The famous Mauna Loa Observatory in Hawaii (NOAA data) recorded an April 2026 monthly average of 431.12 ppm CO₂ — a new record for that month (up from 429.64 ppm in April 2025). Daily values in early May 2026 spiked as high as ~433.5 ppm, with some weekly averages near 432.4 ppm. Headlines rounding to “hit 432 ppm last month” are a reasonable popular summary of the peak seasonal period, even if the strict monthly average is 431.12 ppm.

This is ~0.043% of the atmosphere (often rounded to 0.04%). For comparison, pre-industrial levels around the late 1700s–early 1800s were ~280 ppm (~0.028%). That baseline sits near the end of the Little Ice Age (roughly 1300–1850), a cooler period driven mainly by lower solar activity, volcanic eruptions, and ocean circulation changes. Ice cores show a modest natural CO₂ dip during the coldest phases of the Little Ice Age due to increased terrestrial carbon storage in cooler soils and vegetation — not the primary cause of the cooling, but small feedback.

Oceans act as a major carbon sink, absorbing roughly 25–30% of human CO₂ emissions through simple chemistry (CO₂ dissolving into seawater to form carbonic acid and bicarbonate) and biological uptake by phytoplankton. As atmospheric CO₂ rises, oceans take up more to try to stay in equilibrium.

However, the NASA piece highlights key limits:

• Warming surface waters reduce CO₂ solubility (warmer water holds less gas, like soda going flat faster).
• Increased stratification (layering) from warming limits mixing with deeper, carbonate-rich waters.
• Natural climate oscillations (e.g., Pacific Decadal Oscillation, North Atlantic Oscillation) cause decadal swings in uptake or venting that can temporarily rival or exceed the human signal in certain regions.

Despite these complexities and strong ocean (plus land) sinks, the relentless rise measured at Mauna Loa shows that human emissions (primarily fossil fuels) are still outpacing natural absorption. Levels are now the highest in millions of years, rising ~2–3 ppm per year recently.

CO₂ is a trace gas, but it is an effective greenhouse gas that absorbs and re-emits infrared radiation (heat) escaping Earth. Raising it by ~55% since pre-industrial times (280 → 431+ ppm) produces measurable radiative forcing — consistent with observed warming of ~1.1–1.2°C so far.

The effect is logarithmic (diminishing per additional molecule), but the absolute increase since the Little Ice Age era is significant. Without the greenhouse effect overall, Earth would be frozen; the enhanced effect from our additions explains most recent warming.

The Mauna Loa record documents an unambiguous, human-driven climb to 431–433+ ppm (0.04%) in 2026, even as oceans continue absorbing a large share per the NASA description. The post-Little Ice Age recovery and natural variability explain some 19th-century warming, but not the rapid post-1950 acceleration or current record levels.

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Atmospheric CO2 hits record high as monitoring observatory faces funding cuts

Famous Hawaii observatory shows CO2 hit 432ppm last month the highest yet

Carbon dioxide levels in the atmosphere reached a record high in April, averaging 431 parts per million (ppm), according to data from the US National Oceanic and Atmospheric Administration’s Mauna Loa Observatory in Hawaii. Energy Live News has the story.

The observatory has been tracking atmospheric CO2 since 1958, when April levels stood at under 320 ppm.

Pre-industrial CO2 levels are estimated to have been at 280 ppm or below, with even warmer interglacial periods historically topping out at around 300 ppm.

The latest reading represents a significant and sustained departure from those baselines.

CO2 levels tend to peak in April each year as decaying plants release greenhouse gases following winter.

Some of that CO2 is reabsorbed by plants as they grow through warmer months. However, NOAA’s long-term data show average monthly CO2 levels rising steadily year on year.

Read the full story here.

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The Ocean’s Carbon Balance

The idea seemed simple enough: the more carbon dioxide that people pumped into the atmosphere by burning fossil fuels, the more the oceans would absorb.

The ocean would continue to soak up more and more carbon dioxide until global warming heated the ocean enough to slow down ocean circulation. The NASA Science has the story

Water trapped at the surface would become saturated, at which point, the ocean would slow its carbon uptake. To oceanographers of 30 years ago, the question was less, how will human emissions change the ocean carbon cycle, and more, is the ocean carbon cycle changing yet?

The question matters because if the ocean starts to take up less carbon because of global warming, more is left in the atmosphere where it can contribute to additional warming.

Scientists wanted to understand how the ocean carbon cycle might change so that they could make more accurate predictions about global warming.

Thus motivated, oceanographers began a series of research cruises, trolling across the Pacific from Japan to California, from Alaska to Hawaii, and through the North Atlantic from Europe to North America. On shore, others developed computer models.

After 30 years of research, the question itself hasn’t changed, but the reasoning behind it couldn’t be more different.

Oceanographers started out wanting to know if the ocean was keeping up with the amount of carbon dioxide people are putting into the atmosphere.

Instead, they found that people aren’t the only players changing the ocean carbon cycle. Over decades, natural cycles in weather and ocean currents alter the rate at which the ocean soaks up and vents carbon dioxide.

What’s more, scientists are beginning to find evidence that human-induced changes in the atmosphere also change the rate at which the ocean takes up carbon. In other words, it turns out that the world is not a simple place.

The group surrounds a circular cluster of instruments and 36 three-foot-tall PVC (plastic) bottles, taking turns extracting sea water from the bottles, assembly-line style.

It is a deliberate, well-ordered procedure. The glass sample bottles set aside for oxygen samples are filled first, followed by the massive syringe meant for chlorofluorocarbon (freon) samples, and so on, until 10 to 15 different samples have come out of each bottle.

Everyone has a task and a place. It’s a social event, a break from the lonely hours each will spend in his or her lab analyzing the samples before the next batch is hauled out of the ocean. It might even be fun.

Except that it’s late winter. In the North Pacific. And they are on the deck of a ship, looking at the same faces that they’ve seen day after day for four weeks or more, and they’ll be repeating this procedure again in another 30 nautical miles.

Read the full story here.