Condoms are the cheapest way to reduce carbon emissions, claims a controversial new report.

According to the report for the UK's Optimum Population Trust, putting the brake on global population growth would be five times cheaper than any other method of tackling the world's greenhouse gases.
u00a0
The study, which was compiled by the London School of Economics, found every 4-pound extra spent on family planning for the next 40 years would reduce global CO2 emissions by a tonne. It would cost 19 pounds to achieve the same result with low-carbon technologies, reports The Sun.