[ click on images to enlarge ] |
Differences between datasets are mainly due to the ways temperatures are measured, e.g. ERA5 measures the temperature of the air above oceans, whereas NASA and NOAA measure the surface temperature of the water, which is lower. There can also be differences in how temperatures are measured in areas with sea ice - the sea ice can be measured, or the water underneath the sea ice, or the air above the sea ice. Also, in some areas there once was sea ice that has meanwhile disappeared. Different ways of measuring things can raise the temperature record by as much as 0.2°C and even more in case of earlier years, where the margin of error is also larger.
Importantly, the temperature rise in the above image is compared to the period 1850-1900, which is not pre-industrial. When using a genuinely pre-industrial base, the temperature anomaly may already have been above the 2°C threshold in 2015, when politicians at the Paris Agreement pledged that this threshold wouldn't be crossed.
Importantly, the temperature rise in the above image is compared to the period 1850-1900, which is not pre-industrial. When using a genuinely pre-industrial base, the temperature anomaly may already have been above the 2°C threshold in 2015, when politicians at the Paris Agreement pledged that this threshold wouldn't be crossed.
[ from earlier post ] |
“Individual years pushing past the 1.5 degree limit do not mean the long-term goal is shot", UN Secretary-General Antóno Guterres says: “It is important to emphasize that a single year of more than 1.5°C for a year does NOT mean that we have failed to meet Paris Agreement long-term temperature goals, which are measured over decades rather than an individual year", WMO Secretary-General Celeste Saulo adds.
However, for this argument to hold, the average anomaly would need to fall to under 1.5°C from now. Should we really have to wait for another decade or two, before a confirmation is allowed to be issued that 1.5°C has been crossed. Isn't such a mandate part of downplaying how dire the situation is, an effort to delay the necessary action? Moreover, does such a mandate make sense?
[ click on images to enlarge ] |
[ for more background, also view the Extinction page ] |
Warnings about the potential for such a rise have been sounded before, e.g. see the extinction page.
See also the image below with daily data.
[ temperature anomaly with ENSO shading, trends added, from an earlier post ] |
Human extinction at 3°C
Analysis by Shona and Bradshaw found that, due to co-extinction, global biodiversity collapse occurs at around 5°C heating, as discussed in a 2019 post with the warning that a rise of more than 5°C could happen within a decade, possibly by 2026, and that humans who depend on many other species will likely go extinct with a 3°C rise.
A recent study by Joseph Williamson et al. finds that many species that live together appear to share remarkably similar thermal limits. That is to say, individuals of different species can tolerate temperatures up to similar points. This is deeply concerning as it suggests that, as ecosystems warm due to climate change, species will disappear from an ecosystem at the same time rather than gradually, resulting in sudden biodiversity loss. It also means that ecosystems may exhibit few symptoms of heat stress before a threshold of warming is passed and catastrophic losses occur.
Arctic sea ice
[ Arctic sea ice extent, click on images to enlarge ] |
During the first few months of the year, Arctic sea ice is still growing in extent. In the above image, the red line and red marker shows 2025 sea ice extent. Dots mark Arctic sea ice extent on January 19 for the respective year and Arctic sea ice extent was at a record low for the time of year on January 19, 2025, despite La Niña conditions.
A new El Niño may emerge in the course of 2025, while both Arctic sea ice extent and volume are at record low, while numerous self-reinforcing feedbacks are kicking in with accelerating ferocity and while further mechanisms are active that drive up temperatures such as high sunspots. Such a combination of mechanisms could cause a huge temperature rise and a Blue Ocean Event in 2025, threatening huge amounts of methane to erupt from the seafloor.
[ Arctic sea ice volume, click to enlarge ] |
On Jan 18, 2025, the sea surface temperature south of Svalbard (green circle) was 5.1°C, 3.4°C higher than 1981-2011, as the above image shows.
High ocean temperatures result in low Arctic sea ice volume, as illustrated by the image on the right and discussed in this earlier post.
Guy McPherson discussed the consequences of an ice-free Arctic Ocean in the video below, adding that "a near-term, ice-free Arctic Ocean—the so-called Blue Ocean Event—is the extinction-causing event over which we have the least control. The rate of environmental change in the wake of such an event will suffice to cause the extinction of all life on Earth.
I’m not a fan."
Climate Emergency Declaration
The situation is dire and the precautionary principle calls for rapid, comprehensive and effective action to reduce the damage and to improve the situation, as described in this 2022 post, where needed in combination with a Climate Emergency Declaration, as discussed at this group.
https://wmo.int/news/media-centre/wmo-confirms-2024-warmest-year-record-about-155degc-above-pre-industrial-level
https://www.metoffice.gov.uk/about-us/news-and-media/media-centre/weather-and-climate-news/2025/2024-record-breaking-watershed-year-for-global-climate
• Berkeley Earth - Global Temperature Report for 2024
https://berkeleyearth.org/global-temperature-report-for-2024
• NASA - Goddard Institute Surface Temperature (GISTEMP v4) analysis
https://data.giss.nasa.gov/gistemp
https://data.giss.nasa.gov/gistemp
• NASA - Temperatures Rising: NASA Confirms 2024 Warmest Year on Record
https://www.nasa.gov/news-release/temperatures-rising-nasa-confirms-2024-warmest-year-on-record
https://unfccc.int/process-and-meetings/the-paris-agreement
• NOAA - 2024 was the world’s warmest year on record
https://www.noaa.gov/news/2024-was-worlds-warmest-year-on-record
https://unfccc.int/process-and-meetings/the-paris-agreement
• pre-industrial
• Clustered warming tolerances and the nonlinear risks of biodiversity loss on a warming planet - by Joseph Williamson et al.
also discussed on Facebook at:
• Sunspots
https://arctic-news.blogspot.com/p/sunspots.html
• Arctic and Antarctic Data Archive System (ADS) of the National Institute of Polar Research of Japan
https://ads.nipr.ac.jp
• nullschool.net
https://earth.nullschool.net
https://arctic-news.blogspot.com/p/sunspots.html
• Arctic and Antarctic Data Archive System (ADS) of the National Institute of Polar Research of Japan
https://ads.nipr.ac.jp
• nullschool.net
https://earth.nullschool.net
• Double Blue Ocean Event 2025?
• Guy McPherson - consequences of an ice-free Arctic Ocean
https://ocean.dmi.dk/arctic/icethickness/thk.uk.php
• The first ice-free day in the Arctic Ocean could occur before 2030 - by Céline Heuzé et al. https://www.nature.com/articles/s41467-024-54508-3
als0o discussed on facebook at:
https://www.facebook.com/groups/arcticnews/posts/10162207185219679
• Transforming Society
https://arctic-news.blogspot.com/2022/10/transforming-society.html
• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html
• Climate Emergency Declaration
https://arctic-news.blogspot.com/p/climate-emergency-declaration.html
• Transforming Society
https://arctic-news.blogspot.com/2022/10/transforming-society.html
• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html
• Climate Emergency Declaration
https://arctic-news.blogspot.com/p/climate-emergency-declaration.html