Limiting global warming to 1.5 degrees Celsius would reduce risks to humans by up to 85%
New research led by the University of East Anglia (UEA) quantifies the benefits of limiting global warming to 1.5 degrees Celsius and identifies the hotspot regions for future climate change risk.
The study calculates the reduction in human exposure to a range of risks – water scarcity and heat stress, vector-borne diseases, coastal and river flooding – that would result from limiting global warming to 1.5 degrees Celsius instead. of 2 or 3.66 degrees Celsius. Effects on agricultural yields and the economy are also included.
Researchers from the UK, including scientists from UEA and the University of Bristol, and from PBL Netherlands Environmental Assessment Agency, find that global risks are reduced by 10-44% if warming is reduced to 1.5 degrees Celsius instead of 2 degrees Celsius.
Currently, insufficient climate policies have been implemented globally to limit warming to 2 degrees Celsius, so the team also compared risks that would occur with higher levels of global warming.
The risks will be greater if global warming is greater. The risks of a warming of 3.66 degrees Celsius are reduced by 26-74% if warming is instead limited to just 2 degrees Celsius. They will be reduced even further, by 32-85%, if warming can be limited to just 1.5 degrees Celsius. The ranges are wide because the percentage depends on which of the indicators, for example human exposure to drought or flooding, is considered.
The findings, published today in the journal Climate changesuggest that in percentage terms the avoided risk is highest for river flooding, drought and heat stress, but in absolute terms the risk reduction is greatest for drought.
The authors also identify West Africa, India and North America as regions where risks from climate change are expected to increase the most by 1.5 degrees Celsius or 2 degrees Celsius of average global warming by 2100.
The study follows the Intergovernmental Panel on Climate Change’s (IPCC) sixth assessment report, which finds net zero CO globally.2 emissions must be achieved in early 2050 to limit warming to 1.5 degrees Celsius without or with limited exceedance, and by the early 2070s to limit warming to 2 degrees Celsius.
Lead author Prof. Rachel Warren, of the Tyndall Center for Climate Change Research at UEA, said: “Our findings are important because the goal of the Paris Agreement is to limit global warming to ‘well below’ 2 degrees Celsius and to to continue’ to limit it to 1.5 degrees Celsius. This means decision makers need to understand the benefits of aiming for the lower figure.
In addition, last year’s COP26 commitments from countries were not sufficient to meet the Paris targets. At present, current policies would result in an average warming of 2.7 degrees Celsius, while nationally determined contributions for 2030 limit warming. would limit it to 2.1 degrees Celsius.
“While there are a number of planned additional actions to further reduce emissions, potentially limiting warming to 1.8 degrees Celsius in the most optimistic case, these have yet to be implemented and further additional measures are needed to reduce warming to 1. .5 degrees Celsius.”
For this study, the researchers conducted advanced computer simulations of climate change risk, using a common set of climate change scenarios in which global temperatures rise by 2 degrees Celsius and individually by 1.5 degrees Celsius and 3.66 degrees Celsius. Then they compared the results.
The findings include:
- In general, the global population’s exposure to malaria and dengue fever is 10% lower if global warming is limited to 1.5 degrees Celsius instead of 2 degrees Celsius.
- Population exposure to water scarcity is most evident in western India and the northern region of West Africa.
- It is estimated that the global drought risk is constantly increasing with global warming, with hundreds of millions of people additionally affected by drought at each successively higher warming level.
- If we don’t adapt, by 2100, if we don’t adapt, global warming of 1.5 degrees Celsius would expose an additional 41 to 88 million people annually to coastal flooding (associated with 0.24-0, 56 m sea level rise), while an additional 45-95 million people per year would be at risk of global warming of 2 degrees Celsius (corresponding to 0.27-0.64 m sea level rise) in 2100.
- The global economic impact of climate change is 20% lower if global warming is limited to 1.5 degrees Celsius instead of 2 degrees Celsius. The net worth of damage is reduced accordingly from $61 trillion to $39 trillion.
The study used 21 alternative climate models to simulate the regional patterns of climate change corresponding to 2 degrees Celsius and 1.5 degrees Celsius warming, respectively. Previous research has used simpler models, a narrower range of climate models, or addressed different risk indicators.
Quantifying risks avoided by limiting global warming to 1.5 or 2 degrees C above pre-industrial levels, Rachel Warren et al, published in Climate change on June 29.
More than 6 billion people will be increasingly exposed to extremes due to global warming
Quantification of avoided risks by limiting global warming to 1.5 or 2°C above pre-industrial levels, Climate change (2022). DOI: 10.1007/s10584-021-03277-9
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