Today an international group of hundreds of climate scientists released a report on how nations can act to limit climate change.

The three-part report from the Intergovernmental Panel on Climate Change (IPCC) assesses the current state of climate change science. The organisation has just published the final part of the report, looking at how the world can cut carbon dioxide emissions.

Carbon dioxide is a greenhouse gas, meaning it traps heat in the atmosphere. Scientists now understand that this warming is changing the climate.

The first instalment of the IPCC’s report, released last September, says scientists are more sure than ever – 95 per cent certain – that humans are causing extra warming in the oceans, land and atmosphere. As a result, snow and ice is melting and sea levels are rising.

Scientists now know much more about the risks the world faces as the climate changes, too. The IPCC says climate change is already contributing to problems like flooding, disruption to farming and food supply and species migration and extinction.

Limiting the problem

After setting out the extent of the problem in its first two reports, the IPCC turns its attention to how humans can ensure global temperatures don’t rise too far above where they were before the industrial revolution.

Scientists call efforts to limit emissions  ‘mitigating’ climate change.

The IPCC doesn’t tell the world’s decision-makers what to do. Instead, it suggests different potential future scenarios, based on the scientific evidence available.

Beyond 2C of warming, the effects of climate change will be much more unpredictable and harder to adapt to, nations have agreed.

The reports says that global emissions have grown faster in recent years,  and will continue to do so. Unless the world changes course, we are likely to take the planet beyond a two-degree temperature rise.

Where emissions come from

Countries are responsible for different past levels of emissions. But looking to the present,  the development of poorer countries is an important part of why emissions are rising and will continue to do so.

Development does not necessarily have to follow a high-emissions path, however.

The report says with the right policies it’s possible to prevent dangerous human-caused climate change, allow ecosystems to adapt, make sure global food production is not threatened and ensure countries can develop sustainably – all at the same time.

The report identifies many areas in which mitigation policies can benefit societies in other ways. For example, cutting emissions can make air safer to breathe. But politicians must  be aware of potentially damaging side-effects – like how growing crops to make fuels – called biofuels – can affect food production.

Governments have agreed that because climate change affects everyone, nations must cooperate to limit it.

In doing this, it is essential that countries feel international decisions about cutting emissions are fair and just. It will only be possible to limit the extent of climate change if nations  work together.