The World Meteorological Organization (WMO) published its annual report, namely, State of the Global Climate 2023, on March 19, 2024. According to the report, the year 2023 had broken every single climate indicator to become the warmest year on record. The global average temperature in 2023 remained at 1.45 °C (with a margin of uncertainty of ± 0.12 °C) above the 1850–1900 average. Till 2023, it has never been so close to the 1.5 °C lower limit of the Paris Agreement on Climate Change. According to the WMO report, many records for indicators of the climate system were broken, including greenhouse gas (GHG) levels, surface temperatures, ocean heat, sea level rise, Antarctic Sea ice cover, glacier retreat, etc. Every continent was devastated by heatwaves, floods, droughts, wildfires and powerful tropical cyclones, which also resulted in significant socioeconomic losses. These effects were especially terrible for vulnerable groups that have been bearing the brunt of the consequences disproportionately.
Key Climate Indicators
The report has provided a synopsis on the state of the climate indicators in 2023 and how these indicators have changed over time.
Some key climate indicators include:
Greenhouse gases Greenhouse gases include carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). These gases trap the incoming solar radiation in the atmosphere and contribute to global warming. Climate change has been mostly caused by greenhouse gases released in the atmosphere, mostly by human activities, since the industrial revolution. In 2022, the concentration of these greenhouse gases reached record-high, with carbon dioxide at 150 per cent, methane at 264 per cent, and nitrous oxide at 124 per cent of the pre-industrial (1750) levels. CH4 saw its second-highest rate of increase on record, following 2021, while N2O experienced its highest recorded rate of increase. CO2, growing at 2.2 ppm, slightly lagged behind the 10-year CO2, growing at 2.46 ppm per year. CO2 growth tends to be lower in the La Nina years like 2022 and higher in the El Nino years such as 2016.
Near-surface temperature According to the report, the global mean near-surface temperature in 2023 was 1.45 ± 0.12 °C, which was above the 1850–1900 average. It was the warmest ten-year period on record. The previous joint warmest years were 2016 at 1.29 °C + 0.13 °C and 2020 at 1.27 °C + 0.12 °C. The year 2023 has been the warmest year in the past 174 years. The second highest margin by which a September record was broken in the past 60 years was negligible at 0.03 to 0.17 °C in 1983. July became the warmest month of 2023.
Some of the temperature rise from 2022 to 2023 could have been caused by the transition from La Nina which lasted from mid-2020 to early-2023 to fully developed El Nino conditions by September 2023.
Between the Northern Hemisphere spring and the end of the year, global average sea-surface temperatures (SSTs) were 0.21 °C to 0.27 °C higher in 2023. The eastern North Atlantic, the Gulf of Mexico and the Caribbean, the North Pacific stretching eastwards from the Sea of Japan, the Arabian Sea and sizable areas of the Southern Ocean, all recorded extreme warmth in comparison to the 1991–2020 baseline.
Observed global land temperature anomalies reached record levels in July and August, but in September 2023, the average reached a record high by a large margin of 0.53 to 0.71 °C. Thus, in 2023, most land areas were warmer than the 1991–2020 average. Huge stretches of northern Canada, the southern US, Mexico, Central America, and South America were all reported to have unusually warm temperatures. Southeast Asia, Japan, and huge parts of North Africa and the Arabian Peninsula, as well as western Europe and Central Asia, were all abnormally warm.
Ocean Warming waters, sea-level rise, and ocean acidification have had a significant effect on the ocean as well as plants and animals that have been living in it and also the people who rely upon it for their livelihoods.
Ocean heat content The ocean heat content peaked in 2023, according to a 65-year observational record. Since 1971, the oceans have absorbed almost 90 per cent of the excess heat trapped by GHGs, causing them to gradually warm up.
According to the report, the upper 2000 metres of the ocean continued to remain warm in 2023. It is expected that this warming would continue, a chance which is irreversible on centennial to millennial timescales. The strongest warming in the upper 2000 metres occurred in the Southern Ocean (60°S–35°S), North Atlantic (20°N–50°N) and South Atlantic (60°S–0°S). With almost 32 per cent of the global ocean heat content increase in the upper 2000 metres since 1958, the Southern Ocean domain has been the largest heat reservoir. About 31 per cent of the global ocean heat content rise between 0 and 2000 metres of ocean heat content has been in the Atlantic Ocean, while 26 per cent has been in the Pacific Ocean.
