Arctic News: Arctic sea ice May 2025

Saturday, May 3, 2025

Arctic sea ice May 2025

[ Arctic sea ice thickness, click on images to enlarge ]

The above combination image shows Arctic sea ice thickness on March 13, 2025 (left), April 28, 2025 (center) and May 13, 2025 (right). The image on the right shows more open water off the coast of Siberia.

[ Arctic sea ice concentration ]

The above image is a screenshot of part of a NASA Worldview satellite image for May 1, 2025. The image similarly shows open water off the coast of Siberia. The red dots indicate fires.

The image on the right, adapted from NSIDC, shows Arctic sea ice concentration on May 13, 2025.

Arctic sea ice is under threat as numerous conditions are becoming increasingly dire, as discussed in earlier posts such as this one.

For some of these conditions, further updates are added below (carbon dioxide, temperature, variables and Arctic sea ice).

Carbon dioxide

A daily carbon dioxide (CO₂) concentration of 431.25 parts per million (ppm) was recorded on May 10, 2025, at Mauna Loa, Hawaii, the highest daily average on record.

CO₂ concentrations haven't been below 430 ppm for 14 days in a row at Mauna Loa, Hawaii, as illustrated by the above image, which shows CO₂ for the last 31 days through May 10, 2025. The image below gives another view of daily concentrations.

One has to go back millions of years in time to find CO₂ concentrations this high, while the impact of high CO₂ concentrations back in history was lower due to lower solar output and the rate of change was also much slower, as also discussed in an earlier post.

The image below illustrates that the weekly mean CO₂ concentration at Mauna Loa, Hawaii, was 430.60 ppm in the week beginning on April 27, 2025, i.e. 4.02 ppm higher than the weekly value from one year ago (green inset).

Weekly CO₂ for the week starting May 4, 2025, was 430.86 ppm at Mauna Loa, Hawaii, compared to 426.92 ppm one year ago, a difference of 3.94 ppm, as illustrated by the image below.

The annual global average surface concentration of carbon dioxide (CO₂) for 2024 was 422.79 parts per million (ppm). CO₂ concentrations grew by 3.75 ppm during 2024, the highest growth rate on record, as discussed in an earlier post.

Temperature

The global surface air temperature was 15.72°C on 9 May 2025, the highest temperature on record for this day, as illustrated by the image below.

The global surface air temperature was 15.75°C on 10 May 2025, again the highest temperature on record for this day. The image below shows ERA5 daily temperature anomalies from end 2022 through May 10, 2025, with two trends added, a black linear trend and a red cubic (non-linear) trend that reflects stronger feedbacks and that follows ENSO (El Niño/La Niña) conditions more closely. This red trend warns about further acceleration of the temperature rise.

The shading added in the above image reflects the presence of El Niño conditions that push up temperatures (pink shading), La Niña conditions that suppress temperatures (blue shading), or neutral conditions (gray shading). The trends warn about feedbacks and further mechanisms pushing up temperatures over the next few years.

The above image shows two bases to compare the anomalies with, 1991-2000 (left axis) and 1901-1930 (right axis). Neither of these two bases is pre-industrial, anomalies will be higher when using a genuinely pre-industrial base.

The image below shows NASA monthly data through April 2025 compared to a custom 1903-1924. This 1903-1924 base is not pre-industrial either, anomalies will be higher when using a genuinely pre-industrial base. The monthly temperature anomaly has now been more than 1.5°C higher than this 1903-1924 base for 22 consecutive months (July 2023 through April 2025, marked with red text). Anomalies are rising rapidly, the red line (2-year Lowess Smoothing trend) points at 2°C higher than 1903-1924 getting crossed in the course of 2027.

[ more than 1.5°C above base for 22 consecutive months, trend points at 2°C above 1903-1924 crossed in 2027 ]

The picture can change when using a different base that anomalies are compared with. To illustrate this, the image below uses the decade from 1904 through 1913 as a custom base, resulting in higher anomalies and a trend pointing at 2°C above this base (1904-1913) getting crossed in the course of 2026.

