Arctic News

Thursday, June 18, 2020

2020 Siberian Heatwave continues

Very high temperatures hit Northern Europe and Eastern Siberia near the Arctic Ocean on June 18, 2020. This is a continuation of the heatwave that hit Siberia in May 2020.

The image below, from an earlier post, shows temperature anomalies that were forecast to be at the high end of the scale over Siberia on May 22, 2020, 06:00 UTC, i.e. 30°C or 54°F higher than 1979-2000. At the same time, cold temperatures were forecast for much of eastern Europe.

What enables such a strong heatwave to develop is that the Jet Stream is getting more wavy as the temperature difference between the North Pole and the Equator is narrowing, causing both hot air to move up into the Arctic (red arrow) and cold air to descend out of the Arctic (blue arrow).

On June 19, 2020, at 03:00 UTC, a temperature of 33.2°C or 91.8°F was recorded in Siberia near the Arctic Ocean (green circle).

The image below shows a temperature forecast of 33.5°C or 92.2°F in Siberia near the Arctic Ocean on June 20, 2020, at 03:00 UTC (green circle).

The image below is a forecast for June 23, 2020, showing how a distorted Jet Stream enables cold air to move down into Russia, while at the same time enabling hot air to move north over Scandinavia and Siberia, near the Arctic Ocean.

The image below is a forecast for June 25, 2020, showing the coast of Siberia near the Arctic Ocean getting hit by temperature anomalies at the top end of scale, i.e. 30°C or 54°F higher than 1979-2000.

The image on the right is an update, showing how wavy the Jet Stream turned out to be on June 25, 2020.

This facilitates hot air getting carried north over Western Europe, East Siberia and through the Bering Strait, while cold air is moving south over the European part of Russia. Blocking patterns that prolong such a situation go hand in hand with a more wavy Jet Stream.

Record High Temperature in Arctic

The image below shows that temperatures in Siberia were as high as 40°C or 104°F at 5 cm above the ground on June 21, 2020, at 3 pm, the Ventusky.com map shows.

This indicates how much the soil of what once was permafrost is heating up. At 2 m above ground level, i.e. the default height for air temperature measurements, it was 30°C or 86°F, as the image below shows. The location marked by the star is at 71°28' North latitude and 142°59' East longitude, and at and altitude of 13 m.

The day before, Verkhoyansk in Siberia reached a temperature of 38°C or 100.4°F on June 20, 2020, a record high for the Arctic. Verkhoyansk is located at 67°55′ North latitude.

Both locations are well north of the Arctic Circle that - at 66°30′ N - constitutes the southern limit of the area within which, for one day or more each year, the Sun does not set (about June 21) or rise (about December 21).

High Ocean Temperatures

The heatwave is heating up the sea surface of the East Siberian Arctic Shelf (ESAS), as illustrated by above image. The ESAS is quite shallow, making that heat can quickly reach the seafloor.

Additionally, the heatwave is heating up rivers that carry large amounts of hot water into the Arctic Ocean.

The image on the right shows sea surface temperatures in the Bering Strait as high as 18.9°C or 66.02°F on June 22, 2020.

The nullschool.net website shows that sea surface temperatures in the Bering Strait were as high as 16.1°C or 60.9°F on June 20, 2020, in the Bering Strait (in Norton Sound, Alaska), i.e. 15.1°C or 27.2°F hotter than 1981-2011.

In summary, the Arctic Ocean is heating up in a number of ways:

- Sea currents are moving hot water from the Pacific Ocean into the Arctic Ocean. Similarly, sea currents are moving hot water from the Atlantic Ocean into the Arctic Ocean.

- The Siberian heatwave is heating up the sea surface of the ESAS.

- The heatwave is heating up rivers that carry large amounts of hot water into the Arctic Ocean.

- Numerous feedbacks can speed up the temperature rise, such as changes to the jet stream that can prolong heatwaves and make them more intense.

The rising temperatures result in record low Arctic sea ice volume, as illustrated by the image on the right and as also discussed in an earlier post.

