What we know about Climate Change - Senate Testimony by Prof. A. Dessler
Dessler Hearing Witness Testimony 2014
[n.b. This is one of the best succinct summaries of climate science by Prof. A. Dessler in testimony before the US Senate in January, 2014. HERE is an article summarizing the Dessler testimony].
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Target atmospheric CO2: Where should humanity aim? (J. Hansen et al, 2008)
LINK. Open Atmos. Sci. J., 2, 217-231, doi:10.2174/1874282300802010217
ABSTRACT: Paleoclimate data show that climate sensitivity is ~3°C for doubled CO2, including only fast feedback processes. Equilibrium sensitivity, including slower surface albedo feedbacks, is ~6°C for doubled CO2 for the range of climate states between glacial conditions and ice-free Antarctica. Decreasing CO2 was the main cause of a cooling trend that began 50 million years ago, the planet being nearly ice-free until CO2 fell to 450±100 ppm; barring prompt policy changes, that critical level will be passed, in the opposite direction, within decades. If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm, but likely less that. The largest uncertainty in the target arises from possible changes of non-CO2 forcings. An initial 350 ppm CO2 target may be achievable by phasing out coal use except where CO2 is captured and adopting agricultural and forestry practices that sequester carbon. If the present overshoot of this target CO2 is not brief, there is a possibility of seeding irreversible catastrophic effects.
[n.b. This is the "350" paper that started 350.org]
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Global climate evolution during the last deglaciation
LINK; Supplement; News article
Peter U. Clark et. al. PNAS February 13, 2012
Deciphering the evolution of global climate from the end of the Last Glacial Maximum approximately 19 ka to the early Holocene 11 ka presents an outstanding opportunity for understanding the transient response of Earth’s climate system to external and internal forcings. During this interval of global warming, the decay of ice sheets caused global mean sea level to rise by approximately 80 m; terrestrial and marine ecosystems experienced large disturbances and range shifts; perturbations to the carbon cycle resulted in a net release of the greenhouse gases CO2 and CH4 to the atmosphere; and changes in atmosphere and ocean circulation affected the global distribution and fluxes of water and heat. Here we summarize a major effort by the paleoclimate research community to characterize these changes through the development of well-dated, high-resolution records of the deep and intermediate ocean as well as surface climate. Our synthesis indicates that the superposition of two modes explains much of the variability in regional and global climate during the last deglaciation, with a strong association between the first mode and variations in greenhouse gases, and between the second mode and variations in the Atlantic meridional overturning circulation.
[n.b. This paper gives the details of the transition from the last ice age. Carbon dioxide was instrumental. Another fallacy of the climate contrarians is thereby demolished]
From the news article:
The measurements from the previous studies were taken from ice cores extracted from thick glaciers in Antarctica. The new work supplements that data with temperature evidence from 80 locations around the globe.
The results show that while temperature increases around Antarctica appear to have led increases in atmospheric CO2, the picture globally was the opposite – CO2 increases paved the way for temperature increases...
[n.b. Here is the mechanism as described in the news article:] The team's results show that the initial trigger for warming to end the last ice age was a periodic change in the angle of Earth's tilt and in the orientation of its axis. This brought more sunlight to warm northern latitudes. As mile-thick ice sheets covering vast areas of the northern hemisphere's continents began to melt, fresh water poured into the oceans, particularly into the North Atlantic, changing mechanisms that governed the climate.
Sea levels rose five to 10 meters within a few hundred years, and the Atlantic's deep-ocean “conveyor belt” slowed. Typically, the conveyor pulls warm surface water north from the tropics to cool, sink, and move south along the bottom as colder water. But the added fresh water from melting ice sheets slowed the conveyor, cooling the north and warming the southern ocean, which reaches Antarctica.
The warmer waters in the southern ocean reduced the extent of sea ice around the continent, leaving more surface water exposed to exchange gases with the atmosphere. Changing wind patterns from the warming increased the pace at which CO2-rich water deep in the ocean welled up and vented CO2 into the atmosphere.
