2023-07-11 16:00:00
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In the Paris Agreement, countries pledged to try to limit the temperature rise to 1.5℃ above pre-industrial levels. However, even if they kept their promises to reduce emissions, the truth is that an increase of around 2.7 ℃ is still predicted.
Given the circumstances, it is not surprising that almost two thirds of the scientists who are part of the Intergovernmental Panel on Climate Change (IPCC, for its acronym in English) affirmed in a survey of the magazine Nature what do you knowe expected a rise in temperatures of 3 ℃ or more.
In this situation,how different the impacts of climate change would be with a temperature rise of 3℃ compared to one of 1.5℃?
future scenarios
From the outset, it is important to note that, even when the negative effects grow in line with the temperature, the climatic impacts of 3 ℃ would be more than double those that we would suffer with 1.5 ℃ more. This is because the temperature is already around 1℃ above pre-industrial levels
so the shocks at a 3℃ rise would actually be more than four times those at 1.5℃ (a rise thereafter of 2℃ vs. 0.5℃).
However, in practice, shocks do not increase linearly with temperature. In some cases, the increase speeds up as the temperature rises, so the 3℃ impacts can be more than four times the 1.5℃ impacts. In the most extreme case, the climate system could reach a tipping point that would lead the planet into substantial change.
Two years ago, a scientific team published a investigation on the impacts of climate change depending on the different levels of global temperature increase. It was found that the average annual probability worldwide of experiencing a major heat wave increases from 5% in the period of 1981-2010 to 30% with 1.5 ℃ more, and up to a 80% in the case of 3 ���.
In the most extreme case, the climate system could reach a tipping point that would lead the planet to a substantial change
On the other hand, the average possibility of experiencing a flood in rivers, which currently stands at 2% of the years, increases to 2.4% with a rise of 1.5 ℃ and doubles to 4% at 3℃ plus. With a temperature rise of 1.5℃, the proportion of dry spells almost doublesand at 3 ℃ more, this figure becomes more than triple.
Photo: Nigel Arnell et al.
Of course, there is some uncertainty in relation to these data, as reflected in the graphs above, which show that the range of possible outcomes widens as temperatures increase.
The impact of a rise in temperatures in each region
There is also great variability in the world, which also grows with rising temperatures, which increases the geographical disparities in the impact. The risk of River flooding would increase especially rapidly in South Asiafor example, while the risk of drought grows in much of the African continent much faster than the world average.
The difference between 1.5 ℃ and 3 ℃ warming can be brutal even in places like the UK, where the impacts of climate change will be relatively less bleak than in other corners of the globe.
In a study recently published it has been found that in England the average annual chance of a heatwave, as defined by the UK National Weather Service, goes from around 40% today to around 65% with a warming of 1 .5℃ and exceeds 90% in case the planet’s temperature rises 3℃.
Precisely also at 3 ℃ more, the probability of experiencing at least one day a year of high heat stress becomes more than 50%.
Photo: Nigel Arnell et al.
The average proportion of dry spells is increasing at a rate similar to the world average. The chances of what is currently considered a flood in ten years are rising in the North West of England from 10% a year today to 12% at 1.5℃ plus and 16% at 3℃ per year. above the current one.
Heat waves and droughts, increasingly likely
On a global scale, significant variability is observed in terms of UK wide impact: especially in the south and east of the country, the risks related to extreme high temperatures and droughts increase, while to the north and west the risks of floods increase.
Once again, there is always room for doubt regarding these calculations, but the difference between the impacts according to the different levels of warming is clear. The real consequences for people they will depend on how these direct physical impacts (droughts, heat waves, sea level rises) affect livelihoods, health and the interactions between different elements of the economy.
Experience during COVID-19 suggests that what may seem like relatively modest initial disturbances to a system at first can cause an unforeseen ripple effect, and the same can happen with climate change.
If the relationship between temperature increases and physical impacts such as melting glaciers and extreme weather is often non-linear, then the relationship between temperature increases and their effect on people, societies and economies is likely to be be much less linear still. Definitely, a world with 3 ℃ more will be much worse than one with 1.5 ℃ more.
*Nigel Arnell is Professor of Climate Change Science and Director of the Walker Institute at the University of Reading. This note originally appeared on The Conversation and is published here under a Creative Commons license.
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