Climate concerns as Siberia experiences record-breaking heat

Heat wave sparks concerns about devastating wildfire season and melting permafrost.
Image: Satellite imagery of a wildfire in Siberia, Russia above the arctic circle on May 19, 2020

Satellite imagery of a wildfire in Siberia, Russia above the arctic circle on May 19, 2020Copernicus Sentinel/Sentinel Hub/Pierre Markuse

By Luke Denne and Olivia Sumrie

One of the coldest regions on Earth has been experiencing a record-breaking heat wave in recent weeks amid growing fears about devastating wildfires and melting permafrost.

Khatanga, a town in Siberia’s Arctic Circle, registered highs of over 80 degrees Fahrenheit this week, according to Accuweather, far above the 59 degrees F historical average, as the whole of western Siberia basked in unseasonable warmth.

While locals flocked to popular spots to sunbathe, experts sounded alarms about the possible implications for the region’s wildfire season this summer, with some blazes already breaking out in recent months.

Image: People on a sandy shore of the Novosibirsk Reservoir on the Ob River in Sovetsky District of Novosibirsk, during the pandemic of the novel coronavirus disease
People on a sandy shore of the Novosibirsk Reservoir on the Ob River in Novosibirsk on May 20.Kirill Kukhmar / TASS/Getty

Fires burned huge areas in the region last year and, at its peak, smoke engulfed an area larger than the whole European Union, the World Meteorological Organization reported.

“It is very much possible that this year, we will have another fire catastrophe in Siberia,” Anton Beneslavskiy, a wildfire expert with Greenpeace Russia, said.

“Catastrophes became the new business as usual for Siberia in the last 20 years,” he added.

From January to April, Russia was 11 degrees F warmer than average, according to the climate science nonprofit Berkeley Earth.

“That’s not only a new record anomaly for Russia. That’s the largest January to April anomaly ever seen in any country’s national average,” Robert Rohde, Berkeley Earth lead scientist tweeted.

The pace of global warming in Russia is over twice as fast as the global average, Russia’s deputy U.N. envoy said last year. But the situation in the Arctic is even more stark with the region warming at over three times the global average.

Much of the Arctic region is covered by permafrost — carbon rich soil that should remain frozen throughout the year — and rapid warming is causing it to melt, said Thomas Smith, an assistant professor of environmental geography at the London School of Economics.

Permafrost, he said, stores vast amounts of carbon, which means that when it melts, planet-warming greenhouse gasses are emitted.

“That can further drive climate change and global warming,” he said.

Image: A satellite image showing wildfires in the Novosibirsk Region, south Siberia on April 27, 2020
A satellite image showing wildfires in the Novosibirsk Region, south Siberia on April 27.NASA

“The second problem is that if the land is thawed out, and if it dries out with these high temperatures, then that soil is actually available to burn as a fuel for a fire,” he added.

These fires that emit greenhouse gases can smolder for weeks or months, “even when it has rained,” Smith said.

The unusual heat has also disrupted a number of natural cycles, according to the Siberian Times, with river ice breaking, blooms coming earlier and insects emerging earlier than normal.

While temperatures in the region have temporarily dropped, the heat is forecast to return next week.

Inslee says COVID-19 transmission in Washington is rising as temperatures warm

With temperatures rising across Western Washington this weekend, Governor Jay Inslee warned Friday that the transmission rate of the novel coronavirus could rise too. (Photo: KOMO News)

With temperatures rising across Western Washington this weekend, Governor Jay Inslee warned Friday that the transmission rate of the novel coronavirus could rise too.

With this weekend set to be the warmest of the year, paired with Mother’s Day Sunday, Inslee acknowledged that people will be getting out.

To those who plan on being outdoors, he once again urged that social distancing be practiced.

“With COVID-19 lurking, we do have to hope people will both enjoy an amazing weekend and do it in a way that keeps themselves and their loved ones safe,” Inslee said.

At Lake Union Park, plenty of people gathered to soak up the sun, many groups doing a good job of spreading out. Although in some places, social distancing was hard to come by.

“This is the most packed that I’ve seen it,” said Briana Jarrett. “I think it’s hard to judge and say ‘Oh, they’re sitting too close and not social distancing’ because you could be out here with your family our someone in your quarantine circle.”

“Honestly, it’s pretty busy right now,” said Damian Troisch. “The first real hot day of the year so I think everyone is just out here enjoying it.”

As AIR 4 flew over parts of the Puget Sound, beachgoers could be spotted at Dash Point and some spectators had returned to catch a glimpse of Snoqualmie Falls.

The heat wave comes as new data from the Institute for Disease Modeling shows that since early April, the reproductive rate of the virus has slowly climbed.

At the beginning of the pandemic, the reproductive rate sat around three in King County, meaning for every one infected person, it was likely they could infect three others.

Citing social distancing, that rate dropped to below one. The upward trend isn’t just something the Seattle-area is seeing, but Eastern Washington, as well.

“The number of people who will be infected and the number of people who will lose their lives is going to rise again in the state of Washington,” said Inslee should that rate continue to grow.

The findings come as some continue to urge the governor to re-open the state.

Nearly three weeks ago, protesters took to the Capitol Campus in Olympia, demanding businesses be allowed to get back to work. Another rally is set to take place Saturday.

“I don’t think we’re moving at a fast enough rate,” said Tyler Miller who organized the “Hazardous Liberty” event on Facebook.

Cole Miller | COVID-19 transmission, temperatures rising

When pressed about the balance between the health of the public and restarting the economy, Miller responded with the following.

“It’s going to be in businesses’ best interest to show how they are keeping their employees safe and how they’re keeping their businesses safe for customers and come and patronize them so I don’t see there being too much conflict in being able to find that balance.”

It’s already getting too hot and humid in some places for humans to survive

Extreme conditions are happening more often than scientists previously thought

Temperatures Soar To Highest Of The YearPhoto by Peter Macdiarmid/Getty Images

A combination of heat and humidity so extreme that it’s unendurable isn’t just a problem for the future — those conditions are already here, a new study finds. Off-the-chart readings that were previously thought to be nearly nonexistent on the planet today have popped up around the globe, and unyielding temperatures are becoming more common.

Extreme conditions reaching roughly 115 degrees Fahrenheit on the heat-index scale — a measurement of both heat and humidity that’s often referred to as what the temperature “feels like” — doubled between 1979 and 2017, the study found. Humidity and heat are a particularly deadly combination, since humidity messes with the body’s ability to cool itself off by sweating. The findings imply that harsh conditions that scientists foresaw as an impending result of climate change are becoming reality sooner than expected.

“We may be closer to a real tipping point on this than we think,” Radley Horton, co-author of the new study published today in the journal Science Advances, said in a statement. His previous research had projected that the world wouldn’t experience heat and humidity beyond human tolerance for decades.

More intense and frequent heat events are one of the symptoms of climate change, a lot of research has shown. But most of those studies were based on readings that looked at averages over a wide area over a long period of time. Instead, Horton and his co-authors looked closely at hourly data from 7,877 weather stations around the world. They used the “wet bulb” centigrade scale, which measures other factors such as wind speed and solar radiation on top of heat and humidity.

