Arctic News: A huge rise in temperature in 2026?

Monday, April 6, 2026

A huge rise in temperature in 2026?

Carbon dioxide (CO₂) recorded by NOAA was at a record high of 433.24 parts per million (ppm) on April 5, 2026, at Mauna Loa, Hawaii.

The image below shows a global average CO₂ of 427.54 ppm on April 5, 2026.

The above image shows daily averaged CO₂ through April 5, 2026, from four observatories: Barrow, Alaska (in blue), Mauna Loa, Hawaii (in red), American Samoa (in green), and South Pole, Antarctica (in yellow). The thick black lines represent the average of the smoothed seasonal curves and the smoothed, de-seasonalized curves for each of the records. These lines are a very good estimate of the global average levels of CO₂.

The annual maximum for CO₂ is typically reached in May, so the daily average CO₂ looks set to reach even higher levels in May 2026.

The image below, from an earlier post, shows CO₂ over thousands of years through April 1, 2026, when the daily average CO₂ concentration recorded by the Keeling Curve, maintained by Scripps Institution of Oceanography at Mauna Loa Observatory, was 432.81 ppm.

Concentrations of CO₂ haven't been this high for millions of years. A recent analysis led by Sarah Shackleton and Julia Marks-Peterson finds that, while the average temperature of the ocean has decreased by 2 to 2.5°C over the past 3 million years, average atmospheric CO₂ levels have likely remained below 300 ppm over this time, as discussed in an earlier post.

This makes the recent daily concentration of 431.95 ppm at Mauna Loa even more threatening. It means that, in addition to the key role of heat-trapping greenhouse gases, there were also important contributions from other components of the climate system such as Earth’s reflectivity, variations in vegetation and/or ice cover and ocean circulation.

According to the IPCC, limiting warming to 2°C would have required global greenhouse gas emissions to have peaked before 2025 at the latest, which hasn't happened. In other words, we're headed for a rise that may exceed 3°C above pre-industrial soon. How fast could such a rise eventuate? The two images and text below are from the earlier post What Does Runaway Warming Look Like?

Forcing caused by the rapid rise in the levels of greenhouse gases is far out of line with current temperatures. A 10°C higher temperature is more in line with these levels, as illustrated by the image below, based on 420,000 years of ice core data from Vostok, Antarctica.

How fast could such a 10°C temperature rise eventuate? The image below gives an idea.

A study led by James Hansen concludes that equilibrium global warming for today’s amount of greenhouse gases is 10°C, which is reduced to 8°C by today’s human-made aerosols, and while James Hansen doesn't expect a 10°C rise soon, he warns that decline of aerosol emissions could increase global warming rapidly, in addition to the acceleration already occurring now.

James Hansen doesn't expect a huge rise to occur soon, as the temperature rise of the atmosphere is held down by take up of extra energy by oceans, land and ice. According to the IPCC AR6 WG1, 91% of the extra energy is taken up by oceans, 5% by land, 3% by ice melting and 1% remains in the atmosphere.

However, the extra energy is increasing as greenhouse gas concentrations keep rising, while additionally the capacity of oceans, land and ice to take up extra energy is increasingly compromised. This could cause a huge rise in temperature soon, especially on land in the Northern Hemisphere where there is proportionally more land. The temperature can be expected to rise even faster during heatwaves and especially in large cities that are additionally affected by the Urban Heat Island effect.

How fast could the Northern Hemisphere land-only temperature rise exceed 3°C?

The above image illustrates that the upcoming El Niño could trigger a rapid and steep rise in temperature on land in the Northern Hemisphere in the course of 2026. The image shows land-only data in the Northern Hemisphere through February 2026, with a polynomial trend added that points at 3°C crossed later in 2026. About 0.5°C of the rise can be attributed to El Niño, with further contributions from feedbacks and further forcers. Note that the 1901-2000 base is not pre-industrial, the outlook may be even more dire when using a genuinely pre-industrial base. Ominously, the ECMWF April 2026 forecasts indicate that a strong El Niño is on the way, as illustrated by the combination image below.

[ click on images to enlarge ]

Arctic sea ice decline

Arctic sea ice decline could strongly contribute to the temperature rise, as discussed in an earlier post. The image below, adapted from dmi.dk, shows that Arctic sea ice volume was at a record low for the time of year on April 6, 2026.

Climate Emergency Declaration

The situation is dire and unacceptably dangerous, and the precautionary principle necessitates rapid, comprehensive and effective action to reduce the damage and to improve the outlook, where needed in combination with a Climate Emergency Declaration, as described in posts such as in this 2022 post and this 2025 post, and as discussed in the Climate Plan group.