Heat threatens to destabilize methane hydrates

As discussed in earlier posts such as this one, this heat threatens to destabilize methane hydrates contained in sediments at the seafloor of the Arctic Ocean.

As the panel on the left shows, sea surface temperatures in the Bering Strait were as much as 15.1°C or 27.2°F hotter than 1981-2011 on June 20, 2020 (in Norton Sound, Alaska, at the green circle).

The bathymetry map in the right panel of above image shows how shallow seas in the Arctic Ocean can be. The water over the ESAS is quite shallow, making that the water can warm up very quickly during summer heat peaks and heat can reach the seafloor, which comes with the risk that heat will penetrate cracks in sediments at the seafloor. Melting of ice in such cracks can lead to abrupt destabilization of methane hydrates contained in sediments.

Large abrupt methane releases will quickly deplete the oxygen in shallow waters, making it harder for microbes to break down the methane, while methane rising through waters that are shallow can enter the atmosphere very quickly.

The situation is extremely dangerous, given the vast amounts of methane present in sediments in the ESAS, given the high global warming potential (GWP) of methane following release and given that over the Arctic there is very little hydroxyl in the air to break down the methane.

[ from earlier post ]

Ominously, the MetOp-1 satellite recorded a peak methane level of 2847 parts per billion on the afternoon of June 24, 2020, at 469 mb.

The next day, on the afternoon of June 25, 2020, MetOp-1 recorded a mean methane level of 1903 parts per billion at 293 mb. The 469 mb pressure level on above image corresponds with altitude of 6,041 m or 19,820 feet on the conversion table below. The 293 mb mean on the image below corresponds with a much higher altitude, i.e. 9,318 m or 30,570 feet on the conversion table below.

Methane reaching the Stratosphere

The MetOp satellites typically record the highest annual mean methane level in September. The image below, from an earlier post, shows that on the afternoon of September 30, 2019, the MetOp-1 satellite recorded the highest mean methane level, i.e. 1914 parts per billion, at 293 mb.

Above image shows that methane levels have risen most at higher altitude over the years. As discussed in an earlier post, methane eruptions from the Arctic Ocean can be missed by measuring stations that are located on land and that often take measurements at low altitude, thus missing the methane that rises in plumes from the Arctic Ocean. Since seafloor methane is rising in plumes, it hardly shows up on satellite images at lower altitude either, as the methane is very concentrated inside the area of the plume, while little or no increase in methane levels is taking place outside the plume. Since the plume will cover less than half the area of one pixel, such a plume doesn't show up well at low altitudes on satellite images.

Over the poles, the Troposphere doesn't reach the heights it does over the tropics. At higher altitudes, methane will follow the Tropopause, i.e. the methane will rise in altitude while moving closer to the Equator.

Methane rises from the Arctic Ocean concentrated in plumes, pushing away the aerosols and gases that slow down the rise of methane elsewhere, which enables methane erupting from the Arctic Ocean to rise straight up fast and reach the stratosphere.

The rise of methane at these high altitudes is very worrying. Once methane reaches the stratosphere, it can remain there for a long time. The IPCC in 2013 (AR5) gave methane a lifetime of 12.4 years. The IPCC in 2001 (TAR) gave stratospheric methane a lifetime of 120 years, adding that less than 7% of methane did reach the stratosphere.

Further Feedbacks

Furthermore, the Siberian heatwave is also threatening to trigger forest fires that can cause huge amounts of emissions, including black carbon that can settle on the snow and ice cover, further speeding up its demise and causing albedo changes that result in a lot more heat getting absorbed in the Arctic, instead of getting reflected back into space as was previously the case. This is illustrated by the image below showing forest fires in East Siberia on June 19, 2020.

Finally, more intense forest fires threaten to cause organic carbon compounds to enter the stratosphere and damage the ozone layer, as discussed in an earlier post.

The situation is dire and calls for immediate, comprehensive and effective action as described in the Climate Plan.

