Consequences of twenty-first-century policy for multi-millennial climate and sea-level change

Most of the policy debate surrounding the actions needed to mitigate and adapt to anthropogenic climate change has been framed by observations of the past 150 years as well as climate and sea-level projections for the twenty-first century. The focus on this 250-year window, however, obscures some of the most profound problems associated with climate change. Here, we argue that the twentieth and twenty-first centuries, a period during which the overwhelming majority of human-caused carbon emissions are likely to occur, need to be placed into a long-term context that includes the past 20 millennia, when the last Ice Age ended and human civilization developed, and the next ten millennia, over which time the projected impacts of anthropogenic climate change will grow and persist. This long-term perspective illustrates that policy decisions made in the next few years to decades will have profound impacts on global climate, ecosystems and human societies — not just for this century, but for the next ten millennia and beyond.This is the publisher’s final pdf. The published article is copyrighted by Nature Publishing Group and can be found at: http://www.nature.com/nclimate/index.htm

Narrowing the uncertainty for deep-ocean injection efficiency

Publisher Summary The chapter proposes a basic ground rule for future studies of ocean injection efficiency: to be credible they must also demonstrate the associated model's skill in simulating the global inventory of GFG-11 and the global mean for radiocarbon in the deep ocean. A model that performs well in regards to both those constraints will be more likely to simulate reasonable global injection efficiencies. Nonetheless, efficiencies for a given injection site in coarse resolution models could be biased. For instance, the majority of injection sites will be located on eastern or western boundaries, which have known problems in coarse resolution models. Furthermore, coarse-resolution grids are unable to resolve important subgrid-scale processes (e.g., eddies, boundary currents, convection). Properly accounting for these processes may affect large-scale transport and could alter model predictions of CO2 sequestration efficiency. Although, global-scale ocean general circulation models are now becoming available which do resolve these processes, their high resolution means that they can only be integrated for relatively short periods, a few decades at most

Long-term imatinib therapy promotes bone formation in CML patients

Copyright © 2007 by American Society of HematologyImatinib inhibits tyrosine kinases important in osteoclast (c-Fms) and osteoblast (PDGF-R, c-Abl) function, suggesting that long term therapy may alter bone homeostasis. To investigate this question, we measured the trabecular bone volume (TBV) in iliac crest bone biopsies taken from CML patients at diagnosis and again following 2-4 years of imatinib therapy. Half the patients (8/17) showed a substantive increase in TBV (> 2 fold), following imatinib therapy, with the TBV in the post treatment biopsy typically surpassing the normal upper limit for the patient's age group. Imatinib treated patients exhibited reduced serum calcium and phosphate levels with hypophosphatemia evident in 53% (9/17) of patients. In vitro, imatinib suppressed osteoblast proliferation and stimulated osteogenic gene expression and mineralised matrix production by inhibiting PDGF receptor function. In PDGF stimulated cultures, imatinib dose dependently inhibited activation of Akt and Crk L. Using pharmacological inhibitors, inhibition of PI3-kinase/Akt activation promoted mineral formation, suggesting a possible molecular mechanism for the imatinib mediated increase in TBV in vivo. Further investigation is required to determine if the increase in TBV associated with imatinib therapy may represent a novel therapeutic avenue for the treatment of diseases that are characterised by generalised bone loss.Stephen Fitter, Andrea L Dewar, Panagiota Kostakis, L. Bik To, Timothy P Hughes, Marion M Roberts, Kevin Lynch, Barrie Vernon-Roberts, and Andrew CW Zannettin