That’s how they found more than a thousand readings of severe heat and humidity, reaching wet bulb readings of 31 degrees Celsius, that were previously thought to be very rare. Along the Persian Gulf, they saw more than a dozen readings above what’s thought to be the human tolerance limit of 35 degrees Celsius on the wet bulb scale. That’s the highest wet bulb reading that scientific literature has ever documented. In 2015, the city of Bandar Mahshahr in Iran experienced a wet bulb reading just under 35 degrees Celsius. At more than 160 degrees Fahrenheit on the heat-index scale, that’s about 30 degrees higher than where the National Weather Service’s heat-index range ends — and it’s a scenario that climate models hadn’t forecast to happen until the middle of the century.

They make the case that future studies ought to take a similarly localized look to get a better understanding of how climate change is playing out in communities that will feel the crunch ahead of the rest of the world. A Pulitzer prize-winning series by The Washington Post took this sort of approach in a series about places where average temperatures have already risen 2 degrees Celsius, the threshold at which the Paris climate accord aims to keep the globe from surpassing.

“If you zoom in you see things that you don’t see at a larger scale,” says Colin Raymond, lead author and a postdoctoral researcher at NASA’s Jet Propulsion Laboratory. “At the smallest scale, it’s more intense.” One of the limitations to their study, according to Raymond, is that there are places across the globe that simply lack weather stations. So what they were able to document could be happening at an even wider scale, there just aren’t tools in place yet to make those measurements everywhere.

Extreme heat already kills more people in the US than any other weather-related event.

In 50 years, between 1 to 3 billion people could find themselves living in temperatures so hot that they’re outside the range in which humans have been able to thrive, found another study published this week. Just how many billions will face that future depends on what action is taken now to stop the planet from dangerously overheating.

The emergence of heat and humidity too severe for human tolerance


 See all authors and affiliations

Science Advances  08 May 2020:
Vol. 6, no. 19, eaaw1838
DOI: 10.1126/sciadv.aaw1838


Humans’ ability to efficiently shed heat has enabled us to range over every continent, but a wet-bulb temperature (TW) of 35°C marks our upper physiological limit, and much lower values have serious health and productivity impacts. Climate models project the first 35°C TW occurrences by the mid-21st century. However, a comprehensive evaluation of weather station data shows that some coastal subtropical locations have already reported a TW of 35°C and that extreme humid heat overall has more than doubled in frequency since 1979. Recent exceedances of 35°C in global maximum sea surface temperature provide further support for the validity of these dangerously high TW values. We find the most extreme humid heat is highly localized in both space and time and is correspondingly substantially underestimated in reanalysis products. Our findings thus underscore the serious challenge posed by humid heat that is more intense than previously reported and increasingly severe.


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Humans’ bipedal locomotion, naked skin, and sweat glands are constituents of a sophisticated cooling system (1). Despite these thermoregulatory adaptations, extreme heat remains one of the most dangerous natural hazards (2), with tens of thousands of fatalities in the deadliest events so far this century (34). The additive impacts of heat and humidity extend beyond direct health outcomes to include reduced individual performance across a range of activities, as well as large-scale economic impacts (57). Heat-humidity effects have prompted decades of study in military, athletic, and occupational contexts (89). However, consideration of wet-bulb temperature (TW) from the perspectives of climatology and meteorology began more recently (1011).

While some heat-humidity impacts can be avoided through acclimation and behavioral adaptation (12), there exists an upper limit for survivability under sustained exposure, even with idealized conditions of perfect health, total inactivity, full shade, absence of clothing, and unlimited drinking water (910). A normal internal human body temperature of 36.8° ± 0.5°C requires skin temperatures of around 35°C to maintain a gradient directing heat outward from the core (1013). Once the air (dry-bulb) temperature (T) rises above this threshold, metabolic heat can only be shed via sweat-based latent cooling, and at TW exceeding about 35°C, this cooling mechanism loses its effectiveness altogether. Because the ideal physiological and behavioral assumptions are almost never met, severe mortality and morbidity impacts typically occur at much lower values—for example, regions affected by the deadly 2003 European and 2010 Russian heat waves experienced TW values no greater than 28°C (fig. S1). In the literature to date, there have been no observational reports of TW exceeding 35°C and few reports exceeding 33°C (9111415). The awareness of a physiological limit has prompted modeling studies to ask how soon it may be crossed. Results suggest that, under the business-as-usual RCP8.5 emissions scenario, TW could regularly exceed 35°C in parts of South Asia and the Middle East by the third quarter of the 21st century (1416).

Here, we use quality-assured station observations from HadISD (1718) and high-resolution reanalysis data from ERA-Interim (1920), verified against radiosondes and marine observations (see the Supplementary Materials) (2122), to compute TW baseline values, geographic patterns, and recent trends. Uncertainties in TW from station data due to instrumentation and procedures are on the order of 0.5° to 1.0°C in all regions considered, an important consideration for proper interpretation of the results. Our approach of using TW and sea surface temperature (SST) observations as guidance for future TW projections offers a different line of evidence from previous research that used coupled or regional models without explicitly including historical station data.


Our survey of the climate record from station data reveals many global TW exceedances of 31° and 33°C and two stations that have already reported multiple daily maximum TW values above 35°C. These conditions, nearing or beyond prolonged human physiological tolerance, have mostly occurred only for 1- to 2-hours’ duration (fig. S2). They are concentrated in South Asia, the coastal Middle East, and coastal southwest North America, in close proximity to extraordinarily high SSTs and intense continental heat that together favor the occurrence of extreme humid heat (214). Along coastlines, the marine influence is manifest via anomalous onshore low-level winds during midday and afternoon hours, and these wind shifts can cause rapid dew point temperature (Td) increases in arid and semiarid coastal areas (figs. S3 to S9). Regionally coherent observational evidence supports these intense values: Of the stations along the Persian Gulf coastline with at least 50% data availability over 1979 to 2017, all have a historical 99.9th percentile of TW (the value exceeded roughly 14 times in 39 years) above 31°C (Fig. 1; see fig. S1 for the all-time maximum). In the ERA-Interim reanalysis, the highest values are similarly located over the Persian Gulf and immediately adjacent land areas, as well as parts of the Indus River Valley (fig. S10). The spatiotemporal averaging inherent in reanalysis products causes ERA-Interim to be unable to represent the short durations and small areas of critical heat stress, causing its extreme TW values to be substantially lower than those of weather stations across the tropics and subtropics (fig. S11). In the Persian Gulf and adjacent Gulf of Oman, these differences are consistently in the range of −2° to −4°C (fig. S12). Larger bias but similar consistency is present along the eastern shore of the Red Sea, presenting a basis for future studies examining the reasons for this behavior, as well as further comparisons between station and reanalysis data.

Fig. 1 Observed global extreme humid heat.

