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Climate Change: There are two dimensions - warming and cooling. The history of the Earth is one of climate change.
Warming: The Earth has warmed since the invention of reliable thermometers in the 1850s and their dispersion to many areas by the early 1900s. This early period coincided with the end of the most recent Little Ice Age. If the Medieval Warm Period had not been hidden by scientists, as is now clear due to the leaked emails of ClimateGate, the present warmth would be shown to be similar to the warmth of a thousand years ago.
Dangerous warming (or is it dangerous cooling?): Consider the impact of one frost in Kansas in June. Now, how bad is warming versus cooling? Most of civilization's advances came since the last ice-age. As a former NOAA climate-cooling official, I fear it far more than warming. If the sun does not wake up soon from its dormant phase, we are in for a deep freeze and mass starvation. That is where our fear should be centered, and our budget allocated to develop cold-resistant plants and animals at least as much as for heat-tolerant ones.
Climate Data: The global climate data are a mess. Since records began, there have been constant improvements in technology that improve accuracy or recording or assimilation. For example ocean temperatures first came from a bucket of surface water, then a ship's intake monitor from well below the surface, to a in-situ buoy to a distant satellite sensor. All have to be calibrated. The same transition occurred on land, yet the original land data have been destroyed and so independent verification of calibration methods cannot be conducted. Scientists hid behind the wall offered by the fact that many nations consider their environmental data proprietary and a salable commodity. Locations and the matching of data to locations cannot be disclosed in public documents. It is a real problem, but not if we are serious about getting at the truth. As an IPCC impact scientist for a dozen years, we learned to distrust any science literature or impacts assessment that did not consider all data available, whether modeling, the instrumented record back into the 1800s and/or the paleo and historical temperature reconstructions. If the data are truncated, there is likely an agenda. Many of us have learned, either formally, or informally, how to detect misrepresentation by statistical treatments and graphics.
Climate Data - the effect of development: The land data have not been properly adjusted for such things as urban heat island effects (are the city temps warmer than the suburbs where you live? Has the city grown since 1850? Have the runways increased near the temp gage at your airport since 1920?), and is the gage closer to the pavement after widening of the road. This is particularly true of the global data set, even though "urbanization has caused regional increases in temperature that exceed those measured on a global scale, leading to urban heat islands as much as 12°C hotter than their surroundings". The fact that satellite-derived land data do not show global warming and that US temperatures, where NOAA has done a better job at correcting bad locations or data, show we are at the historic average, argue convincingly that the land data are skewed by human development and land use practices.
Consensus by manipulation: As ClimateGate proves what many have alleged for years, the consensus on climate change has been fabricated by excluding scientists with other views from meetings, from working groups, from citation in IPCC documents, from peer reviews, and from publication in key journals through intimidation of journal editors. There is no consensus. Science is not settled. At first it was mostly the Russian climatologists and paleo scientists that were excluded, but in recent years it has become global. Perhaps ClimateGate will cause changes and make available the raw data and model code so that the world can check what is now done by a few. Few beyond the skeptics knew before last week that even information about the list of station locations was a secret, never mind the measurements.
ClimateGate: This is a very important turn of events. With the advent of ClimateGate (hacked emails among the IPCC elite modelers and data gurus), outright fraud has become a real possibility. What many suspected for a long time when they couldn't replicate IPCC results, and could not access the IPCC-used data, seems to be true, at least to them. The fallout has been immense. One thing is certain, we now know how the Medieval Warm Period (MWP) was suppressed to make the current warmth appear "unprecedented".The MWP lasted about AD 800–1300 and polar ice melted sufficiently that that Vikings settled Northern Greenland where only ice exists now. This was a major problem for the hockey stick crowd. We also know now how the present stabilization (or perhaps cooling) has been hidden. Among the techniques were to use data sets that did not contain data for the warm periods of the middle ages (or that did not show warming), and to put a proxy (non-thermometer) set that showed recent cooling behind (on the chart) those showing warming (from thermometers, including in urban centers). These proxy sets were the basis of the pre-thermometer data and should have been kept in the mix for the current era so similar things are being compared. Too many scientists had themselves believing that they were right and all others wrong. They were so convinced that they convinced others. Rather than being THE CONSENSUS, they are probably the minority, and the gullible (opposite of Skeptics) have been mislead. These scientists could be correct, but I think they are wrong in several key facets. In addition to having science that does not appear valid when compared to observations, the inner-circle scientists appear to have done some very bad things. Chief among these are: advocacy for environmental causes to justify exaggeration of warming and its impacts, threatening of key journals that published non-conforming science, exclusion of non-agreeing scientists from meetings, workshops and peer reviews, and their science from citation in IPCC documents. These things make bad science, but it seems these people also deliberately destroyed underlying data and refused access to computer code that would allow their findings to be questioned, interwove data sets to hide the medieval warm period so the present warmth would appear unprecedented and the recent cooling shown in proxy data to seemingly not exist, defied Freedom of Information requests by withholding information and destroying correspondence, and did not remove the impact of city temperatures as had been asserted. The friends of the ClimateGate scientists, and the investigators say that the science has not changed, but it has. Others used these same manipulations to exaggerate past and future warming and spread alarmism and to stifle dissent. Many key scientists were present during discussions of data manipulation, or of restricting participation to the core modeling group, or otherwise knew what was going on. Compare Richard Nixon saying "Destroy the tapes" to Phil Jones' "Delete any emails". And now, all the science is suspect, not just that developed or interpreted by a few rotten apples. Also see our index page article on falsification of data.
