Understanding Global Warming of 1.5°C

We are facing the greatest environmental challenge of our generation.  As a threat multiplier[1], climate change compounds existing issues such as migration, poverty, social conflict[2], and political instability[3]. It disproportionately affects the poorest of the poor through food insecurity, higher food prices, lost livelihood opportunities, and adverse health impacts. As further affirmed in the IPCC Fifth Assessment Report (AR5), human influence on climate has been the dominant cause of observed warming since the mid-20th century as the global average surface temperature warmed by 0.85°C between 1880 and 2012.

But what is more alarming is that the current business-as-usual trend in global carbon emissions leads to a 4°C global warming scenario by the end of the century, according to IPCC Special Report on Special Report on Global Warming of 1.5°C.[4]

For vulnerable developing countries[5] like the Philippines, 1.5 is that threshold of chance and hope. Limiting global warming to 1.5°C is still technically and economically feasible, but will require rapid and far-reaching transitions, especially in land, energy, industry, buildings, transport, and cities[6].  To contain warming at this level, man-made global net carbon dioxide (CO2) emissions would need to fall by about 45 percent by 2030 from 2010 levels and reach “net zero” by mid-century[7].  This means that any remaining emissions would need to be balanced by removing CO2 from the air.

Impact of 1.5°C or 2°C Warming

The IPCC Special Report on Global Warming of 1.5°C underscores that meeting a 1.5°C (2.7°F) target is possible but would require deep emission reductions and rapid, far-reaching and unprecedented changes in all aspects of society. It also finds that “limiting global warming to 1.5°C compared with 2°C would reduce challenging impacts on natural ecosystems, human health, and well-being” and that a 2°C temperature increase would exacerbate diminishing Arctic sea ice, rising sea levels , and extreme weather/climate events, and second-order impacts, such as coral bleaching , and degradation of ecosystems, among others. There would be increased risks to health, livelihoods, food security, water supply, human security, and economic growth. 

Impact vectors include reduction in crop yields and nutritional quality. Livestock are also affected with rising temperatures as reflected by the changes in feed quality, incidence of diseases, and limited water resource availability. Further, risks from vector-borne diseases like malaria and dengue fever are also projected to increase.[8] 

Limiting global warming to 1.5°C could reduce the number of people both exposed to climate-related risks and susceptible to poverty by up to several hundred million by 2050.[9]


[1] https://www.un.org/peacebuilding/fr/news/climate-change-recognized-%E2%80%98threat-multiplier%E2%80%99-un-security-council-debates-its-impact-peace

[2] Climate Change as a Threat Multiplier for Human Disaster and Conflict. https://www.thehagueinstituteforglobaljustice.org/wp-content/uploads/2015/10/working-Paper-9-climate-change-threat-multiplier.pdf

[3] Why climate change is a ‘threat multiplier’. https://yaleclimateconnections.org/2019/06/why-climate-change-is-a-threat-multiplier/

[4] “The current NDCs, extending only to 2030, do not limit warming to 1.5°C. Depending on mitigation decisions after 2030, they cumulatively track toward a warming of 3°-4°C above pre-industrial temperatures by 2100.” https://www.ipcc.ch/sr15/chapter/chapter-1/

[5] https://www.un.org/en/development/desa/policy/wesp/wesp_current/2012country_class.pdf

[6] Summary for Policymakers of IPCC Special Report on Global Warming of 1.5°C approved by governments. https://www.ipcc.ch/2018/10/08/summary-for-policymakers-of-ipcc-special-report-on-global-warming-of-1-5c-approved-by-governments/

[7] Ibid.

[8] Climate change and vector-borne diseases: a regional analysis. https://www.who.int/bulletin/archives/78(9)1136.pdf.

[9] A Degree of Concern: Why Global Temperatures Matter. https://climate.nasa.gov/news/2865/a-degree-of-concern-why-global-temperatures-matter