Color symbols represent the 99.9th percentile of observed daily maximum TW for 1979–2017 for HadISD stations with at least 50% data availability over this period. Marker size is inversely proportional to station density.

Other >31°C hotspots in the weather station record emerge through surveying the globally highest 99.9th TW percentiles: eastern coastal India, Pakistan and northwestern India, and the shores of the Red Sea, Gulf of California, and southern Gulf of Mexico (Fig. 1). All are situated in the subtropics, along coastlines (typically of a semienclosed gulf or bay of shallow depth, limiting ocean circulation and promoting high SSTs), and in proximity to sources of continental heat, which together with the maritime air comprise the necessary combination for the most exceptional TW (11). That subtropical coastlines are hotspots for heat stress has been noted previously (2324); our analysis makes clear the broad geographic scope but also the large intraregional variations (Fig. 1). Western South Asia stands as the main exception to this coastline rule, likely due to the efficient inland transport of humid air by the summer monsoon together with large-scale irrigation (1525). Tropical forest and oceanic areas generally experience TW no higher than 31° to 32°C, perhaps a consequence of the high evapotranspiration potential and cloud cover, along with the greater instability of the tropical atmosphere. However, more research is needed on the thermodynamic mechanisms that prevent these areas from attaining higher values.

Steep and statistically significant upward trends in extreme TW frequency (exceedances of 27°, 29°, 31°, and 33°C) and magnitude are present across weather stations globally (Fig. 2). Each frequency trend represents more than a doubling of occurrences of the corresponding threshold between 1979 and 2017. Trends in ERA-Interim are strongly correlated with those of HadISD but are smaller for the highest values (Fig. 2), consistent with ERA-Interim’s underestimation of extreme TW that is largest for the most extreme conditions (fig. S11). We also find a sharp peak in the number of global TW = 27°C and TW = 29°C extremes during the strong El Niño events of 1998 and 2016. Linearly detrending this global-TW-extremes time series reveals that the El Niño–Southern Oscillation (ENSO) correlation is largest for TW values that are high but not unusual (~27° to 28°C) across the tropics and subtropics (fig. S13). Further work is necessary to test to what extent this relationship may be related to the effect of ENSO on hydrological extremes at the global scale, on tropospheric-mean temperatures, or on SSTs in particular basins, and the implications of these effects for TW predictability (2627). Overall, TW extremes in the tropics largely correspond on an interannual basis to mean TW (fig. S14), indicating that climate forcings and modes of internal variability resulting in mean temperature shifts can be expected to modulate tropical TW extremes. This is the case in the subtropics as well, although to a somewhat lesser extent.

Fig. 2 Global trends in extreme humid heat.

(A to D) Annual global counts of TW exceedances above the thresholds labeled on the respective panel, from HadISD (black, right axes, with units of station days) and ERA-Interim grid points (gray, left axes, with units of grid-point days). We consider only HadISD stations with at least 50% data availability over 1979–2017. Correlations between the series are annotated in the top left of each panel, and dotted lines highlight linear trends. (E) Annual global maximum TW in ERA-Interim. (F) The line plot shows global mean annual temperature anomalies (relative to 1850–1879) according to HadCRUT4 (40), which we use to approximate each year’s observed warming since preindustrial; circles indicate HadISD station occurrences of TW exceeding 35°C, with radius linearly proportional to global annual count, measured in station days.

We also observe modulation on a seasonal scale, by considering as an illustrative example the South Asian monsoon region. There, the timing of peak TW varies with the advance of the summer monsoon (15). Splitting South Asia into “early monsoon” and “late monsoon” subregions, we find that the number of TW extremes is largest around the time of the local climatological monsoon onset date (Fig. 3). Although equivalent extreme values of TW are possible before, during, and after the monsoon rains in any given year, they are of a different character; especially in the northern and western parts of the subcontinent, they become continually moister and have lower dry-bulb temperatures as summer progresses. Across the globe, such temperature and humidity variations occur within a well-defined bivariate space (fig. S15). That these variations are systematically associated with the summer monsoon in South Asia emphasizes the important role of moisture, and of weather systems on synoptic to subseasonal time scales, in controlling extreme TW (1528). Our findings underscore the diversity of conditions that can lead to extreme humid heat in the same location at different times, suggesting that impacts adaptation strategies may benefit from taking this recognition into account. Such intraseasonal variability in TW also matters for physiological acclimation, which requires several-day time scales to develop (29); TW character is especially relevant when considering effects on human systems that vary in their sensitivity to humidity and temperature—for example, thermoregulation and energy demand for artificial cooling are strongly affected by TW, whereas the materials that make up the built environment are principally affected by temperature alone (1330).

Fig. 3 Monsoon-modulated seasonality of extreme humid heat.

(A) Early monsoon areas (light orange shading; <June 15 average onset date) and late monsoon areas (green shading; ≥June 15 average onset date) in South Asia. (B) (Solid line) Mean annual number of TW exceedances of 31°C per station, by pentad, in the early monsoon areas. (Dashed line) Mean relative humidity associated with these exceedances. The division between the brown- and blue-shaded sections represents the station-weighted-average climatological monsoon onset date. (C) Same as in (B), but for the late monsoon areas.

While our analysis of weather stations indicates that TW has already been reported as having exceeded 35°C in limited areas for short periods, this has not yet occurred at the regional scale represented by reanalysis data, which is also the approximate scale of model projections of future TW extremes considered in previous studies (1415). To increase the comparability of our station findings with these model projections, we implement a generalized extreme value (GEV) analysis to estimate the amount of global warming from the preindustrial period until TW will regularly exceed 35°C at the global hottest ERA-Interim grid cells, currently all located in the Persian Gulf area (Fig. 4). Complete details of this procedure are in Materials and Methods. In brief, we fit a nonstationary GEV model to the grid cells experiencing the highest TW values, with the GEV location parameter a function of the annual global-mean air-temperature anomaly. This enables us to quantify how much global warming is required for annual maximum TW ≥ 35°C to become at most a 1-in-30-year event at any grid cell. We conduct this analysis solely for grid cells where the nonstationary GEV model is a significantly (P < 0.05) better fit to the annual maximum time series (1979–2017) than a stationary alternative. We then define the temperature of emergence (ToE) as the amount of global warming required until TW ≥35°C is at most a 1-in-30-year event at the ERA-Interim spatiotemporal scale, such that the lowest ToE at any grid cell approximates the first occurrences of TW = 35°C that are widespread and sustained enough to cause serious or fatal health impacts, as estimated from physiological studies (61031).

Fig. 4 Projections of extreme humid heat exceeding the physiological survivability limit.

(A) Shading shows the amount of global warming (since preindustrial) until TW = 35°C is projected to become at least a 1-in-30-year event at each grid cell according to a nonstationary GEV model. In blank areas, more than 4°C of warming is necessary. Black dots indicate ERA-Interim grid cells with a maximum TW (1979–2017) in the hottest 0.1% of grid cells worldwide. (B) Total area with TW of at least 35°C, as a function of mean annual temperature change 〈T〉 from the preindustrial period. Red (green) vertical lines highlight the lowest 〈T〉 for which there are nonzero areas over land (sea)—the respective ToE. (C) Bootstrap estimates of the ToE. See text for details of this definition and calculation.

