State of the Global Climate 2020

Unpacking the indicators

The global climate system is complex.

In order to unpack such complexity, the WMO State of the Global Climate uses seven Climate Indicators to describe the changing climate—providing a broad view of the climate at a global scale. They are used to monitor the domains most relevant to climate change, including the composition of the atmosphere, the energy changes that arise from the accumulation of greenhouse gases and other factors, as well as the responses of land, oceans and ice. The following site aims to provide an overview of the annually produced State of the Climate report.

📖:  Read the full report  (also available at the end of the page).


Greenhouse Gases

The atmospheric concentrations of greenhouse gases reflect a balance between emissions from human activities, sources and sinks. Increasing levels of greenhouse gases in the atmosphere due to human activities are a major driver of climate change.

The Big 3

Carbon dioxide (CO2) is the most commonly addressed greenhouse gas, and its atmospheric concentration is measured by parts per million (ppm). Methane (CH4) and nitrous oxide (N2O) are also extraordinarily important for the global climate and are measured by parts per billion (ppb).

In 2019, greenhouse gas concentrations reached new highs.

  • Carbon dioxide: 410.5±0.2 ppm = 148% of preindustrial levels
  • Methane: 1877±2 ppb = 260% of preindustrial levels
  • Nitrous oxide: 332.0±0.1 ppb = 123% of pre-industrial levels.

 

Despite setbacks from COVID-19, global greenhouse gas emissions increased in 2020.

Why do greenhouse gases matter?

Global Mean Surface Temperature

As greenhouse gas concentrations rise, so does global mean surface temperature (GMST). GMST is measured using a combination of air temperature two meters over land, and sea surface temperature in ocean areas from various databases, typically expressed as an anomaly from a baseline period.

In 2020, GMST was 1.2 ± 0.1 °C warmer than the pre-industrial baseline (1850-1900).

Despite developing La Niña cooling conditions, 2020 was one of the three warmest years on record. 

The last decade, 2011-2020, is the warmest on record.

Warming does not distribute equally around the planet.

Since the mid-1980s, Arctic surface air temperatures have warmed at least twice as fast as the global average, while sea ice, the Greenland ice sheet and glaciers have declined over the same period and permafrost temperatures have increased.

This has potentially large implications not only for Arctic population, infrastructure and ecosystems, but also for the global climate through various feedbacks.

Extreme Events

Rising global temperatures have contributed to more frequent and severe extreme weather events around the world, including cold and heat waves, floods, droughts, wildfires and storms.

The map below is not exhaustive but aims to illustrate a few key examples from the year.  Click here to explore the map .

Extreme precipitation in 2020

Regions with unusually high precipitation amounts in 2020 included East and North-East Africa, South and East Asia, south-eastern North America and the Caribbean and North-East Europe.

Unusually low precipitation amounts were observed in Southern and North-West Africa, South America, North-East and West Asia, south-western and north-eastern North America and northern New Zealand.

Total precipitation in 2020, expressed as a percentile of the 1951–2010 reference period, for areas that would have been in the driest 20% (brown) and wettest 20% (green) of years during the reference period, with darker shades of brown and green indicating the driest and wettest 10%, respectively. (Source: Global Precipitation Climatology Centre (GPCC)

Ocean Heat Content

Around 90% of the excess energy that accumulates in the earth system due to increasing concentrations of greenhouse gases, goes into the ocean.

Ocean Heat Content (OHC) is a measure of this heat accumulation in the Earth system. It is measured at various ocean depths, up to 2000m deep.

All data sets agree that ocean warming rates show a particularly strong increase in the past two decades across all depths.

In 2019, the 0–2000m depth layer of the global ocean reached a new record high, and a preliminary analysis based on three global data sets suggests that 2020 exceeded that record.

1960–2019 ensemble mean time series and ensemble standard deviation (2-sigma, shaded) of OHC anomalies relative to the 2005–2017 climatology for the 0–300 m (grey), 0–700 m (blue), 0–2000 m (yellow) and 700–2000 m (green) depth layers. Source: Updated from Von Schuckmann, K. et al. (2016) The ensemble mean OHC (0–2000 m) anomaly (relative to the 1993–2020 climatology) has been added as a red point, together with its ensemble spread, and is based on CMEMS (CORA), Cheng et al., 2017 and Ishii et al., 2017 products.

