From 2003 to 2016, Greenland lost about 255 billion tons of ice per year. (Visual China/Photo)
Global climate change is not a problem of the future, and the increase in greenhouse gas emissions by humans has led to changes in the Earth's climate, with wide-ranging effects on the environment: glaciers and ice sheets are shrinking, ice sheets in rivers and lakes are breaking up ahead of schedule, the geographical range of flora and fauna is changing, the flowering time of plants and trees is advancing earlier, sea levels are rising at an accelerated rate, and longer, more intense heat waves are frequent. Will record temperatures and shocking floods, droughts and storms devastate many parts of the world in 2022 continue in 2023?
Sea ice melting accelerates
Heading into 2023, global sea ice continues to melt.
Sea ice in Antarctica may have reached its lowest level in 2023, according to the National Snow and Ice Data Center, further confirming researchers' expectations that continued melting will occur at a record rate.
On February 21, 2023, at the peak of summer in the region, Antarctic sea ice reached its annual minimum area of 1.79 million square kilometers, the second consecutive year of lowest sea ice on record, according to the center. The shrinking extent of sea ice means that waves will hit the shores of the huge ice sheets more violently, further reducing the ice shelf around Antarctica. And Vostok Station, located deep in the interior of East Antarctica, reached a relatively mild -17.7°C, the warmest temperature measured in its 65-year history, and Antarctic sea ice reached the lowest range in 44 years of satellite records during the southern hemisphere summer.
On the other side of the planet, Greenland's ice sheet is also melting at an accelerating rate.
The Greenland Ice Sheet covers 1.7 million square kilometers in the Arctic. If it melts completely, global sea levels will rise by about 7 meters, though scientists are not yet sure how quickly the ice sheet will melt.
A study using simulations, published in Geophysical Research Letters in March 2023, identified two tipping points in the Greenland ice sheet. The study revealed that the Greenland ice sheet is already melting, losing about 255 billion tons of ice annually from 2003 to 2016. So far, most of the melting has occurred in the southern part of the ice sheet. Air, water temperature, ocean currents, precipitation and other factors all determine how quickly the ice sheet melts and the specific sites where it is lost. Previous studies have found that global warming of 1°C to 3°C is the threshold for irreversible melting of the Greenland ice sheet, and once crossed, it will inevitably continue to melt, even if the carbon dioxide in the atmosphere is reduced to pre-industrial levels, it will not be enough to stop the ice sheet from continuing to melt.
Not only that, but another team of researchers has found that the deep-sea circulation that forms around Antarctica could collapse and have further impacts on climate and marine ecosystems for centuries to come.
The study, published in Nature in February 2023, shows that the deep ocean circulation in Antarctica, driven by cold subsidence near Antarctica, is facing a trend of collapse. This circulation is a network of currents that span the world's oceans, the longest and strongest current on Earth, encircling the Antarctic continent from west to east, across the Pacific, Atlantic and southern tip of the Indian Ocean, and is associated with all other ocean currents. It is not only an extremely important part of the ocean-air interaction system in the Southern Ocean, but also plays an important role in climate change in the southern hemisphere and even the world.
Models show that if global carbon emissions continue to grow at their current rate, the overturning rate of the Antarctic Deep Ocean Loop will slow by more than 40% over the next 30 years, and it seems to be heading towards collapse, and the melting of ice sheets has a huge impact on the flipping circulation that regulates the Earth's climate, and this profound change in ocean heat, fresh water, oxygen, carbon and nutrients will have profound effects on Antarctic ecosystems and the global carbon cycle for centuries to come.
Many countries have seen the beginning
2022 was the fifth hottest year on record and the hottest La Niña year on record.
Despite the strong short-term cooling effect of La Niña events, much of the world in 2022 will still be much warmer than the average of previous years. Parts of Europe, South Asia, the North and Southwest Pacific, and the Atlantic and South-East Pacific all saw record high temperatures. Regions with cooler-than-average temperatures are limited to the central and eastern tropical Pacific, with Europe and Asia being the second warmest year after 2020, Africa being the 10th warmest year, and North America, South America and Oceania being the hottest in the top 20.
This year's weather conditions have already been revealed in many countries. In the first week of 2023 alone, many countries in Europe experienced their warmest January on record, with Antarctic Ocean ice cover shrinking to an all-time low in February, and thicker ice shelves supporting the Antarctic ground ice sheet exposed to waves and higher temperatures. The EU climate monitoring agency also released that since 2020, although the impact of La Niña weather patterns has slowed the global temperature rise, the past 8 years have been the hottest 8 years on record. Data from the Copernicus Climate Change Agency shows that the average temperature in 2022 was the 5th hottest year since records began in the 19th century, and climate change has made a series of unprecedented natural disasters more likely and deadlier.
Over the past 30 years, temperatures in Europe have risen more than twice as much as the global average, and the region has risen at the highest rate of temperature on any continent.
Spain experienced its hottest year on record in 2022, Spain's National Meteorological Service said in January 2023, adding that several cities in northern Spain were also unusually warm on New Year's Day 2023.
In March 2023, fires in the province of Corrientes in northern Argentina engulfed about 6,000 hectares of forest in just a few days, hit by a heat wave and drought. Argentina has faced waves of heat since the beginning of 2023, with fires already burning more than 100,000 hectares in the Corrientes region, according to data from Argentina's National Institute of Agricultural Technology; In February, Argentina issued health warnings in several provinces with temperatures close to 40°C, and while occasional heat waves are normal, climate change makes them more persistent and intense.