Our method yields a ToE of 1.3°C over the waters of the Persian Gulf (90% confidence interval, 0.81° to 1.73°C) and of 2.3°C for nearby land grid cells (1.4° to 3.3°C) (Fig. 4). Adjusting these numbers for ERA-Interim’s robust Persian Gulf differences of approximately −3°C for extreme TW (fig. S12) supports the conclusion from the station observations that recent warming has increased exceedances of TW = 35°C, but that this threshold has most likely been achieved on occasion throughout the observational record (Fig. 2). The strong marine influence on these values is also apparent in Fig. 1.

To further assess the physical realism of our GEV extrapolation, we additionally examine observed annual maximum (monthly mean) SSTs. An atmospheric boundary layer fully equilibrated with the ocean surface would be at saturation and have the same temperature as the underlying SSTs, meaning that, in principle, 35°C is the lowest SST that could sustain the critical 35°C value of TW in the air above. In reality, equilibrium will not be achieved if air-mass residence times over extreme SSTs are too short, which is more likely if the vertical profile of the atmosphere allows strong surface heating to trigger deep convection (10). Current large-scale SSTs and their trends may therefore provide some guidance as to whether our projections of extreme TW are physically plausible. It is in this context that we note monthly mean SSTs exceeding the 35°C threshold for the first time, reaching 35.2°C in the Persian Gulf in 2017 (Fig. 5). As a result, our GEV projection of large-scale maritime TW ≥ 35°C, for less than 1.5°C warming, appears physically consistent with SST observations at the same scale. Analogous corroboration of station-based TW ≥ 35°C events is provided by point scale, hourly SST and TW across the Persian Gulf from an independent database of marine observations (see the Supplementary Materials) (21), in which we find SSTs have exceeded 35°C in every year since 1979, with ~33% of July to September 2017 observations above this threshold. During the summer of 2017, reports of Persian Gulf over-water TW ≥ 35°C also peaked at ~6% of all TW measurements there.

Fig. 5 Trends and maxima of observed SST.

(A) Annual maximum of monthly SST across all grid cells in the HadISST dataset; orange dashed line is a running 30-year average, and red line marks 35°C. (B) All-time maximum SST around the Persian Gulf and Arabian Sea. The blue points mark locations where monthly mean SST rose above 35°C in 2017.


The station-based approach that we take here and the model-based approach taken in previous studies (1416) represent different methods for obtaining valuable perspective on the genesis and characteristics of global TW extremes. The primary strength of station data is its ability to precisely capture local conditions, but even the best-available station data have limitations, uncertainties, and potential unobserved humidity biases (for example, due to observational procedures, instrumentation type, or siting), as well as highly incomplete spatial coverage (see discussion in the Supplementary Materials) (3233). In contrast, reanalysis products and high-resolution regional models satisfy the need for spatiotemporal continuity and consistency and allow analysis of additional variables, but often underestimate extremes (34).

In this study, we demonstrate that efforts to better understand extreme TW would benefit from further close examination, and improved standardization and integration, of station data to alleviate model shortcomings—especially along coasts where TW can vary markedly over small distances and where high-quality humidity data are therefore essential—but that station-based and physical modeling–based approaches are fundamentally complementary. Further research into the origins of extreme-TW biases in gridded products and continued advances in data assimilation would also help enable the development of a more unified approach drawing on all available sources of knowledge. For instance, it is important to understand the treatment of extreme values in reanalyses, and whether false-positive or false-negative rejections might be taking place, particularly as temperature and humidity distributions shift toward ever-higher values. Key multiscale TW processes necessitating closer comparison between observations and models include coastal upwelling, atmospheric convection, land-atmosphere interactions, and atmospheric variability linked to SSTs (28)—for instance, at the hourly, 1- to 10-km scale. Detailed analyses of individual events could help illuminate the unfolding interactions of processes and provide additional investigative power, such as in tracing and forecasting the rapid increases in humidity, which tend to accompany TW extremes (fig. S5), and in assessing the role of topography and land use/land cover in creating apparent TW hotspots (fig. S4). Studies comparing biases and trends in TW and SSTs among reanalyses, models, and regions would be especially beneficial, as would investigation of the sensitivity of extreme-TW projections to historical variability, changes in forcing patterns, and statistical methodologies.

Imminent severe humid heat provides incentive for a broad interdisciplinary research initiative to better characterize health impacts. Increased collection of high-resolution health data, international collaborations with public health experts and social scientists, and dedicated modeling projects would aid in answering questions about how vulnerable populations (such as the elderly, outdoor laborers, and those with preexisting health conditions) will be adversely affected as peak TW advances further into the extreme ranges we consider here. Of particular salience is the need to ascertain how acclimation to high-heat-stress conditions is diminished as the physiological survivability limit is approached. Such efforts may also help resolve the reasons for the paucity of reported mortality and morbidity impacts associated with observed near 35°C conditions (1114).

Our findings indicate that reported occurrences of extreme TW have increased rapidly at weather stations and in reanalysis data over the last four decades and that parts of the subtropics are very close to the 35°C survivability limit, which has likely already been reached over both sea and land. These trends highlight the magnitude of the changes that have taken place as a result of the global warming to date. At the spatial scale of reanalysis, we project that TW will regularly exceed 35°C at land grid points with less than 2.5°C of warming since preindustrial—a level that may be reached in the next several decades (35). According to our weather station analysis, emphasizing land grid points underplays the true risks of extreme TW along coastlines, which tends to occur when marine air masses are advected even slightly onshore (14). The southern Persian Gulf shoreline and northern South Asia are home to millions of people, situating them on the front lines of exposure to TW extremes at the edge of and outside the range of natural variability in which our physiology evolved (36). The deadly heat events already experienced in recent decades are indicative of the continuing trend toward increasingly extreme humid heat, and our findings underline that their diverse, consequential, and growing impacts represent a major societal challenge for the coming decades.


Weather station observations

We use HadISD, version, which is produced by the Met Office Hadley Centre as a more rigorously quality-controlled version of the National Climatic Data Center Integrated Surface Database (ISD) (1718). HadISD results from the implementation of additional data availability and quality control procedures to ISD, including checks on both temperature and Td, the two variables required for computing TW. Because of a lack of good-quality data in the tropics, our conclusions are most reliable in the subtropics and midlatitudes, especially where multiple nearby stations are in agreement. TW uncertainties range from ~0.5°C for the most recent data from North America and Europe to ~1.2°C for the oldest data and that from South Asia, Africa, and Latin America. Data validation is considered in depth in the Supplemental Materials.

We use a MATLAB implementation (37) of the formula of (38) for computing TW. We compute TW daily maxima irrespective of stations’ temporal resolutions, which vary from 1 to 6 hours. TW values are for 2 m above ground level, with station surface pressure calculated from its elevation using a standard atmosphere and an assumed sea-level pressure of 1013 mb. A sensitivity analysis reveals the error in TW owing to this assumption to be on the order of 0.1°C.

