Article: "Atmospheric CO2 Concentrations over the Last Glacial Termination."
- Correlation between CO2 concentration and Antarctic temperatures over 6000 years indicates Southern Ocean had important role in causing CO2 increase.
- Comparison of deuterium (proxy for temperature) and CO2 indicate lag of CO2 behind temperature change by 410 years.
- CO2 in the atmosphere rose from 189 ppmv to 265 in 6000 years.
Source: Science, Volume 291, Number 5501.
Date: 2001 January 5
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Article: "Rising CO2 Levels and the Fecundity of Forest Trees."
Carbon dioxide enrichment of 19-year-old loblolly pine for three years resulted in trees twice as likely to be reproductively mature, and produced three times as many cones and seeds.
Source: Science, Volume 292, Number 5514.
Date: 2001 April 6
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Article: "Paleobotanical Evidence for Near Present-Day Levels of Atmospheric CO2 During part of the Tertiary."
- Carbon dioxide levels in the atmosphere remained between 300-400 parts per million by volume during 14-18 million years ago, and 54-60 million years ago.
- Results suggest factors in addition to carbon dioxide are required to explain these past intervals of global warmth.
Source: Science, Volume 292, Number 5525.
Date: 2001 June 22
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Article: "Changes in Forest Biomass Carbon Storage in China Between 1949 and 1998."
Chinese forests released about 0.68 petagram of carbon between 1949-1980, then increased by 0.37 petagram by 1998.
Source: Science, Volume 292, Number 5525.
Date: 2001 June 22
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Article: "Warming of the Southern Ocean Since the 1950s."
- Mid-depth Southern Ocean temperatures have risen 0.16 degrees C from the 1950s to the 1980s, nearly double the global trend.
- Carbon dioxide storage capacity of the Southern Ocean has decreased since the 1950s.
Source: Science, Volume 295, Number 5558.
Date: 2002 February 15
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Article: "Climatic Control of the High-Latitude Vegetation Greening Trend and Pinatubo Effect."
- Gradual lengthening of growing season in high northern latitudes has resulted in greening trend.
- Following Mount Pinatubo volcano eruption in 1991, trend was interrupted, producing increased carbon sink, contributing to slowdown in global rate of atmospheric carbon dioxide growth.
Source: Science, Volume 296, Number 5573.
Date: 2002 May 31
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Article: "Super ENSO and Global Climate Oscillations at Millenial Time Scales."
- Since last glacial maximum, 22,000 years ago, sea surface temperatures of tropical Pacific ocean have warmed about 2 degrees Celcius (summer) and 3 degrees (winter).
- Variability of tropical Pacific temperature over past glacial period (22,000 years ago to 64,000 years ago) average 1-2 degrees celcius.
- In western tropical Pacific, ocean was saltier through much of past 70,000 years than today.
- Millennial-scale El Nino-like conditions may have shifted atmospheric convection away from west tropical Pacific, explaining lower atmospheric carbon dioxide, N2O, and methane during stadial periods.
Source: Science, Volume 297, Number 5579.
Date: 2002 July 12
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Article: "The Pliocene Paradox (Mechanisms for a Permanent El Nino)."
- 3 to 5 million years ago, globally averaged temperatures were substantially higher than today, atmospheric carbon dioxide was similar, but surface temperature at poles was higher that Northern Hemisphere had no continental glaciers.
- Amplification of response of climate to orbital forcing began 3 million years ago, resulting in drastic oscillations between ice ages and warmer periods over the past 1 million years.
- El Nino was continual rather than intermittent up to 3 million years ago.
- A persistence of high carbon dioxide concentrations could result in return to globally warm world.
Source: Science, Volume 312, Number 5779.
Date: 2006 June 9
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Article: "Permafrost and the Global Carbon Budget."
- Climate warming will thaw permafrost, releasing trapped carbon, about 100 gigatons.
- The Earth's atmosphere presently contains about 730 gigatons of carbon.
Source: Science, Volume 312, Number 5780.
