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20
2001: Climates of the twentieth and twenty-first centuries simulated by the NCAR Climate System Model
- J. Climate
"... The Climate System Model, a coupled global climate model without ‘‘flux adjustments’ ’ recently developed at the National Center for Atmospheric Research, was used to simulate the twentieth-century climate using historical greenhouse gas and sulfate aerosol forcing. This simulation was extended thro ..."
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The Climate System Model, a coupled global climate model without ‘‘flux adjustments’ ’ recently developed at the National Center for Atmospheric Research, was used to simulate the twentieth-century climate using historical greenhouse gas and sulfate aerosol forcing. This simulation was extended through the twenty-first century under two newly developed scenarios, a business-as-usual case (ACACIA-BAU, CO 2 � 710 ppmv in 2100) and a CO2 stabilization case (STA550, CO2 � 540 ppmv in 2100). Here we compare the simulated and observed twentieth-century climate, and then describe the simulated climates for the twenty-first century. The model simulates the spatial and temporal variations of the twentieth-century climate reasonably well. These include the rapid rise in global and zonal mean surface temperatures since the late 1970s, the precipitation increases over northern mid- and high-latitude land areas, ENSO-induced precipitation anomalies, and Pole– midlatitude oscillations (such as the North Atlantic oscillation) in sea level pressure fields. The model has a cold bias (2�–6�C) in surface air temperature over land, overestimates of cloudiness (by 10%–30%) over land, and underestimates of marine stratus clouds to the west of North and South America and Africa. The projected global surface warming from the 1990s to the 2090s is �1.9�C under the BAU scenario and �1.5�C under the STA550 scenario. In both cases, the midstratosphere cools due to the increase in CO 2, whereas
Solar total irradiance variations and the global sea surface temperature record. 1. Geophys. Res
, 1991
"... The record of globally averaged sea surface temperature (SST) over the past 130 years shows a highly significant correlation with the envelope of the I 1-year cycle of solar activity over the same period. This correlation could be explained by a variation in the sun's total irradiance (the sola ..."
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Cited by 29 (0 self)
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The record of globally averaged sea surface temperature (SST) over the past 130 years shows a highly significant correlation with the envelope of the I 1-year cycle of solar activity over the same period. This correlation could be explained by a variation in the sun's total irradiance (the solar "constant") that is in phase with the solar-cycle envelope, supporting and updating an earlier conclusion by Eddy (1976) that such variations could have played a major role in climate change over the past millennium. Measurements of the total irradiance from spacecraft, rockets, and balloons over the past 25 years have provided evidence of long-term variations and have been used to develop a simple linear relationship between irradiance and the envelope of the sunspot cycle. This relationship has been used to force a one-dimensional model of the thermal structure of the ocean (Hoffert et al., 1980), consisting of a 100-m mixed layer coupled to a deep ocean and including a thermohaline circulation. The model was started in the mid-seventeenth century, at the time of the Maunder Minimum of solar activity, and mixed-layer temperatures were calculated at 6-month intervals up to the present. The total range of irradiance values during the period was about 1%, and the total range of SST was about IøC. Cool periods, when temperatures were about 0.5øC below present-day values, were found in the early decades of both the nineteenth and twentieth centuries. There is direct evidence for the latter period from the historical SST record and some indirect evidence for the earlier cool period. While many aspects of the study are unavoidably simplistic, the results can be taken as indicating that solar variability has been an important contributor to global climate variations in recent decades. It has probably not been the only contributor, however, and in particular, the growing atmospheric burden of greenhouse gases may well have played an important role in the immediate past. This role is likely to become even more important in the near future. 1.
On nonstationarity and antipersistency in global temperature series
, 2002
"... [1] Statistical analysis is carried out for satellite-based global daily tropospheric and stratospheric temperature anomaly and solar irradiance data sets. Behavior of the series appears to be nonstationary with stationary daily increments. Estimating long-range dependence between the increments re ..."
