Many will be satisfied with the professional society policy statements. These are provided first, followed by a list of specific sources providing progressively more scientific detail. Of particular note are Spencer Weart’s The Discovery of Global Warming history and science site at the American Institute of Physics, RealClimate: Climate science from climate scientists with its comprehensive resources, and the Berkeley Earth Surface Temperature project noted for directly addressing issues raised by climate skeptics in the wake of the ”Climategate” controversy. Subsequent sections introduce specific aspects of climate study, and illustrate specific indicator fingerprints of man’s contribution (and cause) of Earth’s warming climate.

The first is a section on Earth’s Atmosphere, how earth’s surface temperature is measured, and how we know anthropogenic greenhouse gases – notably carbon dioxide – are responsible for warming. The fingerprint section looks, as a specific example, at the simultaneous warming of the troposphere and cooling of the stratosphere. This is a differential measurement that largely rejects common mode effects such as varying albedo and solar irradiance.

A Matter of Heat introduces some concepts of radiative transfer and radiative forcing. The section on Anthropogenic Forcing links several papers discussing the predominant role of greenhouse gases in Earth’s current energy imbalance. References are provided showing just how small the forcing from solar variations is relative to human greenhouse gas contributions. Set in the context of the Maunder Sunspot Minimum during the 17th century Little Ice Age, these show a miraculously cooler sun will not free us from our dilemma. Nor will the relatively feeble irradiance forcings from orbital perturbations (Milankovitch Cycles).

As most of earth’s surface heat energy resides in her oceans, we provide a few references that describe how ocean temperatures are measured, and link the results obtained from the modern Argo free-floating system of sounding buoys with those of the pioneering Challenger survey one hundred forty years ago. We introduce Attribution Analysis and cite model studies that link ocean warming patterns to the distribution of anthropogenic greenhouse gases. Models that included only solar variations could not reproduce the fingerprint observed in the Challenger/Argo record.

Most of today’s climate skepticism was generated by the so-called ”Climategate” disinformation campaign running up to the 2009 Copenhagen Climate Conference. We provide a few references to the ensuing witch-hunt before moving on to one beneficial result: the independent review of global warming data and conclusions by Prof. Richard Muller’s Berkeley Earth Surface Temperature project, which found remarkably close agreement between their analysis and those of the major climate research groups.

Mankind’s influence on climate is not limited to anthropogenic greenhouse gases. We conclude with a short section on contributions from soot.

Contents

List of Figures

1.1 Statement of the American Geophysical Union

From the American Geophysical Union’s 2012 Position Statement (pdf):

Continued at AGU Position Statement, Human Impacts on Climate (html).

1.2 Statement of the American Physical Society

From the American Physical Society’s National Policy Statement:

From the 2010 Commentary:

Continued at National Policy Statement 07.1 Climate Change.

2.1 NOAA

National Oceanic and Atmospheric Administration.

NOAA: National Climate Data Center.

NOAA: Global Warming Frequently Asked Questions. (General Audience)

NOAA: The State of the Climate 2009 Highlights. (General Audience)

NOAA: How Do We Know The World Has Warmed (pdf). (General Audience)

NOAA: The State of the Climate 2009. (Scientific)

NOAA: Past Decade Warmest on Record According to Scientists in 48 Countries:

The 2009 State of the Climate report draws on data for 10 key climate indicators that all point to the same finding: the scientific evidence that our world is warming is unmistakable. More than 300 scientists from 160 research groups in 48 countries contributed to the report, which confirms that the past decade was the warmest on record and that the Earth has been growing warmer over the last 50 years...

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Figure 1: Ten Climatic Indicators

Source: The State of the Climate 2009.

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”Despite the variability caused by short-term changes, the analysis conducted for this report illustrates why we are so confident the world is warming. When we look at air temperature and other indicators of climate, we see highs and lows in the data from year to year because of natural variability. Understanding climate change requires looking at the longer-term record. When we follow decade-to-decade trends using multiple data sets and independent analyses from around the world, we see clear and unmistakable signs of a warming world.” -Peter Stott, head of Climate Monitoring and Attribution, UK Met Office Hadley Centre.