We additionally eliminate HadISD station data that fail any one of the following meteorological and climatological tests. Tests are listed in the order implemented, with the fraction of HadISD 31+°C readings removed at each successive step shown in parentheses:

1. A TW extreme occurs in conjunction with a dew point depression of ≤0.5°C (65/10,492).

2. The Td associated with a TW extreme is more than 10°C different from the elevation-adjusted value at the closest grid cell and time step in the ERA-Interim reanalysis (289/10,427).

3. A TW extreme occurring in 1979–1993 is greater than the maximum in 2003–2017 (67/10,138).

4. A TW extreme is followed at any point by at least 1000 consecutive days of missing Td data (365/10,071).

5. A TW extreme occurs on a day when the daily maximum and daily minimum T or Td are identical (53/9706).

6. A TW extreme is more than 7.5°C higher than any other TW value co-occurring in a 7.5° × 7.5° box centered on the station (405/9653).

7. A TW extreme is associated with a Td change of more than 8°C in 1 hour or 12°C in 3 hours (77/9248).

8. A TW extreme is associated with a Td greater than the previously reported, although unofficial, global maximum value of 35°C recorded at Dhahran, Saudi Arabia, on 8 July 2003 (18/9171).

9. A TW extreme occurs during a period with two or more consecutive identical daily maximum TW and Td values (289/9153).

10. A TW extreme before 2001 is higher than any value recorded since 2001 (270/8864).

11. The top five TW extremes at a station all occur within a 365-day period (60/8594).

12. The Td associated with a TW extreme is higher than the 99.5th percentile of the first 5000 days, only at stations where this value is more than 1°C larger than the 99.9th percentile of the last 5000 days (55/8534).

13. The Td associated with a TW extreme is higher than the 99.5th percentile of the last 5000 days, only at stations where this value is more than 6°C larger than the 99.9th percentile of the first 5000 days (362/8479).

14. A TW extreme is associated with a relative humidity of ≥95% (29/8117).

15. A TW extreme occurs on a day when the daily maximum TW takes place before 11:00 a.m. or after 8:00 p.m. local standard time (26/8088).

16. A TW extreme is the all-time maximum at a station and is more than 2°C higher than the next largest value (6/8062).

17. A remaining ≥33°C TW extreme is manually ascertained to be associated with a significant changepoint or not fully supported by gridded humidity and temperature data (508/8056).

Remaining TW = 35°C readings are also closely examined on a subdaily basis so as to ensure validity to the extent possible. We deem valid all other values that pass the above additional quality control measures, beyond the original quality control and homogenization (1718). Summaries of the TW = 33°C and 35°C values in the final dataset are given in tables S1 and S2.

Interannual trends are calculated using an ordinary least squares regression, with significance evaluated using a t test on the slope coefficient. Our assessment of extreme TW frequency considers threshold exceedances in 2°C increments from 35° to 27°C, so as to strike a balance between values that are sufficiently distinct from one another while being high enough to remain relevant from an impact perspective.

Marine observations

We use monthly SSTs from the 1° HadISST version 1.1 dataset (20) to assess the physical realism of our GEV extrapolations and use in situ point observations of SST and TW from International Comprehensive Ocean-Atmosphere Data Set (ICOADS) (21) as an independent (versus HadISD) check on the extreme TW values reported at nearby land-based weather stations. Details of these comparisons are provided in the Supplementary Materials.

Marine and vertical profile data

The ICOADS integrated dataset (21) is used as validation of near-surface conditions over water. Radiosondes are from the Integrated Global Radiosonde Archive (2239).

GEV modeling of TW extremes in reanalysis data

We fit a GEV distribution to the time series of annual maximum TW from selected grid cells in ERA-Interim, a reanalysis dataset that optimally blends observations with a numerical hindcast and, thus, provides an estimate of the atmospheric state less sensitive to observation error and microclimatic variability (19). While well suited to identifying and extrapolating global trends, it is inevitable in such an approach that decadal temperature trends and other large-scale variability may affect our results modestly.


Warmest Oceans on Record Could Set Off a Year of Extreme Weather

  • Pacific, Atlantic and Indian Oceans have reached record highs
  • Hurricanes, wildfires and severe thunderstorms all affected

The world’s seas are simmering, with record high temperatures spurring worry among forecasters that the global warming effect may generate a chaotic year of extreme weather ahead.

Parts of the Atlantic, Pacific and Indian Oceans all hit the record books for warmth last month, according to the U.S. National Centers for Environmental Information. The high temperatures could offer clues on the ferocity of the Atlantic hurricane season, the eruption of wildfires from the Amazon region to Australia, and whether the record heat and severe thunderstorms raking the southern U.S. will continue.

In the Gulf of Mexico, where offshore drilling accounts for about 17% of U.S. oil output, water temperatures were 76.3 degrees Fahrenheit (24.6 Celsius), 1.7 degrees above the long-term average, said Phil Klotzbach at Colorado State University. If Gulf waters stay warm, it could be the fuel that intensifies any storm that comes that way, Klotzbach said.

“The entire tropical ocean is above average,” said Michelle L’Heureux, a forecaster at the U.S. Climate Prediction Center. “And there is a global warming component to that. It is really amazing when you look at all the tropical oceans and see how warm they are.”

Simmering Seas

The deeper the red, the warmer the water in this illustration from NOAA’s National Environmental Satellite, Data and Information Service.


The record warm water in the Gulf of Mexico spilled over into every coastal community along the shoreline with all-time high temperatures on land, said Deke Arndt, chief of the monitoring section at the National Centers for Environmental Information in Asheville, North Carolina. Florida recorded its warmest March on record, and Miami reached 93 degrees Wednesday, a record for the date and 10 degrees above normal, according to the National Weather Service.

While coronavirus has the nation’s attenton right now, global warming continues to be a threat. Sea water “remembers and holds onto heat” better than the atmosphere, Arndt said.

Overall, the five warmest years in the world’s seas, as measured by modern instruments, have occurred over just the last half-dozen or so years. It’s “definitely climate-change related,” said Jennifer Francis, a senior scientist at the Woods Hole Research Center in Massachusetts. “Oceans are absorbing about 90% of the heat trapped by extra greenhouse gases,”

Worldwide, sea temperatures were 1.49 degrees Fahrenheit above average in March. That’s the second highest level recorded since 1880 for the month of March, according to U.S. data. In 2016, temperatures were 1.55 degrees above average.

The first of Colorado State’s 2020 storm reports, led by Klotzbach, forecast this year that eight hurricanes could spin out of the Atlantic with an above-average chance at least one will make landfall in the U.S. during the six-month season starting June 1. The U.S. is set to issue its hurricane forecast next month.

Arctic Systems

The searing global temperatures this year can also be traced back to intense climate systems around the Arctic that bottled up much of that region’s cold, preventing it from spilling south into temperate regions. Combined with global warming, this was a one-two punch for sea temperatures that’s brought them to historic highs.