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Cited by 12 (4 self)
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[1] Statistical analysis is carried out for satellite-based global daily tropospheric and stratospheric temperature anomaly and solar irradiance data sets. Behavior of the series appears to be nonstationary with stationary daily increments. Estimating long-range dependence between the increments reveals a remarkable difference between the two temperature series. Global average tropospheric temperature anomaly behaves similarly to the solar irradiance anomaly. Their daily increments show antipersistency for scales longer than 2 months. The property points at a cumulative negative feedback in the Earth climate system governing the tropospheric variability during the last 22 years. The result emphasizes a dominating role of the solar irradiance variability in variations of the tropospheric temperature and gives no support to the theory of anthropogenic climate change. The global average stratospheric temperature anomaly proceeds like a 1-dim random walk at least up to 11 years, allowing good presentation by means of the autoregressive integrated moving average (ARIMA) models for monthly series.
Potential climate change effects on loblolly pine forest productivity and drainage across the Southern United States
- Ambio
, 1996
"... PnET-IIS, a well validated, physiologically based, forest ecosystem model combined soil and vegetation data with six climate change scenarios. The model predicted annu-al net primary productivity and drainage on loblolly pine sites in the southern US states of Texas, Mississippi, Florida and Virgini ..."
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PnET-IIS, a well validated, physiologically based, forest ecosystem model combined soil and vegetation data with six climate change scenarios. The model predicted annu-al net primary productivity and drainage on loblolly pine sites in the southern US states of Texas, Mississippi, Florida and Virginia. Climate scenario air temperature changes were +2°C to +7°C> historic (1951 to 1984) val-ues and climate scenario precipitation changes were-10 % to +20 %> historic values. Across the sites, increas-ing air temperature would have much greater impact on pine forest hydrology and productivity than would changes in precipitation. These changes could seriously impact the structure and function of southern United States forests by decreasing net primary productivity and total leaf area. Water use per unit area would increase, but total plant water demand would decrease because of reduced total leaf area, thus increasing regional pine forest drainage. An average annual air temperature increase of 7°C, caused a considerable reduction in the loblolly pine range.
The faint young Sun problem
- Rev. Geophys
, 2012
"... [1] For more than four decades, scientists have been trying to find an answer to one of the most fundamental questions in paleoclimatology, the “faint young Sun problem. ” For the early Earth, models of stellar evolution predict a solar energy input to the climate system that is about 25 % lower tha ..."
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Cited by 7 (1 self)
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[1] For more than four decades, scientists have been trying to find an answer to one of the most fundamental questions in paleoclimatology, the “faint young Sun problem. ” For the early Earth, models of stellar evolution predict a solar energy input to the climate system that is about 25 % lower than today. This would result in a completely frozen world over the first 2 billion years in the history of our planet if all other parameters controlling Earth’s climate had been the same. Yet there is ample evidence for the presence of liquid surface water and even life in the Archean (3.8 to 2.5 billion years before present), so some effect (or effects) must have been compensating for the faint young Sun. A wide range of possible solutions have been suggested and explored dur-ing the last four decades, with most studies focusing on higher concentrations of atmospheric greenhouse gases like carbon dioxide, methane, or ammonia. All of these solutions present considerable difficulties, however, so the faint young Sun problem cannot be regarded as solved. Here I review research on the subject, including the latest suggestions for solutions of the faint young Sun problem and recent geo-chemical constraints on the composition of Earth’s early atmosphere. Furthermore, I will outline the most promising directions for future research. In particular I would argue that both improved geochemical constraints on the state of the Archean climate system and numerical experiments with state-of-the-art climate models are required to finally assess what kept the oceans on the Archean Earth from freezing over completely.
The Incommunciability of Content
- Mind
, 1966
"... Evaluating the impact of number controls, choice and competition: an analysis of the student profile and the student learning environment in the new higher education ..."
