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Tag: Extreme Weather

  • [Science] Climate Change Strengthened Hurricane Polo More Than El Niño, Study Finds

    [Science] Climate Change Strengthened Hurricane Polo More Than El Niño, Study Finds

    When Hurricane Polo intensified into one of the strongest and longest-lasting Category 5 hurricanes recorded in the eastern Pacific in September 2026, an exceptionally strong El Niño seemed the obvious explanation. But a rapid scientific analysis released on October 15 found that human-caused climate change had an even greater influence than El Niño on the ocean and atmospheric conditions that allowed Polo to become so extreme.

    The distinction matters because El Niño is a temporary climate pattern, while human-caused warming keeps raising the planet’s long-term temperature baseline. That means conditions capable of supporting an exceptionally intense hurricane can keep becoming more likely, even in years when El Niño is absent altogether.

    原論文情報 / Original Paper
    Title: Effect of climate change at least as large as El Niño in strengthening Hurricane Polo
    Authors: Friederike Otto et al. (World Weather Attribution / Climate Central)
    Journal: World Weather Attribution rapid report, Grantham Institute, Imperial College London (not yet peer-reviewed)
    DOI: 10.25560/144926

    A Record-Breaking Storm, Dissected

    Hurricane Polo intensified explosively over the eastern Pacific in late September 2026, with maximum sustained winds climbing by roughly 90 knots (about 167 km/h) in 24 hours — a jump the US National Hurricane Center called “truly remarkable.” The storm peaked at about 165 mph (265 km/h), Category 5 strength, and the Associated Press described it as the longest-lasting Category 5 storm on record in the Pacific. Polo went on to make landfall in Mexico’s Baja California Sur and cross into Sonora, and the flooding that followed killed at least five people across Jalisco and Sonora, according to local reports cited in the WWA assessment; roughly 1,000 people were evacuated in New Mexico over fears a dam could fail.

    As soon as the storm weakened, World Weather Attribution (WWA) — the international scientist network known for analyzing extreme weather events within days of them happening, rather than waiting years for a full peer-reviewed study — teamed up with the nonprofit Climate Central to work out how much of Polo’s power came from decades of ocean warming versus this year’s unusually strong El Niño. The team included researchers based in Mexico, the United States, the United Kingdom, Ireland and the Netherlands, working with partners at Imperial College London, the Royal Netherlands Meteorological Institute (KNMI) and the Red Cross Red Crescent Climate Centre.

    Three Ways to Measure the Effect

    To separate the two influences, the researchers mainly relied on a measure called “potential intensity” — a thermodynamic estimate, built from sea-surface temperature, air temperature and humidity, of the strongest a storm could theoretically become in a given patch of ocean. It is not a prediction of the exact wind speed a real storm will reach, since that also depends on wind shear, storm structure and other factors. The team compared potential intensity in the real, warmed-up world against a hypothetical world without human-caused warming, and separately against a world without this year’s El Niño.

    Bar chart comparing climate change and El Nino's contribution to Hurricane Polo's intensity
    Source: created from World Weather Attribution (2026) data

    The results point the same way on multiple measures. Conditions associated with Polo’s extreme potential intensity were estimated to be about 23 times more likely in today’s climate than in a world without human-caused warming — roughly a 1-in-115-year event — compared with about 14 times more likely from this year’s El Niño relative to neutral conditions, roughly a 1-in-70-year event. In terms of potential intensity itself, climate change added an estimated 5 m/s, versus about 4.2 m/s from El Niño. Separately, the researchers estimated that climate change increased Polo’s actual peak wind speed by about 2.7 m/s, or roughly 6 mph. The ocean water Polo crossed was also assessed on its own: it was about 1.4°C warmer than it would have been in a pre-industrial climate, a level of warmth made roughly 100 to 200 times more likely by climate change.

    Why a Few Miles an Hour Matters

    A few extra miles per hour might not sound dramatic, but it is not a small thing physically. The kinetic energy wind carries rises roughly with the cube of its speed, so a modest increase in wind speed can translate into a disproportionately larger jump in the force a storm can exert — even before accounting for how a particular coastline’s buildings, storm surge and terrain shape the actual damage. That nonlinearity is why hurricane scientists pay close attention to marginal gains in wind speed, and why researchers note that a storm carrying Polo’s extra climate-driven intensity toward a more densely populated coastline could have caused significantly more damage than it did striking a relatively sparsely populated stretch of Mexico.

    El Niño Fades, Warming Doesn’t

    “El Niño comes and goes, but climate change only gets worse.”

    That line, from WWA’s Friederike Otto, captures why the study’s authors consider the finding noteworthy even though El Niño’s own contribution was substantial. El Niño is a natural, temporary swing in Pacific Ocean temperatures that typically lasts anywhere from several months to a year or more before fading. Climate Central’s Daniel Gilford has compared the two influences to a traffic light and an accelerator: in some regions, El Niño can reduce the high-altitude wind shear that would otherwise tear a storm apart, acting like a green light, while warmer ocean water supplies extra heat and moisture that fuel a storm once it starts to intensify. Neither factor guarantees a storm will intensify, but the light will eventually turn red again as El Niño fades. The long-term warming trend, tied to the heat still accumulating in the climate system, does not reset the same way.

