The Climate Crisis Explained, How 1.1°C of Warming Already Costs the US $150 Billion Annually

A tenth of a degree does not sound like much. It is the kind of number that barely registers on a home thermostat. Yet when scientists talk about global warming, fractions of a degree are exactly the unit that separates a stable climate from one that regularly produces disasters costing the United States well over a hundred billion dollars a year. This piece walks through what that number actually means, where it comes from, and how it connects to real, documented losses rather than abstract projections.

Where the 1.1°C figure comes from, and why it is already out of date

The 1.1°C figure comes from the Intergovernmental Panel on Climate Change’s landmark Sixth Assessment Report, which measured human-caused warming at 1.1°C above the 1850 to 1900 pre-industrial baseline, averaged over the decade from 2011 to 2020. It became one of the most widely cited numbers in climate reporting because it was the first time the world’s leading climate science body could say, with high confidence, exactly how much of the warming already underway was caused by human activity rather than natural variation.

It is worth being direct with readers here. That number has already been overtaken by events. By 2024, global average temperatures had crossed 1.5°C above the pre-industrial baseline for a full calendar year for the first time, according to the Copernicus Climate Change Service. The three-year average from 2023 through 2025 came in above 1.5°C as well, the first time any three-year period has crossed that threshold. Most independent estimates of the underlying long-term warming trend, stripping out short-term natural swings, now put the figure closer to 1.3 to 1.4°C. The 1.1°C mark is not wrong. It is history. It is the number that describes the climate the US was already living in a few years ago, and the losses tied to it are the floor, not the ceiling, of what warming has cost the country so far.

What $150 billion actually measures

The $150 billion figure is not a projection or a modelled estimate of future risk. It is a direct tally of documented losses from individual weather and climate disasters that each caused at least $1 billion in damage, adjusted for inflation. For decades this dataset was maintained by NOAA’s National Centers for Environmental Information, and it remains one of the most cited sources in American climate and economic reporting precisely because it tracks confirmed costs rather than hypothetical ones.

The number holds up well against the underlying data. NOAA’s own analysis put the five-year average cost of billion-dollar disasters at $149.3 billion annually for 2020 through 2024, more than double the 45-year historical average of $64.8 billion. A separate industry analysis extending that window through 2025 put the 2020 to 2025 annual average even closer to $147 billion. Individual recent years have swung both higher and lower around that average. 2024 alone produced 27 separate billion-dollar disasters, totalling $182.7 billion. 2025 came in somewhat lower at $115 billion across 23 events, still the third highest annual total on record, trailing only 2023 and 2024.

One important disclosure belongs in any accurate accounting of this data. In May 2025, the Trump administration discontinued NOAA’s Billion Dollar Weather and Climate Disasters programme, ending federal maintenance of the dataset. The nonprofit Climate Central, working with Adam Smith, the scientist who led the NOAA programme for 15 years, has since taken over the database using the same peer-reviewed methodology and continues to publish updated figures. The $150 billion figure cited in this piece reflects the combined federal and successor dataset, and readers researching this topic further should know the tracking has changed hands, even though the underlying accounting method has not.

What actually qualifies as a billion-dollar disaster?

The billion-dollar threshold is not an arbitrary cutoff chosen for dramatic effect. It filters out routine, everyday weather damage and isolates only the events large enough to require major federal, state, and insurance industry response, the kind of events that actually show up in national economic accounts. The dataset tracks eight categories: drought and heat waves, flooding, freeze events, severe storms, tropical cyclones, wildfires, and winter storms, going back to 1980.

The costliest single event of 2025 illustrates how concentrated this damage can be. The Los Angeles wildfires in January 2025 alone exceeded $60 billion in losses, making them the most expensive wildfire event on record, nearly double the previous record set in 2018. Researchers who studied the conditions behind those fires found that the hot, dry, and windy weather that fuelled them was made roughly 35 per cent more likely by human-caused warming. That single statistic is a useful bridge between the abstract 1.1°C figure and the very concrete $150 billion figure. It is not that warming causes wildfires that would not otherwise exist. It is that warming loads the dice, making the most extreme and expensive versions of ordinary weather events measurably more likely.

Why the frequency matters as much as the total cost

The dollar figure tells only part of the story. The pace at which these disasters are arriving has also compressed dramatically. In the 1980s, the US experienced a billion-dollar disaster on average once every 82 days. Over the most recent decade, that gap has shrunk to about once every 19 days. Response agencies built around the older, slower pace have not caught up. The Federal Emergency Management Agency has entered a state of immediate needs funding, in which it pauses all non-life-saving activities because it has exhausted its disaster budget in ten separate years since 2001, and in the 2025 fiscal year it had already spent half its annual disaster budget just eight days in.

This is the practical reason a small number of degrees matters so much. Climate systems do not respond to warming in a smooth, linear way. Small shifts in average temperature translate into outsized shifts in the frequency of extreme heat, extreme rainfall, and the atmospheric conditions that dry out vegetation ahead of wildfire season. The insurance and disaster response systems the US built over the twentieth century were sized for a climate that no longer exists, and the gap between that older baseline and the current reality is exactly what shows up in the billion-dollar disaster numbers year after year.

What this means for how the figures should be read going forward

The clearest way to understand the relationship between 1.1°C and $150 billion is not as a single cause and effect pair, but as two data points from the same trend line. The 1.1°C figure describes where global temperatures stood a few years ago. The $150 billion figure describes the economic toll the US was already absorbing at that point. Both numbers have continued moving in the same direction since. Global temperatures are now running closer to 1.3 to 1.4°C above pre-industrial levels, and disaster costs have not levelled off either, with 2023, 2024, and 2025 ranking as three of the four costliest years for the number of billion-dollar events since records began.

None of this requires speculation about the future to be alarming. Every figure in this piece describes damage that has already happened, tallied by scientists using a consistent methodology across more than four decades of data. The climate crisis, measured this way, is not a forecast. It is a bill that has already arrived, and it has been getting larger nearly every year for the past decade.