Models: As ClimateGate shows, there is concern as to why the models did not show the cooling, or stability, in the face of growing CO2. Part of this is because the model complexity is so great, the only person (s) who knows the model is the one who has worked with it for years or decades. There are a couple dozen leading models and about as many modelers, who may or may not have a decent background in climatology. We can say thousands agree or disagree, but all we know is based on these few people. Nothing can really be peer - reviewed because of the inherent complexity. All we have to really go on is whether results match observations, preferably in the form of forecasts. Models are tuned to match the past observations, so it is no big deal if they get that part correct. However, it is a very big deal when October 2009 comes in as the 3rd coldest on record in the US and the past 12 months is right at average and the models did not have a clue. As ClimateGate shows, the world data set includes the big urban heat islands (despite statements that they had been removed), that have temperatures 20 deg F above the surrounding suburban areas. Most of the US urban areas have been removed or adjusted in the NOAA data and even though there are data problems, I think it is the real guide to what is happening until we can get a global data set for areas outside the cities and away from roads.
CO2 as a greenhouse gas: There is physical evidence that CO2 is a greenhouse gas, able to trap heat. There is also physical evidence that this ability has a logarithmic function and that we are already at the cusp of saturation. There is no physical evidence that more CO2 will, or can, influence further warming. Only models are able to produce a temperature rise with CO2. It is eye-opening to go to Guayaquil Ecuador and see miles of closed greenhouses at sea level at the equator. Closing indicates CO2 is being pumped in (it is plant food and slows water loss) and of course the plants grow faster when warm, as do most cold-blooded animals. We can think all we want that CO2 is evil, but in reality plants are starved for it after millions of years of converting it into coal and oil. We must not put lots of crud into our environment, but CO2 is not necessarily evil (should we stop exhaling it?).
Influence of the Sun: Scientists affiliated with the IPCC believe solar influences are not important to the recent warming and that are actually in the wrong direction. Other scientists believe that the IPCC analysis is flawed and that the actual mechanisms through which the Sun affects Earth climate were not used in the analysis. They believe that most of the Earth's temperature variation is explained by the sun's activity and our proximity to it..
Indicators of climate change: For me, global sea ice extent, despite data only going back to 1979, is the key indicator of warming or cooling. As of today it is less than 5% below the mean. If we have Arctic warming but no Antarctic warming, we do not have GLOBAL warming.
The IPCC: I support the IPCC process. It is a reasonable way to coordinate the development of policy advice on global issues. I believe the technical chair persons are able to exert enough authority to keep the reports from becoming merely political statements. However, there does appear to be "cherry picking" of science and results to advance some policy agendas or anthropogenic greenhouse warming. (See more).
There is no true answer, but rather many questions about the answers we have. The arguments for and against whether the Earth is warming, or cooling, and whether humans are to blame will go on a while further. I try to cover these points and many more on http://www.ClimateChangeFacts.info without bias. As an IPPC lead author/Chair for a dozen years, I believe in the basic process (but not its politicization into an excuse for environmental activism) but am concerned that the dissenters have been shut out from the beginning in 1988.
Last reviewed or updated in December 2009
This page updated or reviewed in January 2012