Over The Past Few Thousand Years, How, If At All, Has Sea Level Been Changing?

Research Article

Irreversible climate modify due to carbon dioxide emissions

1. ^aChemical Sciences Partition, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305;
2. ^bInstitute of Biogeochemistry and Pollutant Dynamics and
3. ^cInstitute for Atmospheric and Climate Scientific discipline, ETH CH-8092, Zurich, Switzerland; and
4. ^dInstitut Pierre Simon Laplace/Laboratoire des Sciences du Climat et de 50'Environnement, Unité Mixte de Recherche 1572 Commissariat à l'Energie Atomique–Center National de la Recherche Scientifique–Université Versailles Saint-Quentin, Commissariat a l'Energie Atomique-Saclay, l'Orme des Merisiers, 91191 Gif sur Yvette, France

See all Hide authors and affiliations

1. Contributed by Susan Solomon, December xvi, 2008 (received for review November 12, 2008)

Abstruse

The severity of damaging human-induced climate modify depends not only on the magnitude of the change but also on the potential for irreversibility. This paper shows that the climate modify that takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years later on emissions stop. Following cessation of emissions, removal of atmospheric carbon dioxide decreases radiative forcing, but is largely compensated by slower loss of heat to the ocean, so that atmospheric temperatures practice non drop significantly for at to the lowest degree ane,000 years. Amid illustrative irreversible impacts that should be expected if atmospheric carbon dioxide concentrations increase from electric current levels near 385 parts per million by volume (ppmv) to a meridian of 450–600 ppmv over the coming century are irreversible dry-season rainfall reductions in several regions comparable to those of the "dust bowl" era and inexorable sea level rise. Thermal expansion of the warming sea provides a conservative lower limit to irreversible global boilerplate sea level rise of at to the lowest degree 0.4–ane.0 m if 21st century CO_ii concentrations exceed 600 ppmv and 0.6–1.9 one thousand for height CO_ii concentrations exceeding ≈i,000 ppmv. Boosted contributions from glaciers and ice sheet contributions to future bounding main level ascent are uncertain but may equal or exceed several meters over the next millennium or longer.

• dangerous interference
• atmospheric precipitation
• sea level rise
• warming

Over the 20th century, the atmospheric concentrations of key greenhouse gases increased due to homo activities. The stated objective (Commodity 2) of the United Nations Framework Convention on Climatic change (UNFCCC) is to achieve stabilization of greenhouse gas concentrations in the atmosphere at a depression enough level to forestall "dangerous anthropogenic interference with the climate system." Many studies have focused on projections of possible 21st century dangers (i⇓–three). Yet, the principles (Commodity 3) of the UNFCCC specifically emphasize "threats of serious or irreversible harm," underscoring the importance of the longer term. While some irreversible climate changes such as ice sheet collapse are possible but highly uncertain (1, iv), others can now be identified with greater confidence, and examples among the latter are presented in this newspaper. Information technology is not mostly appreciated that the atmospheric temperature increases caused by ascent carbon dioxide concentrations are not expected to decrease significantly even if carbon emissions were to completely finish (5⇓–seven) (come across Fig. one). Time to come carbon dioxide emissions in the 21st century will hence lead to agin climate changes on both short and long time scales that would be essentially irreversible (where irreversible is divers hither every bit a fourth dimension scale exceeding the terminate of the millennium in year 3000; note that nosotros practice not consider geo-engineering measures that might be able to remove gases already in the atmosphere or to introduce active cooling to counteract warming). For the same reason, the physical climate changes that are due to anthropogenic carbon dioxide already in the atmosphere today are expected to exist largely irreversible. Such climate changes volition atomic number 82 to a range of damaging impacts in different regions and sectors, some of which occur promptly in clan with warming, while others build up nether sustained warming considering of the time lags of the processes involved. Here nosotros illustrate two such aspects of the irreversibly altered world that should be expected. These aspects are among reasons for concern just are not comprehensive; other possible climate impacts include Arctic bounding main ice retreat, increases in heavy rainfall and flooding, permafrost melt, loss of glaciers and snowpack with attendant changes in water supply, increased intensity of hurricanes, etc. A complete climate impacts review is presented elsewhere (eight) and is across the telescopic of this paper. We focus on illustrative adverse and irreversible climate impacts for which 3 criteria are met: (i) observed changes are already occurring and there is evidence for anthropogenic contributions to these changes, (two) the phenomenon is based upon concrete principles thought to be well understood, and (3) projections are bachelor and are broadly robust across models.

