Climate Change: Facts and Projections
“So here we are. We need, in the next twenty-five years or so, to do something never before done. We need to consciously redesign the entire material basis of our civilization. The model we replace it with must be dramatically more ecologically sustainable, offer large increases in prosperity for everyone on the planet, and not only function in areas of chaos and corruption, but also help transform them.” (Alex Steffen, In: World Changing: A User’s Guide for the 21st Century, 2006)
“A new green ideology, properly defined, has the power to mobilize liberals and conservatives, evangelicals and atheists, big business and environmentalists around an agenda that can both pull us together and propel us forward. That’s why I say: We don’t just need the first black president. We need the first green president. We don’t just need the first woman president. We need the first environmental president. We don’t just need a president who has been toughened by years as a prisoner of war but a president who is tough enough to level with the American people about the profound economic, geopolitical and climate threats posed by our addiction to oil – and to offer a real plan to reduce our dependence on fossil fuels.” (Thomas L. Friedman, The Power of Green, NYT Magazine, April 15, 2007)
"If there's no action before 2012, that's too late. What we do in the next two to three years will determine our future. This is the defining moment." (Dr. Rajendra Pachauri, the head of the UN Intergovernmental Panel on Climate Change, 2008)
Introduction – Although some may think that climate change is a partisan political or special interest issue, the truth is that it is first and foremost a scientific reality. Today, because of mankind’s contribution to global warming, it is also an issue or right and wrong. The purpose of the Kitchen Table Climate Study Group is to inform you about the causes and effects of climate change, especially global warming, and to tell you about what’s happening now and what’s projected for the future. We also want to provide you with some ideas about how to reduce energy consumption as well as some sources of information that will help you to monitor ongoing developments.
I. Early history of climate change
· The earth had a variable climate, with notable hot and cold periods (snowball earth; dinosaur earth) in the very distant past.
The graphs show two sea level reconstructions during the last 500 Myr. The scale of change during the last glacial/interglacial transition is indicated with a black bar. Note that over most of geologic history long-term average sea level has been significantly higher than today. Higher sea levels are associated with warmer temperatures. From http://en.wikipedia.org/wiki/Sea_level
· During the last 3 million years, however, the earth has been slowly cooling. The progressive cooling, shown by the downward trend in the graph below, is sometimes referred to as the Great Ice Age.
Higher levels of O18 isotope in ocean shells (down in the graph) indicates cooler temperatures. From Hansen et al, Climate change and trace gases, Phil. Trans. R. Soc. A, 365: 1945, 2007
II. More recent history of climate change
· The earth’s recent climate cycle - During the last million years of gradual cooling, a repetitive cycle of long (about 100,000 years), cold, dry glacial periods (called “Ice Ages” by some) interrupted by short (about 12,000 years), warm, wet interglacial periods has developed. All of recorded human history has occurred during the most recent interglacial phase.
As measured (or inferred) from Antarctic ice cores, temperature (red curve) and CO2 levels (blue curve) have changed together during the past 350,000 years. The rise and fall of temperature constitute the earth’s ongoing climate cycle. From Understanding and Responding to Climate Change, National Academy of Science, 2006 - http://dels.nas.edu/basc/Climate-LOW.pdf
· During the coldest part of the last glacial period, about 20,000-years-ago, average global temperatures were 7.2º F to 12.6º F (4º C to 7º C) cooler than now and the northern part of the North America was covered with a giant ice sheet that extended from the North Pole all the way to what is now the Pennsylvania/New York state line. See figure below. Northern Europe was also covered by a large ice sheet.
· Due to so much water being stored as ice at the poles and in the ice sheets, sea level was about 396 ft (120 m) below the current level. The new, exposed coastline can be seen in the figure above. As the current warm interglacial period developed, sea level rose to near what it is today. See also the figure below - http://en.wikipedia.org/wiki/Sea_level.