NOAA: The State of the Climate 2011 report is not just a rehash of 2009, and has different organization.

2.2 American Institute of Physics

The Discovery of Global Warming: A hypertext history of how scientists came to (partly) understand what people are doing to cause climate change. (December 2011, periodically updated.) For those interested in historical and geophysical details, Spencer R. Weart (former Director of the Center for History of Physics of the American Institute of Physics) has intended this informative little project to be a one-stop shop for climate change at several levels. Recommended.

2.3 Intergovernmental Panel on Climate Change

IPCC: Home Page.

IPCC: Publications and Data Reports.

IPCC: Assessment Reports.

2.4 Center for Climate and Energy Solutions

”Launched in November 2011, C2ES is the successor to the Pew Center on Global Climate Change. C2ES believes that ensuring safe, reliable, affordable energy for all – while protecting the global climate – is a paramount challenge of the 21st century.” This is actually a pretty large and comprehensive site; not lending itself to sound-bite synopsis. Here are a select-pew links:

C2ES: Home Page.

C2ES: Science Impacts.

C2ES: Global Warming Facts and Figures

C2ES: The Candidates on Climate and Energy: A Guide to the Key Policy Positions of President Obama and Governor Romney

2.5 National Academy of Science

NAS: Home Page

NAS: Publications

NAS: America’s Climate Choices Final Report. 2011. Comprehensive Policy Statement and Recommendations.

NAS: What You Need to Know About Energy. 2008. Informative basic overview.

SkS: Video on Climate Change Lines of Evidence by the National Academy of Science.

2.6 RealClimate

RealClimate: Climate science from climate scientists maintains another, more comprehensive one-stop directory of links to climate change information. It includes Spencer Weart’s The Discovery of Global Warming site referenced above, as well as links to information provided by NCAR, NASA, National Academy of Science, SUNY Suffolk, UK Government, IPCC, New Scientist, UK Met Office, and more. (Much more. Global Circulation and Radiative Transport Codes. Data. Visualization. Sigh.) Highly recommended.

2.7 SkepticalScience

Skeptical Science gets skeptical about global warming skepticism. Explaining climate change science & rebutting global warming misinformation:

• Skeptical Science Home.
• Global Warming and Climate Change Myths.
• The Scientific Guide to Global Warming Skepticism (html). The Scientific Guide to Global Warming Skepticism (pdf).

Edited and largely written by climate and journalism professionals, a comprehensive resource for up-to-date information on misinformation. Plenty of good climate science, too. Recommended.

2.8 The Daily Climate

The Daily Climate is, of course, weather. It is also rather more variable and eclectic in the variety of its topics than some other sites.

2.9 Global Warming, Man or Myth?

Global Warming, Man or Myth?. Scott A. Mandia is Professor of Earth and Space Sciences and Assistant Chair of the Physical Sciences Department at Suffolk County Community College, Long Island, New York, USA. From his introduction:

2.10 Berkeley Earth

The Berkeley Earth Surface Temperature Study (BEST) was initiated by Physics Prof. Richard Muller with the aim of independently verifying the climate research inaccuracies alleged by skeptics following the 2009 theft and selective dissemination of emails between East Anglica’s Climatic Research Unit Director Phil Jones and other members of the climate community. The BEST study group consisted of physicists and mathematicians not otherwise associated with climate research. Their results confirmed that the accepted ”main stream” temperature data was valid and

In a 30 July 2012 New York Times column, Prof. Muller wrote:

Also see Berkeley Earth below.

2.11 Other

Other comprehensive references as I find them:

• Prospects for Future Climate Change and the Reasons for Early Action . ISSN:1047-3289 J. Air & Waste Manage. Assoc. 58:735786 (2008) DOI:10.3155/1047-3289.58.6.735. 53 page review article by Michael MacCracken, Climate Institute, Washington DC.

  ”This review seeks to provide a bridge from basic understandings about physics and the climate system to the latest results that are presented in support of acting to limit further change. The review does not attempt to be comprehensive, and is instead organized around six over-arching findings related to the nature and impacts of climate change. These findings are each strongly supported by the understanding gained through the IPCC assessments, presenting the underlying reasoning and seeking to build intuitive understanding.”

