pending ecological catastrophe, 31 scientists from around the world convened in Aspen, CO during summer of 1991 to better define the scope of the problem, identify areas in need of improved research, and identify pathways for solutions. The conclusions reached at this meeting are recorded in this inaugural installment of AGCI's ongoing Elements of Change series. Inside this report, particular attention is directed towards understanding the linkages between biodiversity and development.

The understanding of climate change due to human activities is dependent on an understanding of the energy balance of the Earth. Clouds, their type and spatial coverage, play a key role in the EarthÕs energy balance. Better understanding of clouds and ways to more accurately represent them in models is key to the development of better climate models. This Elements of Change report discusses various observational methods from microphysical, synoptic, and the global scale as well as theoretical understanding of cloud formation and attenuation of incoming and outgoing radiation. Also included within this report are recommendations for observational needs and techniques along with a set of theoretical approaches for cloud parameterization in climate modeling.

Recently, much attention has focused on trends in extreme climate events. An increase in annual financial damages, as well an uptick in deaths, resulting from such events has given rise to speculation that these extreme events are increasing in frequency. Although data in some regions may have the potential robustness to reveal long-term trends, there is still an overall lack of long-term, worldwide data suitable for analysis of extreme climate variability. Where data does exist, there appear to be increases in temperature and precipitation extremes, as well as droughts and tropical storms. However, more high-quality, long-term climate data around the globe is needed to improve understanding.

Since the onset of satellites, particularly Landsat in 1972, the ability to map vegetative cover type and changes in its aerial extent has led to a fundamentally new way of understanding the Earth and rates of change to its surface. This Elements of Change report explores the technical aspects of remote sensing and analysis of data along with a variety of ground truthing techniques. Furthermore, it uncovers the types of change in vegetative cover brought about by human activity. This report provides case studies from several continents and presents related issues such as the edge effect as a disturbance factor beyond the actual cover change area which is particularly evident in cover change in the Amazon.

While carbon sequestration in the terrestrial biosphere may play a necessary role in mitigating anthropogenic climate change, current climate mitigation policies do not generally take into account the effects of the resulting changes in land surface albedo, the fluxes of sensible and latent heat to the atmosphere, and the distribution of energy within the climate system. As a result, proposed mitigation strategies may not achieve their desired result. This paper summarizes the interactions between the land surface and the atmosphere and explains why these complex interactions ought to be incorporated into proposed national and international carbon-credit trading regimes.

Although there is much focus from a policy standpoint on the climate impact of human-generated greenhouse gas emissions, less attention is given to the effects of human-caused land-use change, even though a growing body of research suggests that the latter may have a greater warming potential than the former. For example, one major warming impact that is not yet readily quantifiable is the surface heat fluxes that come as a result of changes in vegetation cover. As this article explains, impacts resulting from land-use change must be better quantified in order that they can be successfully incorporated into policies and international treaties.

Little is known about the biogeochemical, energy, and water cycles of the Northern Eurasian landmass, a carbon-rich region capable of significantly influencing global climate. In response to this deficiency, the Northern Eurasian Earth Science Partnership Initiative (NEESPI) was formed in 2004 to better understand and quantify feedbacks between Northern Eurasia and the global climate. This partnership actively monitors and analyzes natural and human-induced changes within Northern Eurasia and assesses the effects of these changes on current and future global climate. This article summarizes the first group of NEESPI projects, which have mostly focused on assembling regional data bases, organizing improved environmental monitoring of the region, and studying the individual environmental processes.

In recognition of imperiling consequences of human-generated greenhouse gasses, this report lays out strategies will enable the world to achieve CO2 stabilization. As a summary of an AGCI meeting on the same topic, this report lays out a range of innovative solutions, such as drawing upon renewable energy sources, eliminating carbon emissions from fossil fuel combustion, and geoengineering the climate. With each idea presented, there is a technical evaluation of the idea's feasibility, a risk assessment, and an analysis of the benefits and costs.