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The Hockey Stick and the Climate Wars: Dispatches from the Front Lines
Michael E. Mann
In its 2001 report on global climate, the Intergovernmental Panel on Climate Change of the United Nations prominently featured the "Hockey Stick," a chart showing global temperature data over the past one thousand years. The Hockey Stick demonstrated that temperature had risen with the increase in industrialization and use of fossil fuels. The inescapable conclusion was that worldwide human activity since the industrial age had raised CO2 levels, trapping greenhouse gases in the atmosphere and warming the planet.
The Hockey Stick became a central icon in the "climate wars," and well-funded science deniers immediately attacked the chart and the scientists responsible for it. Yet the controversy has had little to do with the depicted temperature rise and much more with the perceived threat the graph posed to those who oppose governmental regulation and other restraints to protect our environment and planet. Michael E. Mann, lead author of the original paper in which the Hockey Stick first appeared, shares the real story of the science and politics behind this controversy. He introduces key figures in the oil and energy industries, and the media front groups who do their bidding in sometimes slick, bare-knuckled ways to cast doubt on the science. Mann concludes with an account of the "Climategate" scandal, the 2009 hacking of climate scientists' emails. Throughout, Mann reveals the role of science deniers, abetted by an uninformed media, in once again diverting attention away from one of the central scientific and policy issues of our time.
[n.b. This is a great book. Read it.]
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Impact of declining intermediate-water oxygen on deepwater fishes in the California Current - LINK
J. Anthony Koslow, Ralf Goericke, Ana Lara-Lopez, William Watson
ABSTRACT: ... We report the apparent impact of declining oxygen on midwater fishes within the OMZ of the southern California Current (CC). Principal component analysis ... indicates ...marked decline of the region’s mesopelagic fishes during periods of reduced oxygen...The mesopelagic fish fauna provides a vital trophodynamic link between the marine plankton and many higher predators. The decline of deepwater fish populations has profound implications for commercial fisheries, marine food webs and marine conservation: climate models predict a 20 to 40% decline in global deepwater oxygen concentrations over the coming century.
[n.b. This paper shows that global warming is leading to oxygen-dead zones in the ocean, which will increasingly reduce fish population crucial to the marine food chain]
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Cool the Earth, Save the Economy: Solving the Climate Crisis is EASY
This practical book by Dr. John and Mary Ellen Harte maintains that money can be saved and the climate crisis mitigated by the "EASY" plan, which if implemented will achieve a 75% reduction in current U.S. greenhouse gas emissions by 2030.
The EASY plan has four major components:
E = Energy efficiency
A = Automotive efficiency
S = Solar, wind and geothermal technology
Y = You are part of the solution
All of the above involve available, acceptable and affordable technologies. In fact, a cost/benefits analysis comparing the EASY plan to business-as-usual, based on conservative economic assumptions (Chapter 3), shows that the EASY plan will cost $21.6 trillion, but doing nothing will cost $22.1 trillion – i.e., the U.S. will save about $0.5 trillion over the next 20 years if the US invests in the EASY plan now.
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Atmospheric Carbon Injection Linked to End-Triassic Mass Extinction
Micha Ruhl, Nina R. Bonis, Gert-Jan Reichart, Jaap S. Sinninghe Damsté, Wolfram M. Kürschner
Science 22 July 2011: Vol. 333 no. 6041 pp. 430-434 DOI: 10.1126/science.1204255
The end-Triassic mass extinction (~201.4 million years ago), marked by terrestrial ecosystem turnover and up to ~50% loss in marine biodiversity, has been attributed to intensified volcanic activity during the break-up of Pangaea. Here, we present compound-specific carbon-isotope data of long-chain n-alkanes derived from waxes of land plants, showing a ~8.5 per mil negative excursion, coincident with the extinction interval. These data indicate strong carbon-13 depletion of the end-Triassic atmosphere, within only 10,000 to 20,000 years. The magnitude and rate of this carbon-cycle disruption can be explained by the injection of at least ~12 × 103 gigatons of isotopically depleted carbon as methane into the atmosphere. Concurrent vegetation changes reflect strong warming and an enhanced hydrological cycle. Hence, end-Triassic events are robustly linked to methane-derived massive carbon release and associated climate change.
