|Having found data that supports the argument that there is an acceleration in sea level rise, ocean heat uptake and atmospheric greenhouse gas concentrations, I have now turned my attention to global warming – the warming of the close-to-ground (“near surface”) air and upper ocean water temperatures.|
|I’m still waiting to see the data for the new HadCRUT4 adjustments, so in the meantime, I have taken a look at the work of NASA GISS, and the international team who have agreed historical global warming influences – known as “radiative forcings”. Here’s the overall picture :-
Although it seems clear that the build-up of greenhouse gas emissions in the air is causing radiative forcing to rise (Figure 1), it is not very clear what is happening to temperatures – as there appear to be phases where conditions are different.
I have therefore roughly split up the period 1880 to 2011 into subsections with what appear to me to be internal consistency, and here is what I get :-
The “doldrums” in global warming in the period between 1945 and 1970 is easily explained, so an initial comparison must be between the 1915 – 1945 period and the 1970 – 2011 period. The rate of change of temperature rise has increased from the first period to the second.
It appears that global warming is accelerating in response to the acceleration in net radiative forcing – which is strongly dependent on accelerating concentrationss of greenhouse gases in the atmosphere.
And of course, the acceleration in the amount of greenhouse gases in the air is directly attributable to the activities of mankind – mostly through the burning of fossil fuels and deforestation and other changes in land use :-