The Global Climate 2011-2020
A decade of accelerating climate change
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 decadal reports differ from annual reports by taking analyzing these indicators over longer periods of time. This allows trends, such as acceleration, to become more visible.
Greenhouse Gases
Increasing levels of greenhouse gases in the atmosphere due to human activities are a major driver of climate change.
The atmospheric concentrations of greenhouse gases reflect a balance between sources, emissions from human activities, and sinks.
Each of the past three decades has had successively higher fossil fuel CO 2 emissions.
Although the change might not look significant, concentrations of greenhouse gases are not just growing, they are accelerating.
Explore the charts to find out the growth rates from one decade to the next.
The accelerating change in methane (CH 4 ) concentration has been even more pronounced: the growth rate between decades has nearly doubled.
The acceleration in methane has been driven by the growth in emissions from agriculture, waste, and fossil fuel production and use, though natural emissions from wetlands have also contributed to a smaller degree.
It's not all bad news:
Thanks to actions taken under the Montreal Protocol, the ozone hole was smaller in 2011-2020 than the two previous decades.
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 over land, and sea surface temperature in ocean areas, typically expressed as a difference from a baseline period.
At approximately 1.10° above the pre-industrial average (1850-1900), it was the warmest decade on record by a clear margin.
Each successive decade since the 1990s has been warmer than all previous decades.
Another indicator of long-term changes in extreme heat is the occurrence of record high temperatures.
Of 96 WMO Members who reported their highest temperatures from 1961-2020, 37 reported their highest temperature during 2011-20, and 2 more their equal-highest, higher than in any other decade, and nearly twice as much as the previous decade.
Precipitation
Compared to temperature, precipitation is characterized by higher spatial and temporal variability.
There were large differences in precipitation by region over the decade.
Some regions had an abnormally dry decade. Long-term drought was predominant in many subtropical regions, including the south-western United States, the western Mediterranean, eastern Australia south of the tropics, southern Africa, central Chile and northeast Brazil.
On the other hand, the decade shows above average to extreme wet conditions across most of Asia. The year 2020 was exceptionally wet in parts of China and Pakistan.
Ocean Heat Content
As greenhouse gases accumulate in the atmosphere, temperatures warm on land and in the ocean.
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 measures how this energy warms the ocean at various depths down to 2000m deep.
It is expected that the ocean will continue to warm well into the future – a change which is irreversible on centennial to millennial time scales.
The upper 2000m depth of the ocean continued to warm throughout 2011-2020, reaching a record high in 2020.
This continues a sequence of record years that began in 2013 in most data sets, and it is expected that this trend will continue in the future.
But why does ocean warming matter?
Coral bleaching
Corals are extremely sensitive to temperature changes. Their health is vital as they create entire ecosystems, serve as a source of food for millions, protect coastlines from storms and erosion and can be key tourist attractions.
Sea Level Rise
As water warms, it expands. Therefore, rising ocean temperatures are a key contributor to rising sea levels around the globe.
Sea Level Rise
The global sea level is rising for a number of reasons.
Ocean warming and melting ice sheets and glaciers all contribute to overall rise.
Between 2011-2020, sea level rose at a rate of approximately 4.5mm/yr.
In the previous decade (2001-2010), sea levels rose at a rate of rate of only 2.9mm/yr.
This means sea level rise is also accelerating.
Since 1993, the acceleration of rise has been estimated at approximately 0.11mm/yr 2 .
Ocean Acidification
Rising greenhouse gas concentrations impact the planet in other ways besides warming.
Another impact of rising CO 2 concentration is ocean acidification.
The ocean absorbs around 25% of the annual emissions of anthropogenic CO 2 to the atmosphere, helping to alleviate the impacts of climate change but at a high ecological cost to the ocean.
CO 2 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 encourage tourism.
As the pH of the ocean decreases, meaning that its acidity increases, its capacity to absorb CO 2 from the atmosphere also declines.
Global mean ocean pH has been steadily declining at rates not seen for at least the past 26,000 years.
As more CO 2 is added to the ocean, there is a greater abundance of hydrogen ions (H+), and the water becomes more acidic.
However, this doesn't happen uniformly. Some areas of the ocean are becoming more acidic than others.
Sea Ice Extent
Changes in global temperature resulting from increasing greenhouse gases also impact bodies of ice, both at sea and on land.
Sea ice extent is estimated from measurements taken from satellites.
It serves as a useful indicator of climate change, particularly given how quickly change occurs in the Arctic and how widespread the repercussions of changes in its cover can be.
Arctic Sea Ice
Arctic sea-ice extent continued to decline from 2011-2020, particularly during the summer melt season.
Arctic Sea Ice
The mean seasonal minimum during the 2011-2020 period was 4.37 million km 2 , 30% below the 1981-2010 average of 6.22 million km 2 .
Antarctic Sea Ice
By contrast, Antarctic sea ice extent shows no clear long-term trend. Overall, mean sea ice extent for the decade was close to the average of the preceding years.
Ice Sheets
The Greenland and Antarctic Ice Sheets are the largest freshwater reservoirs on Earth, storing a volume of 29.5 million km 3 of frozen water.
When ice sheets lose mass, they directly contribute to raising sea level. Monitoring the volume of ice they gain or lose is therefore critical to assessing sea level change.
During the 2011-2020 decade, Greenland lost mass at an average rate of 251 Gt/yr and reached a new record mass loss of 444 Gt in 2019.
Antarctica lost ice at an average rate of 143 Gt yr -1 during this decade, nearly 75% more than the rate of the previous decade.
Glacier Mass Balance
Glaciers are found around the world, with many in the high mountain ranges of Asia, and North and South America.
They are formed from snow that has compacted to ice, which then flows downhill to lower, warmer altitudes, where it melts.
Glaciers provide ecosystem services and freshwater to millions around the world. As they shrink, there are significant and direct impacts on both the global climate and sustainable development.
Approximately 40 of the glaciers monitored worldwide by the World Glacier Monitoring Service have long-term observations and are used to estimate glacier mass balance.
The glaciers have been losing mass nearly every year since records began.
From 2011-2020, glacial loss was nearly double the previous decade.
On average, measured glaciers thinned by approximately 1m per year.
What does mass loss look like? Swipe to see how glaciers are shrinking in Switzerland:
View of Vadret da Tschierva and Piz Roseg in 1935 (left) and 2022 (right) (Photo: swisstopo and VAW / ETH Zurich )
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. More details on specific events can be found in the report.
A selection of extreme events from 2011-2020, with triangular icons representing event types. Events are not intended to be exhaustive but rather representative of key extremes over the course of the decade. Click on any event for more information, including impacts to the SDGs.
Impacts to Sustainable Development
It is becoming increasingly clear that climate extremes are affecting our ability to develop sustainably.
Taking Action on Climate & the SDGs
Climate action is the 21 st century’s greatest opportunity to drive forward all the Sustainable Development Goals.
The connections between climate and the SDGs are not just negative.
In the 2023 Synthesis Report, the IPCC demonstrated that there are many more synergies between climate and SDG action than there are trade offs.
Building off this knowledge, UNDESA and UNFCCC published a report to strengthen the evidence base to show addressing climate change and achieving the SDGs are inextricably intertwined.
For example, one case study showed how the energy system transition across Africa's largest cities could significantly reduce global air pollution and, in so doing, prevent as many as 350,000 premature deaths across Accra, Cairo, Johannesburg, and Lagos between 2023 and 2040 .
There are many more possibilities for synergistic action, across all sectors and regions.
We must solve the climate emergency and sustainable development challenges together, or we will not solve them at all.
How will you get in involved?
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