[ trend points at 2°C above 1904-1913 getting crossed in 2026 ]

An earlier analysis of pre-industrial suggests that using 1750 as a base could add as much as 0.3°C to the historic rise, while using a 3480 BC base could add as much as 0.79°C to the historic rise.

Those who seek to sabotage climate action typically call for use of a base that minimizes the historic temperature rise. A higher historic rise can imply that temperatures are already higher than the thresholds that politicians at the adoption of the Paris Agreement pledged wouldn't be crossed, and it can also imply that the temperature rise is accelerating more due to stronger feedbacks such as more water vapor in the atmosphere and disappearance of lower clouds, so that would constitute a stronger call for climate action.

The Arctic is hit hardest by the temperature rise, as illustrated by the image below, which shows temperature anomalies compared to 1951-1981 for the period from November 2024 through April 2025.

The image below illustrates that the global temperature was at a record high for the time of year for five days in a row, i.e. from April 24, 2025, through April 28, 2025.

Variables

Some variables have a short-term impact on the temperature rise, including volcanoes, sudden stratospheric warming, sunspots and El Niño/La Niña variations. There have been no volcano eruptions and no sudden stratospheric warming events recently that could have provided significant cooling. Sunspots are at a high point in this cycle, which pushes up temperatures. Regarding ENSO (El Niño-Southern Oscillation), current conditions are ENSO-neutral, highlighting the significance of the high current temperatures, while a new El Niño may emerge soon. The image below shows NOAA's ENSO outlook dated May 11, 2025.

The image below shows temperatures through May 9, 2025, in Niño 3.4, an area in the Pacific (inset) that is critical to the development of El Niño.

[ temperature in Niño 3.4 area ]

Mechanisms such as self-amplifying feedbacks and crossing of tipping points, and further developments such as loss of the aerosol masking effect, can jointly contribute to further accelerate the temperature rise, resulting in a rise from pre-industrial of more than 10°C, while in the process also causing the clouds tipping point to get crossed and that can push the temperature rise up by a further 8°C, as discussed in earlier posts such as this one.

Arctic sea ice volume and area

Loss in sea ice can dramatically push up temperatures, as discussed in earlier posts such as this one. High ocean temperatures are causing Arctic sea ice volume to be very low compared to earlier years. The image below shows Arctic sea ice volume over the years in red for April, the month when Arctic sea ice typically reaches its maximum volume for the respective year.

The image below shows Arctic sea ice volume from 2000, with markers indicating volume in September (red) and in April (blue), corresponding to the year's minimum- and maximum volume.

The image below shows Arctic sea ice volume through May 14, 2025.

The image below illustrates that Arctic sea ice disappears not only as it melts away from below, due to heating up of the water of the Arctic Ocean. Arctic sea ice can also disappear as it gets broken up by ocean currents and moves out of the Arctic Ocean. The image shows how, on May 6, 2025, the sea ice gets broken up just north of the northern tip of Greenland, due to ocean currents that will also move the pieces to the south, alongside the edges of Greenland, toward the North Atlantic.

[ click on images to enlarge ]

On May 13, 2025, Arctic sea ice area was second lowest on record for that day, as illustrated by the image below.

The comparison with the year 2012 is important, since Arctic sea ice area reached its lowest minimum in 2012. Arctic sea ice area was only 2.24 million km² on September 12, 2012, i.e. 1.24 million km² above a Blue Ocean Event. While on May 13, 2025, Arctic sea ice area was only 0.8 million km² lower than on May 8, 2012, the difference between anomalies typically gets narrower in May. Therefore, if the difference between 2025 and 2012 will widen again, a Blue Ocean Event may occur in September 2025, as discussed in an earlier post.

Methane

Loss of Arctic sea ice can also trigger a very dangerous feedback: eruptions of methane from the seafloor of the Arctic Ocean. Methane in the atmosphere is already very high and large additional methane releases threaten to cause hydroxyl depletion, in turn extending the lifetime of all methane currently in the atmosphere.

