Allan Macrae, mining and geotechnical engineer: Earth may now be entering another natural cooling trend. Earth Surface Temperature warmed approximately ("~") 0.7 degrees Celsius ("C") from ~1910 to ~1945, cooled ~0.4 C from ~1945 to ~1975, warmed ~0.6 C from ~1975 to 1997, and has not warmed significantly from 1997 to 2007. CO2 emissions due to human activity rose gradually from the onset of the Industrial Revolution, reaching ~1 billion tonnes per year (expressed as carbon) by 1945, and then accelerated to ~9 billion tonnes per year by 2007. Since ~1945 when CO2 emissions accelerated, Earth experienced ~22 years of warming, and ~40 years of either cooling or absence of warming. it is appropriate to cease all CO2 abatement programs that are not cost-effective, and focus efforts on sensible energy efficiency, clean water and the abatement of real atmospheric pollution, including airborne NOx, SOx and particulate emissions. The tens of trillions of dollars contemplated for CO2 abatement should be saved or re-allocated to truly important global priorities.