A few comparatively small areas have been cooling, such as the subpolar North Atlantic Ocean extending from near the surface down to a depth of over 800 metres. The distinct patterns of the North Atlantic’s warming (20°N–50°N) and cooling (50°N–70°N) have been linked to localised interactions between air and sea as well as slowing of the Atlantic Meridional Overturning Circulation. The northwest, southwest, and southwest Indian Oceans are the other cooling regions.
Sea level The mean sea level globally hit a record high in 2023. Since the first 10 years of the satellite record (1993–2002), the pace of rise in sea level has more than doubled in the last 10 years between 2014 and 2023. This record rise could be attributed to the El Nino. In most of the eastern tropical Pacific, between April and June 2023, sea levels increased in comparison to the long-term mean, due to the warming of the surface waters during the early stages of El Nino in 2023. Above average sea levels were also observed in the tropical and north-east Atlantic, associated with the anomalous warming in these areas during Northern Hemisphere summer. El Nino pattern continued to develop towards the end of the year. The shift to the positive phase of the Indian Ocean Dipole (IOP) also led to higher-than-average sea level in the western Indian Ocean and lower-than-average sea levels in the east.
Marine heatwaves and cold spells Since early November 2023, most of the global ocean had been in a marine heatwave state, from 20° North to South of the equator. On the other hand, in 2023, there were hardly any occurrences of marine cold spells within 60° North or South of the equator. An average of 32 per cent of the global ocean experienced marine heatwaves in 2016, which has been significantly more than the previous record of 23 per cent. On the contrary, marine cold spells average daily coverage was only four per cent, a significant decrease from seven per cent of 2022.
Ocean acidification Ocean acidification, caused by the absorption of anthropogenic CO2 emissions by the ocean, is a significant threat to marine ecosystems. This process alters seawater chemistry, reducing pH levels and impacting biodiversity, habitats, and fisheries. Recent data indicate that open ocean surface pH is at its lowest in at least 26,000 years with unprecedented rates of change. Despite global efforts, many regions lack sufficient observation data, hindering our ability to understand and address this issue. Current observations under the Sustainable Development Goal 14.3.1 Indicator reveal inadequate coverage and insufficient time series to determine trends. While global trends show a decrease in pH due to CO2 emissions, regional and temporal variations necessitate high-resolution and long-term observations to understand the full extent of ocean acidification and its impacts.
Cryosphere The cryosphere is made up of the frozen parts of Earth, such as permafrost, sea ice, snow, and glaciers and icesheets. Long-term cryosphere observations have occasionally proven difficult to the hostile and frequently isolated conditions in which ice is formed.
Sea-ice In 2023, the extent of Arctic Sea ice remained significantly below normal, with the annual minimum and maximum extents ranking being fifth and sixth, respectively, in the 45-year (1979–2023) satellite record. In February, the extent of Antarctic Sea ice hit a record low for the satellite era. From June to early November, ice extent was at a record low for the season; in September, the yearly high was about one million km2 which was less than the previous record low maximum.
Ice sheets Ice sheets, expanses of ice covering over 50,000 sq. km2, are fundamental components of the Earth’s climate system, with Greenland and Antarctica hosting the principal ice sheets. The total mass balance (TMB) of an ice sheet comprises three components: surface mass balance (SMB), marine mass balance (MMB), and basal mass balance (BMB). The SMB represents the difference between snow accumulation and meltwater runoff. The MMB accounts for mass loss at the ice sheet edge due to calving of icebergs and melting of ice in contact with the ocean. The BMB includes melting at the ice sheet bed due to geothermal heat and friction as the ice slides over the ground. A negative mass balance indicates ice loss, while a positive balance indicates gain.
In 2023, Greenland experienced its warmest summer on record, with temperatures at the Summit station surpassing previous highs by 3.4 °C. Despite positive snow accumulation exceeding surface melt in most years, Greenland’s ice sheet continued to lose mass, with an estimated total mass balance of –217 Gt. The summer melt season was particularly intense, marked by significant melting events and the third-highest cumulative melt-day area on record. The Ice Sheet Mass Balance Intercomparison Exercise (IMBIE) highlighted a concerning trend of accelerated mass loss from both Greenland and Antarctica, contributing to a combined sea level rise of approximately 1 mm per year. However, while Greenland continued its trend of mass loss, Antarctica experienced a gain in mass due to higher-than-normal snow accumulation.