Advances in modeling accept led non simply to improvements in complex Atmosphere–Ocean General Apportionment Models (AOGCMs) for projecting 21st century climate, but likewise to the implementation of Earth System Models of Intermediate Complexity (EMICs) for millennial time scales. These 2 types of models are used in this paper to show how different peak carbon dioxide concentrations that could be attained in the 21st century are expected to lead to substantial and irreversible decreases in dry-season rainfall in a number of already-dry out subtropical areas and lower limits to eventual sea level ascent of the social club of meters, implying unavoidable overflowing of many pocket-sized islands and low-lying littoral areas.

Results

Longevity of an Atmospheric CO₂ Perturbation.

Every bit has long been known, the removal of carbon dioxide from the atmosphere involves multiple processes including rapid substitution with the land biosphere and the surface layer of the ocean through air–ocean exchange and much slower penetration to the bounding main interior that is dependent upon the buffering effect of ocean chemistry forth with vertical transport (nine⇓ ⇓–12). On the time scale of a millennium addressed here, the CO_two equilibrates largely betwixt the atmosphere and the ocean and, depending on associated increases in acidity and in ocean warming (i.e., an increase in the Revelle or "buffer" cistron, see below), typically ≈xx% of the added tonnes of CO₂ remain in the atmosphere while ≈80% are mixed into the sea. Carbon isotope studies provide important observational constraints on these processes and fourth dimension constants. On multimillenium and longer time scales, geochemical and geological processes could restore atmospheric carbon dioxide to its preindustrial values (ten, 11), merely are not included here.

Fig. 1 illustrates how the concentrations of carbon dioxide would be expected to fall off through the coming millennium if manmade emissions were to cease immediately post-obit an illustrative futurity rate of emission increase of two% per year [comparable to observations over the by decade (ref. 13)] upward to peak concentrations of 450, 550, 650, 750, 850, or 1,200 ppmv; like results were obtained across a range of EMICs that were assessed in the Intergovernmental Panel on Climate change (IPCC) Fourth Assessment Written report (five, 7). This is non intended to be a realistic scenario but rather to correspond a test example whose purpose is to probe concrete climate system changes. A more gradual reduction of carbon dioxide emission (as is more probable), or a faster or slower adopted rate of emissions in the growth period, would atomic number 82 to long-term behavior qualitatively similar to that illustrated in Fig. 1 (come across also Fig. S1). The example of a sudden abeyance of emissions provides an upper bound to how much reversibility is possible, if, for case, unexpectedly damaging climate changes were to be observed.

• Download figure
• Open in new tab
• Download powerpoint

Fig. 1.

Carbon dioxide and global hateful climate system changes (relative to preindustrial weather condition in 1765) from one illustrative model, the Bern 2.5CC EMIC, whose results are comparable to the suite of assessed EMICs (five, 7). Climate system responses are shown for a ramp of CO₂ emissions at a rate of two%/year to peak CO₂ values of 450, 550, 650, 750, 850, and 1200 ppmv, followed by naught emissions. The rate of global fossil fuel CO₂ emission grew at ≈1%/year from 1980 to 2000 and >3%/year in the period from 2000 to 2005 (13). Results have been smoothed using an 11-twelvemonth running mean. The 31-twelvemonth variation seen in the carbon dioxide fourth dimension serial is introduced by the climatology used to strength the terrestrial biosphere model (15). (Top) Falloff of CO₂ concentrations following zero emissions after the superlative. (Middle) Globally averaged surface warming (degrees Celsius) for these cases (note that this model has an equilibrium climate sensitivity of 3.2 °C for carbon dioxide doubling). Warming over state is expected to be larger than these global averaged values, with the greatest warming expected in the Arctic (5). (Lesser) Sea level ascent (meters) from thermal expansion only (non including loss of glaciers, ice caps, or water ice sheets).

Carbon dioxide is the but greenhouse gas whose falloff displays multiple rather than single fourth dimension constants (run into Fig. S2). Current emissions of major not-CO₂ greenhouse gases such as methane or nitrous oxide are pregnant for climate change in the next few decades or century, just these gases do not persist over time in the same manner as carbon dioxide (14).