One of the best-known examples of how oceans drive global weather patterns is the development of the climate system known as El Nino. It occurs when unusually warm waters in the equatorial Pacific interact with the atmosphere to alter weather patterns worldwide. In the Atlantic, for instance, El Ninos can cause severe wind shear that can break up developing storms with the potential to become dangerous hurricanes.

This year, the chance of an El Nino developing are small, and scientists are theorizing one reason could be that climate change is warming all the world’s oceans. El Nino “depends on contrasts, as well as absolute values of sea-surface temperatures,” according to Kevin Trenberth, a scientist at the National Center for Atmospheric Research.

Strengthening Their Fury

Meanwhile, if the Atlantic stays warm through the six-month storm season that starts June 1, the tropical systems can use it as fuel to strengthen their fury.

The oceans also play a role in setting the stage for wildfires. In the case of Australia and the Amazon, really warm areas of the ocean can pull rain away from the land, causing drier conditions and, in extreme cases, drought. Last year, for instance, the Indian Ocean was really warm off Africa, so that is where all the storms went. Australia was left high and dry.

Back in the Atlantic, research by Katia Fernandes, a geosciences professor at the University of Arkansas, has also shown a correlation between sea surface temperatures in the northern tropical Atlantic and drought and wildfires in the Amazon. The warmer the water, the further north rainfall is pulled across South America.

According to Fernandes model, even Atlantic temperatures in March can serve to predict if the Amazon will be dry and susceptible to fires.

For California, the outlook isn’t as clear. Wildfires there depend as much on how well vegetation grows, providing fuel for the flames, as it does on the weather conditions coming off the Pacific.

“Tricky question,” said Mike Anderson, California state climatologist. “Our weather outcomes are influenced by sea-surface temperatures in the Pacific, but it depends on where and when the warm waters appear and how long they persist. In the end we have a highly variable climate that doesn’t map in a statistically convenient way to patterns of sea-surface temperatures.”

‘Megadrought’ emerging in the western US might be worse than any in 1,200 years

Doyle Rice

  • Scientists say that about half of this historic drought can be blamed on man-made global warming.
  • The study covers an area stretching across nine U.S. states from Oregon down to New Mexico.
  • Naturally-occurring western megadroughts have occurred many times before.

Fueled in part by human-caused climate change, a “megadrought” appears to be emerging in the western U.S., a study published Thursday suggests.

In fact, the nearly-20-year drought is almost as bad or worse than any in the past 1,200 years, scientists say.

Megadroughts – defined as intense droughts that last for decades or longer – once plagued the Desert Southwest. Thanks to global warming, an especially fierce one appears to be coming back:

“We now have enough observations of current drought and tree-ring records of past drought to say that we’re on the same trajectory as the worst prehistoric droughts,” said study lead author A. Park Williams, a bioclimatologist at Columbia University, in a statement. This is “a drought bigger than what modern society has seen.”

Scientists say that about half of this historic drought can be blamed on man-made global warming. Some of the impacts today include shrinking reservoirs and worsening wildfire seasons.

What do you want to know? We’re answering coronavirus questions daily. Ask here.

A drought in 2011 parched O.C. Fisher Lake in San Angelo, Texas. Fueled in part by human-caused climate change, a “megadrought” appears to be emerging in the western U.S., a study published Thursday suggests.

Since temperatures are projected to keep rising, it is likely the drought will continue for the near future – or fade briefly only to return, researchers say.

The study covers an area stretching across nine U.S. states from Oregon and Montana down through California, New Mexico and part of northern Mexico.

Daniel Swain, a UCLA climate scientist who wasn’t part of the study, called the research important because it provides evidence “that human-caused climate change transformed what might have otherwise been a moderate long-term drought into a severe event comparable to the ‘megadroughts’ of centuries past.”

What winter?:Earth just had its second-warmest December-February on record

Williams said that “because the background is getting warmer, the dice are increasingly loaded toward longer and more severe droughts. We may get lucky, and natural variability will bring more precipitation for a while.

“But going forward, we’ll need more and more good luck to break out of drought, and less and less bad luck to go back into drought,” he said.

Williams said the region could stay dry for centuries. “That’s not my prediction right now, but it’s possible.”

Naturally occurring western megadroughts have taken place many times before. In fact, most of the USA’s droughts of the past century, even the 1930s Dust Bowl that forced migrations of Oklahomans and others from the Plains, “were exceeded in severity and duration multiple times by droughts during the preceding 2,000 years,” the National Climate Assessment said.

Megadroughts:Will plague the Southwest as climate warms, study says

The difference now, of course, is the western USA is home to more than 70 million people who weren’t here for the previous medieval megadroughts. The implications are far more daunting.

University of Michigan environment dean Jonathan Overpeck, who studies southwestern climate and was not part of the study, calls this drought “the first observed multidecadal megadrought in recorded U.S. history.”

Global warming:2020 expected to be Earth’s warmest year on record, scientists say

To identify past droughts, scientists studied thousands of tree rings to find out how much – or little – rain fell hundreds of years ago. Scientists used historical data in combination with several computer model simulations to reach their conclusions.

One additional worrisome fact from the study was that the 20th century was the wettest century in the entire 1,200-year record. It was during that time that the population boomed in the western U.S., and that has continued.

“The 20th century gave us an overly optimistic view of how much water is potentially available,” said study co-author Benjamin Cook, a NASA climate scientist, in a statement.

“It goes to show that studies like this are not just about ancient history,” he said. “They’re about problems that are already here.”

The study was published Thursday in the peer-reviewed journal Science.

Contributing: The Associated Press

Domino effect could heat up Earth by 5 degrees Celsius — despite Paris climate deal


Even if the Paris agreement is successfully implemented, the planet could still heat up by 5 degrees Celsius, scientists warn. This “hothouse” climate would make parts of the world uninhabitable.

Man walking with dog on cracked, dried earth of Alcora Lake in Spain (picture-alliance/AP Photo/F. Bustamante)

A joint study by international climate scientists from Germany, Sweden, Denmark and Australia presents a bleak prognosis: Even if the goals of the Paris climate agreement are achieved and global warming is limited to maxiumum 2 degrees Celsius (3.6 degrees Fahrenheit) compared to pre-industrial levels, the climate system could still pass a devastating tipping point.

“Human emissions of greenhouse gas are not the sole determinant of temperature on Earth,” said Will Steffen, lead author of the study and climate researcher at the Australian National University and the Swedish research institute Stockholm Resilience Centre.

“Our study suggests that human-induced global warming of 2 degrees Celsius may trigger other Earth system processes, often called ‘feedbacks,’ that can drive further warming — even if we stop emitting greenhouse gases,” he said.

The global average temperature in such a case would in the long term settle between 4 to 5 degrees warmer compared to pre-industrial levels, their study found.

Sea levels would rise 10 to 60 meters (33 to 197 feet), flooding numerous islands and coastal cities such as Venice, New York, Tokyo and Sydney. Such major population centers would have to be abandoned.

