1.5ºC: achievable, politically improbable, but necessary

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The Intergovernmental Panel on Climate Change (IPCC) has released its long-awaited report on limiting the rise in global average temperatures from climate change to 1.5ºC above pre-industrial levels, which details in stark terms the benefits of limiting global warming to 1.5ºC compared to 2ºC but also the deep, fundamental and challenging changes across all areas of society needed to do so.

In what is a blunt read, the IPCC’s
Special Report on Global Warming of 1.5ºC, released on Monday in Incheon, Korea, says that limiting global warming to 1.5ºC would require rapid, far-reaching and unprecedented changes in all aspects of the way we live, but that these could also go hand in hand with ensuring a more sustainable and equitable society.

To limit warming to 1.5°C means drastically and immediately ramping up action to reduce emissions, according to the report. ‘Rapid and far-reaching’ transitions to low and ultimately zero carbon emissions would be needed in the energy, land use, industrial, built environment, transport and urban sectors. Net emissions of carbon dioxide would need to fall by 45% on 2010 levels by 2030, and reach ‘net zero’ by 2050.

The focus on net zero is important as any emissions that are left in the economy by 2050 would have to be cancelled out by technologies to take carbon dioxide out of the atmosphere. These could have the effect of mitigating an ‘emissions overshoot’ scenario, where the cumulative stock of carbon dioxide in the atmosphere temporarily exceeds safe levels for 1.5°C and is then artificially lowered after 2050.

‘Limiting warming to 1.5ºC is possible within the laws of chemistry and physics but doing so would require unprecedented changes,’ said Jim Skea, Co-Chair of IPCC Working Group III and former President of the Energy Institute. Skea
told the Guardian that while hitting 1.5ºC is technically possible, doing so rests on the political will of the governments that are receiving the report.

The level of overshoot seen would directly impact the reliance on so-called
negative emissions technologies to remove carbon dioxide from the atmosphere and return temperatures to below a 1.5ºC rise by 2100, such as bioenergy with carbon capture and storage (BECCS). But, as the report points out, these techniques are unproven at large scale and could come with significant feasibility and sustainability impacts.

But while the transition needed to reach 1.5°C will be hard, the report also highlights the huge benefits of staying below the threshold.

‘Limiting global warming to 1.5°C compared with 2°C would reduce challenging impacts on ecosystems, human health and well-being, making it easier to achieve the United Nations Sustainable Development Goals,’ said Priyardarshi Shukla, Co-Chair of IPCC Working Group III.

The report highlights the climate change impacts that could be avoided by limiting global warming to 1.5ºC compared to 2ºC:

  • by 2100 global sea level rise would be around 10 cm lower;
  • the likelihood of a sea ice-free Arctic Ocean in summer would be once per century compared with at least once per decade; and
  • coral reefs would decline by 70–90% with global warming of 1.5°C, whereas all but 1% would be lost under 2ºC.

‘Every extra bit of warming matters, especially since warming of 1.5ºC or higher increases the risk associated with long-lasting or irreversible changes, such as the loss of some ecosystems,’ said Hans-Otto Pörtner, Co-Chair of IPCC Working Group II.

Furthermore, the lower the rise in warming, the higher the likelihood the Earth will not pass certain tipping points that could lead to runaway climate change. Limiting global warming would give people and ecosystems more room to adapt and remain below relevant risk thresholds, said Pörtner.

‘The next few years are probably the most important in our history,’ said Debra Roberts, Co-Chair of IPCC Working Group II, who emphasised that the decisions made today are critical in ensuring a safe and sustainable world for its inhabitants now and into the future.

The IPCC’s special report was invited by the United Nations Framework Convention on Climate Change (UNFCCC) after governments worldwide reached the Paris Agreement in 2015 to aim to keep global temperature rises to well-below 2°C above pre-industrial levels, and pursue efforts to limit the temperature increase to 1.5°C.

The report explores pathways and
technologies to keep warming down to 1.5 ºC. All the pathways explored use some form of carbon dioxide removal technologies to take between 100 and 1,000 gigatonnes of carbon dioxide out of the atmosphere before the end of the century.

But the report comes as global temperatures have already passed an average 1ºC rise on pre-industrial levels; the International Energy Agency
is warning that emissions from energy use are once more on the rise; and the US has announced it is planning to leave the Paris Agreement.

The gulf between the IPCC 1.5ºC report’s messages and what countries have currently signed up to in the Paris Agreement is large, with the current emissions pledges from Paris (which only a number of countries are on track with) projected to result in around 3ºC of warming. Business-as-usual would result in far more catastrophic levels of warming.

And some effects of climate change are being felt today. ‘One of the key messages that comes out very strongly from this report is that we are already seeing the consequences of 1°C of global warming through more extreme weather, rising sea levels and diminishing Arctic sea ice, among other changes,’ said Panmao Zhai, Co-Chair of IPCC Working Group I.

The report is published ahead of world governments meeting in Katowice, Poland, in December for the next major round of international climate change talks
COP 24 which will see countries discuss and attempt to finalise the rulebook for implementing emissions reductions under the Paris Agreement. Reports from prior UNFCCC meetings this year indicate that progress towards this is behind schedule.

Bob Perciasepe, President of the Center for Climate and Energy Solutions, said: ‘The IPCC’s special report reinforces, with even greater certainty, what was already abundantly clear – climate change poses truly grave risks, and we can avoid the worst of them only by quickly ramping up our collective efforts.’

‘The report makes clear that we need to use all the tools at hand. Even as we continue pushing as hard as we can on renewables and efficiency, we’ll need to rely heavily on other available and developing technologies, including nuclear and carbon capture, to achieve carbon neutrality. It’s not a competition – we need them all. Only through rapid innovation and deployment can we replicate in transportation and industry the encouraging progress achieved in the power sector.’

Sarah Butler-Sloss, Founder-Director at Ashden, said: ‘Limiting global temperatures to 1.5°C is arguably the biggest challenge the human race has ever faced. Renewable energy, sustainable farming practices and zero-emission transport would have to be rolled out at an unprecedented rate if we are to have any chance of stopping further rises, let alone reversing the trend.’

‘We have to do things very differently, and quickly, and this will require some fundamental rewiring of the systems we currently inhabit. Government policy to support almost total decarbonisation, and serious commitment from the financial sector to divert funding away from fossil fuels and into sustainable energy technology are a must.’

Professor Kevin Anderson from the University of Manchester said: ‘To genuinely reduce emissions in line with 2°C of warming requires a transformation in the productive capacity of society, reminiscent of the Marshall Plan. The labour and resources used to furnish the high-carbon lifestyles of the top 20% will need to shift rapidly to deliver a fully decarbonised energy system. No more second or very large homes, SUVs, business and first-class flights, or very high levels of consumption. Instead, our economy should be building new zero-energy houses, retrofitting existing homes, huge expansion of public transport, and a four-fold increase in (zero-carbon) electrification.’

Graphic: To reach 1.5°C carbon dioxide emissions need to reach net zero by mid-century

Source: IPCC

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