IPCC Global Warming Indicators
GISS Surface Temperature Report
The GISS Goddard Institute for Space Studies, operated by NASA, is a leading research institute for monitoring and reporting on changes to the planet's biosphere, and in particular the observable extent and consequences of climate change.
The GISS is a foremost source of climatology data, collating more than 5 decades of satellite and ocean and land-based sensor data to match adapting climate models. They announced in 2007 the stunning news that 5 of the warmest years on record had occurred in the previous decade.
Dr. Jim Hansen is a prominent atmospheric scientist with a long association with NASA and the GISS.
The GISS Surface Temperature Study
There is hard evidence that average global temperatures have been rising since the advent of the Industrial Revolution (towards the end of the 18th century), when largescale combustion of fossil fuels began.
NASA's Goddard Institute for Space Studies (GISS) has been analysing data from a global network of meteorological stations, ships and satellites, since the 1970s, and currently holds what is possibly the most comprehensive record of Earth surface, ocean and atmospheric temperatures. Their findings are conclusive:
- The average global temperature on Earth has increased by about 0.8° Celsius since 1880.
- Two-thirds of the warming has occurred since 1975, at a rate of roughly 0.15-0.20°C per decade.
- The 1980s was the hottest decade to date since records began (1880s). The first decade of the 21st century became the hottest decade to date, with 5 years between 1998 and 2006 the hottest years ever.
- 2015 was the warmest year since records began, in 1880.
The map (courtesy of NASA GISS, 2006) is a coloured representation of temperature anomalies. The blue and red colouring graphically represents temperature variations from the baseline reference, which is the mean between 1951 and 1980.
Taking the average temperature for the years 1951-80 as a baseline for comparison, GISS has prepared the above maps, which show how much deviation there is in the two decades, 1970-79 and 2000-09. All of the deviations are positive, and at an increasing rate of increase. This observation is exactly in line with the theory that greenhouse gases from human activities are responsible for the retention of heat by the Earth, the so-called 'Greenhouse Effect'.
Solar activity, aerosols, and C02 are all modelled against this data to determine the correlations. The conclusion is inevitably the same: the increase in temperature is greater than the range of uncertainty, and is due to the changes in balance between the amount of energy the Earth receives from the Sun, and the amount it radiates back into space. The incoming solar radiation varies, but to a much smaller extent than the variation in the amount of energy re-radiated. This change cannot be correlated to the variations in solar activity. The conclusion is that the cause is changes to the composition of the atmospheric gases.
It can be seen that the general trend is towards unevenly distributed warming of the globe, with the polar regions receiving more than the average increase in temperature.