The decline of Arctic sea ice is an integral part of anthropogenic climate change. Sea-ice loss is already having a significant
impact on Arctic communities and ecosystems. Its role as a cause of climate changes outside of the Arctic has also attracted
much scientific interest. Evidence is mounting that Arctic sea-ice loss can affect weather and climate throughout the Northern
Hemisphere. The remote impacts of Arctic sea-ice loss can only be properly represented using models that simulate interactions
among the ocean, sea ice, land and atmosphere. A synthesis of six such experiments with different models shows consistent
hemispheric-wide atmospheric warming, strongest in the mid-to-high-latitude lower troposphere; an intensification of the
wintertime Aleutian Low and, in most cases, the Siberian High; a weakening of the Icelandic Low; and a reduction in strength
and southward shift of the mid-latitude westerly winds in winter. The atmospheric circulation response seems to be sensitive to
the magnitude and geographic pattern of sea-ice loss and, in some cases, to the background climate state. However, it is unclear
whether current-generation climate models respond too weakly to sea-ice change. We advocate for coordinated experiments
that use different models and observational constraints to quantify the climate response to Arctic sea-ice loss.

The overuse of synthetic fertilizers in some regions of the world has led to unintended negative environmental impacts, such as nitrogen-related air and water pollution. Meanwhile, in other regions of the globe, inadequate nutrient inputs have resulted in mass malnourishment. In this article, published in the 19 June 2009 edition of Science, 16 international ecology and agriculture experts compare fertilizer use in three corn-growing regions of the world -- northern China, sub-Saharan Africa, and the Midwestern United States -- and discuss the research needed to design more sustainable food production practices.

Although the relationship between climate change and extreme weather events, such as hurricanes and floods, is still uncertain, many scientists believe the two to be linked. This report focuses on the methods and evidence surrounding such a link. It presents existing data that suggests an upward trend in extreme weather and discusses how existing climate models can be reinterpreted or improved to forecast more accurately future climatic conditions. This report also discusses the impact expected increases in natural disasters and weather extremes may have on the natural world and human society.

Much attention in climate modeling has focused on how to downscale from large scale model output to smaller scales in order to resolve critical features such as mountain ranges. This Elements of Change report looks at the other side of the scale problem. It addresses the problem of known as upcaling, which is scaling from areas measured in square meters to larger aggregates. In this report are discussions of the practical and theoretical problems that arise with upscaling in a variety of regions. Since upscaling is widely required in models that forecast climate and other forms of global change, a better apprehension of this topic will serve to improve our models and understanding of key change.

In December 2017, AGCI's Board of Directors adopted our Commitment to Diversity, Equity, & Inclusion. We recognize the role that AGCI can play in improving diversity and inclusion within the sciences, and this statement of commitment serves as a foundation for our actions as we embrace that role. We see this as an ongoing process and dialogue, and welcome feedback on how we can continue to improve our practices.

Changes to weather and climate extremes are likely to become the most vivid and disruptive manifestations of climate change over the course of this century. While it is already understood that human-induced global warming increases the intensity and occurrence of extreme temperatures and precipitation, evidence suggests that hurricanes will also become more ferocious as the world warms. This report constitutes the first specific assessment of observed and projected changes in weather and climate extremes across North America--it details what is already known about extreme climate and weather, explains the understood causes of those events, offers projections of future weather and climate extremes, and suggests how scientific efforts can be better directed to increase understanding of this subject.

The U.S. Global Change Research Program Act of 1990 requires the U.S. government to do periodic climate impact assessments of the United States. This Elements of Change report serves as a guide to help outline the content and approach taken for this important assessment. The content of this report reflects the discussions that took place at a 1997 AGCI meeting among federal agency representatives, university academics, and others. During the meeting, participants explored the critical scientific issues relating to the assessment and drafted a plan for its completion.