Earth’s atmospheric temperature and pressure both smoothly vary with altitude. Pressure decreases, but temperature both decreases in some regions and increases in others. Atmospheric scientists divide the atmosphere into four such regions – Troposphere, Stratosphere, Mesosphere, and Thermosphere – separated by boundaries where temperature stops decreasing with with altitude and begins increasing (tropopause and mesopause), or alternatively stops increasing with altitude and and begins decreasing again (stratopause). A fifth region, the Exosphere, is the very top-most region of the atmosphere whose lower boundary is loosely defined as that altitude above which molecular collisions are rare and upward-moving gas molecules follow essentially ballistic trajectories, being brought back to earth only by the attraction of earth’s gravity. Extending roughly half the distance to the moon, the exosphere is the transitional zone between Earth’s atmosphere and interplanetary space. These atmospheric layers are illustrated in Fig. 2. Radiation penetration depths and layer properties are respectively diagrammed in Figs. 3 and 4.

3.1 Taking earth’s temperature

As with most geophysical measurements, taking an accurate reading of earth’s mean global surface air temperature is a bit harder than it looks. For example, one must define what one means by ”surface air”, as sunlight-warmed ground can heat the air in its closest proximity by direct convection. Sources of information:

• Direct measurement by surface thermometer: Instrumental temperature record.
• Direct measurement by satellite: For example, Envisat’s Advanced Along Track Scanning Radiometer provided surface temperature measurements good to with 0.3C (0.5F) with stability to within 0.1C/decade.
• Indirect inference from oxygen isotope ratios in Ice Cores.
• National Academy of Sciences Surface Temperature Reconstructions for the Last 2,000 Years (2006):

  ”The Earth warmed by roughly 0.6${}^{\circ }$C (1${}^{\circ }$F) during the 20th century and is projected to warm by an additional $2^{\circ }-6$${}^{\circ }$C during the 21st century.

An overview of temperature determination with periodic updates is at GISS Surface Temperature Analysis (GISTEMP). A cited scientific reference explaining the NASA/GISS approach is Hansen et al. (2010) Global Surface Temperature Change (pdf).

3.2 Taking man’s fingerprint

Beginning at the turn of the last century with the work of Swedish chemist Svante Arrhenius, geoscientists eventually obtained two seminal results:

• First, early observations of the relative infrared saturation of CO2 and water vapor notwithstanding, any increase in surface CO2 concentration must eventually propagate upward through the atmosphere and raise the effective CO2 emission altitude. The temperature at this altitude – whatever it is – must remain constant for a given solar constant, and increasing its altitude must require warming at the surface and all levels in between.³ The same holds for water vapor or any other greenhouse gas: adding more to the atmosphere must result in warming at the surface. (See Simple Models of Climate Change for further explanation.)
• Second, Carbon dioxide is the long-lived thousand year tail that wags the ephemeral water vapor dog: increased surface CO2 emissions that warm the lower atmosphere (troposphere) will cause additional net water evaporation there as well. But as water’s saturation vapor pressure drops precipitously beneath its freezing point, most water is trapped in the troposphere. The stratosphere and mesosphere remain relatively dry.⁴
• Moreover, as air grows colder and less dense, there becomes less and less overlap between the emission/absorption bands of water vapor and those of CO2. Although the latter is thoroughly mixed throughout the troposphere, stratosphere, and mesosphere, in the upper two regions CO2 becomes largely transparent to radiation from water vapor in the lower troposphere. ⁵
• Increased tropospheric water vapor increases tropospheric infrared emission far beyond that due to increased carbon dioxide alone. In the absense of increased solar radiation, the total amount of energy radiated by the atmosphere must remain constant: increased tropospheric water vapor shifts the bulk of the atmospheric radiation to a lower altitude, and shifts the radiation frequency bands to those of water vapor from those of CO2.
• But even as CO2 levels increase throughout all levels of the atmosphere, increased water emission from the troposphere comes at the expense of CO2 emission from that region. As result, stratospheric and mesospheric CO2, while continuing to radiate upward, receives less warming in its absorption bands from below. These upper levels then cool even as the troposphere warms.
• As an aside, it should also be noted that ozone depletion also contributes to stratospheric cooling. However, it also leads to net tropospheric cooling as well. From Wikipedia’s Ozone depletion:

