Temperature mean global

Atmospheric concentrations of both CO2 and CH4 are increasing. The graph shows data for CO2, whose amount has increased by 30% as humans consume more and more fossil fuel. The graph also shows that the global mean temperature has risen by nearly 1 °C. 

Figure 8. Sea surface temperature (SST), Land area temperature (LAT), and Combined global mean temperature (MEAN) (NOAA-NCDC, 2001)...

The error of this approximation is less than 0.01% for relevant global mean temperatures (see the Appendix). The thickness of the atmospheric layers, which is increasing with the altitude, is correlated to the optical depth of the... 

In a steady-state situation all net heat generated is emitted to space. Therefore, by adding the calculated geothermal mean heat flow (0.068 W m-2) and the total thermal pollution (0.020 W m-2), the total net OLR becomes 0.088 W m-2. Equation (3) then gives that this net OLR requires a SST of 17.8 °C and a LAT of 12.0 °C resulting in a future global mean temperature of 16.1 °C. 

Thus, the global thermal pollution will at steady state have increased the sea surface temperature by 1.9 °C, the land area temperature by 3.9 °C and the global mean temperature by 2.5 °C. Since part of this heating has already begun, further temperature increases of 1.4 °C (Ocean), 2.7 °C (Land), and 1.8 °C (Mean) should be expected (Figure 11). 

This approximation gives an error <0.01% for relevant global mean temperatures. 

Very large uncertainty in global mean temperature increase and impacts. 

Anthropogenic addition to radiative forcing at stabilisation (W/m2) Stabilisation level for C02 only (ppm C02) Multi-gas concentration level (ppm C02-eq.) Global mean temperature °C increase above pre-industrial at equilibrium," using best estimate climate sensitivity of 3°C Peaking year for C02 emissions Change in C02 emissions in 2050 (% of 2000 emissions) ... 

The global mean temperature at equilibrium is different from expected global mean temperature at the time of stabilisation of GHG concentrations owing to the inertia of the climate system. In most scenarios, stabilisation of GHG concentrations occurs between 2100 and 2150. 

Note that global mean temperatures are now within 1°C of the highest temperatures that have occurred over the past 1 million years. 

Wigley, T. M. L., Global-Mean Temperature and Sea Level Consequences of Greenhouse Gas Concentration Stabilization, Geophys. Res. Lett., 22, 45-48 (1995). 

A controversy with possibly far-reaching consequences concerns the impact of atmospheric particles on the earth s climate. Temperature is one of the most easily monitored indicators of climatic change. Among the many discussions of the effects of aerosols on the global mean temperature, we direct the reader to the monograph by Twomey (1977) and the paper by Toon and Pollack (1980), from which some of the following is taken. 

Typical changes in the global mean temperature over the past 1000 years seem to have been of order 1°C, although climate has changed considerably as in the Little Ice Age from about a.d. 1500 to 1900. The difference between average Ice Age (1.75 million to 10,000 years ago) temperatures and the... 

The relationship between the global C02 cycle and land vegetation is manifested by the dependence of primary production and the rate of dead biomass decomposition on temperature and C02 concentration in the atmosphere. Temperature dependence is most apparent in northern latitudes where global mean temperature... 

The global mean SAT in 2003 exceeded the average for 1961-1990 by 0.46°C. According to data from satellite thermal sensing, the global mean temperature of the middle troposphere in 2003 was one-third that of average warming for 1979-1998. 

Clear correlations between CO2 and global mean temperature are evident in much of the glacial-interglacial palaeo-record. This relationship ofC02 concentration and temperature may carry forward into the future, possibly causing significant positive climatic feedback on CO2 fluxes. 

Gavrilov, N.M., and R.G. Roble, The effect of gravity waves on the global mean temperature and composition structure of the upper atmosphere. J Geophys Res 99, 25,773, 1994. 

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