Due to the extreme importance of this, I will use correct punctuation and capitalization for this post. On Thursday, February 1st, the Intergovernmental Panel on Climate Change [link: www.ipcc.ch] adopted the Summary for Policymakers of the first volume of "Climate Change 2007", also known as the Fourth Assessment Report (AR4).
Here is the Media Advisory from the IPCC's website:
IPCC adopts major assessment of climate change science
Paris, 2 February 2007 – Late last night, Working Group I of the Intergovernmental Panel on Climate Change (IPCC) adopted the Summary for Policymakers of the first volume of “Climate Change 2007”, also known as the Fourth Assessment Report (AR4).
“Climate Change 2007: The Physical Science Basis”, assesses the current scientific knowledge of the natural and human drivers of climate change, observed changes in climate, the ability of science to attribute changes to different causes, and projections for future climate change.
The report was produced by some 600 authors from 40 countries. Over 620 expert reviewers and a large number of government reviewers also participated. Representatives from 113 governments reviewed and revised the Summary line-by-line during the course of this week before adopting it and accepting the underlying report.
The Summary can be downloaded in English from www.ipcc.ch and http://ipcc-wg1.ucar.edu. A webcast of the final press conference has also been posted. The Summary will be available in Arabic, Chinese French, Russian and Spanish at a later date. The full underlying report will be published in English by Cambridge University Press.
[link: http://www.ipcc.ch/press/prwg2feb07.htm]
Did you just read that? I really hope you did. 600 authors. 620 expert reviewers. debated line-by-line. Is that enough credibility for you? You might be wondering what this phrase "Climate Change" is. Well its Global Warming. A lot of people are using the phrase Climate Change now instead of Global Warming because there are many more (bad) issues going on with this world's climate other than just the warming of the globe.
Now I doubt many of you will read the whole summary. So I will try to bullet some interesting points taken directly from the Summary. But first let me remind you that the IPCC put out the Third Assessment Report or TAR. The new AR4 is a newer version. Keep in mind that in the last five years, there has been MANY studies and reports done about climate change. Furthermore, there is MUCH BETTER climate modeling software that scientists have used in the past 5 years. (And you know exactly what I mean in terms of computer technology. Remember the first iPod? Think iPhone. )
- 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 determined from ice cores spanning many thousands of years (see Figure SPM-1). The global increases in carbon dioxide concentration are due primarily to fossil fuel use and land-use change, while those of methane and nitrous oxide are primarily due to agriculture.
- Figure SPM-1:
- The understanding of anthropogenic warming and cooling influences on climate has improved since the Third Assessment Report (TAR), leading to very high confidence7 that the globally averaged net effect of human activities since 1750 has been one of warming, with a radiative forcing of +1.6 [+0.6 to +2.4] W m-2.
- Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level (see Figure SPM-3).
- The average atmospheric water vapour content has increased since at least the 1980s over land and ocean as well as in the upper troposphere. The increase is broadly consistent with the extra water vapour that warmer air can hold. (aka more rain and hurricanes)
- Observations since 1961 show that the average temperature of the global ocean has increased to depths of at least 3000 m and that the ocean has been absorbing more than 80% of the heat added to the climate system. Such warming causes seawater to expand, contributing to sea level rise.
- At continental, regional, and ocean basin scales, numerous long-term changes in climate have been observed. These include changes in Arctic temperatures and ice, widespread changes in precipitation amounts, ocean salinity, wind patterns and aspects of extreme weather including droughts, heavy precipitation, heat waves and the intensity of tropical cyclones.
- Paleoclimate information supports the interpretation that the warmth of the last half century is unusual in at least the previous 1300 years. The last time the polar regions were significantly warmer than present for an extended period (about 125,000 years ago), reductions in polar ice volume led to 4 to 6 metres of sea level rise. [ARE YOU READING THIS?]
- Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations. This is an advance since the TAR’s conclusion that “most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations”. Discernible human influences now extend to other aspects of climate, including ocean warming, continental-average temperatures, temperature extremes and wind patterns.
- Continued greenhouse gas emissions at or above current rates would cause further warming and induce many changes in the global climate system during the 21st century that would very likely be larger than those observed during the 20th century.
- There is now higher confidence in projected patterns of warming and other regional-scale features, including changes in wind patterns, precipitation, and some aspects of extremes and of ice.
- Projected warming in the 21st century shows scenario-independent geographical patterns similar to those observed over the past several decades. Warming is expected to be greatest over land and at most high northern latitudes, and least over the Southern Ocean and parts of the North Atlantic ocean.
- Snow cover is projected to contract. Widespread increases in thaw depth are projected over most permafrost regions.
- Sea ice is projected to shrink in both the Arctic and Antarctic under all SRES (modeling) scenarios. In some projections, Arctic late-summer sea ice disappears almost entirely by the latter part of the 21st century.
- It is very likely that hot extremes, heat waves, and heavy precipitation events will continue to become more frequent.
- Based on a range of models, it is likely that future tropical cyclones (typhoons and hurricanes) will become more intense, with larger peak wind speeds and more heavy precipitation associate with ongoing increases of tropical SSTs.
- Anthropogenic warming and sea level rise would continue for centuries due to the timescales associated with climate processes and feedbacks, even if greenhouse gas concentrations were to be stabilized.
- Climate-carbon cycle coupling is expected to add carbon dioxide to the atmosphere as the climate system warms, but the magnitude of this feedback is uncertain. This increases the uncertainty in the trajectory of carbon dioxide emissions required to achieve a particular stabilization level of atmospheric carbon dioxide concentration. Based on current understanding of climate carbon cycle feedback, model studies suggest that to stabilise at 450 ppm carbon dioxide, could require that cumulative emissions over the 21st century be reduced from an average of approximately 670 GtC to approximately 490 GtC.
Okay, that enough quotes from the Summary for Policymakers release. I hope you read it yourself, or you have at least read this far. I want to include one more figure showing the surface temperatures of the globe and individual continents over the last 100 years. The observed temperatures are plotted on the black line. You might notice, that the earths temperature went down a bit from about 1940-1970. Older folks may remember back in the 70's there was actually concern of a global cooling. What people don't realize is that aerosols exert a cooling influence. Aerosols are particulates, alternatively referred to as particulate matter (PM), or fine particles. Some aerosols occur naturally, originating from volcanoes, dust storms, forest and grassland fires, living vegetation, and sea spray. Then there are
anthropogenic aerosols. These are made by human activity like sulphate aerosols from fossil fuel combustion and particulate pollution such as smog. See, aerosols or particulates block sunlight, and thus cools the earth. With the introduction of many industries at the beginning of the century, many anthropogenic aerosols were introduced into the atmosphere. The effect of these aerosols had a quick effect on the atmosphere and its believed this may have initially caused a slight cooling period in the middle of the century. But greenhouse gases and carbon dioxide emissions have completely overtaken the effect and are warming the globe.
plant a freaking tree and ride your bike.
link here for more information on IPCC AR4 and the Summary for Policymakers and to download it.
http://ipcc-wg1.ucar.edu./
