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.

·         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.

·         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 more).  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?” - http://www.surfridermb.orgorwww.scseagrant.org/oldsite/library/
library_coaher.htm

·         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.