Links

• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html

• Very High Greenhouse Gas Levels
https://arctic-news.blogspot.com/2020/05/very-high-greenhouse-gas-levels.html

• April 2020 temperatures very high
https://arctic-news.blogspot.com/2020/05/april-2020-temperatures-very-high.html

• Methane Erupting From Arctic Ocean Seafloor
https://arctic-news.blogspot.com/2017/03/methane-erupting-from-arctic-ocean-seafloor.html

• When Will We Die?
https://arctic-news.blogspot.com/2019/06/when-will-we-die.html

• Could Humans Go Extinct Within Years?
https://arctic-news.blogspot.com/2020/01/could-humans-go-extinct-within-years.html

• Fast Path to Extinction
https://arctic-news.blogspot.com/2020/06/fast-path-to-extinction.html

• Arctic records its hottest temperature ever
https://www.cbsnews.com/news/arctic-records-its-hottest-temperature-ever-2020-06-20/

Sunday, June 14, 2020

Fast Path to Extinction

[ click on images enlarge ]

May 2020 was the hottest May on record, the third monthly record in the year to date, even though there was no El Niño in 2020 (yet). An El Niño event later in 2020, combined with further warming elements, such as loss of the aerosol masking effect due to COVID-19 lockdowns, could trigger a huge temperature rise, as the red trend illustrates. The year 2020 looks set or close to become the hottest on record, as illustrated by the blue trend that points at a continuing rise reaching 3°C by 2026, i.e. likely driving humans into extinction.

The May 2020 ocean temperature anomaly on the Northern Hemisphere was 0.94°C or 1.67°F higher than the 20th century average, the highest May anomaly on record.

The latent heat tipping point threatens to be crossed as ocean temperature anomalies on the Northern Hemisphere reach 1°C above the 20th century average, in turn threatening the methane hydrates tipping point to get crossed, i.e. as ocean temperature anomalies on the Northern Hemisphere become higher than 1.35°C above the 20th century average.

Arctic sea ice is getting very thin and, at this time of year, it is melting rapidly from below, due to the rising temperature of the Arctic Ocean. The sea ice underneath the surface of the Arctic Ocean is disappearing rapidly, due to the influx of warm and salty water from the Atlantic Ocean and the Pacific Ocean.

Sea surface temperature anomalies from the 20th century on the Northern Hemisphere in °C.
Yellow circles are anomalies for the month May, red circles are anomalies for other months.

An earlier analysis indicates that the latent heat tipping point threatens to get crossed as ocean temperature anomalies on the Northern Hemisphere reach 1°C above the 20th century average. As above image indicates, the tipping point was briefly crossed before, but this year it looks set to get crossed irreversibly.

At that point, there will be little or no Arctic sea ice left underneath the sea surface all year long, so the sea ice has lost most of its capacity to act as a buffer to consume further heat arriving from the Atlantic Ocean and the Pacific Ocean.

Arctic sea ice volume has been at record low for almost all of 2020 to date, while 2019 volume was at a record low from October, making that volume has been at record low for almost 8 months straight.

Crossing the latent heat tipping point means that huge amounts of incoming heat will get absorbed by the Arctic Ocean, instead of getting consumed by the melting of sea ice, as was previously the case.

As long as there is sea ice in the water, this sea ice will keep absorbing heat as it melts, so the temperature will not rise at the sea surface.

There is ever less sea ice left underneath the surface to absorb ocean heat, and the amount of energy that used to be absorbed by melting ice is as much as it takes to heat an equivalent mass of water from zero to 80°C.

Meanwhile, global heating continues and more than 90% of global heating is going into oceans.

As discussed in an earlier post, the loss of subsurface sea ice is only one of ten tipping points hitting the Arctic. As the temperature of the oceans keeps rising, more heat will reach sediments at the seafloor of the Arctic Ocean that contain vast amounts of methane, as discussed in this page and this post. The danger is that this heat will destabilize the ice and the hydrates, resulting in huge releases of methane. The methane hydrates tipping point threatens to get crossed as ocean temperature anomalies on the Northern Hemisphere become higher than 1.35°C above the 20th century average, which threatens to occur early next year.

The danger is illustrated by the image below, posted in February 2019 and showing a potential rise of 18°C or 32.4°F from 1750 by the year 2026.

Indeed, a rise of 18°C could eventuate by 2026, as illustrated by the image below and as discussed in an earlier post.

