Global Warming: 1.5 Degrees Celsius Higher Temperature Spells Higher Catastrophic Risks

The study, led by the University of East Anglia (UEA), estimates that limiting global warming to 1.5 degrees Celsius rather than 2 or 3.66°C would reduce human exposure to several risks, including water scarcity and heat stress, coastal and river flooding, as well as vector-borne diseases. It also includes effects on the economy and some agricultural yields.

Researchers from the UK have discovered that global risks are decreased by 10-44 percent if warming is kept to 1.5 degrees Celsius as opposed to 2°C. These researchers include scientists from UEA, the University of Bristol, and the PBL Netherlands Environmental Assessment Agency.

The team also compared the risks with higher levels of global warming because not enough climate policy has been implemented globally to keep warming to 2°C.

1.5°C vs 3.66°C

Greater global warming will increase risks. If warming is limited to just 2°C, the risks at 3.66°C warming are decreased by 26-74%. If warming is kept to just 1.5°C, they are decreased even more, by 32-85%t. The ranges are broad because the percentage changes depending on which indicators are taken into account.

The research, which was presented today in the journal Climatic Change, suggests that while drought, river flooding, and heat stress pose the greatest percentage-based risks, drought poses the greatest absolute risks.

The authors also note that with 1.5 or 2°Cof average global warming by 2100, West Africa, India, and North America are projected to experience the greatest increases in climate change-related risks.

According to the IPCC's Sixth Assessment Report, global net-zero CO2 emissions must be achieved by the early 2050s to keep global warming to 1.5°Cs with no or little overshoot and by the early 2070s to keep it to 2°C.

Prof. Rachel Warren of the Tyndall Centre for Climate Change Research at UEA said that Because the Paris Agreement aims to keep global warming "well below" 2°C and "pursue efforts" to keep it below 1.5°C, their findings are significant. As a result, decision-makers must comprehend the advantages of aiming for the lower figure. Warren is the principal author of the study.

Furthermore, the reductions in greenhouse gas emissions pledged by nations at COP26 last year were insufficient to meet the Paris goals. While the Nationally Determined Contributions for 2030 would cap warming at 2.1°C, current policies would result in average warming of 2.7°C.

She also emphasized that even though several additional actions are planned to reduce emissions even further, possibly limiting warming to 1.8 degrees Celsius in the most optimistic case, these still need to be implemented and additional action is required to limit warming to 1.5°C.

Using a standard set of climate change scenarios in which global temperatures rise by 2°C and separately by 1.5°C and 3.66°C, the researchers ran sophisticated computer simulations of climate change risk for this study. The outcomes were then compared, Science Daily reports.

The Findings

Here is a summary of their findings:

Global population exposure to dengue and malaria is reduced by 10% if warming is limited to 1.5°C as opposed to 2°C.
In the northern part of West Africa and western India, population exposure to water scarcity is most noticeable.
With global warming, it is estimated that the risk of drought will increase steadily, affecting hundreds of millions of additional people at each successively higher warming level.
If we don't adapt, global warming of 1.5°C by 2100 would put an additional 41-88 million people at risk of coastal flooding worldwide (corresponding to 0.2-0.56 m of sea-level rise), while global warming of 2°C would put an additional 45-95 million people at risk (corresponding to 0.27-0.64 m of sea-level rise).
The effects of climate change on the world economy are 20% less severe if warming is kept to 1.5°C as opposed to 2°C. Accordingly, the total amount of damages is decreased from 61 trillion to 39 trillion US dollars.

To simulate the regional patterns of climate change corresponding to 2°C warming and 1.5°C warming, respectively, the study used 21 alternative climate models. Previous studies have covered various risk indicators, used simpler models, or have access to a smaller selection of climate models, The Weather Channel reports.