Glaciers According to the report, data from the global set of reference glaciers for the hydrological year 2022–23 has showed that they had experienced the largest loss of ice on record (1950–2023). This was driven by extremely negative mass balance in both western North America and Europe. The annual mass loss for Swiss glaciers in 2022–23 was the second largest on record (1950–2023) at 4.4 per cent of the remaining ice volume. Together with the record mass loss in 2021–22 of 5.9 per cent, glaciers in Switzerland lost around 10 per cent of their remaining volume since 2021.
Snow cover In the Northern Hemisphere, seasonal snow cover in the late spring and summer has been steadily declining over time. Snow cover extent in May 2023 in the Northern Hemisphere was the eighth lowest on record (1967–2023). May 2023 saw the lowest on-record snow cover in North America (1967–2023).
Climate Monitoring and Renewable Energy
The report also detailed about the renewable energy generation and climate monitoring.
Renewable energy generation, driven by solar radiation, wind and water cycles has been gaining momentum for climate action and decarbonisation targets. In 2023, renewable capacity additions increased by 50 per cent from 2022, reaching 510 GW. This has demonstrated the potential to triple global renewable energy capacity to reach 11,000 GW by 2030.
The WMO and the International Renewable Energy Agency (IRENA) on Climate-driven Global Renewable Energy Potential Resources and Energy Demand in 2022 have collaborated to highlight the critical nexus between climate variability and renewable energy. The report has emphasised the link between renewable resources and weather conditions, particularly in developing countries like Africa. It has called for better accounting for climate variability for improved energy resource management and planning.
Stratospheric Ozone and Ozone-Depleting Gases
The Montreal Protocol successfully ended the use of halons and chlorofluorocarbons in Antarctica, but their levels are still being monitored. The long lifetimes of these compounds would cause ozone destruction in Antarctica, resulting in the annual spring event, Antarctic ozone hole. It is an area where the total column ozone in the stratosphere falls below 220 Dobson units. In 2023, the onset of the ozone hole was early and was the sixth largest in the satellite era. According to NASA and Copernicus Atmosphere Monitoring Service (CAMS), it expanded to 26 million km2.
The unusual persistence of ozone holes has been attributed to below average stratospheric temperatures and a strong polar vortex lasting until December 2023. Stronger polar vortex has been driven by water vapour injected into the stratosphere by the eruption of Hunga Tonga–Hunga Ha’apai (a submarine volcano in the South Pacific), wind patterns in the Southern Hemisphere, and climate change.
Short-Term Climate Drivers
In 2023, the El Nino–Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD), and the North Atlantic Oscillation (NAO) contributed mainly to major weather and climate events across large areas of the world.
ENSO, characterised by variations in sea-surface temperatures in the tropical Pacific, transitioned from a multi-year La Nina event to a strong El Nino, resulting in widespread climate impacts. The IOD which affects sea-surface temperatures in the Indian Ocean, experienced its first positive phase since 2019, exacerbating dry conditions in Australia while bringing heavy rainfall to the Horn of Africa. The NAO, which influences pressure systems in the North Atlantic, contributed to a heatwave in Greenland and recorded warmth in Europe and Canada. These climate phenomena underscore the complex interplay of natural factors shaping global weather patterns and highlight the importance of understanding and monitoring them for climate prediction and adaptation efforts.
Precipitation
In 2023, precipitation patterns varied globally. Regions experiencing above-average precipitation included East and Central Asia, parts of northern Asia, the western Indian summer monsoon region, parts of the Maritime Continent, northern New Zealand, various parts of Africa and Europe, southern Scandinavia, the western Middle East, northwest, southwest, and southeastern region of North America, the Greater Antilles, and of southeastern parts of South America. Conversely, regions with notable rainfall deficits encompassed southeast South America, the Amazon Basin, much of Central America, southern Canada, the western Mediterranean region, Southwest Europe, parts of Africa and Asia, the eastern Indian Monsoon region, parts of southeast Asia and the Maritime Continent, southwest and coastal north Australia, and numerous Pacific Islands.
