The UK is hosting a summit aimed at bringing climate change under control.

The meeting, in Glasgow until 12 November, could change our everyday lives.
What is COP26 and why is it happening?

The world is warming because of emissions from fossil fuels used by humans, like coal, oil and gas.

Extreme weather events linked to climate change - including heatwaves, floods and forest fires - are intensifying. The past decade was the warmest on record and governments agree urgent collective action is needed.

For this conference - called COP26 - 200 countries have been asked for their plans to cut emissions by 2030.

They all agreed in 2015 to make changes to keep global warming "well below" 2C - and to try aim for 1.5C - so that we avoid a climate catastrophe.

This is what's known as the Paris Agreement. It means countries have to keep cutting emissions until reaching net zero in 2050.
What has been agreed at COP26?

Many countries set out plans to reduce emissions before the summit, but there has been a flurry of new announcements:

Trees: More than 100 world leaders promised to tackle deforestation, which is important because trees can absorb vast amounts of CO2. There have been similar initiatives before, but this one's better funded
Methane: More than 100 countries joined a scheme to cut methane emissions by 30% by 2030. Big emitters China, Russia and India haven't joined
Coal: More than 40 countries agreed to shift away from coal, the single biggest contributor to climate change. Some of the world's most coal-dependent countries, including Australia, India, China and the US, haven't signed up
Money: 450 organisations controlling $130 trillion dollars - around 40% of global private assets - agreed to back "clean" technology, such as renewable energy

COP26: So far, so good-ish
Who is at COP26?

Up to 25,000 people are expected in Glasgow, including world leaders, negotiators and journalists.

However, the Russian and Chinese presidents have been criticised for not coming.

Thousands of businesses and campaigners also go to attend events and hold protests.
COP26 in numbers: 25,000 delegates from 200 countries; 10,000 police officers from across the UK; 100,000 expected to protest; 1.5C is the agreed limit for the temperature to avoid a climate catastrophe; nearly 200 countries are being asked to submit new plans to reduce their emissions; $100bn is what wealthy countries are being asked to help poorer nations. Updated 1 Nov.
What are the sticking points likely to be?

Expect a lot of talk about money and climate justice. Developing countries tend to pollute less per head of population and are not responsible for most emissions in the past.

But they experience some of the worst effects of climate change.
Family in floodwater in BangladeshImage source, Getty Images

They need money to help reduce emissions and cope with climate change. It could mean more solar panels in countries that depend on energy from coal and flood defence systems.

There will also be a battle over compensation for developing countries affected by climate change.

In 2009, wealthy countries pledged $100bn (£720m) a year to help poorer nations by 2020. However, this goal has still not been met and could slip to 2023.
Climate finance chart

China's commitments at COP26 are also very important. It's the world's biggest polluter, so it matters that President Xi hasn't come in person or backed the plan to reduce the use of coal.

What do the poorest countries want from climate summit?
What action are the biggest carbon polluters taking?

You will hear a lot of jargon:

COP26: COP stands for Conference of the Parties. Established by the UN, COP1 took place in 1995 - this will be the 26th
Paris accord: The Paris Agreement united all the world's nations - for the first time - in a single agreement on tackling global warming and cutting greenhouse-gas emissions
IPCC: The Intergovernmental Panel on Climate Change examines the latest research into climate change
1.5C: Keeping the rise in global average temperature below 1.5C - compared with pre-industrial times - will avoid the worst impacts of climate change, scientists say

How will we know COP26 is a success?

As host, the UK wants all participants to recommit to net zero emissions by 2050 - as well as big reductions by 2030.

It will also want more specific pledges, like those already agreed on deforestation and methane.

Developing countries will want a significant financial package over the next five years, to help them adapt to rising temperatures.

Anything short of this is likely to be judged inadequate because there simply isn't more time to keep the 1.5C goal alive.

However, some scientists believe world leaders have left it too late and no matter what is agreed at COP26, 1.5C will not be achieved.