On October 8, 2018, a summary report on the impacts of a 1.5˚C increase in global temperatures was approved by the IPCC in Korea. The summary for policymakers states that the current increase in global temperatures above pre-industrial levels (of 1.0˚C) has impacts and preventing an increase above 1.5˚C will benefit humans and the global environment.
“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 in an IPCC press release on October 8. Zhai is a co-chair for the IPCC working group on the physical science of climate change.
The report is intended to provide policymakers with information to consider and integrate climate change concerns within local policies.
What is the state of current and future global warming?
The IPCC special report outlines the current and projected state of global warming: human activities are estimated to have cases around 1.0˚C of warming compared to pre-industrial levels. Global warming is likely to reach 1.5˚C between 2030 and 2052.
The risks of sea level rise and the impacts to biodiversity and ecosystems from species loss are expected to be less severe from a 1.5˚C increase in global warming compared to a 2.0˚C increase. A 2.0˚C increase will also have a more severe impact on ocean temperatures, ocean acidity and oxygen levels. Likewise, the risks to human health, food/water supply and economic growth are not as severe from a 1.5˚C increase. And less investments in adaptation and mitigation are required.
What is proposed to limit global warming to 1.5˚C?
The summary report describes various pathways that are possible for global anthropogenic emissions. To limit global warming to 1.5˚C, comprehensive reductions in emissions are required across all sectors. The pathways projected to limit global warming require “rapid and far-reaching transitions in energy, land, urban and infrastructure (including transport and buildings), and industrial systems.”
Not all emissions reductions come from actually reducing source emissions. The pathways are aided with the use of carbon dioxide removal technologies and carbon capture and storage.
The role of land use and regional planning
As a global issue that requires comprehensive action, land use has a role in limiting global warming to 1.5˚C. In urban areas, infrastructure system transitions require “changes in land and urban planning practices” (C2.4). All pathways that limited global warming to 1.5˚C required a transition in global and regional land use (C2.5). These transitions were included in the pathways:
- Conversion of 0.5 to 8 million km2 of pasture
- Conversion of 0 to 5 million km2 of non-pasture agricultural land for food and feed crops into 1 to 7 million km2 for energy crops
- 1 million km2 reduction to 10 million km2 increase in forests by 2050 relative to 2010
The report acknowledges the challenge of the large transitions: “Such large transitions pose profound challenges for sustainable management of the various demands on land for human settlements, food, livestock feed, fibre, bioenergy, carbon storage, biodiversity and other ecosystem services.”
As demand for land increases, proposed mitigation options include:
- Sustainable intensification of land use
- Ecosystem restoration
- Reduce resource-intensive diets
- Overcome barriers (socioeconomic, institutional, technological, financial and environment) that differ across regions to promote regional planning
Download the entire summary report.
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