Scientists call this a “hothouse Earth” climate scenario.

Read moreThe global heat wave that’s been killing us

Climate domino effect

In the study published Monday in the Proceedings of the National Academy of Sciences (PNAS), the international research team analyzed the complete climate system of a 2-degree warmer world across several models.

Interactions and chain reactions among melting glaciers, thawing permafrost, bacteria in the oceans and weakened carbon sinks were discovered.

Read more: When nature harms itself — five scary climate feedback loops

As a result of these feedback processes and tipping points that lead to abrupt changes in the climate system, forests and permafrost transform themselves from “friends” that store CO2 and other greenhouse gases like methane into “enemies” that uncontrollably release stored emissions into the atmosphere.

As such, the individual feedback processes could potentially snowball, explained Johan Rockström, executive director of the Stockholm Resilience Centre and incoming co-director of the Potsdam Institute for Climate Impact Research (PIK).

Nagaragawa River is swollen due to heavy rain in Nagara City, Gifu Prefecture on July 6, 2018 (picture alliance/AP Images/Y. Shimbun)Extreme weather is one consequence of climate change that is becoming ever more palpable

“These tipping elements can potentially act like a row of dominos. Once one is pushed over, it pushes Earth toward another. It may be very difficult or impossible to stop the whole row of dominoes from tumbling over,” he said.

The Earth would then warm at an accelerating tempo — even if humans stopped producing greenhouse gases entirely.

“Places on Earth will become uninhabitable if ‘hothouse Earth’ becomes the reality,” Rockström added.

Read moreCurrent heat waves are linked to climate change, scientists confirm

Minimizing ‘self-amplifying’ change

While the 2015 Paris Agreement, agreed to by 197 nations, settled on a 2-degree target, it is unclear whether this is enough to avert a climate catastrophe, warned Hans Joachim Schellnhuber, director of PIK and co-author of the study.

“We still do not know if the climate system can be safely ‘parked’ at 2 degrees,” he said.

That is in no way to say that the Paris climate agreement is futile and should be abandoned — as United States President Donald Trump did in June 2017 when he pulled the world’s second-largest greenhouse gas emitter out of the deal.

Man in suit with white combed-over hair holds his tiny fingers close together during a speech (Reuters/K. Lamarque)Trump referred to a tiny temperature increase when he announced US withdrawal from the landmark Paris climate agreement

“Fully implementing the Paris climate agreement by following a path of rapid decarbonization through socio-economic transformation minimizes the risk of triggering self-amplifying climate change,” Jonathan Donges, a PIK researcher and co-author of the study, told DW.

He said that meeting the Paris goals — or even better, aiming for a more ambitious target — remains “the best-known strategy to minimize the risk of triggering self-reinforcing feedbacks in the Earth system that could lead to a hothouse climate state.”

To avoid a potential chain reaction, much more needs to be done than just reducing greenhouse gas emissions, the researchers point out.

Humanity must protect the ecosystem as a whole; create more natural carbon sinks; stop deforestation; consume less; control population growth; invest in technologies that extract CO2 from the atmosphere; and much more. For Donges, such “stewardship” of the Earth will also require “transformed social values.”

Read more:  Earth Overshoot Day: Time for a radical rethink

‘Positive message’

Despite the study’s apocalyptic findings, co-author Katherine Richardson of the University of Copenhagen said they are not trying to present a hopeless doomsday scenario.

“I think our study has an incredible positive message,” she told DW, adding that real action on climate change requires increased awareness of its potential effects.

“What we are really doing is understanding ever better our role in the Earth’s system, and acting accordingly,” Richardson added. “We would be screwed if we didn’t recognize the fact that we are just not doing enough.”


  • Date 06.08.2018
  • Author Katharina Wecker (sb)

The Great Barrier Reef likely just experienced its most widespread bleaching event on record

The Great Barrier Reef just experienced its most widespread bleaching on record

The Great Barrier Reef just experienced its most widespread bleaching on record 01:02

(CNN)Australia’s Great Barrier Reef has likely experienced its most widespread bleaching event on record, according to a US government scientist who monitors the world’s coral reefs.

This marks the third mass bleaching event on the reef in just the last five years.
And scientists say that the rapid warming of the planet due to human emissions of heat-trapping gases are to blame.
On the heels of severe bleaching events in 2016 and 2017 that left half of the coral on the Great Barrier Reef dead, scientists fear this one could be a devastating blow.
“If we do not deal with climate change quickly … we are going to continue to see more severe and more frequent bleaching, and we are going to see the loss of coral reefs in much of the world,” said Dr. C. Mark Eakin, coordinator of the National Oceanic and Atmospheric Administration’s (NOAA) Coral Reef Watch.
close dialog
The mass bleaching conditions were observed by Coral Reef Watch, which uses remote sensing and modeling to predict and monitor for signs of bleaching.
A file photo taken in October 2016 shows coral bleaching on the Great Barrier Reef in Australia. Scientists say that another mass bleaching event has occurred in 2020.

Eakin says that the bleaching in 2016 and 2017 was extremely intense, but severe damage was concentrated in a few hotspots in the northern and central parts of the reef.
Early indications show that this latest event was not as damaging, but that a much larger area of reef experienced at least some bleaching.
Past bleaching events have typically occurred in years with a strong El Niño-Southern Oscillation, a climate phenomena that can increase the odds of a host of extreme weather events around the globe.
El Niño is characterized by warmer waters in the Pacific ocean, which makes bleaching events in the region more likely. But there is no El Niño currently, which Eakin says makes this bleaching that much more surprising — and frightening.
“The upper ocean has absorbed a tremendous amount of heat in recent years, and it has really put coral reefs around the globe much closer to their upper thermal limits.”

Why the Great Barrier Reef is so critical

Coral reefs are some of the most vibrant marine ecosystems on the planet — between a quarter and one-third of all marine species rely on them at some point in their life cycle.
And none is more vital than the Great Barrier Reef.
Covering nearly 133,000 square miles, it is the world’s largest coral reef and is home to more than 1,500 species of fish, 411 species of hard corals and dozens of other species.
It’s also a vital resource to Australia’s economy, contributing more than $5.6 billion annually and supporting tens of thousands of jobs.
The abnormally hot ocean temperatures that led to this year’s bleaching began in February and stretched all the way into early March. As you can see from the animation below, almost the entire reef was under a bleaching alert from mid-February until mid-March.
Temperatures have since cooled and the bleaching has subsided, but scientists in Australia are currently assessing the damage to the reef’s health.
A fuller picture should come into focus in the coming weeks. Though initial reports indicate that this year’s bleaching may not be as severe as in 2016 or 2017, Eakin says it appears few parts of the reef have been spared.
“This time it is not as intense, but it’s much more widespread, so we’re seeing it all over the Great Barrier Reef,” he said.

