COP26: Does a climate summit need 25,000 people? And more questions

It's two weeks until the start of the crucial COP26 climate summit in Glasgow - one of the biggest ever world meetings on how to tackle global warming.

Does COP26 really need 25,000 people there? They will generate a lot of CO2, so why can't many elements be online? - David, Birmingham

The pandemic might be seen as the perfect moment for the UN to use technology for negotiations, and it was attempted during a preparatory meeting for COP in June, which ran for three weeks.

Unfortunately, it didn't go well - time-zone and technology challenges made it almost impossible for countries with limited resources, progress was limited and decisions were put off.

As a result, many developing nations have insisted on having an in-person COP. They feel that it is far easier for their voices to be ignored on a dodgy Zoom connection.

They also bring a lived experience of climate change that it is critical for rich countries to hear first-hand. There's some evidence that this works. In 2015, the presence of island states and vulnerable nations was key to securing the commitment to limit temperature changes to 1.5C in the Paris Agreement. Barring a complete collapse in the talks, there are likely to be a range of tangible outcomes.

It's expected that more countries will announce they are moving away from using coal for energy. A growing number of nations will probably sign up to curb methane emissions.

There is set to be agreement on phasing out the internal combustion engine and on ending deforestation.

But don't expect to see to many overnight changes across the world as a result of these steps. They are all likely to have long lead-in times, with more flexibility on dates shown towards developing countries.

On the really big question of keeping the 1.5C temperature threshold within reach, the likelihood is that a significant gap will remain even after Glasgow. Under the terms of the Paris Agreement, those countries that have used fossil fuels the most over the past two centuries - the US and Europe - accept they will make the bigger cuts in the short term.

The larger developing nations that are now the biggest source of CO2 - chiefly China - accept they will make the bigger cuts in the longer term.

In the pact, all emitters - big and small - agreed to bring forward new and more ambitious carbon-cutting plans every five years.