Additionally, the onset of the West African Monsoon occurred around normal timing. The Greater Horn of Africa region, which had been experiencing long-term drought, suffered significant flooding in 2023, particularly later in the year due to heavy rains associated with El Nino and the positive IOD.
Extreme Weather and Climate Events
The extreme weather has had a significant negative socioeconomic impact. Many regions of the world have been impacted by extreme heat. There have been fatalities, property destruction and significant air pollution as a result of wildfires in Hawaii, Canada, and Europe. Flooding brought on by Mediterranean Cyclone Daniel associated with extreme rainfall struck Greece, Bulgaria, Turkey, and Libya. Libya had a heavy loss of life due to this.
Socioeconomic Impacts
In 2023, food security, population displacements, and impacts on vulnerable population have been growing concerns. Weather and climate hazards are some of the main reasons that are exacerbating these situations. The Sendai Framework for Disaster Risk Reduction has increased local disaster risk reduction strategies. The Sendai Framework for Disaster Risk Reduction 2015–2030 aims to achieve the substantial reduction of disaster risk and losses in lives, livelihoods and health and in the economic, physical, social, cultural, and environmental assets of persons, businesses, communities, and countries over the next 15 years. The Framework was adopted at the Third UN World Conference on Disaster Risk Reduction in Sendai, Japan, on March 18, 2015. One of the important components for reducing the impact of disasters is to have effective multi-hazard early warning systems.
Food Security
The number of people who are acutely food insecure worldwide has more than doubled, from 149 million people before the COVID-19 pandemic to 333 million people in 2023. Global hunger levels remained unchanged from 2021 to 2022. The current global food and nutrition crisis is the largest in modern human history. Protracted conflicts, economic downturns, and high food prices further exacerbated by high costs of agricultural inputs driven by ongoing and widespread conflict around the world, are at the root of high global food insecurity levels. This is aggravated by the effects of climate and weather extremes.
Displacement
Millions of people are either in the process of moving or have already left their homes and communities due to natural disasters that have been made worse by climate shocks and stresses. These people include migrants, refugees, and internally displaced people. In 2023, weather risk persisted in causing new, prolonged, and secondary displacement. These patterns show how susceptibility to climatic shocks and stresses has been eroding resilience and posing new threats to protection, which has been threatening the achievements of the SDGs.
Way forward
Having efficient multi-hazard early warning systems in place has become a must. Also, systems for producing disaster risk information, isolating early warnings and disseminating them is also important. Furthermore, having action plans for when the warning come—are all crucial to lessening the impact of disasters. About 102 countries, as of 2023, have reported having multi-hazard early warning systems in place. With the goal of guaranteeing that everyone on earth is protected from hazardous weather, water, or climate disasters by life-saving early warning systems by the end of 2027, the UN Secretary-General has launched the Early Warnings for All initiative in March 2022.
All parties involved are required to act swiftly to increase the amount and calibre of climate funding going forward. Transforming the financial system with a focus on concessional financing and de-risking, bridging climate and development needs, utilising synergies to deliver co-benefits for people and nature, mobilising domestic capital with a focus on enabling policies and regulatory frameworks and enhancing the availability and accessibility of high-quality granular data to measure and manage progress are the key priorities for ensuring more and better climate finance.
Moreover, global climate finance saw a significant increase, almost doubling to nearly US$ 1.3 trillion in 2021–22, primarily driven by accelerated mitigation finance. However, this represents only about 1 per cent of global GDP, indicating a substantial financing gap compared to estimated needs for a 1.5 °C pathway. The cost of inaction, estimated at US$ 1,266 trillion over the period 2025–2100, underscores the urgency of adequate climate financing. Despite this momentum, growth in finance is uneven across sectors and regions, with clean energy investments dominating in a few geographies. Adaptation finance remains insufficient, especially in vulnerable developing countries, highlighting the need to mainstream resilience efforts. To address these challenges, efforts must focus on scaling both the quantity and quality of climate finance, emphasising concessional financing, bridging climate and development needs, mobilising domestic capital, and improving data accessibility and management.
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