How Do We Know The Role Of Climate Change In Weather Events

Bonisiwe Shabane

-Dec 6, 2025, 11:57 PM

how do we know the role of climate change in weather events

Revealing the influence of climate change on local weather around the globe, every day. The Climate Shift Index: Ocean quantifies the influence of climate change on daily sea surface temperatures. It’s grounded in peer-reviewed attribution science and was launched by Climate Central in 2024. Climate change is warming oceans worldwide, and that added heat is fueling stronger hurricanes. This system quantifies how climate change affects tropical cyclone strength. From deadly floods to devastating droughts, extreme weather events are becoming more common and more intense.

But how do we know whether climate change is the cause—or just natural variation? Clair Barnes, an environmental statistician with World Weather Attribution (WWA), helps answer that question. Since 2014, WWA has been producing rapid studies to determine whether human-caused climate change influenced specific weather events. In this interview with Kristine Sabillo of Mongabay, Barnes explains how WWA selects events, collaborates with local experts, and communicates findings quickly—while the world is still paying attention. Clair Barnes: Attribution studies have existed for a while, but traditional ones go through lengthy peer review. By the time they’re published, the public has often moved on.

WWA was created to provide rapid analysis of high-impact weather events while the public conversation is still active. The goal is to inform debate: Was this climate change? Were other factors at play? Our team works with groups like the Red Cross Red Crescent Climate Centre, who monitor disaster alerts. When something major happens, they send a “trigger” to our internal list. We meet weekly to review these triggers and decide which events to study.

As the climate changes, the frequency and intensity of extreme weather events are increasing. As Earth’s climate changes, it is impacting extreme weather across the planet. Record-breaking heat waves on land and in the ocean, drenching rains, severe floods, years-long droughts, extreme wildfires, and widespread flooding during hurricanes are all becoming more frequent and more intense. Human actions since the Industrial Revolution, primarily the burning of fossil fuels, have caused greenhouse gases to rapidly rise in the atmosphere. As carbon dioxide, methane, and other gases increase, they act as a blanket, trapping heat and warming the planet. In response, Earth’s air and ocean temperatures warm.

This warming affects the water cycle, shifts weather patterns, and melts land ice — all impacts that can make extreme weather worse. According to the Intergovernmental Panel on Climate Change (IPCC)’s Sixth Assessment Report released in 2021, the human-caused rise in greenhouse gases has increased the frequency and intensity of extreme weather events. NASA’s satellite missions, including the upcoming Earth System Observatory, provide vital data for monitoring and responding to extreme weather events. To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video It begins quietly. A breeze turns into a gust.

Rain taps gently on your window, then slams down in torrents. The air feels charged, electric, unpredictable. The news flashes alerts: record-breaking heatwaves, massive floods, relentless wildfires, catastrophic hurricanes. The weather, once something we talked about casually in elevators, has become one of the most urgent and fearsome headlines of our time. But behind the headlines lies a deeper, more profound story. A story of imbalance.

A story written in carbon and ice, in rising seas and searing droughts. It’s the story of how our planet is changing, and how that change is driving extreme weather events in ways that were once unimaginable. Climate change is no longer a distant threat. It’s not just about melting glaciers or polar bears stranded on shrinking ice. It’s here, it’s now, and it’s reshaping the weather in every corner of the globe. And the link between climate change and extreme weather events is becoming more undeniable with each passing season.

To understand how climate change fuels extreme weather, we first need to understand what climate is. Climate is not the same as weather. Weather is what happens today—sunny, rainy, snowy. Climate is the long-term pattern of weather over decades. When those patterns shift significantly, we call it climate change. At the heart of this change lies something simple yet powerful: heat.

Since the Industrial Revolution, human activities—especially the burning of fossil fuels—have poured vast amounts of carbon dioxide and other greenhouse gases into the atmosphere. These gases trap heat from the sun, like a blanket wrapped around the Earth. The more gases we emit, the thicker the blanket becomes. The Earth has warmed roughly 2 ℉ since 1850. This means that people almost everywhere are, on average, experiencing warmer weather. But this rise in temperature is also changing humidity and rainfall, with consequences for extreme weather events, says Professor Paul O’Gorman of the MIT Program in Atmospheres, Oceans and Climate.Warmer weather is causing more...

