Global temperatures are now likely to rise by more than 1.5C

The Intergovernmental Panel on Climate Change (IPCC) has released its first major review of the science of climate change since 2013, and the conclusions are stark.

'Today's IPCC Report is a code red for humanity,' says António Guterres, UN Secretary-General.

'The alarm bells are deafening, and the evidence is irrefutable: greenhouse gas emissions from fossil fuel burning and deforestation are choking our planet and putting billions of people at immediate risk.

'Global heating is affecting every region on Earth, with many of the changes becoming irreversible.'

In all predicted scenarios, we are now expected to release enough carbon emissions to cause the planet to warm by 1.5°C by 2040, although with the current trajectory of emissions this will likely be closer to 2034.

The past five years have been the hottest on record since the 1850s. The recent rate of sea-level rise is nearly triple that of 1901-1971 and human influence has caused the global retreat of glaciers since the 1990s.   

We are already seeing devasting impacts on the global climate. This has been directly impacting people around the world as hundreds of thousands have been killed in recent years by heat and floods, while countless more have lost their homes and livelihoods. 

The natural world has not escaped these impacts, either: as warming oceans are decimating coral reefs, land use changes destroying habitats and changing weather patterns pushing an estimated one million species of plants and animals to brink of extinction.    

The report, however, also shows that it is not too late to change course.

If the world can achieve net zero emissions by 2050, it is likely that average surface temperatures can be kept below 2°C of warming. While this is not ideal - the agreed limit during the Paris climate talks in 2015 was 1.5°C - it would help prevent a runaway catastrophe.  

The report comes ahead of the key climate summit to be held in Glasgow in November 2021, known as COP26.

'If we combine forces now, we can avert climate catastrophe,' says Guterres. 'But, as today's report makes clear, there is no time for delay and no room for excuses. I count on government leaders and all stakeholders to ensure COP26 is a success.'

The UK government has already stated ambitions to cut carbon emissions by 78% by 2035 and reach net zero by 2050. This will require more electric cars, low-carbon heating and renewable energy, and a reduction in meat and dairy consumption.

These targets have been welcomed by many, but there are still doubts that this will be achieved considering that the UK is not on track to meet previous climate commitments.

Prof Richard Herrington, Head of Earth Sciences at the Museum, is figuring out ways in which we can transition to a low carbon economy.

'The report findings that the rate of warming is happening more quickly than previously predicted, reinforces the urgent need to switch from fossil fuel burning for our transport and energy systems and hit net zero CO₂ emissions as soon as possible,' says Richard.

'The manufacture of tested technologies that can drastically decarbonise those systems demands the mining of new raw materials, and our challenge is to source and recover those materials in ways that leave a net positive impact for the planet and its people.'

Human activity is driving the climate crisis

The report is far more definitive in stating that human activity is driving the changes to the climate that we are now witnessing in every part of the planet.

'Climate change is already affecting every region on Earth, in multiple ways. The changes we experience will increase with further warming,' says Panmao Zhai, IPCC Working Group I Co-Chair.

It is indisputable that human activities are causing climate change and making extreme climate events, including heat waves, heavy rainfall and droughts, more frequent.

The report demonstrates that we now have a much more advanced understanding of the connections between the emissions that we release and the rise in the global surface temperature, and the resulting changes to the weather and climate around the world. It is unequivocal that the human influence has warmed the atmosphere, ocean and land. 

What is now certain is that heatwaves and extreme heat have become more frequent and intense than during the 1950s, and that human influence has been the main driver of ocean warming and acidification since the 1970s. There has also been a 40% decrease in Arctic sea ice since 1979. 

This report advances our understanding of how human activity affects climate, meaning that we can now better estimate the changes we may experience in the future under different scenarios.

'This report is a reality check,' says Valérie Masson-Delmotte, IPCC Working Group I Co-Chair. 'We now have a much clearer picture of the past, present and future climate, which is essential for understanding where we are headed, what can be done, and how we can prepare.'

Looking to the future

The report is clear that there will be further warming in the coming decades.

'Unless there are immediate, rapid and large-scale reductions in greenhouse gas emissions, limiting warming to 1.5°C will be beyond our reach,' the report states.

We will undoubtedly see an increase in the extreme weather events that have already been raging through communities around the world over the last decade. In some regions, droughts and wildfires will increase in frequency and severity, while in others heavy rainfall will cause heavier and more frequent flooding. 

Prof Andy Purvis is a research leader at the Museum, who's work focuses on the human impacts on global biodiversity.

'This assessment has taken years to put together, and summarises all of the evidence on climate change,' explains Andy. 'The most shocking finding to me is that 1.5 degrees of warming – the level we were hoping to avoid this side of 2100 – is likely to be reached within 20 years unless we change course.'

Every half-degree of warming will see increases in these events, resulting in more lives lost, communities destroyed and biodiversity decimated.

But the report is also clear on what can be done.

If we rapidly reduce global CO₂ emission and reach net zero emissions by 2050, it is extremely likely that we will be able to keep warming below 2°C. If we do this, it is more likely than not that the global average temperatures will gradually recede to around 1.5°C by the end of the century.

The report has also - for the first time - given more detailed regional assessments of climate change. This gives us more useful information that can inform risk assessments and adaptations for governments and policy makers when it comes to how these changes in the climate will impact society and ecosystems.      

'But changing course is still possible,' says Andy. 'Cutting greenhouse gas emissions hard and fast would make a tangible difference to climate within just a few years.

'Nature can help: the large-scale protection and restoration of forests and wetlands could remove a large chunk of the extra CO₂ we’ve put into the atmosphere, while at the same time helping to stop the global decline of biodiversity and securing livelihoods.

'Good nature-based solutions are win-win-win. So, as we step up efforts towards Net Zero for climate, it’s vital that we also aim for Net Zero biodiversity loss too.'