The return of El Niño in 2023 would make the world hotter and jeopardize key climate thresholds. (Visual China/Photo)
El Niño is back
The 2023 UN World Meteorological Organization said in its quarterly update report that El Niño could come this year, and after 3 consecutive years of unusually persistent and persistent La Niña, El Niño is likely to occur in June-August.
This suggests that 2023 will be hotter than 2022 and is on track to be one of the hottest on record. Barring unforeseen events such as major volcanic eruptions, 2014 to 2023 will be the 10 hottest years on record.
What exactly is the difference between La Niña and El Niño? First, we need to know that sea surface temperatures also affect global climate change. According to current standards, when the surface temperature of the sea is above 0.5°C below the climate average and lasts for more than 6 months, it is called La Niña. When the surface temperature of the sea water exceeds the climate average by more than 0.5 °C and lasts for more than 6 months, it is called El Niño, so La Niña is also called anti-El Niño.
So how much impact can a 0.5°C higher or 0.5°C lower surface temperature have on the seawater? The specific heat capacity of seawater is very large, which will directly affect the air temperature on the surface of seawater, resulting in changes in tropical atmospheric circulation (i.e. wind, air pressure and rainfall), which in turn causes global climate anomalies and aggravates droughts and floods in different parts of the world. Therefore, it is not an exaggeration to say that fluctuations of 0.5°C affect the whole body for the global climate.
In the previous 3 years, the cooling effect of La Niña temporarily curbed the rapid rise in global temperatures, but the past 8 years have still been recorded as the hottest 8 years on record, so the arrival of El Niño is likely to cause global temperatures to soar rapidly again. A return to El Niño would make the world hotter and jeopardize critical climate thresholds.
The World Meteorological Organization also said that although La Niña is coming to an end, some of its effects on rainfall are likely to persist due to its long duration, potential effects may continue for some time. El Niño and La Niñas are natural phenomena, but they occur against the backdrop of human-induced climate change, which causes global temperatures to rise, affects seasonal rainfall patterns and makes global weather more extreme.
The potential impact is already being revealed, with the University of Reading in the UK releasing news in 2023 showing that after the hottest February since 1901, the Indian Meteorological Department issued an early heatwave warning in 2023 and predicted higher than normal temperatures from March to May. The report of the United Nations Intergovernmental Panel on Climate Change (IPCC) suggests that for every 1°C increase in global climate, the frequency and intensity of future heat waves will become worse. The return of El Niño in 2023 will have even worse effects. As sea levels continue to warm in the equatorial Pacific, El Niño will bring more droughts and severe heat waves to India.
It is not yet clear how severe and intense India's heatwave will be in 2023, but warning signs are already appearing. These heat waves shorten the spring crop season. If crop yields decline, profit margins are reduced, resulting in fewer people working in the fields. Heat waves have the hardest impact on labour productivity, with India in particular being the country most affected by heat stress. Given that India is one of the world's largest wheat producers, heat waves could also put additional pressure on global food markets.
Sixth Assessment Report
More greenhouse gas emissions will lead to more climate extremes and have widespread damaging effects on the planet. However, these future impacts depend on the total amount of greenhouse gases emitted by humans, especially carbon dioxide, and from this perspective, there is still much humanity can do to mitigate climate change.
From 13 to 19 March 2023, the IPCC completed its report entitled Synthesis report of Sixth Assessment at its 58th session in Interlaken, Switzerland. The report shows that greenhouse gas emissions over the past 10 years have reached the highest level in human history, causing more damage to our lives, infrastructure and ecosystems than the IPCC's last report showed.
The efforts needed to combat climate change are well known: reduce the use of fossil fuels and decarbonize our energy system by using renewable energy sources such as wind and solar to power homes and buildings; Electrify as much as possible, including vehicles, heating systems, appliances, and machines. improving public transport and limiting industrial-scale emissions from the production of materials such as cement, plastic and steel; shifting to more sustainable food systems; Protect and restore forests and other ecosystems.
For humans, the most meaningful way to live in order to combat climate change is to choose low-emission transportation: walking, cycling, taking public transport, switching to electric vehicles if possible, etc. In a sense, the choice of means of transport is one of the greatest potentials for reducing the carbon footprint. On the other hand, adopting a healthier and more sustainable diet and reducing food waste can also have a significant impact in terms of emissions: eating more fruits and vegetables, eating less meat, sugar and packaged processed foods to reduce unnecessary food waste; In addition, when building or renovating houses or buildings, the use of energy-saving materials, electrical appliances and technologies can also reduce greenhouse gas emissions to a certain extent.
However, there are some barriers to widespread acceptance of these lifestyle changes. These barriers may vary from person to person or may be difficult to implement in practice. For example, how can cleaner modes of transport be chosen if infrastructure is not supported? If there are no more efficient home appliances on the market, why buy them selectively?
Beyond that, making this low-carbon lifestyle affordable for the average consumer and enabling everyone to make these transitions will require professionals and decision-makers in industries such as transportation, construction, and food manufacturing to prioritize these products at source. The "burning fire" is slowly extinguished, but if it does not continue to "add firewood", the raging fire may not eventually burn out, and the same is true of global warming.
Southern Weekend contributing writer Zhu Yehua