What will happen if the global average temperature rises by 2 degrees Celsius in the next few years?

What will happen if the global average temperature rises by 2 degrees Celsius in the next few years?

Previous studies have shown that if the global temperature rises by 2 degrees Celsius, some coastal cities including New York in the United States, London in the United Kingdom, Mumbai in India and Shanghai in China will face the risk of disappearing under water.

Worse still, if global temperatures rise by 4 degrees Celsius, sea level rise will double, submerging more land under water, causing devastating blows to coastal cities and forcing more people to move inland.

Figure | If global temperature rises by 2 or 4 degrees Celsius, Durban, South Africa (Source: Xinhuanet)

Although the consecutive La Niña events in early and late 2021 had a cooling effect on global temperatures, this was only a temporary phenomenon and could not reverse the long-term global warming trend.

As long as humans continue to emit greenhouse gases in large quantities, global temperatures will continue to rise, sea levels will continue to rise, the oceans will continue to warm and acidify, glaciers will continue to melt, and extreme weather will become more frequent.

So, what if the global temperature rises by 1.5 degrees Celsius? Although the negative impact will not be as great as that of a 2-degree Celsius rise, it will also force tens of millions of people to move inland, destroy the marine ecological environment, and cause devastating blows to some coastal cities.

And that moment may be approaching at an accelerated pace.

On May 9 local time, the World Meteorological Organization (WMO) stated in its latest climate bulletin that in the next five years, there is a 50% probability that the global average annual temperature will temporarily be 1.5 degrees Celsius higher than the pre-industrial level in at least one year, and this probability is increasing over time (this probability was close to 0 in 2015).

According to the bulletin, between 2022 and 2026, there is a 93% chance that at least one year will become the hottest year on record (2016 is the hottest year on record so far); and the probability that the average global temperature in these five years will be higher than the past five years (2017-2021) is also 93%.

In response, Hermanson, an official from the UK Meteorological Office, said that if humans want, the next (temperature) record can come earlier.

Why 1.5 degrees Celsius?

In 2016, 175 world leaders signed the Paris Agreement at the United Nations headquarters in New York.

The core goal of the Paris Agreement is to strengthen the global response to the threat of climate change, limit the global temperature rise to well below 2°C compared to the pre-industrial period, and strive to limit the temperature rise to 1.5°C.

Humanity has pledged that from now on, it will make more efforts to curb global warming, sea level rise, etc.

However, in recent years, the trend of global warming has continued to accelerate.

Data shows that global greenhouse gas emissions (including those caused by land use change) reached 55.3 billion tons of carbon dioxide equivalent in 2018. Among them, emissions caused by fossil fuel use and industrial activities reached 37.5 billion tons of carbon dioxide equivalent, an increase of 2% compared with 2017;

In 2019, global greenhouse gas emissions (including those caused by land use changes) reached 59.1 billion tons of carbon dioxide equivalent.

In October 2018, the Intergovernmental Panel on Climate Change (IPCC) released a special report on the impacts of global warming of 1.5 ºC above pre-industrial levels.

The report states that limiting global warming to 1.5 degrees Celsius will require rapid, far-reaching and unprecedented changes in all aspects of society.

Limiting global warming to 1.5°C, compared to 2°C, would not only bring clear benefits to people and natural ecosystems, but also ensure a more sustainable and equitable society.

The report also highlights that limiting global warming to 1.5 degrees Celsius rather than 2 degrees Celsius or more could avoid a range of climate change impacts.

For example, by 2100, limiting global warming to 1.5 degrees Celsius would reduce global sea level rise by 10 centimeters relative to 2 degrees Celsius;

The probability of an Arctic Ocean free of summer sea ice is once per century at 1.5°C, compared to at least once every decade at 2°C.

Coral reefs could decline by 70-90% at 1.5°C warming, and by 99% at 2°C warming.

In addition, some countries and regions have frequently experienced extreme weather such as droughts, wildfires, heat waves, tropical cyclones, and floods in recent years, which is also related to rising global temperatures.

Climate change is a global issue

Climate change refers to long-term changes in temperature and weather patterns. These changes can have natural causes, such as shifts in the solar cycle. However, since the 19th century, human activities have become the main cause of global climate change, particularly the burning of fossil fuels such as coal, oil and natural gas.

The burning of fossil fuels produces greenhouse gas emissions that act like a blanket around the Earth, trapping the sun's heat and causing temperatures to rise.

(Source: United Nations)

Scientifically speaking, greenhouse gases that cause climate change include carbon dioxide and methane. The sources of these gases include gasoline consumed by cars and coal burned for industrial production and heating of human residences.

In addition, clearing land and forests also releases carbon dioxide, and landfills are a major source of methane emissions.

The rising sea levels caused by climate change will not only bring devastating blows to coastal cities, but the resulting severe weather, such as floods and heat waves, will further threaten the survival of all mankind.

In recent years, although humans have begun to use more new energy to replace traditional fossil energy in response to climate change, as the latest climate bulletin shows, human efforts are far from enough because the trend of global warming has not slowed down.

Climate change remains a global issue that needs to be addressed and paid for by all of humanity.

References:

https://public.wmo.int/en/media/press-release/wmo-update-5050-chance-of-global-temperature-temporarily-reaching-15%C2%B0c-threshold

https://www.bbc.com/news/science-environment-61383391

https://www.un.org/en/global-issues/climate-change

https://www.ipcc.ch/languages-2/chinese/
https://www.ipcc.ch/sr15/download/