    What the Study Can and Can’t Show

    The analysis has not yet been peer-reviewed, which is standard for WWA’s rapid-response studies — the trade-off the group accepts in order to publish within days of a disaster rather than months later. The researchers also tried to quantify climate change’s effect on Polo’s extreme rainfall, but found that available climate models could not reproduce historical rainfall trends in the region closely enough to draw a reliable conclusion, so they left that question open rather than guess.

    Separately, the Associated Press reported that several hurricane scientists not involved in the study — including Jeff Masters, Michael Mann and Carl Schreck — have suggested the climate-change contribution to Polo could be an underestimate, pointing to a 2024 study by Gilford that found climate change added as much as 16 mph to some Atlantic hurricanes. Gilford, a co-author of the new Polo study, told the AP he sees the new analysis as a deliberately conservative one. Either way, the study’s authors are careful to say it shows that a warmer world raised the odds of extreme conditions for this particular storm — not that every future hurricane will necessarily be stronger than the ones before it.

    What This Means Going Forward

    Polo fits a broader pattern this blog has covered before: this year’s global climate indicators report found that seven of sixteen tracked planetary vital signs hit record extremes in 2026, with warming accelerating rather than leveling off. Polo’s real significance may be less about one storm and more about the baseline it was built on. El Niño years will keep arriving and receding on their own schedule, occasionally stacking with warm oceans to produce an especially intense storm. But because the underlying warming trend persists between those cycles, each future El Niño has a slightly warmer ocean to draw on than the last one did — which is exactly the mechanism this study was designed to isolate.

    Sources: World Weather Attribution, The Associated Press (via KSAT), NASA Earth Observatory, Full study (Imperial College London)

  • [Science] Earth’s Climate Indicators Hit Record Extremes in 2026 as Warming Speeds Up

    [Science] Earth’s Climate Indicators Hit Record Extremes in 2026 as Warming Speeds Up

    A new annual climate report finds that seven of Earth’s sixteen tracked climate indicators, including ocean heat, sea level, and ice loss, have reached record extremes in 2026. Just as notable, the authors estimate that the rate of global surface warming has climbed sharply over the past few decades. The findings matter well beyond climate science circles: if the recent pace continues, warming thresholds long treated as distant milestones could arrive within the working lifetime of people reading this, not generations from now.

    The Planet, Checked Like a Patient

    The findings come from “The 2026 State of the Climate Report: Challenges and Opportunities,” published on October 14, 2026 in the peer-reviewed journal BioScience. It is the latest edition of an annual series led by William Ripple, a distinguished professor at Oregon State University’s College of Forestry, and Christopher Wolf of Terrestrial Ecosystems Research Associates, with co-authors including climate scientist Michael Mann of the University of Pennsylvania and Johan Rockström of the Potsdam Institute for Climate Impact Research.

    The authors track sixteen “planetary vital signs” to monitor changes in Earth’s climate system. These include atmospheric greenhouse gas concentrations, global surface temperature, ocean heat content (the total heat stored in ocean water, including far below the surface, not just sea-surface temperature), sea level, and ice loss. Alongside these, they track the human activities behind the changes, such as fossil fuel consumption and the growth of renewable energy. Much as a doctor reads blood pressure or heart rate over time rather than relying on one measurement, the point of this framework is to follow a consistent set of numbers year after year, rather than judging the climate by any single dramatic event.

    Record Extremes and a Faster Warming Rate

    Of the sixteen indicators, seven, or 44 percent, are now at record extremes. Atmospheric carbon dioxide exceeded 428 parts per million (meaning about 428 CO₂ molecules per million molecules of dry air) in May 2026, roughly 50 percent above pre-industrial levels. Methane and nitrous oxide, two other greenhouse gases, also reached record levels based on year-to-date 2026 averages, though as the year is not yet complete, these figures remain provisional.

    The report’s warming-rate estimate is one of its most discussed figures. Using a segmented trend analysis, the authors put the rate of global surface warming at roughly 0.05 degrees Celsius per decade between 1880 and 1970, rising to about 0.19 degrees per decade between 1970 and 2010, and then to about 0.36 degrees per decade between 2010 and 2024. That is roughly seven times the earliest rate, though comparing periods of such different lengths calls for some caution: the most recent interval spans only 14 years, so it is more exposed to short-term swings such as El Niño than the 90-year span at the start of the record. Even allowing for that, the direction, a clearly faster recent pace, is consistent across the three periods. If this recent rate were to persist, the authors warn, warming could pass 2 degrees Celsius above pre-industrial levels before 2050; that is a conditional extrapolation from the observed trend, not a guaranteed forecast, since both natural variability and future policy choices could shift it either way.

    The rate of global surface warming rose from about 0.05°C per decade before 1970 to about 0.36°C per decade since 2010 — roughly seven times faster.
    Bar chart showing global warming rate rising from 0.05 to 0.19 to 0.36 degrees Celsius per decade across three periods
    Source: Ripple et al., BioScience (2026), “The 2026 State of the Climate Report”

    The authors describe several indicators as showing accelerating trends or abrupt shifts that could make some future changes harder to anticipate than the steadier patterns of past decades.