Sea level change since the end of the last glacial episode. Geologists can track and correlate past sea level changes from different sites around the globe by observing the position of coastal sediment deposits. Changes displayed in meters.
· The present situation, with no ice sheet over the northern hemisphere and the current relatively high stand of sea level is, or course, proof positive of global warming as a natural phenomenon. In fact, every interglacial phase is a relatively short period of warming. A recent paper implicates slight variations in solar heat output on timescales of 100,000 years, exactly the interval between ice ages. See http://environment.newscientist.com/article.ns?id=mg19325884.500&print=true
· These findings indicate that earth’s climate is quite dynamic and is capable of switching, sometimes fairly rapidly, between warm and cold conditions.
III. Climate change today. There is very widely supported evidence for a small but significant, unexpected, and rapid global warming due to human activities here in the last hundred years of this interglacial phase. The latest report to and by the governments of the world (the Fourth Intergovernmental Panel on Climate Change or IPCC4) considers it to be “very likely” that the sharp increase in global warming seen since around 1900 is due to human activity, in particular the release of vast quantities of greenhouse gases, due to fossil fuel use. Here are some of the things that are happening:
· Increased warming, about 1.3º F (0.7º C) as a global average, of near earth surface temperatures, especially during the last century. See figure below. (http://www.pik-potsdam.de/~stefan/warmingfacts.pdf; see also http://dels.nas.edu/dels/rpt_briefs/Surface_Temps_final.pdf).
Up until about 1910 aerosols in the air reflected enough sunlight to allow the average temperature to slightly cool. Beginning about then, increasing concentration of greenhouse gases produced enough excess warming to begin to dominate. With passage of the Clean Air Act in the late 1970's and the ensuing reduction in aerosols, greenhouse gas induced warming began a more rapid increase.
· Worldwide melting of mountain glaciers.
· Warming of the oceans, even down to nearly two miles below the surface.
· Thermal expansion of the oceans, leading to increasing sea level.
· Increasing acidification of the world’s oceans.
· Increased water vapor due to warmer air and water temperatures.
· Reduction in snow cover and permafrost in both hemispheres.
· Increased release of methane from melting permafrost.
· Rapid ice shelf collapses in the Arctic and Antarctic.
· Increased rate of ice flow into the ocean from glaciers no longer buttressed by ice shelves in the Arctic,Greenland, and the Antarctic.
· Decreased stability of ice sheets, especially around their edges (Greenland and Antarctica).
· Reduction in the summer area of the Greenland Ice Sheet.
Accelerating rate of sea level rise (from
around 2 mm/yr to perhaps as much as 4 mm/yr or
more, which is 0.91 to 1.82 inches/decade or
For a recent publication concerning sea
level rise along the SC coast see the Winter
2007 edition of Coastal Heritage, “Rising Tide:
Will Climate Change Drown Coastal Wetlands?” -
· Increasing loss of summer Arctic sea ice.
· Rising snowlines on many mountain tops
· Northward migration of tree lines in Scandinavia
· Earlier arrival of Spring-like temperatures and later arrival of Winter-like temperatures.
· Hot nights and heat waves are more frequent.
· Increased frequency of intense storm events, including hurricanes.
IV. The human contribution to global warming: Natural variations in solar radiance, El Nino type phenomenon, and volcanic activity appear not to be able to account for the recent increase in the earth’s temperature. See figure below, which was taken from an article that provides a fine discussion of some of the problems associated with using computer climate models. (http://bostonreview.net/BR32.1/emanuel.html; see also http://dels.nas.edu/basc/Climate-LOW.pdf).
Natural variables (including variations in solar output and volcanic emissions; blue curve) are unable to account for the recent spurt in global warming. When greenhouse gases are taken into account the prediction of computer models agrees with observations (red and black curve). From http://bostonreview.net/BR32.1/emanuel.html
· Greenhouse gases and the greenhouse effect. Greenhouse gases cause more of the sun’s heat to be retained (reflected back towards the earth). Water vapor, methane, N2O, and CO2 are considered to be the principal greenhouse gases.
