Noticed less sunshine lately? In this documentary we see that Scientists have discovered that the amount of sunlight reaching the Earth’s surface has been falling over recent decades.

If the climatologists are right, their discovery holds the potential for powerful disruption to life on our planet. Already it may have contributed to many thousands of deaths through drought and famine.

Essentially, the phenomenon called “global dimming” may mean that even the direst predictions about the rate of global warming have been seriously underestimated.

Until recently many scientists had never heard of global dimming. Among those who had, a lot remained sceptical. Now, thanks in part to the work of Australian researchers, the debate is set to edge into public consciousness.

This special report from the BBC’s Horizon program reveals how global dimming was gradually unmasked by isolated groups of scientists across the world … in Israel, Germany, the US and Australia.

Global dimming is a product of the fossil fuels that cause global warming. It is the result of tiny airborne pieces of soot, ash and sulphur compounds reflecting back the heat of the sun.

By allowing less sunlight to reach the Earth, global dimming is cushioning us from the full impact of global warming, climatologists say. They fear that as we burn coal and oil more cleanly, and dimming is reduced, the full effects of global warming will be unleashed.

The worst-case scenario has temperatures rising by up to 10 degrees by the end of the century – twice more than previously thought.

Scientists have also linked global dimming to the failure of rains in sub-Saharan Africa – and the catastrophic droughts that hit Ethiopia in the 1980s. They worry that the same thing will happen again in areas like Asia, home to billions of people.

The overriding concern expressed by climate scientists in this program is that our climate will be radically altered, rendering many parts of the planet uninhabitable – unless concerted action is taken to combat both global dimming and global warming.