  ”One of the strongest predictions of the greenhouse effect is that the stratosphere will cool.⁶ Although this cooling has been observed, it is not trivial to separate the effects of changes in the concentration of greenhouse gases and ozone depletion since both will lead to cooling. However, this can be done by numerical stratospheric modeling. Results from the National Oceanic and Atmospheric Administration’s Geophysical Fluid Dynamics Laboratory show that above 20 km (12 mi), the greenhouse gases dominate the cooling.⁷”

To repeat: (1) Increasing carbon dioxide and water vapor at the earth’s surface results in an expanded and warmer lower atmosphere (troposphere) and cooler stratosphere, as opposed to (2) increasing solar radiation which results in warming at all levels.⁸,⁹

Of course, atmospheric heating is a bit more complicated than this qualitatitive one dimensional radiation transport argument. Meaningful quantitative results require coupling radiative transport to at least a simple atmospheric circulation model to account for convection and water vapor transport.¹⁰

Accurate stratospheric temperatures have been available the past 50 years, and clearly display the tell-tale tropospheric heating / stratospheric cooling signature expected of low-altitude heating from greenhouse gases. This is illustrated by the following figure from The State of the Climate 2009:

Of further interest from Wikipedia’s Instrumental temperature record:

See Berkeley Earth below. As compelling as they may be, atmospheric temperature profiles and land surface temperatures are not quite the entire story: some mention might also be made of near-surface sea temperature and heat content. Man’s fingerprints may be found on those as well.

Early 19th century natural scentists – particularly those in Europe – were fascinated with field observations that suggested much greater glacial extent in the perhaps not-too-distant geological past, and a coincident cooler climate. They were also beginning to get a handle on heat. We introduce the solar constant as a measure both of the solar radiation incident upon earth, and the power the earth must reflect or radiate to maintain constant temperature. This allows us to define radiative forcing as a measure of the imbalance in atmospheric energy flow introduced by increasing (or decreasing) atmospheric greenhouse gases, atmospheric aerosols, or surface reflectivity (albedo). We then look at man’s contribution to Earth’s present heat imbalance. In subsequent subsections we look at studies of the effect of possible variations in the solar constant as exemplified during the Little Ice Age, and the effects variations in Earth’s orbital parameters had (or may have had) on climate during the Pleistocene Ice Age. We see these solar and orbital effects are dwarfed by modern anthropogenic greenhouse forcing.

The Solar Constant (total solar irradiance, total solar insolation) is defined as the quantity of solar energy at normal incidence outside the atmosphere at the mean sun-earth distance. The luminousity of the Sun, its total energy output, is $L\approx 3.86\times 10^{26}$ Watts. Earth’s mean distance from the sun, 1 AU (astronomical unit) is $r\approx 1.5\times 10^{11}$meters. The power per unit area at 1 AU is the solar constant: $L∕\left(4\pi r^2\right)\approx 1366$$\mathrm{W∕<msup><mrow>m</mrow><mrow>2</mrow></msup>}$. (DJ Jeffery Lecture 8: The Sun.)

The Earth’s mean radius $R_E=6,371$km, and its surface area $5.1006\times 10^{14}{\mathrm{m}}^2$. 340 Watts is the average amount of power received by each square meter of the Earth’s surface. Ignoring the (relatively) small amount of energy contributed by cooling of the earth’s core,¹³ 340 watts is also the amount of power each square meter must either reflect or radiate, on average, when the earth’s temperature is at equilibrium. About 48% of this (163 watts) is actually absorbed by the earth’s surface, the remainder is reflected or directly absorbed by the atmosphere as illustrated in Fig. 6:

4.1 Radiative Forcing

”Radiative Forcing” has several similar but not quite identical definitions. From Wikipedia:

This second, more restricted definition allows climate scientists to speak of the relative forcing contribution of water vapor independent of that of carbon dioxide, even though the actual amount of water vapor in the atmosphere depends strongly upon temperature, and is therefore sensitive to the amount of carbon dioxide. The tropopause is the boundary between the troposphere and stratosphere, the nominal elevation at which temperature stops decreasing with altitude in the turbulent troposphere, and begins its gradual increase with altitude in the calm stratosphere where heating is driven by oxygen and ozone absorption of ultraviolet radiation. See Troposphere, Stratosphere, and Idealized Greenhouse Model.