Why does ocean heat content matter?

Marine Heatwaves

In 2020, more than 80% of the ocean experienced at least one MHW, causing significant impacts to marine life and the communities that depend on it.

Coral bleaching

Corals are extremely sensitive to temperature changes. Their health is vital as they create entire ecosystems, serve as source of food for millions, protect coastlines from storms and erosion and serve as a source of tourism.

Cyclones

Warmer oceans can lead to more intense tropical cyclones. The number of tropical cyclones in 2020 was above average. 98 cyclones over the course of the year have caused billions of dollars of damage and claimed hundreds of lives.

As the ocean warms, its volume increases. Thermal expansion, as well as the melting of Greenland, the Antarctic and glaciers all over the world are causing sea levels to rise.

Sea Level Rise

Globally, sea level has been rising an average of 3.29 (+/- 0.3) mm per year, peaking in 2020. A small decrease in the latter part of 2020 is likely related to La Niña conditions in the tropical Pacific.

What's the big deal?

Glacial Mass

Glaciers, including ice sheets, are distributed across the planet, with concentrations in the high mountain ranges of Asia, and North and South America. As providers of ecosystem services and freshwater supply to millions around the world, glacial loss has significant and direct impacts on both the global climate and sustainable development.

Swipe to see how fast glaciers are shrinking worldwide.

Preliminary results for 2020, based on a subset of evaluated glaciers, indicate that glaciers continued to lose mass in the hydrological year 2019/2020.

Although, mass balance was slightly less negative, with an estimated ice loss of 0.98 metre water equivalent, there is a clear trend towards accelerating glacier mass loss in the long term.

Eight out of the ten most negative mass balance years have been recorded since 2010.

Annual (blue) and cumulative (red) mass balance of reference glaciers with more than 30 years of ongoing glaciological measurements. Global mass balance is based on an average for 19 regions to minimize bias towards well-sampled regions. Annual mass changes are expressed in metre water equivalent (m w.e.), which corresponds to tons per square metre (1000 kg m-2). Source: World Glacier Monitoring Service, 2021, updated

Sea Ice Extent

Sea ice extent measures areas covered by an areal ice concentration greater than 15%.

It serves as a useful indicator of climate change particularly given how quickly change occurs at the poles and how widespread the repercussions of its cover can be.

While Antarctic sea ice remained close to the long-term average:

Sea-ice extent difference from the 1981-2010 average in the Antarctic for the months with maximum ice cover (September) and minimum ice cover (February). Data from EUMETSAT OSI SAF v2p1 (Lavergne et al., 2019) and NSIDC v3 (Fetterer et al., 2017).

In the Arctic, the annual minimum sea-ice extent was the second lowest on record and record low sea-ice extents were observed in the months of July and October 2020.

Sea-ice extent difference from the 1981-2010 average in the Arctic for the months with maximum ice cover (March) and minimum ice cover (September). Data from EUMETSAT OSI SAF v2p1 (Lavergne et al., 2019) and NSIDC v3 (Fetterer et al., 2017).

Why do we care about arctic sea ice?

Greenhouses gases are not only the cause of the Earth's warming, they also contribute to the acidification of the ocean.

Ocean Acidification

One impact of rising CO2 concentration is ocean acidification.

The ocean absorbs around 23% of the annual emissions of anthropogenic CO2 to the atmosphere, helping to alleviate the impacts of climate change but at a high ecological cost to the ocean.

CO2 reacts with seawater and increases its acidity. It endangers organisms and ecosystem services, including food security, by endangering fisheries and aquaculture. It also affects coastal protection by weakening coral reefs, which shield the coastline, and tourism.

Global mean ocean pH has been steadily declining:

Global mean surface pH from 1985-2020. The shaded area indicates the estimated uncertainty in each estimate.