Much progress has been made in recent years to improve climate modeling, but a failure to fully incorporate variables such as the carbon cycle prevent the accurate projection of stabilization scenarios. As a result, a next-generation of climate models is needed. This article lays out a roadmap for a new stage of climate modeling efforts, suggesting that two timeframes be addressed�near-term (2005-2030) and long-term (2005-2100). The near-term would disregard the effects of the carbon cycle and use already committed to CO2 levels to gauge regional impacts. The long-term models would assess climate outcomes on the basis of potential policy options and incorporate carbon cycle feedbacks through the use of three different experiments.

Societal ability to understand, build resiliency, and respond to natural hazards will be put to the test as global environmental changes, such as climate change, are likely to make natural disasters and hazard more common. This Elements of Change report discusses the main components of natural disaster reduction and illustrates why better disaster management and response is necessary in face of looming environmental change. Included in this report is a description of expected environmental changes that pose a threat to society, suggested procedures for natural disaster reduction, and the role of various private, government, civilian sectors in reducing the impacts of natural hazards.

In August 2007, a meeting was held at the Aspen Global Change Institute that addressed the role of the Northern Eurasian Landmass in the global Earth system. The meeting brought together members of the Northern Eurasia Earth Science Partnership Initiative (NEEPSI) to discuss how current and future research efforts in the region can better support global climate projections. One conclusion of the meeting was that more attention be focused on local-to-regional-scale biochemistry modeling for the NEEPSI region. This and other recommendations were codified in a protocol and roadmap that were produced at the meeting.

Characterizing uncertainty is a major issue in all scientific discourse, but it is of particular importance in climate change research. Widely publicized climate change findings, such as the periodic reports authored by the Intergovernmental Panel on Climate Change (IPCC), must find precision in their language so that the published findings are neither understated nor exaggerated and can be taken seriously by policymakers, the media, and the public. This Elements of Change report tackles this problem by summarizing the proceedings of a 1996 AGCI meeting that was convened to discuss how uncertainty is communicated in reports such as the one put out by the IPCC. In attendance were climate change researchers, policy analysts, and media experts, and this report addresses scientific, media, and policy related issues pertaining to uncertainty.

It is a generational challenge to meet the world’s energy requirements, while remaining within the bounds of acceptable costs and environmental impacts. To this end, substantial research has explored various energy futures on a global scale. These questions and activities walk undergraduate and graduate level students through exercises that explore the pace and scale of the global energy transition that will unfold over the coming century.

The questions draw on the AGCI Energy Table - an open-access, comprehensive energy reference featuring data on the availability, production, costs, and growth rates of energy sources and storage technologies currently in use or development. Energy sources include coal, oil, natural gas, nuclear, solar, wind, hydropower, ocean, geothermal and biomass. Each cell in the Energy Table provides data from recent peer reviewed publications and major institutional reports (such as the International Energy Administration), with hyperlinked references provided.

Following the 1992 framework of the Convention on Climate Change, there was much discussion about how to create effective policy strategies for climate change. This Elements of Change report explores a variety of binding and non-binding approaches, focusing on the different strategies for developed and developing countries. In addition, the report compares and contrasts climate change policy development to other international environmental agreements such as those for protecting the ozone hole and regulating acid rain.

The conclusions of Aspen Global Change Institute's 2006 summer science session "Earth System Models: The Next Generation" were published in the May 2007 edition of the World Climate Research Programme Summary Report. The synopsis brings to light what models, scenarios and strategies researchers now must consider next in order to best track emissions on both the short- and long-term scales in light of current and future techniques.The development of a new generation of climate models is underway with the expectation that future models will be able to incorporate carbon cycle dynamics and offer more accurately projected stabilization scenarios. This article lays out a roadmap for a new stage of climate modeling efforts, suggesting that two timeframes be addressed near-term (2005-2030) and long-term (2005-2100). The near-term would disregard the effects of the carbon cycle and use already committed to CO2 levels to gauge regional impacts. The long-term models would assess climate outcomes on the basis of potential policy options and incorporate carbon cycle feedbacks through the use of three different experiments (1) long-term benchmark stabilization, (2) carbon cycle response to increasing concentrations, and (3) emissions driven carbon cycle/climate.

