Hello, I'm Ros Atkins. Each week on the BBC World Service, I look at one of the biggest issues in the news.

This time, it's a target we're hearing a lot about.

Net Zero, Net Zero.

Net Zero. Net Zero. Net Zero.

Net Zero Greenhouse Gas gas emissions by 2050.

I'm sure you've heard the phrase Net Zero.

It's a concept that central to the upcoming UN Climate Summit, COP26, and before we go any further, we should hear what it is.

As we release CO2 from burning fossil fuels into the atmosphere.

There are also natural carbon sinks, soils, trees,

etc that absorb carbon dioxide

and to try to keep temperature increased

to below 1.5c Celsius.

We have to make sure that the net amount adds up to zero.

That's Dr Rachel Cletus from the Union of Concerned Scientists.

Put simply, net zero is the point where you take out as much carbon as you put in.

And commitments are being made.

China wants to reach net zero by

2060, the US by 2050, and as we heard, the UK by

2050. In fact, more than 130 countries have either set or are considering a net zero target.

And as host of COP26, the UK is very much promoting net zero.

His Prime Minister Boris Johnson at the UN in September.

We need to pledge collectively to achieve carbon neutrality net zero by the middle of the century and that will be an

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