4.2 Anthropogenic Forcing

In Anthropogenic and natural warming inferred from changes in Earths energy balance,¹⁴ Markus Huber and Reto Knutti describe an extensive study comparing fifty years of observational geothermal and energy data with extensive modeling of natural and anthropogenic forcing factors to provide a natural/anthropogenic attribution estimate independent of spatial warming patterns and dependent only on known changes to Earth’s net energy balance and in radiative forcing. They found that ”since the mid-twentieth century, greenhouse gases contributed 0.85${}^{\circ }$C of warming (5 - 95% uncertainty: 0.6 - 1.1${}^{\circ }$C), about half of which was offset by the cooling effects of aerosols, with a total observed change in global temperature of about 0.56${}^{\circ }$C.” Forcings modeled included CO2, Methane, N2O, Halocarbons and Montreal gases, Stratospheric ozone, tropospheric ozone, direct and indirect aerosols, black and organic carbon, stratospheric water vapour, volcanic ash, gases, and aerosols, and solar. Using the SRES A2 projected emissions scenario (considered most likely), the authors calculate ”the historic cumulative forcing would be doubled in the next 33 (28-38) years and tripled in 52 (45-60) years.”

Huber and Knutti estimate a net positive forcing of 0.54 (0.36-0.76)$\mathrm{W∕<msup><mrow>m</mrow><mrow>2</mrow></msup>}$. See New approach to determining human impact on climate gives same answer for further commentary.

These results are corroborated in a contemporary research briefing by Hansen et al. Earth’s Energy Imbalance:

To repeat: the Earth’s current net energy imbalance is $0.58\pm 0.15\mathrm{W∕<msup><mrow>m</mrow><mrow>2</mrow></msup>}$ positive, at the deepest solar minimum yet recorded.(Modern minimum; see Fig. 7 and ”Solar Variations” below.) The negative solar forcing due to the present (2011-2012) solar minimum is utterly overwhelmed by positive anthropogenic greenhouse gas forcing, even when all other negative forcings are considered. The Hansen group concludes ”(T)he Earth’s energy imbalance confirms an earlier estimate on other grounds that CO2 must be reduced to about 350 ppm or less to stabilize climate...”

Such CO2 reduction is, of course, simply not possible. The toothpaste is out of the tube.

4.3 Solar Variations and the Little Ice Age

The sun is not quite constant, and it has long been speculated the $\sim 600$ year Little Ice Age commencing about 1300 A.D. may have been result of solar variation, as evidenced by the 17th century Maunder Sun-Spot Minimum.¹⁵ The possible degree of solar forcing during that period is quantified and compared with that of greenhouse gases by George Fuelner,¹⁶ who shows the TSI (total solar irradiance) at the Maunder Minimum differed from that of the 2008 minimum by less than 1$\mathrm{W∕<msup><mrow>m</mrow><mrow>2</mrow></msup>}$ (negative), and possibly as little as 0 - 0.3 $\mathrm{W∕<msup><mrow>m</mrow><mrow>2</mrow></msup>}$. Modern GHG forcing is about 3 $\mathrm{W∕<msup><mrow>m</mrow><mrow>2</mrow></msup>}$, and aerosol cooling at about -1.5 $\mathrm{W∕<msup><mrow>m</mrow><mrow>2</mrow></msup>}$, both of which are considerably larger than any possible solar forcings during the Little Ice Age and preceding Medieval Warm Period. Feulner concludes

• Large TSI variations are inconsistent with the climate record
• TSI was only moderately reduced during the Maunder Minimum
• Solar activity was not the dominant driver for the Little Ice Age