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Evaluating the impact of number controls, choice and competition: an analysis of the student profile and the student learning environment in the new higher education
Critical Topics in Global Warming: Supplementary Analysis of the Independent Summary for Policymakers
, 2009
"... The sun affects our climate in direct and indirect ways. The sun changes in its activity on timescales that vary from 11, 22, 80, and 180 years and more. A more active sun is brighter due to the dominance of faculae over cooler sunspots; in this way, the irradiance emitted by the sun and received by ..."
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The sun affects our climate in direct and indirect ways. The sun changes in its activity on timescales that vary from 11, 22, 80, and 180 years and more. A more active sun is brighter due to the dominance of faculae over cooler sunspots; in this way, the irradiance emitted by the sun and received by the Earth is higher during active solar periods than during quiet solar periods. The amount of change of the total solar irradiance (TSI) during the course of an 11-year cycle, based on satellite measurements since 1978, is about 0.1%. This was first discovered by Willson and Hudson (1991) from the results of the SMM/ACRIM1 experiment, and was later confirmed by Fröhlich and Lean (1998). This finding has caused many to conclude that the solar effect on climate is negligible; however, many questions still remain about the actual mechanisms involved and the sun’s variance on century and longer timescales. The irradiance reconstructions of Hoyt and Schatten (1997); Lean et
Increased
, 2009
"... Gases typically measured in parts per million (ppm), parts per billion (ppb) or parts per trillion (ppt) by volume are presented separately to facilitate comparison of numbers. Global Warming Potentials (GWPs) and atmospheric lifetimes are from the Intergovermental Panel on Climate Change (IPCC, 200 ..."
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Gases typically measured in parts per million (ppm), parts per billion (ppb) or parts per trillion (ppt) by volume are presented separately to facilitate comparison of numbers. Global Warming Potentials (GWPs) and atmospheric lifetimes are from the Intergovermental Panel on Climate Change (IPCC, 2007, Table 2.14), except for the atmospheric lifetime of carbon dioxide (CO2) which is explained in footnote 4. Additional material on greenhouse gases can be found in CDIAC's Reference Tools. To find out how CFCs, HFCs, HCFCs, and halons are named, see Name that compound: The numbers game for CFCs, HFCs, HCFCs, and Halons. Sources of the current atmospheric concentrations are given in the footnotes. The concentrations given are mostly derived from data available via the CDIAC Web pages; many corresponding links are given in the footnotes below. These data are contributed to CDIAC by various investigators, and represent considerable effort on their part. We ask as a basic professional courtesy that you acknowledge the primary sources when you refer to data from any of these sites. Guidelines for proper acknowledgment are found at each link, except for the ALE/GAGE/AGAGE database where acknowledgment guidelines are given in the "readme " files; links to those "readme " files are given in footnote 9, below.
GLOBAL CHANGE IN THE HIGH PLAINS OF NORTH AMERICA
, 1991
"... Abstract. The High Plains of North America extends ffom Canada to northern Mexico. This grassland region is subject to prolonged drought, herbivory, and wildfire. Organisms that are indigenous to the High Plains are adapted to these environmental factors. Periodic droughts occur at inexact, but few ..."
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Abstract. The High Plains of North America extends ffom Canada to northern Mexico. This grassland region is subject to prolonged drought, herbivory, and wildfire. Organisms that are indigenous to the High Plains are adapted to these environmental factors. Periodic droughts occur at inexact, but few year, intervals. The grazing by free ranging bison, the indigenous large herbivore, has been replaced by grazing of fenced domestic stock. Fire regimes throughout human occupation of the region have been greatly influenced by human activities. Cultivation of wheat and corn also is carried out in the region. Predicted climate changes in this region are increased temperature and reduced effective precipitation. Paleontological records document past climate changes from which certain predictions may be made about the effects of current models of Global Change. Ecological snrdies at the ecosystem, community, species, and population levels are defensible. Land use modifica-