Subsurface Science and Search for Life in Ocean Worlds

Several worlds in our solar system are thought to hold oceans of liquid water beneath their frozen surfaces. These subsurface ice and ocean environments are promising targets in the search for life beyond Earth, but they also present significant new technical challenges to planetary exploration. With a focus on Jupiter’s moon Europa, here we (1) identify major benefits and challenges to subsurface ocean world science, (2) provide a multidisciplinary survey of relevant sample handling and life detection technologies, and (3) integrate those perspectives into the Subsurface Science and Search for Life in Ocean Worlds (SSSLOW) concept payload. We discuss scientific goals across three complementary categories: (1) search for life, (2) assess habitability, and (3) investigate geological processes. Major mission challenges considered include submerged operation in high-pressure environments, the need to sample fluids with a range of possible chemical conditions, and detection of biosignatures at low concentrations. The SSSLOW addresses these issues by tightly integrated instrumentation and sample handling systems to enable sequential, complementary measurements while prioritizing preservation of sample context. In this work, we leverage techniques and technologies across several fields to demonstrate a path toward future subsurface exploration and life detection in ice and ocean worlds

ClarkConsequencesTwentyFirstCenturySupplement.pdf

Most of the policy debate surrounding the actions needed to mitigate and adapt to anthropogenic climate change has been framed by observations of the past 150 years as well as climate and sea-level projections for the twenty-first century. The focus on this 250-year window, however, obscures some of the most profound problems associated with climate change. Here, we argue that the twentieth and twenty-first centuries, a period during which the overwhelming majority of human-caused carbon emissions are likely to occur, need to be placed into a long-term context that includes the past 20 millennia, when the last Ice Age ended and human civilization developed, and the next ten millennia, over which time the projected impacts of anthropogenic climate change will grow and persist. This long-term perspective illustrates that policy decisions made in the next few years to decades will have profound impacts on global climate, ecosystems and human societies — not just for this century, but for the next ten millennia and beyond

ClarkConsequencesTwentyFirstCenturySupplement.xlsx

Most of the policy debate surrounding the actions needed to mitigate and adapt to anthropogenic climate change has been framed by observations of the past 150 years as well as climate and sea-level projections for the twenty-first century. The focus on this 250-year window, however, obscures some of the most profound problems associated with climate change. Here, we argue that the twentieth and twenty-first centuries, a period during which the overwhelming majority of human-caused carbon emissions are likely to occur, need to be placed into a long-term context that includes the past 20 millennia, when the last Ice Age ended and human civilization developed, and the next ten millennia, over which time the projected impacts of anthropogenic climate change will grow and persist. This long-term perspective illustrates that policy decisions made in the next few years to decades will have profound impacts on global climate, ecosystems and human societies — not just for this century, but for the next ten millennia and beyond

Carbon dioxide and climate impulse response functions for the computation of greenhouse gas metrics: a multi-model analysis

The responses of carbon dioxide (CO2) and other climate variables to an emissionpulse of CO2into the atmosphere are often used to compute the Global WarmingPotential (GWP) and Global Temperature change Potential (GTP), to characterizethe response time scales of Earth System models, and to build reduced-form mod-5els. In this carbon cycle-climate model intercomparison project, which spans the fullmodel hierarchy, we quantify responses to emission pulses of different magnitudes in-jected under different conditions. The CO2response shows the known rapid declinein the first few decades followed by a millennium-scale tail. For a 100 GtC emissionpulse, 24±10 % is still found in the atmosphere after 1000 yr; the ocean has absorbed1060±18 % and the land the remainder. The response in global mean surface air tem-perature is an increase by 0.19±0.10◦C within the first twenty years; thereafter anduntil year 1000, temperature decreases only slightly, whereas ocean heat content andsea level continue to rise. Our best estimate for the Absolute Global Warming Po-tential, given by the time-integrated response in CO2at year 100 times its radiative15efficiency, is 92.7×10−15yr Wm−2per kg CO2. This value very likely (5 to 95% confi-dence) lies within the range of (70 to 115)×10−15yr Wm−2per kg CO2. Estimates fortime-integrated response in CO2published in the IPCC First, Second, and Fourth As-sessment and our multi-model best estimate all agree within 15%. The integrated CO2response is lower for pre-industrial conditions, compared to present day, and lower for20smaller pulses than larger pulses. In contrast, the response in temperature, sea leveland ocean heat content is less sensitive to these choices. Although, choices in pulsesize, background concentration, and model lead to uncertainties, the most importantand subjective choice to determine AGWP of CO2and GWP is the time horizon.ISSN:1680-7375ISSN:1680-736