This Elements of Change report grapples with the difficult question of how to anticipate change in dynamic and complex systems such as the physical, biological, and chemical properties of the Earth system confounded by human interactions with those systems both intentional and unintended. The report reflects the conclusions of an interdisciplinary group of scientists who collaborated to develop a typology of surprise and considered ways to anticipate thresholds and non-linear responses to forcings.

It is a generational challenge to meet the world’s energy requirements, while remaining within the bounds of acceptable costs and environmental impacts. To this end, substantial research has explored various energy futures on a global scale. These questions and activities walk undergraduate and graduate level students through exercises that explore the pace and scale of the global energy transition that will unfold over the coming century.

The questions draw on the AGCI Energy Table - an open-access, comprehensive energy reference featuring data on the availability, production, costs, and growth rates of energy sources and storage technologies currently in use or development. Energy sources include coal, oil, natural gas, nuclear, solar, wind, hydropower, ocean, geothermal and biomass. Each cell in the Energy Table provides data from recent peer reviewed publications and major institutional reports (such as the International Energy Administration), with hyperlinked references provided.

Many of the temperate zone major cities of the world, specifically those in Europe, Asia, and North America, are closely associated with large food-producing areas. This Elements of Change report looks into this relationship and the implications for the future organization of human populations and the quality of conditions necessary for productive agriculture and healthy urban environments. Particular attention is given to the case study of the metro-agro-plex in China. In addition, this report discusses issues associated with urban air and water pollution impacting agricultural productivity downstream and downriver and conversely agriculturally based pollutants from fertilizer, pesticides and soil erosion impacting neighboring urban areas.

The development of a new generation of climate models is underway with the expectation that future models will be able to incorporate carbon cycle dynamics and offer more accurately projected stabilization scenarios. This bulletin lays out a roadmap for a new stage of climate modeling efforts, suggesting that two timeframes be addressed near-term (2005-2030) and long-term (2005-2100). The near-term would disregard the effects of the carbon cycle and use already committed to CO2 levels to gauge regional impacts. The long-term models would assess climate outcomes on the basis of potential policy options and incorporate carbon cycle feedbacks through the use of three different experiments (1) long-term benchmark stabilization, (2) carbon cycle response to increasing concentrations, and (3) emissions driven carbon cycle/climate.

It long has been recognized that habitat destruction and land use change due to human activity pose a serious threat to biodiversity. But what other threats are there and at what scale do they operate? This Elements of Change report explores the scale, mechanisms, as well as the ecological and economic impacts of biological invasion resulting from intentional and unintentional distribution of species accelerated by human activity. Control mechanisms and the consequences of inaction are discussed.

This infographic was derived as a final product of AGCI's 2018 workshop on Technologies and Policies to Decarbonize the Industry Sector. It accompanied the open-access publication in Applied Energy co-authored by the workshop's participants. Industry generated 33% of global emissions in 2014, but 90% of these emissions come from a dozen industries. Technology and policy options can reach net zero industry emissions by 2070. Steel, chemicals, and cement alone generate >55% of global industry emissions. The workshop and its publication highlight the top strategies for decarbonizing global industry, which boil down to a three-pronged approach: 1) Reducing material consumption, 2) lowering energy use and shifting to clean energy, and 3) targeting the top-emitting industries. Policies can incentivize the transition. Companies that invest in the clean energy transition will profit from investing now. To dive deeper on decarbonization strategies for the industry sector, check out the full publication and explore the Agenda + Presentation on the workshop webpage.

Climate plays a key role in biotic systems, and while it is easy to predict how living systems react to gradual changes in climate, less certainty exists about the effects of extreme weather events. This article presents research showing specific examples of how extreme weather events have brought about manifest changes to species populations, behavior, morphology, as well as ecosystem-level effects. The authors argue that understanding the impact of these events is key to understanding the overall effect of climate change on the biosphere.