Limiting global warming to 1.5°C: the IPCC report

Early October, the Intergovernmental Panel on Climate Change (IPCC) published its awaited special report on the impacts of global warning of 1.5°C above pre-industrial levels. The IPCC was commissioned as part of the Paris Agreement to produce this report. The Paris Agreement includes the aim of “holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels”. Pre-industrial levels refer to the period of around 1850-1900.

Climate change effects already visible

Extreme weather, rising sea levels and diminishing Artic sea ice are the consequences of 1°C above pre-industrial levels. The IPCC report states that human activities are estimated to have caused this 1°C global warming above pre-industrial levels, and that global warming is likely to reach 1.5°C between 2030 and 2050. However, the report highlights that warming from anthropogenic emissions from the pre-industrial period to the present will persist for centuries to millennia but that these emissions alone are unlikely to cause global warming of 1.5°C. Anthropogenic emissions are also unlikely to cause further warming of more than 0.5°C over the next two to three decades. Climate change effects are already visible. Many land regions experience a warming greater than the global annual average. Moreover, scientists observe a trend in some climate and weather extremes that are occurring more frequently and with more intensity.

Future impacts of climate change

Climate related risks for natural and human systems are higher for global warming of 1.5°C than at present, but lower than at 2°C. Future climate-related risks depend on the rate, peak and duration of warming. An additional 0.5°C of warming compared to present will bring further detectable changes in the extremes. Impacts of climate change will not be evenly the same. Climate models project robust differences in regional climate characteristics between present-day and global warming of 1.5°C, and between 1.5°C and 2°C. It will impact the mean temperature in most land and ocean regions, create hot extremes in most inhabited regions, give way to heavy precipitation in several regions and drought and precipitation deficits in other regions. On land, impacts on biodiversity and ecosystems, including species loss and extinction, are projected to be lower at 1.5°C of global warming compared to 2°C. Climate-related risks to health, livelihoods, food security, water supply, human security and economic growth are projected to increase with global warming of 1.5°C, and increase further with 2°C.

Limiting global warming to 1.5°C

Warming of 1.5°C or higher increases the risk associated with long-lasting or irreversible changes. Yet the report highlights that a number of impacts of climate change can be avoided by limiting global warming to 1.5°C compared with 2°C. Moreover, limiting global warming to 1.5°C would avoid climate change impacts on sustainable development, eradication of poverty and reducing inequalities. This would require system transitions that could be enabled by an increase of adaptation and mitigation investments, policy instruments, the acceleration of technological innovation and behaviour changes.

Pathways available to limit warming to 1.5°C

The IPCC report argues that sustainable development supports, and often enables, the fundamental societal and systems transitions and transformations that help limit global warming to 1.5°C. The reports highlights as well that strengthening the capacities for climate action of national and sub-

national authorities, civil society, the private sector, indigenous peoples and local communities can support the implementation of ambitious actions implied by limiting global warming to 1.5°C. Moreover, adaptation options specific to national context will have benefits for sustainable development and poverty reduction with global warming of 1.5°C. Similarly, mitigation options consistent with 1.5°C pathways are associated with multiple synergies and trade-offs across the Sustainable Development Goals (SDGs).

Source: GLOBAL WARMING OF 1.5°C – an IPCC special report – Summary for Policymakers