Gadget by The Blog Doctor.
Monday, August 24, 2015
Climate Science - lines of evidence
Under Construction That global temperatures have been warming is known since the 1980s James Hansen and Sergej Lebedeff Global trends of measured surface air temperature First published: 20 November 1987 Journal of Geophysical Research Abstract We analyze surface air temperature data from available meteorological stations with principal focus on the period 1880–1985. The temperature changes at mid- and high latitude stations separated by less than 1000 km are shown to be highly correlated; at low latitudes the correlation falls off more rapidly with distance for nearby stations. We combine the station data in a way which is designed to provide accurate long-term variations. Error estimates are based in part on studies of how accurately the actual station distributions are able to reproduce temperature change in a global data set produced by a three-dimensional general circulation model with realistic variability. We find that meaningful global temperature change can be obtained for the past century, despite the fact that the meteorological stations are confined mainly to continental and island locations. The results indicate a global warming of about 0.5°–0.7°C in the past century, with warming of similar magnitude in both hemispheres; the northern hemisphere result is similar to that found by several other investigators. A strong warming trend between 1965 and 1980 raised the global mean temperature in 1980 and 1981 to the highest level in the period of instrumental records. The warm period in recent years differs qualitatively from the earlier warm period centered about 1940; the earlier warming was focused at high northern latitudes, while the recent warming is more global. We present selected graphs and maps of the temperature change in each of the eight latitude zones. A computer tape of the derived regional and global temperature changes is available from the authors source: http://onlinelibrary.wiley.com/doi/10.1029/JD092iD11p13345/abstract Northern Hemisphere Surface Air Temperature Variations: 1851–1984 P. D. Jonesa, , S. C. B. Rapera, , R. S. Bradleyb, , H. F. Diazc, , P. M. Kellyoa, and , and T. M. L. Wigleya aClimatic Research Unit, School of Environmental Sciences, University of East Anglia, Norwich, UK bDepartment of Geography and Geology, University of Massachusetts, Amherst, MA cNOAA, ERL, Boulder, CO American Meteorological Society February 1986 Abstract A new compilation of monthly mean surface air temperature for the Northern Hemisphere for 1851–1984 is presented based on land-based meteorological station data and fixed-position weather ship data. This compilation differs from others in two ways. First, a considerable amount of new data, previously hidden away in archives, has been included, thus improving both spatial and temporal coverage. Second, the station data have been analyzed to assess their homogeneity. Only reliable or corrected station data have been used in calculating area averages. Grid point temperature estimates have been made by interpolating onto a 5° latitude by 10° longitude grid for each month of the 134 years. In the period of best data coverage, 58% of the area of the Northern Hemisphere is covered by the available data network. (The remaining area is mainly ocean too far from land-based stations to warrant extrapolation.) The reliability of hemispheric estimates is assessed for earlier periods when coverage is less than this maximum. Year-to-year estimates are considered reliable back to about 1875. Estimates earlier than this are judged sufficiently good to indicate trends back to 1851. This new land-based hemispheric temperature curve is compared with recent estimates of Northern Hemisphere temperatures based on marine data. The two independent estimates agree well on the decadal time scale back to the start of the century, but important discrepancies exist for earlier times. Source: http://journals.ametsoc.org/doi/abs/10.1175/1520-0450%281986%29025%3C0161%3ANHSATV%3E2.0.CO%3B2 Empirical Data on Contemporary Global Climate Changes (Temperature and Precipitation) K. Ya Vinnikov, P. Ya Groisman, and K. M. Lugina State Hydrological Institute, Leningrad, USSR American Meteorological Society June 1990 Abstract New data are presented on the changes of mean global surface air temperature and annual precipitation over extratropical continents of the Northern Hemisphere. Global warming occurred during the last century with a mean trend of 0.5°C/100 years. It is shown that for the same period the annual precipitation over the land in the 35°–70°N zone increased by 6%. The observed variations of precipitation coincide with the results of general circulation modeling of doubled CO2 equilibrium climate change by sign but contradict by scale.