· The contribution of the US – We, with 4.5% of world’s population, use about 25% of world’s energy resources compared to India where 17% of world’s population uses 3.2%.
· Total greenhouse gas emissions for North America and for China, India, Brazil, Mexico, and South Africa are now about the same, but China’s economy is booming and they are bringing many more coal-fired electric power plants on line than we are, so their contribution will increase rapidly
· Water vapor has a potent greenhouse effect and the amount of water vapor in the atmosphere increases as the atmosphere and oceans warm. However, the increased warming due to increasing water vapor could be diminished due to increased cloud formation. There is little agreement among climate scientists on this point, which may be the basis for the claim by some climate scientists that the present spike in global warming may be temporary.
· Meanwhile, the recent increase in warming correlates well with the rise in CO2 and does not seem to be accounted for without taking CO2 into account.
V. What’s going to happen in the future? Here are the “likely” or “very likely” happenings according to IPCC4:
- Average global warming of an additional 5.4º F (3º C) by 2100, perhaps as much as 8.1 – 9.0º F (4.5º to 5º C). Temperature increases will be considerably higher at the poles.
- Significant ice cap melting and rises in sea level will occur. Based on computer modeling, the IPCC4 projects a minimum rise in sea level of 5 – 23 inches by 2100 and expects sea level rise to continue for centuries. Note that the estimate for 2100 does not take into account ice sheet instabilities, accelerated glacial flow into the sea, and a number of positive feedback processes that seem to be developing. One study that was too recent to be considered for IPCC4 predicts a sea level rise of up to 2.6 to 3.3 feet (100 cm = 3.3 ft) or more by 2100 (Rahmstorf, S. A semi-empirical approach to projecting future sea level rise, Science 315:368-370, 2007).
Rahmstorf’s projection of sea level rise in the coming century based on the historical correlation between global warming and sea level rise. The thick red line is the smoothed sea level data since the late 1800’s. Dashed lines extending out to 2100 show the projected rise based on different temperature change scenarios. (Science 315: 368, 2007)
- Flooding of low lying areas, dependent on the rate and extent of sea level rise.
- More frequent intense storms, both thunderstorms and tropical cyclones.
- It should be noted that the above estimates do not take into account certain positive feedbacks that may be coming into play and which could cause faster, more intense warming or sea level rise.
1. Loss of sea ice reduces reflection of the sun’s rays and causes greater absorption of heat in the Arctic. This effect may be countered by increased cloud formation (http://earthobservatory.nasa.gov/Study/ArcticReflector/).
2. Melting of permafrost releases methane gas (a 20-times more powerful greenhouse gas than CO2)
3. Ocean warming may cause methane gas clathrates to be released from the ocean bottom.
4. Warmer soils do not absorb as much CO2 as cooler soils.
5. Instabilities of ice shelves and Ice sheets have been found to be much greater than believed a few years ago and are especially sensitive to warming ocean waters.
- Don’t panic. But remember, although many
major changes for the US are probably
decades away, the window of opportunity for
averting very disruptive future changes is
short, perhaps only four or five
- Don’t give up hope because the task seems
so frightening and huge. This is an
entirely new problem for human
consciousness, so it is natural that it
feels too big to handle. In fact,
there is no telling what we can accomplish
if we are willing to work together. A
large number of people are already working on
mitigation and ways to begin adapting.
See for example the US Government’s
Climate Change Science Program
the link to Synthesis and Assessment
- We should especially encourage young people
to grapple with this problem since their minds
are less conditioned to the status
- We must all find ways to reduce our own and
our society’s use of fossil fuels,
especially coal; we must work on reducing our
own carbon footprints.
- Energy efficiencies and renewable energy
sources must be encouraged and
- Innovative, sustainable energy technologies
must be encouraged and rapidly
- We must begin a program to educate
ourselves, our children, and our politicians
about the earth’s climate cycle, the importance
of beginning our adaptations to the spike in
global warming, and the need to develop a
- We must begin a reassessment of our values
that, if the situation worsens,
our most cherished ones will survive and
- We may very well have to develop a new
vision of progress, one compatible with lower
population and economic growth.
