Gary W. Yohe

A globally coherent fingerprint of climate change impacts across natural systems

Causal attribution of recent biological trends to climate change is complicated because non-climatic influences dominate local, short-term biological changes. Any underlying signal from climate change is likely to be revealed by analyses that seek systematic trends across diverse species and geographic regions; however, debates within the Intergovernmental Panel on Climate Change (IPCC) reveal several definitions of a ‘systematic trend’. Here, we explore these differences, apply diverse analyses to more than 1,700 species, and show that recent biological trends match climate change predictions. Global meta-analyses documented significant range shifts averaging 6.1 km per decade towards the poles (or metres per decade upward), and significant mean advancement of spring events by 2.3 days per decade. We define a diagnostic fingerprint of temporal and spatial ‘sign-switching’ responses uniquely predicted by twentieth century climate trends. Among appropriate long-term/large-scale/multi-species data sets, this diagnostic fingerprint was found for 279 species. This suite of analyses generates ‘very high confidence’ (as laid down by the IPCC) that climate change is already affecting living systems.

Indicators for social and economic coping capacity—moving toward a working definition of adaptive capacity

This paper offers a practically motivated method for evaluating systems’ abilities to handle external stress. The method is designed to assess the potential contributions of various adaptation options to improving systems’ coping capacities by focusing attention directly on the underlying determinants of adaptive capacity. The method should be sufficiently flexible to accommodate diverse applications whose contexts are location specific and path dependent without imposing the straightjacket constraints of a ‘‘one size fits all’’ cookbook approach. Nonetheless, the method should produce unitless indicators that can be employed to judge the relative vulnerabilities of diverse systems to multiple stresses and to their potential interactions. An artificial application is employed to describe the development of the method and to illustrate howit might be applied. Some empirical evidence is offered to underscore the significance of the determinants of adaptive capacity in determining vulnerability; these are the determinants upon which the method is constructed. The method is, finally, applied directly to expert judgments of six different adaptations that could reduce vulnerability in the Netherlands to increased flooding along the Rhine River. r 2002 Elsevier Science Ltd. All rights reserved.

Avoiding dangerous climate change

The impacts of climate change are already being observed in a variety of sectors and there is greater clarity that these changes are being caused by human activities, mainly through release of greenhouse gases. In 2005 the UK Government hosted the Avoiding Dangerous Climate Change conference to take an in-depth look at the scientific issues associated with climate change. This volume presents the most recent findings from the leading international scientists that attended the conference. The topics addressed include critical thresholds and key vulnerabilities of the climate system, impacts on human and natural systems, socioeconomic costs and benefits of emissions pathways, and technological options for meeting different stabilisation levels of greenhouse gases in the atmosphere. The volume provides invaluable information for researchers in environmental science, climatology, and atmospheric chemistry, policy-makers in governments and environmental organizations, and scientists and engineers in industry.Tropical forests affect atmospheric carbon dioxide concentrations, and hence modulate the rate of climate change - by being a source of carbon, from land-use change (deforestation), and as a sink or source of carbon in remaining intact forest. These fluxes are among the least understood and most uncertain major fluxes within the global carbon cycle. We synthesise recent research on the tropical forest biome carbon balance, suggesting that intact forests presently function as a carbon sink of approx. 1.2 Pg C a ^-1, and that deforestation emissions at the higher end of the reported 1 - 3 Pg C a^ -1 spectrum are likely. Scenarios suggest that the source from deforestation will remain high, whereas the sink in intact forest is unlikely to continue, and remaining tropical forests may become a major carbon source via one or more of (i) changing photosynthesis/respiration rates, (ii) functional/biodiversity changes within intact forest, or widespread forest collapse via (iii) drought, or (iv) fire. Each scenario risks possible positive feedbacks with the climate system suggesting that current estimates of the possible rate, magnitude and effects of global climate change over the coming decades may be conservative.

Assessing dangerous climate change through an update of the Intergovernmental Panel on Climate Change (IPCC) “reasons for concern”

Article 2 of the United Nations Framework Convention on Climate Change [United Nations (1992) http://unfccc.int/resource/docs/convkp/conveng.pdf. Accessed February 9, 2009] commits signatory nations to stabilizing greenhouse gas concentrations in the atmosphere at a level that “would prevent dangerous anthropogenic interference (DAI) with the climate system.” In an effort to provide some insight into impacts of climate change that might be considered DAI, authors of the Third Assessment Report (TAR) of the Intergovernmental Panel on Climate Change (IPCC) identified 5 “reasons for concern” (RFCs). Relationships between various impacts reflected in each RFC and increases in global mean temperature (GMT) were portrayed in what has come to be called the “burning embers diagram.” In presenting the “embers” in the TAR, IPCC authors did not assess whether any single RFC was more important than any other; nor did they conclude what level of impacts or what atmospheric concentrations of greenhouse gases would constitute DAI, a value judgment that would be policy prescriptive. Here, we describe revisions of the sensitivities of the RFCs to increases in GMT and a more thorough understanding of the concept of vulnerability that has evolved over the past 8 years. This is based on our expert judgment about new findings in the growing literature since the publication of the TAR in 2001, including literature that was assessed in the IPCC Fourth Assessment Report (AR4), as well as additional research published since AR4. Compared with results reported in the TAR, smaller increases in GMT are now estimated to lead to significant or substantial consequences in the framework of the 5 “reasons for concern.”

The economic cost of greenhouse-induced sea-level rise for developed property in the United States

Estimates of the true economic cost that might be attributed to greenhouse-induced sea-level rise on the developed coastline of the United States are offered for the range of trajectories that is now thought to be most likely. Along a 50-cm sea level rise trajectory (through 2100), for example, transient costs in 2065 (a year frequently anticipated for doubling of greenhouse-gas concentrations) are estimated to be roughly

Sea-Level Change: The Expected Economic Cost of Protection Or Abandonment in the United States

70 million (undiscounted, but measured in constant 1990

Mitigative Capacity – the Mirror Image of Adaptive Capacity on the Emissions Side

). More generally and carefully cast in the appropriate context of protection decisions for developed property, the results reported here are nearly an order of magnitude lower than estimates published prior to 1994. They are based upon a calculus that reflects rising values for coastal property as the future unfolds, but also includes the cost-reducing potential of natural, market-based adaptation in anticipation of the threat of rising seas and/or the efficiency of discrete decisions to protect or not to protect small tracts of property that will be made when necessary and on the (then current) basis of their individual economic merit.

Risk aversion, time preference, and the social cost of carbon

Three distinct models from earlier work are combined to: (1) produce probabilistically weighted scenarios of greenhouse-gas-induced sea-level rise; (2) support estimates of the expected discounted value of the cost of sea-level rise to the developed coastline of the United States, and (3) develop reduced-form estimates of the functional relationship between those costs to anticipated sea-level rise, the cost of protection, and the anticipated rate of property-value appreciation. Four alternative representations of future sulfate emissions, each tied consistently to the forces that drive the initial trajectories of the greenhouse gases, are considered. Sea-level rise has a nonlinear effect on expected cost in all cases, but the estimated sensitivity falls short of being quadratic. The mean estimate for the expected discounted cost across the United States is approximately

Towards a General Comparison of Price Controls and Quantity Controls under Uncertainty

2 billion (with a 3% real discount rate), but the range of uncertainty around that estimate is enormous; indeed, the 10th and 90th percentile estimates run from less than

Chapter 2: Adopting a risk-based approach

0.2 billion up to more than