    Oceans and Ice Absorb the Impact

    Much of the planet’s response to rising greenhouse gases plays out beneath the ocean surface rather than in the air people breathe. The report finds ocean heat content and global sea level at record highs, while glacier thickness and the mass of the Greenland ice sheet sit at record lows. Energy-related carbon dioxide emissions, meanwhile, passed 41 gigatons for the first time in 2025.

    The overall trend is clear, although scientists continue to refine how they measure ocean heat uptake region by region. A separate study published this month by researchers at the University of Bonn combined satellite and ocean-float data to estimate how much heat different ocean basins are absorbing. For the Indian Ocean during 2005–2015, the new estimate came in at 0.58 watts per square meter, against 1.09 watts per square meter from a commonly used climate reanalysis dataset, ORAS5, a nearly two-fold gap for that basin and period specifically. Xsciens covered that study in more detail here. The gap does not overturn the broader picture that oceans are absorbing most of Earth’s excess heat; it is a reminder that even well-established indicators like ocean heat content keep being refined as measurement methods improve.

    Glaciers are a visible, land-based counterpart to that underwater story. Switzerland’s glacier monitoring network reported that Swiss glaciers lost roughly 5.5 percent of their ice volume in 2026, the second-largest annual loss on record after 2022, a sign that frozen water reserves relied on for seasonal water supply are shrinking at a pace that leaves less room for error in regional water planning.

    The Human Toll, and How to Read It

    The report documents a series of disasters from the past year that illustrate the human costs of extreme weather. Hurricane Melissa, which struck the Caribbean in October 2025, caused 95 deaths and more than 12 billion dollars in damage. A separate storm in November 2025, combined with monsoon flooding in Indonesia, killed 708 people. A June 2026 heatwave across Europe is associated, in a preliminary statistical estimate, with around 14,000 excess deaths, meaning deaths above the number that would normally be expected, calculated from mortality data and a model rather than counted individually; the figure is not yet finalized and could be revised.

    The report’s authors write that these events “were at least partly attributable to climate change,” a deliberately qualified statement: it does not claim that any single storm or heatwave would have been impossible without global warming, but that warming is believed to have raised the odds or intensity of each one to some degree. That is consistent with how formal event-attribution science generally works, comparing the likelihood of an event in today’s warmer climate against a hypothetical world without human-caused warming, rather than issuing a simple yes-or-no verdict.

    Beyond individual disasters, the authors flag rising risk around climate “tipping points”: thresholds beyond which feedbacks could drive changes that become difficult, or in some cases effectively impossible, to reverse on human timescales. Two examples they highlight are a weakening of the Atlantic Meridional Overturning Circulation, the ocean current system that helps regulate temperatures across the North Atlantic region, and the risk of large-scale Amazon rainforest dieback, which the report suggests could be triggered by the combined effects of warming and deforestation at as little as 1.5 to 1.9 degrees Celsius of warming. The authors describe continued warming and interacting feedbacks as raising the risk of a self-reinforcing “hothouse” trajectory, marked by weakening natural carbon sinks and accelerating ice loss, though they present this as an elevated risk worth monitoring closely, not an outcome they predict is imminent.

    A Mixed Picture on Energy

    The report is not uniformly bleak. Low-carbon energy sources collectively supplied about 43 percent of global electricity in 2025, and solar and wind consumption grew by roughly 18 percent over the previous year. For the first time in more than a century, renewable energy sources globally surpassed coal as an electricity source. Battery storage, which helps make intermittent solar and wind power more usable around the clock, is also expanding quickly.

    Yet the authors are blunt that this progress remains far short of what is needed. Global fossil fuel consumption still rose by 0.9 percent in 2025, because rising overall energy demand has outpaced the growth of clean alternatives rather than being displaced by them. On adaptation, the gap is starker still: the report cites roughly 64 billion dollars in international public adaptation finance reaching developing countries in 2024, against an estimated need of 310 to 365 billion dollars per year by 2035.

    What the Report Recommends

    The authors call for pursuing rapid cuts to greenhouse gas emissions alongside faster investment in adaptation and resilience, rather than treating the two as separate tracks. They point to measures such as mangrove and wetland restoration, which both protect coastlines and store carbon, early warning systems for extreme weather, and a stronger emphasis on climate justice so that adaptation funding reaches local and frontline communities rather than only large infrastructure projects. They also point to interactive public tools, such as the En-ROADS climate simulator and the Drawdown Explorer, for evaluating the trade-offs between different policy choices.

    The report does not predict inevitable catastrophe. It documents a climate system under increasing, and in some respects accelerating, pressure, while pointing to specific areas where policy and technology can still change the trajectory. Its underlying message is less a single verdict than a status update: of sixteen vital signs checked in 2026, seven are flashing red, the pace of change is quickening, and the choices made over the next few years will help determine how many more join them.

    Sources: American Institute of Biological Sciences / EurekAlert, Ripple et al., “The 2026 State of the Climate Report,” BioScience (2026), University of Bonn, GPB/NPR on Swiss glacier loss