Tuesday, May 19, 2020

An uncharted 21-23rd centuries’ climate territory

by Andrew Glikson

Precis

21–23ʳᵈ centuries’ transient ocean cooling events (stadials), triggered by ice melt flow from the Greenland and Antarctic ice sheets into the adjacent oceans, herald conditions analogous in part to those of the Younger Dryas stadial (12.9–11.7 kyr) which succeeded the pre-Holocene Bölling-Allerod thermal maximum. The subsequent Younger Dryas cooling event was associated with penetration of polar air masses and ocean currents, leading to storminess, analogous to recent breaching of the weakened polar jet stream boundary, ensuing in major snow storms in North America and Europe and cooling of parts of the North Atlantic Ocean and parts of the circum-Antarctic ocean triggered by the flow of ice melt water from melting glaciers.

21–23ʳᵈ Centuries’ Stadial freeze events

IPCC climate change projections for 2100-2300 portray linear to curved temperature progressions (SPM-5). By contrast, examination of transient cooling events (stadials) which ensued from the flow of ice melt water into the oceans during peak interglacial warming events portray abrupt temperature variations (Fig. 1). The current flow of ice melt water from Greenland and Antarctica ensuing from Anthropogenic global warming is leading to regional ocean cooling in the North Atlantic near Greenland and around Antarctica (Rahmstorf et al, 2015; Hansen et al. (2016); Bronselaer et al. 2018; Purkey et al. 2018; Vernet et al. 2019) (Fig. 2). The incipient developments of ice melt-derived cold water pools in ocean regions adjacent to the large ice sheets imply portents of future stadial events such as, inexplicably, are not indicated by the predominantly linear IPCC climate projections for the 21–23ʳᵈ centuries (IPCC AR5). By contrast, as modelled by Hansen et al. (2016) and Bronselaer et al. (2018), under high greenhouse gas and temperature rise trajectories (RCP8.5), the ice meltwater flow into the oceans from the Antarctic and Greenland ice sheets would lead to cooling of large regions of the ocean, with major consequences for future climate projections. This would include the build-up of large cool ocean pools in the North Atlantic south of Greenland (Rahmstorf et al, 2015) (Fig. 2A) and around Antarctica (Fig. 2B).

Depending on different greenhouse emission scenarios (IPCC 2019; van Vuren et. al. (2011), including the CO₂ forcing-equivalents of methane (CH4) and nitrous oxide (N2O), the total CO₂–equivalent rise amounts to 496 ppm (NOAA, 2019), close to transcending the melting points of large parts of the Greenland and Antarctica ice sheets. Given the extreme rise in temperature since the mid-20th Century, where the oceans heat contents is rising, an incipient cooling of near-surface sub-Greenland and sub-Antarctic ocean regions raises the question whether incipient stadial events, perhaps analogous to the Younger Dryas stadial (Johnsen et al. 1972; Severinghaus et al. 1998), may be developing?

Interglacials, late Pleistocene and early Holocene stadial events

Stadial effects in the late Pleistocene record follow peak interglacial temperatures (Cortese et al., 2007) (Fig. 1). During the last glacial termination (LGT) stadial effects included the Oldest Dryas at ~16 kyr, the Older Dryas at ~14 kyr and the Younger Dryas at 12.9 - 11.7 kyr (Fig. 3), the latter with sharp transitions as short as 1 to 3 years (Steffensen et al., 2008), signifying a return to glacial conditions. A yet younger stadial event is represented at ~8.4 - 8.2 kyr when large-scale melting of the Laurentian ice sheet ensued in the discharge of cold water via Lake Agasiz (Matero et al. 2017; Lewis et al., 2012) into the North Atlantic Ocean. The Laurentian cooling involved temperature and CO₂ decline of ~25 ppm over ~300 years (Fig. 3B and C) and a decline of the North Atlantic Thermohaline circulation.

