In 2015, world leaders came together to address the issue of global warming. The talks culminated in the Paris Climate Agreement, an international treaty that set a key goal: limiting global warming to 1.5 degrees Celsius, or “well below” 2 degrees Celsius above pre-industrial levels.
The 2°C criterion was not chosen at random. Rather, it is the dangerous point or threshold, exceeding which many scientists believe will significantly increase the risk of catastrophic and irreversible changes in our planet’s systems.
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In terms of climate change, 2 degrees Celsius means the average increase in global surface temperatures compared to pre-industrial levels (the period between 1850 and 1900).
According To report US National Oceanic and Atmospheric Administration The planet has warmed so far by 1.2 degrees Celsius, while other data sees the planet exceeding the 1.5 degrees Celsius threshold in some years, and many projections indicate that we are “on track” to reach 2 degrees Celsius.
Global warming is not uniform across the world. Some regions, such as the poles, are warming much faster than others. Europe is the fastest warming continent in the world, as its temperature is rising at twice the rate of any other continent.
A freer world
Under the 2°C scenario, the world will see significant temperature changes. And just a report Intergovernmental Panel on Climate Change, the Earth will warm more than the oceans, and the Arctic will warm 2 to 3 times faster than the global average.
Heat waves will also be more frequent and intense in the tropics, with fewer cold waves in high latitudes (which are located near the Earth’s poles), and more hot days and nights globally.
These temperature changes will have cascading impacts on various aspects of Earth’s systems, from weather patterns to terrestrial and aquatic ecosystems.
More extreme weather
One of the most notable effects of a two-degree Celsius rise in temperature is an increase in the frequency and intensity of extreme weather events. These phenomena can have devastating impacts on communities, infrastructure and natural systems.
Heatwaves will become more common, intense and long-lasting in a 2°C warmer world. And she points Research The probability of being exposed to a heat wave like the one that struck Europe in 2003, which caused more than 30,000 deaths, will increase from once every 100 years to once every 4 years under a 2 degree Celsius scenario.
and preference Some studies Regions already exposed to high temperatures, such as the Middle East and North Africa, will experience “extreme heat waves” with temperatures exceeding 50 degrees Celsius, which will make some areas uninhabitable unless serious adaptation measures are taken.
A study conducted in October 2023 warned that heat and humidity levels will reach deadly levels for several hours, days and even weeks in some parts of the world by the end of the century, even if the average global temperature is below two degrees Celsius, making staying outdoors impossible.
Under the two-degree scenario, droughts will become more frequent and severe in many parts of the world. andYou expect The Intergovernmental Panel on Climate Change expects the area of global land affected by drought to increase by 50% at 2°C, compared to 1.5°C.
The most affected regions will be the Mediterranean region, South Africa, parts of Australia and South America in particular.
In addition to impacting water resources, severe and prolonged drought would destroy major food crops and cause high livestock mortality rates, leading to local and global food insecurity.
While some areas will become drier, others will experience greater flooding. With a 2°C rise in temperature, the Intergovernmental Panel on Climate Change estimates that the global population exposed to river floods will increase by up to 170% compared to a 1.5°C scenario.
The intensity and frequency of heavy rainfall will also increase in many regions, especially in high latitudes and the tropics. This increase will lead to more sudden and severe floods, especially in urban areas, where huge losses will occur.
Although the total number of tropical cyclones may not change much, they will be more intense. And she points Studies In a 2°C scenario, the incidence of Category 4 and 5 hurricanes will increase by 13%, and their average intensity will increase by 5%, putting coastal communities and infrastructure at risk.
Variable climate patterns
Combined with extreme weather events, a 2°C rise in temperature will lead to major shifts in global climate patterns, affecting precipitation rates and ocean currents.
Humid areas are likely to become wetter, and dry areas drier, which will exacerbate the water crisis in many parts of the world, as rainfall rates will decrease in subtropical dry areas, including the Mediterranean region, southern Africa, and parts of Australia.
There will also be changes in monsoon systems, affecting billions of people who depend on seasonal rains for agriculture and water provision.
There will also be significant changes in ocean currents that contribute to regulating the global climate and supporting marine ecosystems. With a 2°C rise in temperature, major changes in ocean circulation patterns are expected.
One of the most worrying changes is the weakening of the Atlantic Meridional Overturning Circulation (AMOC). And she points Research In a 2°C scenario, the Atlantic meridional overturning circulation may weaken by 15-20%, which will make northwestern Europe colder and affect weather patterns in the Northern Hemisphere.
Sea level rise is also one of the biggest long-term effects of global warming. With a rise in temperature of two degrees Celsius, it is expected Studies Global average sea level will rise by 0.46-0.99 meters by 2100 compared to 1986-2005 levels. Until global warming stops, sea levels will continue to rise for centuries, according to studies.
Among the effects of sea level rise are more flooding and coastal erosion, threatening low-lying coastal areas and small island states, and saltwater intrusion into coastal aquifers, affecting freshwater resources.
Coastal wetlands will also increasingly lose mangroves, which provide important ecological services, act as natural barriers against storms, and serve biodiversity.
Damage to ecosystems
Under the two-degree scenario, thousands of species, both terrestrial and marine, will face increased risks of extinction as they struggle to adapt to rapidly changing conditions. These disturbances will have cascading impacts on biodiversity, carbon storage, and many ecosystem services on which human societies depend.
And she points Studies 99% of coral reefs will deteriorate due to increased frequency of marine heat waves and ocean acidification. Rapid warming in the Arctic will lead to significant loss of sea ice and change food webs, affecting the organisms that live there.
Higher temperatures and changes in rainfall patterns will also lead to shifts in forest composition and biomass, increased risks of wildfires and pest outbreaks, and loss of biodiversity.
and expected One of the studies The rate of species extinction will accelerate, as 18% of insects, 16% of plants, and 8% of vertebrates will lose more than half of their climatically determined geographic range with a rise in temperature of 2 degrees Celsius.
According to experts, a two-degree Celsius scenario seems too dangerous for humanity to bear, but in the end it will – if it happens – be human-made, as a result of activities such as burning fossil fuels, deforestation, industrial processes and unbalanced exploitation of nature. With warming expected to continue in the coming years, humanity’s choices will determine the future of life on this planet.