[nb: This paper shows that a violent mass extinction was associated with huge methane release and global warming.]
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Robustness of the Mann, Bradley, Hughes reconstruction of Northern Hemisphere surface temperatures: Examination of criticisms based on the nature and processing of proxy climate evidence - LINK
Eugene R. Wahl · Caspar M. Ammann
Climatic Change (2007) 85:33–69 DOI 10.1007/s10584-006-9105-7
Abstract: The Mann et al. (1998) Northern Hemisphere annual temperature reconstruction over 1400–1980 is examined in light of recent criticisms concerning the nature and processing of included climate proxy data...the Mann et al. reconstruction is robust against the proxy-based criticisms addressed. In particular, re- constructed hemispheric temperatures are demonstrated to be largely unaffected by the use or non-use of PCs [principal components] to summarize proxy evidence from the data-rich North American region. When proxy PCs are employed, neither the time period used to “center” the data before PC calculation nor the way the PC calculations are performed significantly affects the results, as long as the full extent of the climate information actually in the proxy data is represented by the PC time series...both the 20th century upward trend and high late-20th century hemispheric surface temperatures are anomalous.
[nb: This paper shows that contrarian attacks on the "Hockey Stick" are false. In particular, the mathematical procedure of "principal components" was grossly misapplied by contrarians. Actually, the fact that recent global warming is due to humans, is independent of the Hockey Stick.]
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Ongoing climate change following a complete cessation of carbon dioxide emissions - LINK
Nathan P. Gillett, Vivek K. Arora, Kirsten Zickfeld, Shawn J. Marshall & William J. Merryfield
... Here we use simulations with the Canadian Earth System Model to show that ongoing regional changes in temperature and precipitation are significant, following a complete cessation of carbon dioxide emissions in 2100, despite almost constant global mean temperatures. Moreover, our projections show warming at intermediate depths in the Southern Ocean that is many times larger by the year 3000 than that realized in 2100. We suggest that a warming of the intermediate-depth ocean around Antarctica at the scale simulated for the year 3000 could lead to the collapse of the West Antarctic Ice Sheet, which would be associated with a rise in sea level of several metres.
- Journal name: Nature Geoscience; Year published: (2011); DOI: doi:10.1038/ngeo1047
[nb: This paper demonstrates that sea level rise by 3000 may be several metres even if CO2 emissions are zero after 2100. This rise will occur sooner if CO2 emissions are not zero.]
See the press release HERE.
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Nonlinear temperature effects indicate severe damages to U.S. crop yields under climate change- LINK
Wolfram Schlenker a,1 and Michael J. Roberts b
a Department of Economics and School of International and Public Affairs, Columbia University, New York, NY 10027; and b Department of Agricultural and Resource Economics, North Carolina State University, Raleigh, NC 27695
www.pnas.org cgi doi 10.1073 pnas.0906865106
This article contains supporting information online at www.pnas.org/cgi/content/full/ 0906865106/DCSupplemental .
... We find that yields increase with temperature up to 29° C for corn, 30° C for soybeans, and 32° C for cotton but that temperatures above these thresholds are very harmful...Holding current growing regions fixed, area-weighted average yields are predicted to decrease by 30 – 46% before the end of the century under the slowest (B1) warming scenario and decrease by 63–82% under the most rapid warming scenario (A1FI) under the Hadley III model.
