Originally published on

by noreply@blogger.com (Sam Carana) at Arctic News

 Heatwaves and Jet Stream Changes

Heatwaves are increasingly hitting higher latitudes, as illustrated by the forecasts below. The background behind this is that the temperature rise caused by people’s emissions is also causing changes to the jet streams. 

[ click on images to enlarge ]
These changes to the Jet Stream are increasingly creating conditions for heatwaves to strike at very high latitudes, as also illustrated by the images on the right.
The first image on the right shows that surface temperatures as high as 48°C or 118.3°F are forecast in the State of Washington for June 30, 2021, at 01:00 UTC, at a latitude of 46.25°N. At the same time, even higher temperatures are forecast nearby at 1000 hPa level (temperatures as high as 119.4°C or 48.6°C). 
The next two images on the right show what happened to the jet stream. One image shows instantaneous wind power density at 250 hPa, i.e. at an altitude where the jet stream circumnavigates the globe, on June 26, 2021 at 11:00 UTC. The image features two green circles. The top green circle marks a location where the jet stream is quite forceful and reaches a speed of 273 km/h or 170 mph. The bottom green circle marks the same location where the 48°C is forecast on June 30, 2021. This shows how heat has been able to move north from as early as June 26, 2021.

The next image on the right shows the situation on June 30, 2021, 04:00 UTC, illustrating how such a jet stream pattern can remain in place (blocked) for several days (in this case for more than five days). The green circle again marks the same location where the 48°C is forecast (in the top image on the right).

This illustrates how a more wavy jet stream can enable high temperatures to rise to higher latitudes, while holding a pattern in place for several days, thus pushing up temperatures over time in the area.  

As said, these changes in the jet stream that are enabling hot air to rise up to high latitudes are caused by global warming. Accelerating warming in the Arctic is causing the temperature difference between the North Pole and the Equator to narrow, which in turn is making the jet stream more wavy.
The next image on the right shows that a UV index reading as high as 12 (extreme) is forecast for a location at 51.56°N in Washington for June 28, 2021, illustrating that such an extreme level of UV can occur at high latitudes, due to changes in the jet stream.

Accelerated Warming in the Arctic

As the temperature rise is accelerating due to people’s emissions, the acceleration is speeding up more in the Arctic than anywhere else on Earth, due to numerous feedbacks and tipping points, including:
• Albedo loss goes hand in hand with decline of the snow and ice cover. Albedo is a measure of reflectivity of the surface. Albedo is higher as more sunlight is reflected back upward and less energy is getting absorbed at the surface. Albedo decline can occur as snow and ice disappears and the underlying darker soil and rock becomes exposed. Even when the snow and ice cover remains extensive, its reflectivity can decline, due to cracks and holes in the ice, due to formation of melt ponds on top of the ice and due to changes in texture (melting snow and ice reflects less light). Calving of the ice can take place where warmer water can reach it, and such calving can increase as storms strengthen and waves get larger.
• Furthermore, albedo loss can occur as dust, soot and organic compounds that are caused by human activities get deposited on the snow and ice cover, reducing the reflectivity of the surface. Organic compounds and nutrients in meltwater pools can lead to rapid growth of algae, especially at times of high insolation. 
• Latent heat loss. As sea ice gets thinner, ever less ocean heat gets consumed in the process of melting the subsurface ice, to the point where – as long as air temperatures are still low enough – there still is a thin layer of ice at the surface that will still consume some heat below the surface, but that at the same time acts as a seal, preventing heat from the Arctic Ocean to enter the atmosphere.
• Jet Stream changes can further amplify the temperature rise As the temperature difference between the North Pole and the Equator narrows, the Jet Stream becomes more wavy, spreading out widely at times. The changes to the jet stream cause more extreme weather, including heatwaves, forest fires, storms, flooding, etc. This can cause more aerosols to get deposited on the snow and ice cover. It can also speed up the flow of warm water into the Arctic Ocean.

Albedo loss, latent heat loss and changes to the jet stream can dramatically amplify the temperature rise in the Arctic. The temperature of the Arctic Ocean is rising accordingly, while there are a number of developments that specifically speed up the temperature rise of the water of the Arctic Ocean, as discussed below.  

Arctic Ocean heating up

The temperature of the water of the Arctic Ocean is rising, due to a number of events and developments:

                 [ from the insolation page ]
  • Solstice occurred on June 21, 2021. The Arctic is now receiving huge amounts of sunlight (see image on the right, from the insolation page).
  • Sea surface temperatures and temperatures on land are very high in Siberia, Canada and Alaska. Strong winds can spread warm air over the Arctic Ocean.
  • Warm water from rivers is flowing into the Arctic Ocean, carrying further heat into the Arctic Ocean.
  • Warm water from the North Atlantic Ocean and the North Pacific Ocean is flowing into the Arctic Ocean and the amount of ocean heat flowing into the Arctic Ocean is rising steadily each year.
  • Arctic sea ice extent is low for the time of year, but at this stage, there still is a lot of sea ice present (compared to September). The sea ice acts as a seal, preventing ocean heat from entering the atmosphere, resulting in more heat remaining in the Arctic Ocean.
  • As mentioned above, latent heat loss is contributing to the rapid temperature rise in the Arctic. The remaining sea ice acts as a buffer, consuming ocean heat from below. Sea ice is getting thinner each year, so ever less ocean heat can get consumed in the process of melting the sea ice from below. 
  • Changes to the jet stream could also cause strong storms that could dramatically speed up the amount of heat flowing into the Arctic Ocean, as discussed at the Cold freshwater lid on North Atlantic page.


The danger of the temperature rise of the Arctic Ocean

The danger of the temperature rise of the Arctic Ocean is that it can cause destabilization of hydrates at its seafloor, resulting in eruption of huge amounts of methane from hydrates and from free gas underneath the hydrates. 
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In conclusion, changes to the jet stream could cause a huge temperature rise soon, while a 3°C rise could cause humans to go extinct, which is a daunting prospect. Even so, the right thing to do is to help avoid the worst things from happening, through comprehensive and effective action as described in the Climate Plan.
• Insolation
• Cold freshwater lid on North Atlantic

• Most Important Message Ever
https://arctic-news.blogspot.com/2019/07/most-important-message-ever.html

• Could temperatures keep rising?

• Latent Heat