Although Delaygue and Bard come to a reasonably agreeable 1$\mathrm{W∕<msup><mrow>m</mrow><mrow>2</mrow></msup>}$ estimate from $\mathrm{B<msup><mrow>e</mrow><mrow>10</mrow></msup>}$ ice core data,¹⁷ Feulner’s conclusion that ”Solar activity was not the dominant driver for the Little Ice Age” is supported by a recent study suggesting vulcanism to be the trigger.¹⁸

The 2008 solar minimum was at about 1365.24 $\mathrm{W∕<msup><mrow>m</mrow><mrow>2</mrow></msup>}$¹⁹ Spencer Weart concludes Changing Sun, Changing Climate? with:

Emphasis added. Additional Solar Variability references are collected at NOAA Paleoclimatology Climate Forcing Data.

4.4 Orbital Variations and Major Glaciations

Facination with Ice Ages and their possible cause was the original driver of the science of climatology. By the end of the twentieth century the idea that, given a suitable global distribution of land mass, glacial periods could be triggered by subtle interactions between orbit variations (Milankovitch Cycles) and carbon dioxide forcings, had gained wide acceptance and remains an area of active research.²⁰ The excellent PBS video Is an Ice Age Coming?helps visualize Milankovitch cycles and their climate couplings during the Quaternary (Pleistocene through present). Here we discuss results of detailed modeling that show the great Pleistocene Glacial Periods (”ice ages”) cannnot recur during the current era of orbital variations and land mass distributions, at our present levels of CO2.

For an Ice Age to occur, continents must be distributed such that there is sufficient land near the poles to support glacial ice caps, and a continuous landlink between the polar regions to direct ocean currents to transfer heat between them. These requirements are met today by the locations of Greenland, Canada, northern Europe and Siberia in the north, Antarctica in the south, and the North-South American continental link between them. The last was completed with the raising of the Panama Isthmus and closing of the Central American Seaway about 5 million years ago.²¹ Estimated global temperatures during this modern epoch are shown in the right half of Fig. 8, CO2 in Fig. 9:

During the recent Pleistocene Ice Age carbon dioxide concentrations fluctuated between a low of about 160-180 ppm during glacial periods, and maximum of about 280 ppm during interglacials, as shown in Fig. 9. The 110 ppm difference between our current post-industrial CO2 level of 390 ppm and the interglacial maximum already exceeds the entire 100 ppm CO2 fluctuation range during that Ice Age. Detailed models that couple climate with glaciation show that with today’s orbital configuration and expected future variances, another glacial period cannot occur until CO2 concentrations again dip beneath 240-280 ppm. Even if we were to stop all greenhouse gas emission today - an impossibility - CO2 concentrations could not drop to such pre-industial levels for tens of thousands of years.²³

Increasing carbon dioxide concentrations will not stop – cannot stop – at today’s 390 ppm. Indeed, greenhouse gases are unlikely to stabilize even beneath 650 ppm CO2 equivalent, well over twice the Pleistocene maximum.²⁵ Developed and developing world economies are all powered by cheap, reliable electricity. For homes, for offices, for farms, and particularly for industry.²⁶ The cheaper and more reliable its electric power, the better off a country’s people, and the more competitive they are with respect to their neighbors and the world economy at large. Coal is cheap to mine, cheap to transport short distances, and coal-fired power plants are cheap to build and get reliably operational without a large amount of additional infrastructure. A nationwide power grid is not required. Coal is ubiquitous and cheap. Cheap as dirt.

The economics of coal are so compelling it is estimated the electric power needs of growing economies in Asia and the subcontinent will be limited not by the abundance of coal, but by the availability of water for mining and transport, and to cool the generators. Only then can they turn to more expensive energy options.²⁷

The Holocene is history. Warmly welcome the Anthrocene!²⁸

Such a numerical experiment is termed an ”attribution analysis”, as it attempts to attribute different contributions of the observed trend to different input components of the models. An example is provided by NCAR, reproduced here as figure 11:

Image source: Meehl, G.A., W.M. Washington, C.M. Ammann, J.M. Arblaster, T.M.L. Wigley and C. Tebaldi, 2004: Combinations of Natural and Anthropogenic Forcings in Twentieth-Century Climate. J. Climate, 17, 3721-3727. Similar results using more recent models are in Solar and Greenhouse Gas Forcing and Climate Response in the Twentieth Century . J. Climate, 16, 426-444.

