Climate change: 2020 set to be one of the three warmest years on record
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The Sun shining through the heat haze from a wildfire in California
The Earth continued to endure a period of significant heating in 2020 according to the World Meteorological Organization (WMO).
Its provisional assessment suggests this year will be one of the three hottest, just behind 2016 and 2019.
The warmest six years in global records dating back to 1850 have now all occurred since 2015.
The most notable warmth was in the Siberian Arctic, where temperatures were 5C above average.
How do we know the temperature for 2020 when the year isn't over yet?
To work out the annual rise in temperatures for their State of the Climate report, the WMO uses information from five different global datasets.
They then compare modern readings to temperatures taken between 1850-1900. This baseline figure is sometimes referred to as pre-industrial levels.
With data available from January to October this year, the WMO says 2020 is set to be around 1.2C above the baseline, but with a margin of error of 0.1C.
All five datasets currently have 2020 as the second warmest, behind 2016 and ahead of 2019, based on comparisons with similar periods in previous years.
However the expectation from scientists is that the temperature data from November and December will likely see enough cooling to push 2020 into third spot.
That's because a La Niña weather event has developed in the Pacific Ocean and this normally depresses temperatures.
The biggest differences from the long term average temperature were seen in the Siberian Arctic
Despite this, the WMO is certain that 2020 will remain one of the warmest three.
"Record warm years have usually coincided with a strong El Niño event, as was the case in 2016," said Prof Petteri Taalas, WMO Secretary General.
"We are now experiencing a La Niña, which has a cooling effect on global temperatures, but has not been sufficient to put a brake on this year's heat."
Are these small temperature differences important?
These relatively similar global temperature figure recorded over the past few years hide considerable differences at local level.
In 2020, Siberia saw temperatures around 5C above average, which culminated in a reading of 38C at Verkhoyansk on the 20th June, which is provisionally the highest known temperature recorded anywhere north of the Arctic Circle.
Icebergs off Greenland as the Arctic summer melt was second largest on record
January to October was also the warmest such period on record in Europe.
But some places were below average including parts of Canada, Brazil, India and Australia.
Overall though the 2020 figure reinforces the view that climate warming, driven by human activities is persisting. The decade from 2011 to 2020 is the warmest yet recorded.
Where 2020's heat went
The majority of the excess heat generated from warming gases in the atmosphere ends up in the oceans.
This is putting added strain on the seas, with around 80% of global waters experiencing at least one marine heatwave this year. These events, similar to heatwaves on land, see prolonged exposure to high temperatures which can have devastating impacts on marine creatures and ecosystems.
A long-running heatwave off the coast of California, known as "the blob", was said to have killed up to a million seabirds in 2015-16.
Researchers say that these events have become more than 20 times more frequent over the past 40 years.
"About 90% of the heat accumulating within the climate system from anthropogenic climate change is stored in the ocean," said Prof John Church from the University of New South Wales in Sydney, Australia.
"This latest update from WMO clearly shows the oceans are continuing to warm, and at an accelerating rate, contributing to sea-level rise. This means climate change has significant momentum committing us to further change over the coming decades."
Ongoing warming
The WMO says that warming continues to drive melting in many parts of the world, including Greenland where around 152 billion tonnes of ice was lost from the ice sheet in the year to August 2020.
There were 30 named storms during the North Atlantic hurricane season, breaking the record for the number of such events.
Europe saw another record-breaking summer in 2020, making life uncomfortable for travellers
As well as record numbers, new evidence suggested that hurricanes get stronger when they hit land because of rising temperatures.
Other impacts noted by the WMO this year included wildfires in Siberia, Australia and along the US West Coast and South America, which saw plumes of smoke circumnavigate the globe.
Floods in Africa and South East Asia displaced large numbers of people and undermined food security for millions.
What has been the reaction to this report?
The findings of the WMO report won't come as a surprise to most observers.
What is climate change?
"The state of the global climate? Parlous," said Prof Dave Reay from University of Edinburgh, UK.
"These annual updates of deteriorating planetary health always make for bleak reading; this year's is a full red alert. Surging heat, intensifying droughts and rampant wildfires all speak of the acute impacts of climate change in 2020. They also warn of the chronic undermining of global carbon sinks - the oceans, trees and soils around the world - that is underway.
"Throw yet more emissions and warming at them and they will rip the Paris climate goals from our grasp forever. The year ahead will be defined by our recovery from Covid-19, the centuries ahead will be defined by how green that recovery actually is."
Hurricane Iota left destruction in its trail in Nicaragua
Environmental campaigners say the report adds urgency to calls for the recovery, post-Covid, to focus on climate change and the environment.
"Although the pandemic will have been the biggest concern to many people in the developed world in 2020, for millions in climate vulnerable places the climate emergency remains the biggest threat and sadly there is no simple vaccine to fix the climate. But keeping fossil fuels in the ground would be a good start," said Dr Kat Kramer, from Christian Aid.
"These findings show just how important it is to ensure the government's economic recovery measures don't entrench the fossil fuel economy but act to accelerate the transition to a zero-carbon world."
Impact on nature
According to a new report from the International Union for the Conservation of Nature (IUCN), climate change is now the biggest threat to the most important world heritage sites.
The IUCN says that 83 such sites are now threatened by rising temperatures, including the Great Barrier Reef where ocean warming, acidification and extreme weather have all contributed to a dramatic decline.
It has been rated as having a "critical" outlook for the first time.
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