Other Answers (16)

• I have read that the interglacial warming period is over and we are in a cooling period, maybe the start of a new ice age. Of course it is not a constant cooling, there are short warming periods (remember about 1000 years ago, the Vikings settled and farmed Greenland, named because it was full of green grass) in this long cool down phase. But they say, since the industrial age began, the temperature has never (in one of the warming periods) risen so far and so fast.
  So it may be natural plus we are speeding it up more than %26quot;a bit.%26quot;
  
  %26quot;A controversial new interpretation of climate history suggests that our ancestors who first developed agriculture may have prevented a new ice age by engaging in land-use practices that led to global warming. If a handful of farmers with primitive technologies could alter global environments, what can modern fossil-fuel based technologies do?
  
  Despite what many people have said, if you just do some real journalistic, literary, and educational research, you can find the answer your looking for and make the decision for yourself. One good thing to look at are peer-reviewed articles or articles that have been published in Journals such as %26quot;Environment%26quot;. These are completely science and fact based journals that only publish items that are proven through research and experiment.
  
  I%26#039;ve read a few things and I find that the articles I like most (while sometimes boring) are the ones that are totally factual.
  
  Many articles like this appear in the Annual Editions journal: Environment published by McGraw-Hill. The articles are chosen by a board that includes professors, scholars, and the like.
  
  I totally recommend that you do your own research, and don%26#039;t buy into websites or the media. You have to go to the facts, and also consider who published what you read, AND who funded the publisher AND the research. Getting the facts is a tricky business, but it is well worth it.
  http://www.sciencemag.org/cgi/content/ab...
  
  The other major cause of natural climate change is the Sun. We have good evidence that the Sun has caused past episodes of climate change, such as the %26quot;Little Ice Age%26quot; of the 19th century. So, is the Sun causing the current warmth? No, it%26#039;s not.
  
  2. If the Sun is causing the current warmth, then we%26#039;re getting more energy, and the whole atmosphere should be getting warmer. If it%26#039;s greenhouse, then we%26#039;re getting the same amount of energy, but it%26#039;s being distributed differently: more heat is trapped at the surface, and less heat is escaping to the stratosphere. So if it%26#039;s the Sun, the stratosphere should be warming, but if it%26#039;s greenhouse, the stratosphere should be cooling.
  
  In fact, the stratosphere has been on a long-term cooling trend ever since we%26#039;ve been keeping radiosonde balloon records in the 1950%26#039;s. Here%26#039;s the data:
  http://hadobs.metoffice.com/hadat/images...
  http://hadobs.metoffice.com/hadat/hadat2...
  http://cdiac.ornl.gov/trends/temp/sterin...
  
  3. If it%26#039;s the Sun, we%26#039;re getting more energy during the day, and daytime temperatures should be rising fastest. But if it%26#039;s greenhouse, we%26#039;re losing less heat at night, and nighttime temperatures should be rising fastest. So if it%26#039;s the sun, the difference between day and night temperatures should be increasing, but if it%26#039;s greenhouse, the day-night difference should be decreasing.
  
  In fact, the daily temperature range has been decreasing throughout the 20th century. Here%26#039;s the science:
  http://ams.allenpress.com/perlserv/?requ...
  http://ams.allenpress.com/perlserv/?requ...
  http://www.bom.gov.au/bmrc/clfor/cfstaff...
  
  4. Total solar irradiance has been measured by satellite since 1978, and during that time it has shown the normal 11-year cycle, but no long-term trend. Here%26#039;s the data:
  http://www.ngdc.noaa.gov/stp/SOLAR/solar...
  
  5. Scientists have looked closely at the solar hypothesis and have strongly refuted it. Here%26#039;s the peer-reviewed science:
  http://www.pubs.royalsoc.ac.uk/media/pro...
  http://www.mpa-garching.mpg.de/mpa/publi...
  
  So if it%26#039;s not orbital forcing, like the ice ages, and it%26#039;s not the Sun, what is causing the current warmth? It%26#039;s people, burning fossil fuels, which puts more CO2 into the air.
  
  6. CO2 levels in the air were stable for 10,000 years prior to the industrial revolution, at about 280 parts per million by volume (ppmv). Since 1800, CO2 levels have risen 38%, to 385 ppmv, with no end in sight. Here%26#039;s the modern data...
  http://www.esrl.noaa.gov/gmd/ccgg/trends...
  ... and the ice core data ...
  http://www.ncdc.noaa.gov/paleo/icecore/a...
  http://www.ncdc.noaa.gov/paleo/icecore/a...
  http://www.ncdc.noaa.gov/paleo/icecore/a...
  ... and a graph showing how it fits together:
  http://farm4.static.flickr.com/3006/2615...
  
  7. We know that the excess CO2 in the air is caused by burning of fossil fuels, for two reasons. First, because the sharp rise in atmospheric CO2 started exactly when humans began burning coal in large quantities (see the graph linked above); and second, because when we do isotopic analysis of the CO2 we find increasing amounts of %26quot;old%26quot; carbon combined with %26quot;young%26quot; oxygen. Here are the peer-reviewed papers:
  http://adsabs.harvard.edu/abs/1984JGR......
  http://www.ingentaconnect.com/content/mk...
  http://www.sciencemag.org/cgi/content/ab...
  
  So what%26#039;s left to prove?