The COP26 climate summit in Glasgow has been billed as a last chance to limit global warming to 1.5C.
But beyond the deals and photo opportunities, what are the key things countries need to do in order to tackle climate change?
1. Keep fossil fuels in the ground
When fossil fuels like oil, gas, and especially coal are burned, carbon dioxide (CO2) is released into the atmosphere, trapping heat and raising global temperatures.
It is an issue that must be addressed at the government level if temperature rises are to be limited to 1.5 degrees Celsius, which is regarded as the threshold for dangerous climate change.
However, many major coal-dependent countries – such as Australia, the US, China and India – have declined to sign a deal at the summit aimed at phasing out the energy source in the coming decades.
2. Curb methane emissions
According to a recent UN report, reducing methane emissions could make a significant contribution to addressing the planetary emergency.
Flaring, or the burning of natural gas during oil extraction, emits a significant amount of methane, which could be reduced with technical fixes. Finding better ways to dispose of trash is also important, because landfills are a major source of methane.
At COP26, nearly 100 countries agreed to cut methane emissions, in a deal spearheaded by the US and the EU. The Global Methane Pledge aims to limit methane emissions by 30% compared with 2020 levels.
3. Switch to renewable energy
Electricity and heat generation contribute more to global emissions than any other economic sector.
Decarbonisation refers to the process of transitioning the global energy system from one based on fossil fuels to one based on clean technology. It is critical for meeting current climate goals.
Wind and solar power will need to dominate the energy mix by 2050 if countries are to deliver on their net zero targets.
There are challenges, however.
Less wind means less electricity generated, but better battery technology could help us store surplus energy from renewables, ready to be released when needed.
4. Abandon petrol and diesel
We’ll also need to change how we power the vehicles we use to travel by land, sea, and air.
It will be critical to abandon gasoline and diesel vehicles in favour of electric vehicles.
Hydrogen fuel, ideally produced using renewable energy, could be used to power trucks and buses.
Scientists are also developing new, cleaner aircraft fuels, though campaigners are urging people to reduce the number of flights they take.
5. Plant more trees
According to a 2018 UN report, removing CO2 from the atmosphere is necessary to have a realistic chance of keeping global temperature rise under 1.5 degrees Celsius.
Forests are excellent at absorbing CO2 from the atmosphere, which is why environmentalists and scientists stress the importance of reducing deforestation to protect the natural world.
Mass tree-planting programmes are seen as a way to offset CO2 emissions.
Trees are likely to play an important role as countries struggle to meet their net zero targets, because once emissions have been reduced as much as possible, remaining emissions could be “cancelled out” by carbon sinks such as forests.
6. Remove greenhouse gases from the air
Emerging technologies that remove CO2 from the atmosphere artificially or prevent it from being released in the first place could play a role.
A number of direct-air capture facilities are being built, including plants in Texas and Switzerland built by Carbon Engineering and Climeworks. They work by pushing air through a chemical filter that absorbs CO2 with massive fans.
Carbon capture and storage is another method that captures emissions at “point sources” where they are produced, such as coal-fired power plants. After that, the CO2 is buried deep underground.
However, the technology is costly – and divisive – because critics see it as aiding in the perpetuation of reliance on fossil fuels.
7. Give financial aid to help poorer countries
Rich countries pledged $100 billion (£74.6 billion) in financing by 2020 at the Copenhagen COP summit in 2009, to assist developing countries in combating and adapting to climate change.
That deadline has not been met, despite the fact that the UK government, as the COP presidency, recently outlined a plan for putting the funding in place by 2023.
Many coal-dependent countries are experiencing severe energy shortages, threatening their recovery from Covid and disproportionately affecting the poor. These factors prevent them from shifting away from polluting industries.
Some experts believe that poorer countries will require ongoing financial assistance to help them transition to greener energy. For example, the United States, the European Union, and the United Kingdom recently provided $8.5 billion to assist South Africa in phasing out coal use.