Although ocean temperatures have spatial and temporal variations of their own, their heat capacity and slow mixing rates relative to the atmosphere allow long-term oceanic temperature trends to complement the land surface temperature record, and in some sense smooth the rapid variations seen in land measurements. We link modeling results that show measured oceanic spatial and temporal thermal variations cannot be explained by models of solar variation alone, but fit remarkably well to models incorporating anthropogenically distributed surface-level greenhouse gas.

In 1872 HMS Challenger commenced an historic three and a half year oceanographic survey, sounding the depths, collecting sediment samples, and recording temperature profiles in nearly 300 locations in the Atlantic and Pacific basins. She discovered the submerged mountains of the Mid-Atlantic Ridge, and the oceans’ stratification by temperature.

The 21st century dawned with deployment of Argo, a global array of over 3,000 free-drifting profiling floats that measure the temperature and salinity of the upper 2000 m of the ocean. This allows, for the first time, continuous monitoring of the temperature, salinity, and velocity of the upper ocean... Deployments began in 2000 and continue today at the rate of about 800 per year.

From Researchers match modern ocean temperature records to those of the 1870s:

Source Article: Nature Climate Change 2, 425-428 (2012) 135 years of global ocean warming between the Challenger expedition and the Argo Programme. DOI: 10.1038/NCLIMATE1461

XBT was an earlier United States Navy float system not originally intended for scientific application. But it was what was available, and Argo data has been beneficial in reducing uncertainties in XBT. Figuring out how fast the ocean is warming concludes ”the oceans have warmed at a rate of $0.64\pm 0.11W∕m^2$ for the entire 16-year period”, consistent with the above $0.59^{\circ }\mathrm{C}\pm 0.12$.

Finally, from The Computer Models Vindicated (1990s-2000s):

In November 2009 unknown parties with unknown agenda stole what had been considered private emails between widely – though not uniformly – respected East Anglica Climate Research Unit (CRU) Director Phil Jones and other members of the climate research community. These created a minor sensation when selectively published out of context on the internet, and there were indignant calls for Jones’ resignation.

Seven University, Parliamentary, and a National Science Foundation investigation later, no scientific misconduct was uncovered and Jones retained his position without reprimand, albeit with the understanding that England’s Freedom of Information Act should be respected regardless of the perceived trollish origins of a particular request, and that the climate community as a whole might better serve the public by being more open with its data. See Additional Climategate Commentary, and Wikipedia’s Climatic Research Unit email controversy.

Such has been done, with one positive outcome being Prof. Richard Muller’s Project Berkeley Earth.

The Berkeley Earth Surface Temperature Study

From The Guardian: Can a group of scientists in California end the war on climate change? .

So, what did The Berkeley Earth Surface Temperature Study find? Essentially, they reproduced the results previously obtained by the ”Big Three” – NASA GISS, NOAA/NCDC, and Hadley/CRU – with remarkable precision. In addition, the Berkeley group pushed the temperature record back another century, to 1750 AD (land coverage $\sim 5\%$). From their Web Page:

Additional commentary:

Climate skeptics perform independent analysis. John Timmer - Oct 24 2011.

Berkeley Earth project is back to re-re-confirm Earth is warming. John Timmer - July 30 2012.

Koch-Funded Study Finds ‘Global Warming Is Real’, ‘On The High End’, and ‘Essentially All’ Due To Carbon Pollution. Joe Romm - Jul 28 2012.

The Conversion of a Climate-Change Skeptic. Richard A. Muller - July 28 2012.