The future of coral reefs looks grim

Warm ocean temperatures are the main driver of coral bleaching.
Corals turn white as a stress response to warm water temperatures by expelling the algae that grows inside them, which is their main energy source and gives them their color.
Bleaching doesn’t kill coral immediately. But if temperatures remain high, eventually the coral will die, destroying a natural habitat for many species of marine life.
“When they’re bleached, corals are starving, injured and more susceptible to disease, so [recovery] is really a question of how long and intense the heat stress is and how healthy the coral was to begin with,” Eakin said.
For the Great Barrier Reef to fully recover from bleaching that has occurred would take decades, Eakin says.
But because of the massive amounts of heat the world’s oceans have already absorbed, the reef likely won’t have the chance to recover before it bleaches again.
“If it takes decades for a reef to recover … what chance do we have for reefs recovering when events are coming back this fast?” he said.
Though researchers around the world are exploring ways to revive reefs, Eakin says those efforts will not be enough if we don’t address the root cause of their demise — human-caused climate change.
“We have to address climate change if we want to have coral reefs in the future.”

Heat wave melts 20% of snow cover from Antarctic island in days

11 hours ago – Energy & Environment
Images showing Antarctica melting under its hottest days on record

The effects of February’s record heat wave on Eagle Island in Antarctica. Photo: NASA

Antarctica’s Eagle Island now has a side that’s almost ice-free following this month’s searing heat wave in the region, images released by NASA show.

Why it maters: “The warm spell caused widespread melting on nearby glaciers,” NASA said in its report. It’s the third major melt event of the 2019-2020 Southern Hemisphere summer, following warm spells in January and last November, according to the United Nation’s World Meteorological Organization (WMO).

Such persistent warmth was not typical in Antarctica until the 21st century, but it has become more common in recent years.”

— NASA statementDriving the news: The Argentine Antarctic research base Esperanza reported a temperature of 64.9°F on Feb. 9 — indicating a “likely legitimate record,” per the WMO, which is still verifying the statistics.

  • The island “experienced peak melt” — about 1 inch — on the day of the reported heat record, leading to a loss of 4 inches in total within 10 days, NASA said in a statement Friday.
  • “About 20% of seasonal snow accumulation in the region melted in this one event on Eagle Island,” the statement added.

What they’re saying: Mauri Pelto, a glaciologist at Nichols College, who observed the warming event as 0.9 square miles of snowpack became saturated with meltwater, said in NASA’s report: “I haven’t seen melt ponds develop this quickly in Antarctica. You see these kinds of melt events in Alaska and Greenland, but not usually in Antarctica.”

Of note: The event comes after scientists in January found for the first time warm water beneath Antarctica’s “doomsday glacier,” so-called because it’s one of the region’s fastest melting glaciers.

The bottom line: “If you think about this one event in February, it isn’t that significant,” Pelto said. “It’s more significant that these events are coming more frequently.”

Go deeper:

‘Scale of This Failure Has No Precedent’: Scientists Say Hot Ocean ‘Blob’ Killed One Million Seabirds


The lead author called the mass die-off “a red-flag warning about the tremendous impact sustained ocean warming can have on the marine ecosystem.”

Dead common murres

Dead common murres were found on the beach in Cochrane Bay, Prince William Sound on Jan 10, 2016. These birds were part of the large die-off of common murres across the Gulf of Alaska in 2015-2016. (Photo: Sarah Schoen/USGS Alaska Science Center)

On the heels of new research showing that the world’s oceans are rapidly warming, scientists revealed Wednesday that a huge patch of hot water in the northeast Pacific Ocean dubbed “the blob” was to blame for killing about one million seabirds.

The peer-reviewed study, published in the journal PLOS ONE, was conducted by a team of researchers at federal and state agencies, conservation groups, and universities. They tied the mass die-off to “the blob,” a marine heatwave that began forming in 2013 and grew more intense in 2015 because of the weather phenomenon known as El Niño.

“About 62,000 dead or dying common murres (Uria aalge), the trophically dominant fish-eating seabird of the North Pacific, washed ashore between summer 2015 and spring 2016 on beaches from California to Alaska,” the study says. “Most birds were severely emaciated and, so far, no evidence for anything other than starvation was found to explain this mass mortality. Three-quarters of murres were found in the Gulf of Alaska and the remainder along the West Coast.”

Given that previous studies have shown “that only a fraction of birds that die at sea typically wash ashore,” the researchers put the death toll closer to a million.

“The magnitude and scale of this failure has no precedent,” lead author John Piatt, a research biologist at the U.S. Geological Survey’s Alaska Science Center and an affiliate professor at the University of Washington, said in a statement. “It was astonishing and alarming, and a red-flag warning about the tremendous impact sustained ocean warming can have on the marine ecosystem.”

Piatt and study co-author and University of Washington professor Julia Parrish explained that the team believes the blob—which spanned hundreds of miles—limited food supply in the region, leading the birds to starve.

“Think of it as a run on the grocery stores at the same time that the delivery trucks to the stores stopped coming so often,” Parrish said. “We believe that the smoking gun for common murres—beyond the marine heatwave itself—was an ecosystem squeeze: fewer forage fish and smaller prey in general, at the same time that competition from big fish predators like walleye, pollock, and Pacific cod greatly increased.”

Piatt added that “food demands of large commercial groundfish like cod, pollock, halibut, and hake were predicted to increase dramatically with the level of warming observed with the blob, and since they eat many of the same prey as murres, this competition likely compounded the food supply problem for murres, leading to mass mortality events from starvation.”

According to CNN, which reported on the study Thursday:

The blob devastated the murres’ population. With insufficient food, breeding colonies across the entire region had reproductive difficulties for years afterward, the study said. Not only did the population decline dramatically, but the murres couldn’t replenish those numbers.

During the 2015 breeding season, three colonies didn’t produce a single chick. That number went up to 12 colonies in the 2016 season—and in reality it could be even higher, since researchers only monitor a quarter of all colonies.

Thomas Frölicher, a climate scientist at the University of Bern in Switzerland who was not involved in the new study, discussed the blob’s connection to the human-caused planetary emergency with InsideClimate News.

“It was the biggest marine heatwave so far on record,” said Frölicher, who noted that such events have doubled in frequency over the past few decades. “Usually, we are used to heatwaves over land. They are much smaller in size, and they do not last as long. In the ocean, this heatwave lasted two or three years.”

Frölicher warned that “if we follow a high-greenhouse-gas-emissions scenario, these heatwaves will become 50 times more frequent than preindustrial times” by 2100. He said that even if the international community achieves a low-emissions scenario in line with the Paris climate agreement, marine heatwaves would still be 20 times more frequent.

“What that means is that in some regions, they will become permanent heatwaves,” he added. “This gives us some insight into the future.”

The study—which its authors expect to inform research on other mortality events related to marine heatwaves—was published just weeks after University of Washington scientists found what some have called “the blob 2.0” forming in the Pacific. That discovery came as “quite a surprise” to those researchers.

University climatologist Nick Bond told local media that “the original blob was so unusual, and stood above the usually kind of variations in the climate and ocean temperatures, that we thought ‘wow, this is going to be something we won’t see for quite a while.'”