AR4 Climate Change
Byline: Francis N. Tolentino
NO doubt, it's a scorching summer that we have. Even in relatively cooler places like Baguio City and Tagaytay, temperatures have steadily increased in the past days. Environmentalists warn that these are indications of sustained global warming, and that should humans continue to be indifferent about what they do to their environment, the worst is yet to come.
Climate Change 2007, the Fourth Assessment Report (AR4) of the United Nations Intergovernmental Panel on Climate Change (IPCC), is well underway. Like the three other reports that preceded it (consecutively released in 1990, 1995, and 2001), the fourth assessment is comprised of four distinct sections, namely:
1. Working Group I Report (WGI): Climate Change 2007: The Physical Science Basis
2. Working Group II (WGII): Climate Change 2007: Impacts, Adaptation, and Vulnerability
3. Working Group III (WGIII): Climate Change 2007: Mitigation of Climate Change
4. The Synthesis Report (SYR)
Of these four parts, two (WGI and WGII) have already been released last February 2, 2007 and April 6, 2007 respectively. The WGIII report is due for release on May 4, 2007 while the Synthesis Report is expected to come out by the last quarter of 2007.
We recall having written sometime in February about the WGI report where the following key conclusions were made:
1. Warming of the climate system is unequivocal.
2. Most of the observed increase in globally averaged temperatures since mid-20th century is very likely due to the observed increase in anthropogenic (human) greenhouse gas concentration.
3. Hotter temperatures and rises in sea level would continue for centuries no matter how much humans control their pollution, although the likely amount of temperature and sea level rise varies greatly depending on the fossil intensity of human activity during the next century.
4. The probability that this is caused by natural climatic processes alone is less than five percent (5%).
5. World temperatures could rise by between 1.1 and 6.4 degrees Celsius during the 21st century and that:
1. Sea levels will probably rise by 18 to 59 cm.
2. There s a confidence level >90% that there will be more frequent warm spells, heat waves and heavy rainfall.
3. There is a confidence level >66% that there will be an increase in droughts, tropical cyclones and extreme high tides. (This would probably explain why we have had stronger typhoons and longer dry spells lately).
6. Both past and future anthropogenic carbon dioxide emissions will continue to contribute to warming and sea level rise for more than a millennium.
7. Global atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have increased markedly as a result of human activities since 1750 and now far exceed pre-industrial values over the last 650,000 years. …