Figure 1. (a) Evolution of sea surface temperatures in 5 glacial-interglacial transitions recorded in
ODP 1089 at the sub-Antarctic Atlantic Ocean. Grey lines – δ¹⁸O measured on Cibicidoides plankton;
Black lines – sea surface temperature. Marine isotope stage numbers are indicated on top of diagrams.
Note the stadial following interglacial peak temperatures (Cortese et al. 2007).
(b) The last glacial maximum and the last glacial termination.
Olds – Oldest Dryas; Old – Older Dryas; Yd – Younger Dryas.

Greenland and Antarctica ice melt events

Oxygen isotopes (¹⁸O/¹⁹O), argon isotopes (⁴⁰Ar/³⁹Ar) and nitrogen isotopes (¹⁵N/¹⁴N) studies of Greenland ice cores (Johnsen et al. 1972; Severinghaus et al. 1998) indicate a rise in temperature to -36°C, followed by a sharp fall to -50°C (Table 1; Fig. 3A). At lower latitudes the mean temperatures drop about -2°C and 6°C (Table 1). In the southern hemisphere temperatures dropped by about -2°C in lower latitudes and about -8°C at high latitudes and (Fig. 4; Table 1) Shakun and Carlson, 2010).

Figure 2. A. The cold ocean region south of Greenland visible on NASA's 2015 global mean temperatures, the warmest year on record since 1880. Colors indicate temperature anomalies (NASA/NOAA; 20 January 2016);
B. Circum-Antarctic summer surface temperatures, showing the large Weddell Sea cold anomaly
and a seasonal warming anomaly in the Ross Sea due to upwelling of warm salty water.

Table 1.
Cooling intervals (stadial events) during late Pleistocene and early Holocene interglacial phases.

Isotopic Stage	Agemax kyr	Agemin kyr	∆tkyr	TmaxoC SST	TminoC SST	∆ToC
Stadial MIS 11-12 Ref. A	434 kyr	424 kyr	10 kyr	19.3oC SST	13.4oC SST	-5.9oC
Stadial MIS 9-10 Ref. B	346 kyr	331 kyr	5 kyr	19oC SST	13oC SST	-6oC
Stadial MIS 7-8 Ref. C	243.5 kyr	241.5 kyr	2.0 kyr	18oC SST	15.5oC SST	-2.5oC
Stadial MIS 5-6 Ref. D	136 kyr	130 kyr	6.0 kyr	19oC SST	15.2oC SST	-3.8oC
Younger Dryas stadial ice core In Greenland MIS 1-2-3 Ref. E	12.86 kyr	11.64 kyr	1.22 kyr	-36oC Greenland ice core	-50oC Greenland ice core	-14±3oC Greenland ice core
Younger Dryas at lower and mid-latitudes of the NH (Fig. 4) Ref. F	12.86 kyr	11.64 kyr	1.22 kyr			-2 to -6oC
8.3 kyr Stadial Ref. G	8.45 kyr	8.1 kyr	0.35 kyr	-28oC CO₂=310 ppm	-30oC CO₂=275 ppm	-2.0oC

Figure 3. A. Temperature variations during the late Pleistocene to the beginning of the Younger Dryas stadial
and the onset of the Holocene, determined as proxy temperatures from ice cores of the central Greenland ice sheet;
B. The ~8.2 kyr stadial event in a coupled climate model (Wiersma et al. 2011);
C. Reconstructed CO₂ concentrations for the interval between ~8,700 and ~6,800 B.P.
based on CO₂ extracted from air in Antarctic ice of Taylor Dome (Wagner et al. 2002).

Figure 4. Magnitude of late Holocene glacial-interglacial temperature changes in relation to latitude.
Black squares are the Northern Hemisphere (NH), gray circles the
Southern Hemisphere (SH) (Shakun and Carlson, 2010)

Antarctic ice melt dynamics

Circum-Antarctic surface air temperatures, precipitation and sea-ice cover (Bronselaer et al. (2018), including testing the effects of ice-shelf melting, identifies penetration of relatively warm circumpolar deep water below 400 m into the grounding line underlying the ice shelf (Figs 5, 6A). The flow of ice melt water into the adjacent ocean forms an upper cold water layer away from ice shelf areas (Figure 6B). These authors indicate the flow of ice-sheet meltwater results in a decrease of global atmospheric warming, shifts rainfall northwards, and increases sea-ice area and offshore subsurface Antarctic Ocean temperatures.