- To accomplish these ends will require that
we recognize that a genuinely compassionate
adaptation to the burgeoning climate crisis is
the means to the ends of reassessing our values
and finding a new vision of
- We must recognize that now is the time to
begin these tasks, with or without the
leadership of our politicians, with a
commitment to Hope and an expectation of
- We must press our views upon and demand progressive action by our elected representatives and by our utility companies.
VII. How to reduce personal energy use now?· Drive less, slow down, car pool more, and strive for fuel efficiency
· Keep tires properly inflated
· Replace regular light bulbs with compact fluorescent bulbs
· Replace old appliances with energy efficient models
· Decrease home heating and cooling, maximize home insulation, retrofit when possible
· Lower the temperature setting on hot water heater; retrofit with an “on demand” hot water heater
· Recycle more
· Use cloth bags for carrying groceries
· Use biodegradable and compostable paper plates and carry-out containers
· Plant a tree
- Turn off electronic devices when not in use
· Build renewable energy sources into your new home
VIII. Resources for learning more and keeping up with the science of global warming and the earth’s climate cycle.
· Real Climate – a very informative website maintained by climate scientists - http://www.realclimate.org/
· Intergovernmental Panel on Climate Change: To see the reports - http://www.ipcc.ch/ For more extensive coverage see - http://www.usgcrp.gov/usgcrp/links/ipcc.htm#4wg1. For more links see IPCC Facts - http://www.ipccfacts.org/index.html
· Live Science - http://www.livescience.com/environment/
· Accuweather - http://global-warming.accuweather.com/
· US Government - http://www.epa.gov/climatechange/
· US Government - http://www.climatescience.gov/
· League of Conservation Voters coverage of Presidential candidates’ positions on climate change - http://www.heatison.org/
· National Wildlife Federation - http://www.nwf.org/globalwarming/
· Newspaper coverage - http://news.independent.co.uk/environment/
· Newspaper coverage - http://www.nytimes.com/pages/science/earth/index.html
IX. Some websites for skeptics. Today, only a few people dispute the reality of an ongoing spike in global warming. There remain, however, some very qualified scientists and other individuals who vigorously dispute that greenhouse gases are the cause of the warming. Variations in solar irradiation, cosmic rays, and sunspots appear to be the main alternate culprits for these individuals. Most of the arguments raised by skeptics have been rebutted at the Real Climate website listed above. The link below can be followed to find some of the skeptical points of view.
X. Reconciling the different points of view. The proof of the pudding will be in the eating: Watch how CO2 levels, temperature, and sea level increase over the course of the next few years compared to what has been predicted (see figure on pg. 6). In addition, pay attention to what’s happening with the Arctic summer sea ice melt and the Greenland and West Antarctic Ice sheets. If rates of change are greater than predicted, then action more rapid than previously anticipated will be required. The McClellanville Kitchen Table Climate Study Group will try to keep you informed with monthly meetings or movies and via regular posting of climate change news at our website.
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“We basically have three choices: mitigation, adaptation and suffering. We’re going to do some of each. The question is what the mix is going to be. The more mitigation we do, the less adaptation will be required and the less suffering there will be.” (John Holdren, President of the American Association for the Advancement of Science, New York Times, Jan. 30, 2007)
"There is such a thing as being too late…. Life often leaves us standing bare, naked, and dejected with lost opportunity…. Over the bleached bones of numerous civilizations are written the pathetic words: ‘Too late.’” (Martin Luther King, Where do we go from here: Chaos or community?)
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(Prepared for the Kitchen Table Climate Study Group, McClellanville, SC, by S. David Stoney, Ph.D. Suggestions for improvements are welcomed – firstname.lastname@example.org 07/26/08)