The summer of 2026 is shaping up to test how much heat the planet — and the people living on it — can absorb. Former federal climate scientists now working with Climate Central told Inside Climate News that atmospheric carbon dioxide concentrations hit a record high in May, and that the monthly average global temperature this summer could climb as much as 3.5°F (1.9°C) above the pre-industrial baseline used to track greenhouse-gas heating.
That figure sits within breathing distance of the 2°C threshold the Paris Agreement was built to avoid. Many climate projections have suggested that 2°C warming could occur around mid-century. The data being released this month complicates that timeline.
Atmospheric scientist Zack Labe opened a Tuesday briefing by warning that human-caused warming will contribute significantly to deadly heat waves, intensified storms and wildfires, according to Inside Climate News. Labe and several of his Climate Central colleagues are former NOAA scientists who launched independent monthly climate briefings after the Trump administration canceled NOAA's public updates last year, citing budget cuts. The briefings are part of a broader effort to keep climate information in public view as federal channels shrink.
Labe explained that CO2 levels peak each May, just before Northern Hemisphere forests enter full growth and start pulling carbon out of the air. The problem is that human emissions are now overwhelming forests and oceans, the planet's two great carbon sponges. About two-thirds of the excess CO2 in the atmosphere has accumulated in just the past 50 years — a compression of geologic-scale change into a single human lifetime.
Former NASA climate scientist James Hansen issued a parallel warning in an update posted to his website last week, predicting that 2026 will likely become the planet's warmest year on record, even though it started cooler than 2024. Hansen argues that mainstream coverage is still underestimating how sensitive Earth's climate system is to greenhouse gases — a critique aimed at the way IPCC sensitivity estimates have been interpreted in the press.
The independent data backs up the alarm. A June 11 report from Copernicus, written by 70 scientists across 56 institutions in 17 countries, found that Earth's climate system is accumulating heat faster than at any point in the known record. Samantha Burgess, Copernicus's strategic lead for climate, said the study shows nearly all of the warming over the last decade is driven by human activities. Lead author Piers Forster, director of the Priestley Centre for Climate Futures at the University of Leeds, pointed to the planet's energy imbalance — the gap between heat coming in and heat going out — as the clearest signal. Without human influence, he said, it should be close to zero. It has doubled in recent decades.
What makes this moment unusual isn't only the numbers. It's who is delivering them. With federal briefings paused, scientific communication has shifted to nonprofits, university centers and individual researchers posting directly to their own sites and social feeds. Groups like Climate Central, Berkeley Earth and the EU's Copernicus service are now filling a gap that federal agencies used to occupy by default.
For readers trying to figure out what to actually do with this information, the honest answer is that no single behavior change moves a 1.9°C anomaly. What individual choices do shape is the political and market environment that decides how fast energy, food and transport systems shift. Eating more plants, flying less, voting on climate, supporting local heat-resilience policy — none of it is heroic on its own. Collectively, it's the only thing that has ever moved the needle.
The summer ahead will be a stress test for infrastructure, agriculture and public health systems built for a cooler century. The scientists tracking it are now doing so on their own time, on independent platforms, because the public record they spent careers building is no longer guaranteed to reach the public.