Figure 5. Schematic circulation and water masses in the Antarctic continental shelf (Purkey et al., 2018) displaying layering of the sub-Antarctic into a cold ice melt-derived upper layer (-2.1°C) overlying a warmer water zone (-1.0°C) which acts as a source of modified warm water penetrating the grounding zone of the glacial ice shelf.

Figure 6. A. The grounding zone where the bedrock-grounded ice sheet transits to a freely floating ice shelf over several km. The floating ice shelf changes in elevation in response to tides, atmospheric air pressure and oceanic processes. B. The Helium (∆He% - Temperature proxy) profile in the Amundsen Sea. The black dots indicate the sampling depth, and the grey dotted lines indicate the isopycnal (density) lines. The shelf break is located at about ∼280 km).

In turn warmer salty water from the circum-polar deep water (CDW) from the circum-Antarctic current can penetrate below the cold off-shelf layer, as is the case in the Weddell Sea Gyre (Figures 5, 6 and 7).

Figure 7. Penetration of relatively warm and salty water from the circum-Antarctic current below the cold off-shelf surface layer of the Weddell Sea Gyre.

Global stadial cooling events

Hansen et al. (2016) suggest that, depending on ice melt rates of the polar ice sheets, transient cooling events (stadials) can be expected to develop at times dependent on the rates of ice melt (Fig. 8). The model is consistent with a slowdown of the Atlantic Meridional Ocean Circulation (AMOC) (Weaver et al. 2012) and the exceptional growth of a cold water region southeast of Greenland, (Rahmstorf et al, 2015). These authors suggest stadial cooling of about -2°C lasting for several decades (Fig. 8B), depending on ice melt rates, can affect temperatures in Europe and North America.

Figure 8. A. Model surface air temperature (°C) change in 2055–2060 relative to 1880–1920 for modified forcings.
B. Surface air temperature (°C) relative to 1880–1920 for several ice melt scenarios.

According to Bronselaer et al. (2018) temporal evolution of the global-mean surface-air temperature (SAT) shows meltwater-induced cooling translates to a reduced rate of global warming (Fig. 9), with a maximum divergence between standard models and models which include the effects of meltwater induced cooling of 0.38 ± 0.02°C in 2055. The SAT response shows the effect of ice meltwater becomes weaker as the ocean becomes more stratified as a result of both moderate to deep level warming and cooling/freshening at the surface (Fig. 6B). As stated by the authors “We demonstrate that the inclusion in the model of ice-sheet meltwater reduces global atmospheric warming, shifts rainfall northwards, and increases sea-ice area”, and “Antarctic meltwater is therefore an important agent of climate change with global impact, and should be taken into account in future climate simulations and climate policy.”

Figure 9. A. 2080–2100 meltwater-induced sea-air temperature anomaly relative to the standard RCP8.5 ensemble. Hatching indicates where the anomalies are not significant at the 95% level.
B. Time series of the global-mean sea-air temperature (SAT) anomaly relative to the 1950–1970 mean.
Orange shows the standard ensemble and blue shows the meltwater-included ensemble. Solid lines show ensemble means, the dark shading shows the 95% uncertainty in the mean and the light shading shows the full ensemble spread of 20-year means. The green bar indicates the period when the standard and meltwater ensembles diverge.

Based on the paleoclimate record, global warming and rates of melting and surface cooling around parts of Antarctica and the North Atlantic (Fig. 2) would determine the future climate of large parts of Earth. Transient stadial cooling events, inherently associated with meters-scale sea level rise, would result in increased temperature polarities between subpolar and tropical latitudes, leading to storminess where polar-derived and tropical-derived air masses and ocean currents collide. Regional to global stadial cooing would, in principle, last as long as ice sheets remain. Once the large ice sheets are exhausted a transition takes place toward tropical Miocene-like and even Eocene-like conditions about 4 to 5 degrees Celsius warmer than Holocene climate conditions, which allowed agriculture and thereby civilization to emerge.

