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Target atmospheric CO2: Where should humanity aim?
Paleoclimate data show that climate sensitivity is ~3 deg-C for doubled CO2, including only fast feedback processes. Equilibrium sensitivity, including slower surface albedo feedbacks, is ~6 deg-CExpand
Convergent Cenozoic CO2 history
Reconstructions of atmospheric carbon dioxide concentrations over the past 65 million years are heading towards consensus. It is time for systematic testing of the proxies, against measurements andExpand
The interdependence of mechanisms underlying climate-driven vegetation mortality.
By integrating new evidence from a wide range of fields, it is concluded that hydraulic function and carbohydrate and defense metabolism have numerous potential failure points, and that these processes are strongly interdependent, both with each other and with destructive pathogen and insect populations. Expand
Maximum leaf conductance driven by CO2 effects on stomatal size and density over geologic time
It is shown that high densities of small stomata are the only way to attain the highest gcmax values required to counter CO2“starvation” at low atmospheric CO2 concentrations, and may represent a mechanism linking CO2 and the increasing gas-exchange capacity of land plants over geologic time. Expand
A humid climate state during the Palaeocene/Eocene thermal maximum
The authors' results provide evidence for a previously unrecognized discrete shift in the state of the climate system during the PETM, characterized by large increases in mid-latitude tropospheric humidity and enhanced cycling of carbon through terrestrial ecosystems. Expand
Present state of global wetland extent and wetland methane modelling: conclusions from a model inter-comparison project (WETCHIMP)
Abstract. Global wetlands are believed to be climate sensitive, and are the largest natural emitters of methane (CH4). Increased wetland CH4 emissions could act as a positive feedback to futureExpand
Paleobotanical evidence for near present-day levels of atmospheric Co2 during part of the tertiary.
This reconstruction indicates that CO(2) remained between 300 and 450 parts per million by volume for these intervals with the exception of a single high estimate near the Paleocene/Eocene boundary, and suggests that factors in addition to CO( 2) are required to explain these past intervals of global warmth. Expand
Phanerozoic atmospheric CO2 change: evaluating geochemical and paleobiological approaches
Abstract The theory and use of geochemical modeling of the long-term carbon cycle and four paleo-PCO 2 proxies are reviewed and discussed in order to discern the best applications for each method.Expand
New constraints on atmospheric CO2 concentration for the Phanerozoic
Earth's atmospheric CO2 concentration (ca) for the Phanerozoic Eon is estimated from proxies and geochemical carbon cycle models. Most estimates come with large, sometimes unbounded uncertainty.Expand
Assessing “Dangerous Climate Change”: Required Reduction of Carbon Emissions to Protect Young People, Future Generations and Nature
Climate impacts of global warming is assessed using ongoing observations and paleoclimate data and simple representations of the global carbon cycle and temperature to define emission reductions needed to stabilize climate and avoid potentially disastrous impacts on today’s young people, future generations, and nature. Expand