Date: 2006 June 16
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Article: "Food for Thought: Lower-Than-Expected Crop Yield Stimulation with Rising Carbon Dioxide Concentrations."
- Large-scale open-air trials of CO2-enriched grain crops elevated yield by 50 percent less than previous enclosed trials 20 years ago.
Source: Science, Volume 312, Number 5782.
Date: 2006 June 30
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Article: "Warming and Earlier Spring Increase Western U.S. Forest Wildfire Activity."
- Since 1970, large wildfire activity in western U.S. increased suddenly and markedly in mid-1980s.
- Increase highly correlated to sub-regional responses to changes in climate.
- Continuing frequency of large wildfires will result in carbon release, becoming a source rather than sink of carbon dioxide.
Source: Science, Volume 313, Number 5789.
Date: 2006 August 18
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Article: "Elevated Eocene Atmospheric Carbon Dioxide and Its Subsequent Decline."
- Temperature peaked 50-52 million years ago, when atmospheric CO2 ranged 1125-3000 parts per million.
- By 20 million years ago, CO2dropped to about 400 ppm.
Source: Science, Volume 313, Number 5795.
Date: 2006 September 29
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Article: "Rapid Early Development of Circumarctic Peatlands and Atmospheric Methane and Carbon Dioxide Variations."
- Development of current circumarctic peatlands began 16,500 years ago, expanded rapidly 8-12,000 years ago during high summer insolation and increasing temperature.
- Peatland development contributed to sustained peak of methane at 650 parts per billion for 1500 years.
- Decline in peatland initiation follows decline in atmospheric methane and carbon dioxide from 10,000 years ago to 6000 years ago.
- Decline in peatland initiation from 6000 years ago to 1700 A.D. does not follow rise in methane and carbon dioxide, so must have some other non-manmade source.
Source: Science, Volume 314, Number 5796.
Date: 2006 October 13
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Article: "A Combined Mitigation / Geoengineering Approach to Climate Stabilization."
- Deliberate injection of sulfate aerosols into the stratosphere could substantially offset future warming and provide additional time to reduce carbon dioxide levels.
Source: Science, Volume 314, Number 5798.
Date: 2006 October 20
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Article: "Negligible glacial-Interglacial variation in continental chemical weathering rates."
- Chemical weathering of the continents, which draws carbon dioxide into the oceans, does not differ greatly between glacial and interglacial periods.
- Enhanced weathering of silicate glacial sediments during interglacial periods results in net draw-down of atmospheric carbon dioxide, creating positive feedback on global climate, promoting cooling.
Source: Nature, Volume 444, Number 7121.
Date: 2006 December 14
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Article: "Climate sensitivity constrained by CO2 concentrations over the past 420 millon years."
- Most estimates of climate sensitivity are based on records of climate change over the past few decades to thousands of years, and may not be applicable to climate change under warmer conditions of the future.
- Based on modelling CO2 over 420 million years, climate sensitivity from weak long-term radiative forcing by CO2 is greater than 1.5 degrees C.
Source: Nature, Volume 446, Number 7135.
Date: 2007 March 29
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Article: "Effect of natural iron fertilization on carbon sequestration in the Southern Ocean."
- The Southern Ocean is most sensitive oceanic body to climate change.
- Iron fertilization of surface waters during glacial times by enhanced dust deposition may explain lower atmospheric CO2 during colder climates.
- Natural iron fertilization from below results in high carbon sequestration efficiency.
- Short-term iron addition experiments cannot be extrapolated to longer timescales.
Source: Nature, Volume 446, Number 7139.
Date: 2007 April 26
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Article: "Indirect radiative forcing of climate change through ozone effects on the land-carbon sink."
- Emissions due to fossil fuel and biomass burning about doubled global mean tropospheric ozone concentration.
- As increases in ozone concentrations negatively affect plant productivity, more CO2 accumulates in the atmosphere.
Source: Nature, Volume 448, Number 7155.
Date: 2007 August 16
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