Fig. ane shows that a quasi-equilibrium amount of CO_two is expected to be retained in the atmosphere by the cease of the millennium that is surprisingly big: typically ≈40% of the peak concentration enhancement over preindustrial values (≈280 ppmv). This tin exist easily understood on the basis of the observed instantaneous airborne fraction (AF^peak) of ≈fifty% of anthropogenic carbon emissions retained during their buildup in the atmosphere, together with well-established sea chemistry and physics that crave ≈xx% of the emitted carbon to remain in the atmosphere on thousand-year timescales [quasi-equilibrium airborne fraction (AF^equi), determined largely by the Revelle factor governing the long-term partitioning of carbon between the body of water and atmosphere/biosphere system] (ix⇓–11). Assuming given cumulative emissions, EMI, the peak concentration, CO_two ^peak (increase over the preindustrial value CO₂ ⁰), and the resulting ane,000-twelvemonth quasi-equilibrium concentration, CO_ii ^equi can be expressed equally and so that Given an instantaneous airborne fraction (AF^peak) of ≈50% during the period of rising CO_two, and a quasi-equilbrium airborne factor (AF^equi) of 20%, it follows that the quasi-equilibrium enhancement of CO₂ concentration above its preindustrial value is ≈40% of the peak enhancement. For example, if the CO₂ concentration were to meridian at 800 ppmv followed by zip emissions, the quasi-equilibrium CO₂ concentration would still exist far higher up the preindustrial value at ≈500 ppmv. Additional carbon cycle feedbacks could reduce the efficiency of the ocean and biosphere to remove the anthropogenic CO₂ and thereby increase these CO₂ values (15, 16). Further, a longer decay fourth dimension and increased CO₂ concentrations at twelvemonth m are expected for large total carbon emissions (17).

Irreversible Climatic change: Atmospheric Warming.

Global boilerplate temperatures increase while CO_two is increasing and then remain approximately abiding (inside ≈ ±0.5 °C) until the end of the millennium despite zero farther emissions in all of the test cases shown in Fig. 1. This important result is due to a near remainder betwixt the long-term subtract of radiative forcing due to CO₂ concentration decay and reduced cooling through estrus loss to the oceans. Information technology arises because long-term carbon dioxide removal and ocean heat uptake are both dependent on the same physics of deep-body of water mixing. Body of water level rise due to thermal expansion accompanies mixing of heat into the bounding main long after carbon dioxide emissions take stopped. For larger carbon dioxide concentrations, warming and thermal sea level rise show greater increases and display transient changes that can be very rapid (i.due east., the rapid changes in Fig. 1 Middle), mainly considering of changes in ocean circulation (18). Paleoclimatic prove suggests that additional contributions from melting of glaciers and ice sheets may exist comparable to or greater than thermal expansion (discussed further below), simply these are not included in Fig. i.

Fig. two explores how shut the modeled temperature changes are to thermal equilibrium with respect to the irresolute carbon dioxide concentration over time, sometimes chosen the realized warming fraction (nineteen) (shown for the different acme CO₂ cases). Fig. ii Left shows how the calculated warmings compare to those expected if temperatures were in equilibrium with the carbon dioxide concentrations vs. time, while Fig. two Right shows the ratio of these calculated time-dependent and equilibrium temperatures. During the period when carbon dioxide is increasing, the realized global warming fraction is ≈l–sixty% of the equilibrium warming, close to values obtained in other models (5, nineteen). After emissions cease, the temperature change approaches equilibrium with respect to the slowly decreasing carbon dioxide concentrations (cyan lines in Fig. ii Right). The continuing warming through yr 3000 is maintained at ≈40–60% of the equilibrium warming respective to the peak CO₂ concentration (magenta lines in Fig. 2 Right). Related changes in fast-responding atmospheric climate variables such as atmospheric precipitation, water vapor, heat waves, cloudiness, etc., are expected to occur largely simultaneously with the temperature changes.

• Download effigy
• Open up in new tab
• Download powerpoint

Fig. two.

Comparison between calculated time-dependent surface warming in the Bern2.5CC model and the values that would be expected if temperatures were in equilibrium with respect to the CO₂ enhancements, illustrative of 2%/year emission increases to 450, 550, 650, 750, 850, and i,200 ppmv as in Fig. 1. (Left) The actual and equilibrium temperature changes (based upon the model's climate sensitivity at equilibrium). The cyan lines in Right show the ratio of actual and equilibrium temperatures (or realized fraction of the warming for the time-dependent CO₂ concentrations), while the magenta lines prove the ratio of actual warming to the equilibrium temperature for the meridian CO_two concentration.

Irreversible Climate Modify: Precipitation Changes.

