Figure 1: Forecast of year-to-year temperature rise from years 2000 to 2050 C.E. (thin line) assuming an increase in the air's greenhouse gas concentration from human activities, based on the Hadley Center's model (UKMO HADCM3 IS92A version). The upper line (labeled "Without Kyoto") is the linear trend fit to the model's forecast temperature rise, without implementation of the Kyoto Protocol. The lower line is the estimate of the impact on temperature with the implementation of the Kyoto Protocol. By the year 2050, around 0.06 C global warming is averted by the implementation of the Kyoto Protocol.One key scientific question is: What has been the response of the climate thus far to the small amount of energy added by humans from increased greenhouse gases in the air? To prove the reliability of their future forecasts, computer simulations need verification by testing past, well-documented temperature fluctuations. New federal investment in technology, especially that of space-based instrumentation, has helped address the issue of observed response of the climate to the air's increased greenhouse gas concentration. Two capitol tests of the reliability of the computer simulations are the past decades of surface temperature and lower troposphere change.
Figure 2: Surface temperature changes sampled worldwide and analyzed by Cambridge Research Unit (CRU) and NASA-Goddard Institute of Space Studies (GISS). The pattern of 20th century temperature change has three distinct phases: an early 20th-century warming, a mid-century cooling, and a late 20th-century warming.First, a strong warming trend of about 0.5 C began in the late 19th century and peaked around 1940. Next, the temperature decreased from 1940 until the late 1970s. Recently, a third trend has emerged -- a modest warming from the late 1970s to the present.
Figure 3: Monthly averaged temperatures sampled nearly globally for the lower troposophere (roughly 5,000 to 28,000 feet altitude) from Microwave Sounder Unit (MSU) instruments onboard NASA satellites. The large spike of warmth resulted from the temporary natural warming of the Pacific Ocean by the 1997 - 1998 El Niño event. The linear trend is +0.04 C per decade
Source of data: http://wwwghcc.msfc.nasa.gov/temperature/
Figure 4: The seasonal average temperature anomaly sampled worldwide for the lower troposphere as measured by radiosonde instruments carried aboard balloons. Although a linear trend of +0.09C per decade is present if fitted across the entire period of the record, that trend is affected by the presence of the abrupt warming that occurred in 1976-1977, owing to the action of the Pacific Decadal Oscillation (PDO). The trends before and after the 1976-1977 Great Pacific Climate Shift indicate no evidence of a significant human-made warming trend.
Source of data: http://cdiac.esd.ornl.gov/ftp/trends/temp/angell/glob.dat
Figure 5: Changes in the sun's magnetism (as evidenced by the changing length of the 22-year, or Hale Polarity Cycle, dotted line) and changes in Northern Hemisphere land temperature (solid line) are closely correlated. The sun's shorter magnetic cycles are more intense, suggesting periods of a brighter sun, then a fainter sun during longer cycles. Lags or leads between the two curves that are shorter than twenty years are not significant, owing to the 22-year time frame of the proxy for brightness change. The record of reconstructed Northern Hemisphere land temperature substitutes for global temperature, which is unavailable back to 1700Based on the key temperature measurements of the last several decades, the actual response of the climate to the increased concentration of carbon dioxide and other human-made greenhouse gases content in the air has shown no significant man-made global warming trend. The magnitude of expected human change is especially constrained by the observed temperature trends of the lower troposphere.
Source: S. Baliunas and W. Soon, 1995, Astrophysical Journal, 450, 896).