Relatively easy (relative to reduction, capture, and sequestration of CO2) solutions include replacement of old diesel engines, coal power plants, and traditional wood and coal-burning cooking stoves with more modern, cleaner-burning alternatives – even those using the same fuels. Education must play a central role: much of the third world (and first) does not know how to get best cleanliness and efficiency from the internal combustion engines they have. And bombing ”them” into oblivion with new cook-stoves won’t do any good if ”they” are left uninformed about how to cleanly burn wood, grass, or coal, and why it is important to do so:

Soot warming ’maybe bigger than greenhouse gases’ - NASA.

Soot Ranks Second After CO2 in Arctic Ice Melt Warming Contribution.

Sulfates plus black carbon a nasty combo for warming.

We make passing mention to atmospheric aerosols. These are mostly short-lived. Wind-blown Dust and volcanic ash fall out by gravity within a few years of injection. The other major atmospheric reflectors are sulfates, mostly SO2 and SO3. These readily react with water vapor and precipitate as acid rain. Apart from some very delicately balanced (CO2, glaciers, sea-ice) eras such as occured during the Little Ice Age, which apparently was ending even before man’s intervention, it would seem aerosols can have no long-term climate effect without frequent or continuous re-injection.

We provided excerpts from AGU and AIP policy papers and provided links to comprehensive climate and global warming resources. We then made cursory introduction to basic ideas of atmospheric layers, heat, and radiation transport.

We discussed three signature fingerprints of man’s responsibility for global warming:

• Increasing troposphere temperature coincides with simulataneous decrease in stratosphere temperature, an effect that – after allowing for stratospheric ozone depletion – may be explained only by increasing greenhouse gases – notably CO2 and water vapor – in the troposphere.
• Earths energy budget shows an increasingly positive flow of solar energy into the combined atmosphere / ocean system at a time of decreasing solar output, a finding that again may be explained only by increasing greenhouse gases in the troposphere.
• Earth’s ocean circulation is at least moderately complex, and the changing temperature gradients with depth and time vary from one location to another throughout the ocean basins. The patterns of these changes are consistent with increased greenhouse gases over the past 135 years, and not consistent with internal ocean variations or variations in solar flux.

We cite studies that show that if the Little Ice Age was caused by decreased solar flux, the negative forcing of that decrease was no more than half the current positive greenhouse forcing. Likewise, if the major Pleistocene glacial periods were triggered by orbital variations, at 390ppm current CO2 levels are at least 100ppm too high for such glaciation to recur. Neither the sun, the moon, nor the planets will relieve us from responsibility for human-induced global warming.

We touched upon the economics of coal and electric power, and the bottom line bears repeating: global greenhouse gas emissions will continue to rise – and probably accellerate – unless we develop and deploy a reliable emissions-free electric power technology that is cheaper to install and become operational, than coal.

We have focused on carbon dioxide and water vapor as the predominant greenhouse gases in this thin overview. They are not the only ones of course, and the role of methane in particular may will significantly increase in the not-too-distant future. An 80% reduction in all greenhouse gas emissions would be necessary to stabilize future greenhouse radiative forcing to 2010 levels. Even if that were possible, the planet will continue to warm until its energy balance again becomes neutral³²:

A similar study

Finally, correlation of future CO2 concentrations with past, current, and projected fossil fuel carbon release is discusssed in Future Climate Change, and illustrated by Fig 17:

For more information see Energy Realities Infographics, which includes population projections, and its CO2 Emissions Scenarios.

1. Nature 484, 228-232 (12 April 2012) Aerosols implicated as a prime driver of twentieth-century North Atlantic climate variability. doi:10.1038/nature10946
   ”Our findings suggest that anthropogenic aerosol emissions influenced a range of societally important historical climate events such as peaks in hurricane activity and Sahel drought. Decadal-scale model predictions of regional Atlantic climate will probably be improved by incorporating aerosol – cloud microphysical interactions and estimates of future concentrations of aerosols, emissions of which are directly addressable by policy actions.”
2. Skeptical Science has a nice video that shows the effect on the recent (35-year) temperature trend of removing the contributions to volcanoes (such as Pinatubo and El Chinchon), solar actrivity (minor) and El Nino / La Nina. Evens out some natural variations in the upward trend, which is seen to be maintaining apace.