Warming is expected to be linked to changes in rainfall (20), which can adversely bear on the supply of water for humans, agronomics, and ecosystems. Precipitation is highly variable but long-term rainfall decreases take been observed in some large regions including, e.g., the Mediterranean, southern Africa, and parts of southwestern North America (21⇓ ⇓ ⇓–25). Confident projection of future changes remains elusive over many parts of the globe and at pocket-size scales. Notwithstanding, well-known physics (the Clausius–Clapeyron law) implies that increased temperature causes increased atmospheric water vapor concentrations, and changes in h2o vapor transport and the hydrologic cycle tin hence be expected (26⇓–28). Further, advances in modeling evidence that a robust characteristic of anthropogenic climatic change is poleward expansion of the Hadley cell and shifting of the pattern of precipitation minus evaporation (P–E) and the tempest tracks (22, 26), and hence a pattern of drying over much of the already-dry out subtropics in a warmer world (≈xv°-40° breadth in each hemisphere) (5, 26). Attribution studies suggest that such a drying blueprint is already occurring in a manner consistent with models including anthropogenic forcing (23), particularly in the southwestern United States (22) and Mediterranean basin (24, 25).

We apply a suite of 22 available AOGCM projections based upon the evaluation in the IPCC 2007 report (5, 29) to characterize atmospheric precipitation changes. Changes in precipitation are expected (5, 20, thirty) to scale approximately linearly with increasing warming (see Fig. S3). The equilibrium relationship betwixt precipitation and temperature may be slightly smaller (by ≈xv%) than the transient values, due to changes in the land/bounding main thermal contrast (31). On the other hand, the observed 20th century changes follow a similar latitudinal blueprint but before long exceed those calculated past AOGCMs (23). Models that include more than complex representations of the land surface, soil, and vegetation interactively are likely to display additional feedbacks so that larger precipitation responses are possible.

Hither nosotros evaluate the relationship betwixt temperature and precipitation averaged for each month and over a decade at each grid signal. Ane ensemble member is used for each model so that all AOGCMs are as weighted in the multimodel ensemble; results are nearly identical if all available model ensemble members are used.

Fig. 3 presents a map of the expected dry-flavour (three driest sequent months at each filigree point) precipitation trends per degree of global warming. Fig. 3 shows that big uncertainties remain in the projections for many regions (white areas). However, it also shows that at that place are some subtropical locations on every inhabited continent where dry out seasons are expected to become drier in the decadal average by up to 10% per degree of warming. Some of these filigree points occur in desert regions that are already very dry, simply many occur in currently more temperate and semiarid locations. We discover that model results are more robust over land beyond the available models over wider areas for drying of the dry flavor than for the annual hateful or moisture flavor (meet Fig. S4). The Insets in Fig. 3 show the monthly hateful projected precipitation changes averaged over several large regions as delineated on the map. Increased drying of respective dry seasons is projected by >90% of the models averaged over the indicated regions of southern Europe, northern Africa, southern Africa, and southwestern North America and by >80% of the models for eastern Due south America and western Australia (meet Fig. S3). Although given item years would show exceptions, the long-term irreversible warming and mean rainfall changes as suggested by Figs. i and three would have important consequences in many regions. While some relief tin be expected in the moisture season for some regions (Fig. S4), changes in dry out-season atmospheric precipitation in northern Africa, southern Europe, and western Australia are expected to exist about 20% for 2 °C warming, and those of southwestern North America, eastern Due south America, and southern Africa would be ≈10% for ii °C of global hateful warming. For comparison, the American "dust basin" was associated with averaged rainfall decreases of ≈ten% over ≈10–20 years, similar to major droughts in Europe and western Australia in the 1940s and 1950s (22, 32). The spatial changes in precipitation every bit shown in Fig. 3 imply greater challenges in the distribution of nutrient and water supplies than those with which the earth has had difficulty coping in the past. Such changes occurring not but for a few decades but over centuries are expected to have a range of impacts that differ by region. These include, e.k., human being water supplies (25), furnishings on dry out-flavor wheat and maize agriculture in sure regions of rain-fed farming such as Africa (33, 34), increased fire frequency, ecosystem change, and desertification (24, 35⇓ ⇓–38).

• Download figure
• Open in new tab
• Download powerpoint

Fig. iii.