Risks & Impacts

Rising atmospheric CO2 concentrations lead to cascading effects via six of the other key climate indicators that perpetuate warming and contribute to high impact events, risking the achievement of the Sustainable Development Goals (SDGs).

Human Mobility & Displacement

Refugees, internally displaced people and migrants are often among those most vulnerable to climate- and weather-related hazards.

Over the past decade (2010–2019), weather-related events triggered an estimated 23.1 million displacements of people on average each year.

Ethiopian migrants collecting ground water for drinking at Alat Ela congregation point near Obock, Djibouti.

Approximately 9.8 million displacements, largely due to hydrometeorological hazards and disasters, were recorded during the first half of 2020, mainly concentrated in South and South-East Asia and the Horn of Africa.

Ethiopian migrants collecting ground water for drinking at Alat Ela congregation point near Obock, Djibouti.

Events in the second half of the year, including displacements linked to flooding across the Sahel region, the active Atlantic hurricane season and typhoon impacts in South-East Asia, are expected to bring the total for 2020 close to the average for the decade.

Ethiopian migrants collecting ground water for drinking at Alat Ela congregation point near Obock, Djibouti.

Food Security

After decades of decline, the recent increase in food insecurity is being driven by conflict, economic slowdown, climate variability and extreme weather events.

In 2020, over 50 million people were doubly hit – by climate-related disasters (floods, droughts and storms) and by the COVID-19 pandemic.

Nearly 690 million people, or 9% of the world population, were undernourished, and about 750 million, or nearly 10%, were exposed to severe levels of food insecurity in 2019.

Food insecurity is projected to worsen by 2030 (shown in the shaded area in the figure to the right).

Overall in 2020, the world remained on course to exceed the agreed temperature thresholds of either 1.5 °C or 2 °C above pre-industrial levels, which will increase the risk of experiencing the pervasive effects of climate change beyond what is already seen. Thus while reducing greenhouse gas emissions remains essential, scaling up adaptation is an urgent need.

The COVID-19 pandemic has brought many challenges, but it also presents opportunities to boost investment in green and resilient societies, setting us on a sustainable path for years to come.


Want to know more? See the State of the Global Climate in 2020 report below.                 

© World Meteorological Organization, 2020

WMO uses datasets developed and maintained by the United States National Oceanic and Atmospheric Administration, NASA’s Goddard Institute for Space Studies, and the United Kingdom’s Met Office Hadley Centre and the University of East Anglia’s Climatic Research Unit in the United Kingdom.

It also uses reanalysis datasets from the European Centre for Medium Range Weather Forecasts and its Copernicus Climate Change Service, and the Japan Meteorological Agency. This method combines millions of meteorological and marine observations, including from satellites, with models to produce a complete reanalysis of the atmosphere. The combination of observations with models makes it possible to estimate temperatures at any time and in any place across the globe, even in data-sparse areas such as the polar regions.

Internationally recognized datasets are used for all other key climate indicators. Full details are available in the provisional report.

Videos

FAO, NASA, UNEP, WMO

Data visualization

Claire Ransom, Valentine Haran, Nirina Ravalitera.

Total precipitation in 2020, expressed as a percentile of the 1951–2010 reference period, for areas that would have been in the driest 20% (brown) and wettest 20% (green) of years during the reference period, with darker shades of brown and green indicating the driest and wettest 10%, respectively. (Source: Global Precipitation Climatology Centre (GPCC)

1960–2019 ensemble mean time series and ensemble standard deviation (2-sigma, shaded) of OHC anomalies relative to the 2005–2017 climatology for the 0–300 m (grey), 0–700 m (blue), 0–2000 m (yellow) and 700–2000 m (green) depth layers. Source: Updated from Von Schuckmann, K. et al. (2016) The ensemble mean OHC (0–2000 m) anomaly (relative to the 1993–2020 climatology) has been added as a red point, together with its ensemble spread, and is based on CMEMS (CORA), Cheng et al., 2017 and Ishii et al., 2017 products.

Global mean surface pH from 1985-2020. The shaded area indicates the estimated uncertainty in each estimate.