Andrew Glikson

Dr Andrew Glikson
Earth and Paleo-climate scientist
ANU Climate Science Institute
ANU Planetary Science Institute
Canberra, Australia

Books:
The Asteroid Impact Connection of Planetary Evolution
http://www.springer.com/gp/book/9789400763272
The Archaean: Geological and Geochemical Windows into the Early Earth
http://www.springer.com/gp/book/9783319079073
Climate, Fire and Human Evolution: The Deep Time Dimensions of the Anthropocene
http://www.springer.com/gp/book/9783319225111
The Plutocene: Blueprints for a Post-Anthropocene Greenhouse Earth
http://www.springer.com/gp/book/9783319572369
Evolution of the Atmosphere, Fire and the Anthropocene Climate Event Horizon
http://www.springer.com/gp/book/9789400773318
From Stars to Brains: Milestones in the Planetary Evolution of Life and Intelligence
https://www.springer.com/us/book/9783030106027
Asteroids Impacts, Crustal Evolution and Related Mineral Systems with Special Reference to Australia
http://www.springer.com/us/book/9783319745442

Friday, May 15, 2020

April 2020 temperatures very high

Temperatures in April 2020 were very high. The image below shows very high temperature anomalies over the Arctic.

The combination image below shows in the left panel the same very high anomalies, compared to 1951-19180. Comparisons with earlier periods can be complicated, due to a lack of data over polar regions, as illustrated by the image in the right panel that shows grey colors over polar regions, indicating missing data.

Temperatures in polar regions have risen strongly, so leaving out the rise in polar regions would downplay the global temperature rise since pre-industrial. A recent analysis of the temperature rise therefore uses an adjustment of 0.1°C to compensate for missing data.

Ocean heat on the Northern Hemisphere is driving up temperatures in the Arctic.

The image below shows that the April ocean temperature anomaly in the Gulf of Mexico in 2020 was 1.71°C or 3.08°F higher than the 1910-2000 average, and the highest on record.

Temperatures in the Gulf of Mexico were already very high in March 2020, as illustrated by the image on the right, from an earlier post.

There are three reasons why this is very worrying:

1. The Gulf Stream carries ever hotter water along the path of the Gulf Stream toward the Arctic Ocean, thus speeding up the temperature rise of the Arctic Ocean.

2. As the Gulf Stream slows down, due to increased meltwater, more heat is accumulating along the path toward the Arctic Ocean, threatening to invade the Arctic Ocean in abrupt strong bursts, powered by stronger winds over the North Atlantic, as discussed in earlier posts such as this one.

3. There's also the danger that a freshwater lid is extending at the surface of the North Atlantic that threatens to cause more ocean heat to move underneath the sea surface toward the Arctic Ocean, as discussed in earlier posts, such as at this one and this one.

As the image below shows, the April ocean temperature anomaly on the Northern Hemisphere in 2020 was 0.97°C or 1.75°F higher than the 20th century average, and the highest on record.

Arctic sea ice is getting very thin and, at this time of year, it is melting rapidly from below, due to rising temperature of the Arctic Ocean.

Arctic sea ice volume has been at record low since the start of 2020, while 2019 volume was at a record low from October, making that volume has now been at record low for almost 8 months straight.

An earlier analysis indicates that there is a tipping point at 1°C at which the sea ice underneath the surface of the Arctic Ocean disappears, which means that there will be little or no buffer left to consume the influx of ever warmer and salty water from the Atlantic Ocean and Pacific Ocean.

As long as there is sea ice in the water, this sea ice will keep absorbing heat as it melts, so the temperature will not rise at the sea surface.

But there is ever less sea ice volume left to absorb ocean heat, and the amount of energy absorbed by melting ice is as much as it takes to heat an equivalent mass of water from zero to 80°C.

Meanwhile, global heating continues and more than 90% of global heating is going into oceans.

As the temperature of the oceans keeps rising, more heat will reach sediments at the seafloor of the Arctic Ocean that contain vast amounts of methane, as discussed in this page and this post. The danger is that this heat will destabilize the ice and the hydrates, resulting in huge releases of methane.