Expected decadally averaged changes in the global distribution of atmospheric precipitation per degree of warming (percentage of change in precipitation per degree of warming, relative to 1900–1950 as the baseline period) in the dry season at each grid point, based upon a suite of 22 AOGCMs for a midrange future scenario (A1B, see ref. 5). White is used where fewer than xvi of 22 models agree on the sign of the change. Information are monthly averaged over several broad regions in Inset plots. Ruby lines show the all-time estimate (median) of the changes in these regions, while the cherry shading indicates the ±i-σ likely range (i.eastward., 2 of three chances) across the models.

Fig. 4Upper relates the expected irreversible changes in regional dry-season precipitation shown in Fig. 3 to best estimates of the respective peak and long-term CO_two concentrations. We use 3 °C every bit the best gauge of climate sensitivity beyond the suite of AOGCMs for a doubling of carbon dioxide from preindustrial values (v) along with the regional drying values depicted in Fig. three and assuming that ≈40% of the carbon dioxide peak concentration is retained after 1000 years. Fig. iv shows that if carbon dioxide were to summit at levels of ≈450 ppmv, irreversible decreases of ≈8–x% in dry-season precipitation would be expected on average over each of the indicated large regions of southern Europe, western Australia, and northern Africa, while a carbon dioxide peak value most 600 ppmv would be expected to lead to sustained rainfall decreases of ≈thirteen–16% in the dry seasons in these areas; smaller but statistically significant irreversible changes would besides exist expected for southwestern Due north America, eastern South America, and Southern Africa.

• Download figure
• Open in new tab
• Download powerpoint

Fig. 4.

Illustrative irreversible climate changes equally a part of peak carbon dioxide reached. (Upper) All-time estimate of expected irreversible dry-season precipitation changes for the regions shown in Fig. 3, equally a function of the peak carbon dioxide concentration during the 21st century. The quasi-equilibrium CO_ii concentrations shown represent to 40% remaining in the long term as discussed in the text. The precipitation change per degree is derived for each region as in Fig. 3; see too Fig. S3. The yellow box indicates the range of precipitation alter observed during typical major regional droughts such as the "dust basin" in North America (32). (Lower) Corresponding irreversible global warming (black line). Too shown is the associated lower limit of irreversible sea level rise (considering of thermal expansion merely based upon a range of 0.ii–0.vi one thousand/°C), from an assessment beyond available models (v). Smaller values (by ≈30%) for expected warming, precipitation, and thermal ocean level rise would be obtained if climate sensitivity is smaller than the all-time estimate while larger values (by ≈50%) would be expected for the upper end of the estimated likely range of climate sensitivity (49).

Irreversible Climate Change: Sea Level Rise.

Anthropogenic carbon dioxide will crusade irrevocable sea level rise. There are 2 relatively well-understood processes that contribute to this and a 3rd that may exist much more important but is also very uncertain. Warming causes the ocean to expand and sea levels to rise as shown in Fig. 1; this has been the ascendant source of body of water level rise in the past decade at least (39). Loss of land water ice also makes important contributions to sea level rising equally the world warms. Mountain glaciers in many locations are observed to be retreating due to warming, and this contribution to sea level rise is also relatively well understood. Warming may too pb to big losses of the Greenland and/or Antarctic ice sheets. Additional rapid ice losses from particular parts of the ice sheets of Greenland and Antarctica take recently been observed (twoscore⇓–42). I recent report uses electric current ice belch data to suggest ice sheet contributions of up to 1–2 m to sea level rise past 2100 (42), but other studies suggest that changes in winds rather than warming may account for currently observed rapid ice canvass flow (43), rendering quantitative extrapolation into the hereafter uncertain. In addition to rapid ice catamenia, slow ice sheet mass residuum processes are some other mechanism for potential large sea level rise. Paleoclimatic information demonstrate large contributions of ice sheet loss to sea level rise (one, 4) but provide limited constraints on the rate of such processes. Some contempo studies suggest that ice sheet surface mass balance loss for height CO₂ concentrations of 400–800 ppmv may be even slower than the removal of manmade carbon dioxide following abeyance of emissions, so that this loss could contribute less than a meter to irreversible sea level rise even afterward many thousands of years (44, 45). It is axiomatic that the contribution from the ice sheets could exist big in the future, merely the dependence upon carbon dioxide levels is extremely uncertain not but over the coming century but also in the millennial time scale.