[nb: This paper exibits again that there is no safe haven from global warming. The U.S. will suffer huge hits to major food production under "business as usual"]
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Probabilistic projections for 21st century European climate - LINK
Met Office, Hadley Centre, Exeter EX1 3PB, UK
Nat. Hazards Earth Syst. Sci., 10, 2009-2020, 2010; www.nat-hazards-earth-syst-sci.net/10/2009/2010/; doi:10.5194/nhess-10-2009-2010
Abstract. We present joint probability distribution functions of future seasonal-mean changes in surface air temperature and precipitation for the European region for the SRES A1B emissions scenario. The probabilistic projections quantify uncertainties in the leading physical, chemical and biological feedbacks and combine information from perturbed physics ensembles, multi-model ensembles and observations.
[nb: This takes care of the complaint that there are uncertainties in the models - the distribution of future temperatures in Europe is given for the A1B scenario of human behavior, basically including ALL model uncertainties, and the temperature always goes UP]
Full Article (PDF, 1249 KB)
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Atmospheric CO2 concentrations during ancient greenhouse climates were similar to those predicted for A.D. 2100 - LINK
D. O. Breecker et al; PNAS January 12, 2010 vol. 107 no. 2 576-580
...We report that greenhouse [CO2]atm have been significantly overestimated because previously assumed soil CO2 concentrations during carbonate formation are too high...past greenhouse climates were accompanied by concentrations similar to those projected for A.D. 2100.
[nb: This indicates that we may be producing huge greenhouse effects by 2100.]
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Global phytoplankton decline over the past century- LINK
D. G. Boyce et al; Nature Volume: 466, Pages: 591–596, Date published: (29 July 2010), doi:10.1038/nature09268
Editor's summary: ...Marine phytoplankton have a crucial role in Earth's biogeochemical cycles, and form the basis of marine ecosystems...What emerges from the records is a century of decline of global phytoplankton biomass.
Abstract: ...We observe declines in eight out of ten ocean regions, and estimate a global rate of decline of ~1% of the global median per year...long-term declining trends are related to increasing sea surface temperatures. We conclude that global phytoplankton concentration has declined over the past century; this decline will need to be considered in future studies of marine ecosystems, geochemical cycling, ocean circulation and fisheries.
See also HERE for interview statements with the authors.
[nb: Phytoplankton is the base of the entire ocean food chain.]
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Restoring the Quality of Our Environment (1965 global warming prediction) - LINK
President's Science Advisory Council, 1965 [the year 1965 is NOT a mistake]
Appendix: Atmospheric Carbon Dioxide
"Through his worldwide industrial civilization, Man is unwittingly conducting a vast geophysical experiment... By the year 2000 the increase in atmospheric CO2 will be close to 25%. This may be sufficient to produce measurable and perhaps marked changes in climate, and will almost certainly cause significant changes in the temperature and other properties of the stratosphere...The climate changes that may be produced by the increased CO2 content could be deleterious from the point of view of human beings..."
[nb: The idea of global warming existed as far back as 1965]
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Climatic Change: Are We on the Brink of a Pronounced Global Warming? (1975) LINK
Paper from 1975
Author(s): Wallace S. Broecker; Source: Science, New Series, Vol. 189, No. 4201 (Aug. 8, 1975), pp. 460-463
Published by: American Association for the Advancement of Science; Stable URL: http://www.jstor.org/stable/1740491
Abstract. If man-made dust is unimportant as a major cause of climatic change, then a
strong case can be made that the present cooling trend will, within a decade or so, give
way to a pronounced warming induced by carbon dioxide. By analogy with similar events
in the past, the natural climatic cooling which, since 1940, has more than compensated
for the carbon dioxide effect, will soon bottom out. Once this happens, the exponential
rise in the atmospheric carbon dioxide content will tend to become a significant factor
and by early in the next century will have driven the mean planetary temperature beyond
the limits experienced during the last 1000 years.
HERE is a review by the professional climate science website, www.RealClimate.org
[nb: This 1975 article predicts and is the first to use the term "global warming"]
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Last update 8Feb2017