Data for the annual increase in methane have been updated by NOAA. in 2024, there was a higher increase than in 2023, the 2024 increase was almost 10 parts per billion (ppb).

The image below shows the annual methane increase data (red circles), with two trends added. A quadratic trend (blue) is based on all available data (1894 through 2024), while a quintic trend (pink) is based on 2017 through 2024 data. The pink trend warns about a huge increase in methane, which could eventuate due to eruptions of seafloor methane.

Below are warnings from earlier posts.

[ from earlier post, also note the recent discussion on monthly methane ]

[ from earlier post ]

Also noteworthy is this analysis by Andrew Glikson and work by Peter Wadhams et al.

In the video below, methane emissions are discussed by Peter Wadhams, Paul Beckwith, Peter Carter and Herb Simmens

Methane concentrations in the atmosphere have been around 1960 parts per billion (ppb) recently at Mauna Loa, Hawaii, as illustrated by the image below.

Methane is more potent as a greenhouse gas than carbon dioxide. Methane also has indirect effects, such as ground-level ozone and stratospheric water vapor, while methane partly turns into carbon dioxide. Importantly, the warming potential of a pulse of methane will decrease over time, given methane's relatively short lifetime.

Accordingly, there are different ways to calculate methane's carbon dioxide equivalent (CO₂e). Also important is whether a specific concentration of methane is used (in ppb) or the weight is used of a pulse of methane. In each of these cases, different multipliers can be used to calculate methane's CO₂e.

When using a multiplier of 200, a methane concentration of 1960 ppb would translate into 392 ppm of CO₂e. As mentioned above, a daily CO₂ concentration of 431.25 ppm was recorded at Mauna Loa, Hawaii, on May 10, 2025. So, when adding up these two, the joint CO₂e would be 823.25 ppm CO₂e, i.e. just 376.75 ppm short of the clouds tipping point (at 1200 ppm). This joint total doesn't yet include contributions of nitrous oxide and other drivers, so the situation is even more dire. Moreover, concentrations of greenhouse gases are increasing and they may increase even more dramatically soon.

So, what multiplier is best used when calculating methane's CO₂e? The IPCC already uses a slightly higher GWP for methane emissions from fossil fuel fugitive emission sources than for other methane emissions. So, the idea of using different multipliers in different scenarios is not new.

One multiplier could be used that does include cooling aerosols and another one that doesn't. Most carbon dioxide results from burning coal and oil, which comes not only with high CO₂ emissions, but also with co-emissions of cooling aerosols. On the other hand, there are little or no cooling aerosols co-emitted with methane emissions. Therefore, inclusion of cooling aerosols could result in a higher multiplier to be used when translating concentrations of methane into CO₂e, compared to carbon dioxide.

[ warming contributions, from earlier post, click on images to enlarge ]

[ warming responsibility by sector ]

To illustrate this point, the above image shows contributions to warming from 2010 to 2019, using IPCC AR6 data. If masking (cooling) would be included in the image by subtracting cooling by sulfates from CO₂, then the contribution of CO₂ would be proportionally lower, while the contribution of methane would be proportionally higher than what the image shows.

The image on the right is from a recent analysis by Gerard Wedderburn-Bisshop.

Given the dire outlook and given methane's higher potency as a greenhouse gas, it makes most sense to seek urgent and dramatic reductions in methane and such action should not be allowed to be sabotaged by those who propose a low multiplier when calculating methane's CO₂e.

IPCC

Meanwhile, the IPCC remains silent. No updates or special reports on topics such as acceleration of the temperature rise. Instead, the IPCC keeps persisting in downplaying the potential for such dangerous developments (in terms of the severity, probability, ubiquity and imminence of their impact), in efforts to hide the most effective climate action. The IPCC keeps pointing at less effective policies such as support for BECCS and biofuel, while continuing to make it look as if there was a carbon budget to divide among polluters, as if polluters could continue to pollute for decades to come.

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 also discussed at this group.