A caveat of this finding is that it is based upon weather balloon data, which “must be treated with great caution, particularly at [higher] altitudes….”  states that the “sign and the magnitude of the global mean cloud feedback depends on so many factors that it remains very uncertain.” This is because some types of clouds trap heat while others reflect it.   found that ice clouds (also called cirrus clouds) exert a “strongly negative” feedback to temperature changes, regardless of whether these changes are increases or decreases.A caveat of this finding is that the feedback process operates “on a time scale of weeks,” and “it is not obvious whether similar behavior would occur on the longer time scales associated with global warming.”  * Other feedbacks that may have “a substantial impact on the magnitude, the pattern, or the timing of climate warming” include snow coverage, temperature gradients in Earth’s atmosphere, aerosols, trace gases, soil moisture changes, and ocean processes. * Per a 2003 report by the United Nations Food and Agriculture Organization, between the mid-1970s and late 1990s, apparent food consumption per person increased by 15% worldwide, 25% in developing countries, and more than 36% in China.* This graph is called the “hockey stick graph” because the curve looks like a hockey stick laid on its side (click on the footnote for a graphic illustration). The red part of the curve represents modern instrument-measured surface temperatures, the blue represents proxy data, the black line is a smoothed average of the proxy data, and the gray represents the margin of error with 95% confidence.  .  Multiple versions of this graph appear in different sections of the IPCC report, including the “Scientific” section, “Synthesis,” and twice in the “Summary for Policymakers.” * This graph has been the subject of disputes in scientific journals,  congressional hearings,  and legal proceedings including a Freedom of Information Act lawsuit.  Just Facts presently does not have the resources to conclusively assess all the competing claims on this issue, but the facts we have verified are as follows: medieval warmth,” and shows the following graph of temperature changes for the Northern Hemisphere over the past 1,300 years.
The 2007 IPCC report uses certain models that project an acceleration of this trend, and the report predicts sea level increases ranging from 7 to 31 inches (18–79 cm) from 1990 to 2100. * Scientists have estimated worldwide sea levels going back to the year 1700 using data from local tide gauges, which are instruments that measure the level of the sea relative to reference points on land. According to some predictions, not long after Bangladesh feels the impact, up to 60 percent of the present population of Florida may have to be relocated.  * In 2008, scientists with the Center for Environment and Geographic Information Services in Bangladesh announced that their study of satellite images and maps shows that Bangladesh gained about 1,000 square kilometers of land since 1973.   * Coral reef islands are typically found in the Pacific Ocean and are primarily composed of gravel, silt and sand that has accumulated on coral reefs.
The report states that: some of the global warming since 1850 could be a recovery from the Little Ice Age rather than a direct result of human activities.
So it is important to recognize that natural variations of climate are appreciable and will modulate any future changes induced by man.
do not allow any observational assessment” because many variables are involved, and “it is not possible …
to insure that only one variable is changing.” found that during 1973–2007, humidity increased in the lowest part of Earth’s atmosphere but decreased at higher altitudes, implying that the “long-term water vapor feedback is negative—that it would reduce rather than amplify” the warming effect of CO2.
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as “an increase in the average temperature of the Earth’s atmosphere,” either by “human industry and agriculture” or by natural causes like the Earth has “experienced numerous” times “through its history.” * Some writers use the phrases “global warming” and “climate change” to mean temperature changes strictly caused by human activity.   Other writers use adjectives such as “man-made” and “anthropogenic” to distinguish between human and non-human causes.  (“Anthropogenic” means “of human origin,” and “AGW” stands for “anthropogenic global warming.”) * Just Facts’ Standards of Credibility require the use of “language that is precise and unambiguous.” Hence, when human causes are stated or implied, this research uses terms like “man-made” and “human-induced.” * The greenhouse effect is a warming effect caused by certain gases that retain heat from sunlight. Without such gases, the average surface temperature of the Earth would be below freezing, and as explained by the , “life, as we know it, would not exist.” The global warming debate is centered upon whether added greenhouse gases released by human activity will overheat the Earth and cause harmful effects. * Human activities currently release about 37 billion metric tons of CO2 per year, which equates to about 5% of natural CO2 emissions.