In December 2015, the Intergovernmental Panel on Climate Change (IPCC) was given a commission to be completed before the Katowice climate summit in December 2018: draft a report setting out the risks and impacts of a 1.5°C temperature increase by the year 2100, the actions required to avoid global warming, and the possible consequences.
As a result of the Paris Agreement and its goal of "holding the increase in the global average temperature to well below 2°C (…) and pursuing efforts to limit the temperature increase to 1.5°C (…)", 195 countries commissioned this special 1.5°C report from the IPCC.
Almost three years later, coinciding with the day on which William Nordhaus, one of the fathers of climate change economics, was awarded the Nobel Prize in Economics 2018 (along with Paul Romer), the IPCC has presented a devastating report that alerts of the damage already caused by global warming, that which is to come, and the actions to avoid it.
This document was released in the run-up to COP 24, when the rules for implementing the Paris Agreement must be ready. Those rules must take account of at least the following aspects that were highlighted in the report:
Impacts of climate change, those seen to date and those to come
The impacts of climate change are a problem being experienced in the present, such as extreme weather conditions, rising sea levels and the decrease of Arctic sea ice, among others. All this is the result of a 1°C increase in temperatures with respect to pre-industrial levels caused by human activities (anthropogenic).
However, numerous impacts could be avoided by limiting the temperature increase to 1.5°C rather than 2°C by the year 2100, notably:
- With global warming of 1.5°C, the increase in sea levels worldwide would be 10 cm less than with a 2°C increase.
- The likelihood of the Arctic Ocean being free of sea ice in summer would be a once-per-century phenomenon with 1.5°C heating, compared with once-per-decade with 2°C.
- Coral reefs would shrink by 70-90% with 1.5°C global warming, whereas practically all of them (>99%) would be lost with 2°C.
The report also analyses regional differences such as food availability, which is expected to increase significantly in Africa, the Mediterranean, Central Europe and the Amazon.
The second-best time to act to reduce emissions is now; the best has already passed
The report states that limiting global warming to 1.5°C requires reducing anthropogenic carbon dioxide emissions by approximately 45% from 2010 levels by 2030, reaching carbon neutrality (zero net emissions) around 2050.
It also expressly recommends not relying on technologies that remove carbon dioxide from the atmosphere, since they are unproven at a large scale and pose very significant risks for sustainable development.
Decarbonise the energy system and, by extension, the economy
To follow a path that keeps the temperature rise below 1.5°C, it will be necessary to effect rapid transitions with far-reaching impacts on land, energy, industry, buildings, transport and cities.
All of this will require deep emission reductions in all sectors, especially in the energy sector, where renewable energies must supply 70-85% by 2050. The path forward also requires a reduction in energy consumption and an increase in energy efficiency, with growing electrification and a greater contribution from low-emission generation sources. The report specifically mentions the role of solar, wind and storage technologies, which will guide the transition in power generation.
This fight will also contribute to achieving the Sustainable Development
Limiting global warming to 1.5°C rather than 2°C would reduce impacts on ecosystems, human health and well-being and facilitate the achievement of the United Nations Sustainable Development Goals (SDGs), especially those related to the eradication of poverty and reduction of inequality.
Climate change affects the ability to achieve the objectives set out in the 2030 Agenda. The road to achieving the SDGs will impact emissions, impacts and vulnerabilities. The responses to climate change in the form of mitigation and adaptation will also interact positively or negatively with sustainable development, which is why fighting climate change is also linked to the path towards sustainable development.
To conclude, the scientific evidence leaves no room for doubt: climate change is advancing inexorably, but there is very good news — there is still a chance to limit global warming to 1.5°C.