These findings aren't at all contradictory, it's just the Reuters article is ambiguous in the way it presents them: the title "Fossil Fuel Curbs May Speed Global Warming: Scientists" may make it sound like it's a good idea to keep on burning fossil fuels, but the scientist's point is actually very different.
What he (Peter Cox) is saying is that there is a substantial cooling effect due to other fossil fuel byproducts such as sulphur dioxide (which cause 'global dimming' by increasing cloud formation and so lowering the amount of sunlight reaching the Earth's surface)
This cooling effect is offsetting some of the global warming caused primarily by man-made emissions of carbon dioxide, so effectively, we are not experiencing all of the warming that we should be at the moment.
A fuller explanation can be found in this article from the American Geophysical Union: http://www.agu.org/sci_soc/prrl/prrl0312.html
So, in short, reducing SO2 emissions (which also cause acid rain) by e.g. fitting SO2 scrubbers to power stations, WITHOUT ALSO REDUCING CO2 EMISSIONS, will make things warmer as the full effect of the warming due to CO2 and other greenhouse gases will be felt.
This is a concern because at the moment reducing sulphur dioxide emissions is a comparitively easy thing to do, whereas so far nobody has come up with an easy way to reduce the CO2 emissions.
Burning more fossil fuels is never going to be a good thing for the climate.
so far I am unconvinced that human-generated emissions from the burning of organic compounds is a significant factor in global mean temperature fluctuations.
warming and cooling trends have occured within pre-industrial recorded history, let alone the shifts we have learned of in prehistory.
I am not inclined to take seriously anything the global warming crowd says.