Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report: Hearing Before the Committee on Commerce, Science, and Transportation, United States Senate, One Hundred Seventh Congress, First Session, May 1, 2001, Volume 4

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Page 27 - I often say that when you can measure what you are speaking about and express it in numbers you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind...
Page 12 - the balance of evidence suggests a discernible human influence on global climate' [5], and was sufficiently confident by the time of the Third Assessment Report to conclude that 'there is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities...
Page 30 - In the light of new evidence and taking into account the remaining uncertainties, most of the observed warming over the last 50 years is likely 7 to have been due to the increase in greenhouse gas concentrations.
Page 12 - Emissions of greenhouse gases and aerosols due to human activities continue to alter the atmosphere in ways that are expected to affect the climate.
Page 12 - ... likely to have been a reduction of about two weeks in the annual duration of lake and river ice cover in the mid- and high latitudes of the northern hemisphere, over the 20th century.
Page 14 - ... for urbanisation over the land. Over both the last 140 years and 100 years, the best estimate is that the global average surface temperature has increased by 0.6 ± 0.2°C. (b) Additionally, the year by year (blue curve) and 50 year average (black curve) variations of the average surface temperature of the Northern Hemisphere for the past 1 000 years have been reconstructed from "proxy" data calibrated against thermometer data (see list of the main proxy data in the diagram).
Page 11 - US scientific agencies and international scientific agencies such as the World Meteorological Organization (WMO) and the United Nations Environment Program (UNEP). The scientific assessments have been conducted and written by the best scientists in the world.
Page 14 - Earths surface temperature is shown year by year (red bars) and approximately decade by decade (black line, a filtered annual curve suppressing fluctuations below near decadal time-scales). There are uncertainties in the annual data (thin black whisker bars represent the 95% confidence range) due to data gaps, random instrumental errors and uncertainties, uncertainties in bias corrections in the ocean surface temperature data and also in adjustments for urbanisation over the land.
Page 14 - Hemisphere for the past 1 000 years have been reconstructed from "proxy" data calibrated against thermometer data (see list of the main proxy data in the diagram). The 95% confidence range in the annual data is represented by the grey region. These uncertainties increase in more distant times and are always much larger than in the instrumental record due to the use of relatively sparse proxy data.
Page 15 - Indicators of the human influence on the atmosphere during the Industrial era (a...

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