An assessed range of models suggests that the eventual contribution to bounding main level ascent from thermal expansion of the ocean is expected to be 0.2–0.6 m per degree of global warming (v). Fig. 4 uses this range together with a best judge for climate sensitivity of iii °C (five) to approximate lower limits to eventual body of water level rise due to thermal expansion alone. Fig. iv shows that even with zero emissions subsequently reaching a peak concentration, irreversible global average sea level rise of at least 0.4–i.0 m is expected if 21st century CO₂ concentrations exceed 600 ppmv and every bit much as 1.9 thousand for a top CO_two concentration exceeding ≈ane,000 ppmv. Loss of glaciers and small-scale ice caps is relatively well understood and is expected to exist largely consummate under sustained warming of, for instance, four °C within ≈500 years (46). For lower values of warming, fractional remnants of glaciers might be retained, just this has not been examined in detail for realistic representations of glacier shrinkage and is not quantified here. Complete losses of glaciers and small ice caps have the potential to raise future ocean level by ≈0.2–0.seven m (46, 47) in addition to thermal expansion. Further contributions due to partial loss of the cracking ice sheets of Antarctica and/or Greenland could add several meters or more to these values but for what warming levels and on what time scales are still poorly characterized.

Ocean level rise can be expected to impact many coastal regions (48). While bounding main walls and other adaptation measures might combat some of this sea level ascent, Fig. 4 shows that carbon dioxide peak concentrations that could be reached in the time to come for the conservative lower limit defined by thermal expansion lone can be expected to be associated with substantial irreversible commitments to time to come changes in the geography of the Earth considering many coastal and island features would ultimately go submerged.

Discussion: Some Policy Implications

It is sometimes imagined that slow processes such as climate changes pose modest risks, on the basis of the assumption that a pick can always be made to quickly reduce emissions and thereby reverse any impairment within a few years or decades. We have shown that this assumption is incorrect for carbon dioxide emissions, because of the longevity of the atmospheric CO₂ perturbation and ocean warming. Irreversible climate changes due to carbon dioxide emissions take already taken place, and time to come carbon dioxide emissions would imply further irreversible effects on the planet, with attendant long legacies for choices made past contemporary society. Disbelieve rates used in some estimates of economical trade-offs assume that more efficient climate mitigation can occur in a future richer world, just neglect the irreversibility shown here. Similarly, understanding of irreversibility reveals limitations in trading of greenhouse gases on the footing of 100-year estimated climate changes (global warming potentials, GWPs), because this metric neglects carbon dioxide's unique long-term effects. In this paper we have quantified how societal decisions regarding carbon dioxide concentrations that take already occurred or could occur in the coming century imply irreversible dangers relating to climatic change for some illustrative populations and regions. These and other dangers pose substantial challenges to humanity and nature, with a magnitude that is straight linked to the peak level of carbon dioxide reached.

Materials and Methods

The AOGCM simulation data presented in this paper are part of the World Climate Research Program'southward (WCRP's) Coupled Model Intercomparison Project phase iii (CMIP3) multimodel data set (29) and are available from the Program for Climate Model Diagnosis and Intercomparison (PCMDI) (www-pcmdi.llnl.gov/ipcc/about_ipcc.php), where further information on the AOGCMs can also be obtained. The EMIC used in this study is the Bern2.5CC EMIC described in refs. seven and 15; it is compared to other models in refs. five and 7. It is a coupled climate–carbon bicycle model of intermediate complexity that consists of a zonally averaged dynamic ocean model, a one-layer atmospheric energy–wet balance model, and interactive representations of the marine and terrestrial carbon cycles.

Acknowledgments

We gratefully acknowledge the modeling groups, the Programme for Climate Model Diagnosis and Intercomparison, and the Earth Climate Research Program's Working Group on Coupled Modeling for their roles in making available the Working Group on Coupled Modeling'south Coupled Model Intercomparison Project phase 3 multimodel data set. Support of this data set is provided by the Role of Scientific discipline, U.South. Department of Energy. We also appreciate helpful comments from 3 reviewers.

Footnotes

• Author contributions: South.S., Yard.-K.P., R.1000., and P.F. designed enquiry; S.South., Chiliad.-K.P., and R.Chiliad. performed research; Yard.-1000.P. and R.1000. analyzed information; and S.S., M.-Chiliad.P., R.G., and P.F. wrote the paper.

• The authors declare no conflict of interest.

• This article contains supporting information online at www.pnas.org/cgi/content/total/0812721106/DCSupplemental.

• Received November 12, 2008.

• © 2009 by The National Academy of Sciences of the Usa

Freely bachelor online through the PNAS open admission option.

View Abstruse

Source: https://www.pnas.org/content/106/6/1704

Posted by: fifeabloome.blogspot.com

Share this post