We often think about how humid it feels outside: That muggy feeling is caused by a high amount of water vapor in the air. And warmer air can hold more water. In fact, says O’Gorman, humidity rises about 3.5% for every degree Fahrenheit that the temperature rises. The higher the humidity, the harder it is for our bodies to cool off by sweating, which can be uncomfortable and also increases health risks from exhaustion, fainting, and even life-threatening heat stroke.Humidity also... In warmer climates, major storms are dropping more rain. Rain gauges show that the rainiest day each year has gotten roughly 3.5% wetter for every degree Fahrenheit of global warming, the same rise we’re seeing in humidity.

This makes sense, says O’Gorman: If there’s more water vapor in the air when a storm starts, more rain will fall during that storm. In some regions, rainfall could rise even more as storms develop stronger winds. And the most intense tropical cyclones, or hurricanes, are expected to become more frequent too. Recent terrible hurricane seasons in the Atlantic are likely a preview of the future. In 2017, for instance, Hurricane Harvey dropped more than 60 inches of rain on Texas’s gulf coast. MIT’s Professor Kerry Emanuel has calculated that, as recently as the 1990s, the state of Texas had only a 1% chance of seeing a storm with that much rain in a given year; now,...

Most models suggest that both tropical cyclones (seen near the equator) and extratropical cyclones (seen in middle or higher latitudes) will become less frequent due to climate change. While fewer storms may seem like a good thing, the fall in extratropical cyclones, which we can already see in the Northern Hemisphere, has actually created an unexpected problem: It tends to make air... “Particularly in the summer,” O’Gorman says, “these cyclones move the air around, bringing air from higher in the atmosphere and ventilating the air that’s near the surface, which can remove air pollution and stop... It turns out it depends. Some parts of the United States, like the Northeast, have seen increasing flooding in recent years, while other areas, like the Southwest, are seeing fewer floods. “The current thinking is that streamflow [the amount of water flowing in rivers and streams] is more complicated than just how much rain fell in the last day,” says O’Gorman.

As weather patterns shift, regions that are getting drier on average might see less flooding even after a spectacular storm.Curious about the effects of climate change on specific weather events? Researchers can run simulations of today’s storms under past climate conditions, allowing us to see what aspects of our current weather are the result of climate change. World Weather Attribution is an international effort to share this data with the public. The website publishes analyses of dozens of recent extreme weather events around the world, explaining how these events were affected by the climate change we are already experiencing. Submit your own question to Ask MIT Climate Get the latest from Ask MIT Climate monthly in your inbox

1 Emanuel, Kerry. "Assessing the present and future probability of Hurricane Harvey's rainfall." PNAS November 28, 2017 114 (48) 12681-12684. https://doi.org/10.1073/pnas.1716222114 Listen to this episode of MIT's "Today I Learned: Climate" podcast on the science of connecting extreme weather events to climate change. How do scientists determine whether climate change is driving extreme weather events like the floods, heat waves and droughts that we’re experiencing today? To find out about the science of attribution, Mongabay’s Kristine Sabillo recently interviewed environmental statistician Clair Barnes of World Weather Attribution (WWA), a global network of researchers that has been analyzing the role of...

The idea behind WWA, Barnes said, “was to look at high-impact weather events and to use the latest science to say something while the conversation is still going on.” WWA works with partners like the Red Cross Red Crescent Climate Centre that monitor various emergency and disaster alerts channels and issues what it calls a “trigger” when a disaster has major humanitarian consequences. This can be a heat wave setting temperature records in a region, or a flood killing or displacing a certain number or proportion of the population. Once WWA researchers decided on an event to study further, they work with local experts who understand the meteorological and geographical processes behind that event. A rapid analysis can take from a few days to up to a few weeks to finish. Barnes said they use observational weather data and statistical and climate models to understand the role of climate change in the event.

Climate Change has become a key topic of discussion, especially when it comes to understanding extreme weather events. People want to know how much climate change affects events like heatwaves, storms, and floods. There are two main ways researchers try to answer this question: the "risk-based" approach and the "storyline" approach. The risk-based approach looks at the likelihood of certain weather events happening in a world with climate change versus a world without it. In contrast, the storyline approach focuses on a specific event and examines how a warmer climate might affect that event. In this article, we will connect these two approaches using a method known as Bayes theorem.

This will help us see how both methods can be related and how we can better understand the impact of climate change on weather events. The risk-based approach is like a general analysis. It tries to find out how often a certain type of weather event happens when considering human impact on the climate. Researchers compare this with how often the same event would happen if humans had not influenced the climate. Researchers gather Data from past weather events and climate models to draw conclusions. For instance, if there's a major flooding event, this approach can help estimate how much more likely that flooding became due to climate change.

How Do We Know The Role Of Climate Change In Weather Events

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