Cold Snaps and Global Warming (AAAS)

 

Cold Snaps and Global Warming

 

Does a cold snap or cold winter disprove 120 years of climate science and meteorological observations? Read on for the scientific explanation. Contributing scientists at The American Association for the Advancement of Science (AAAS) Sci-line give us the ice-cold facts:

 

“Periodic bouts of extreme cold do not invalidate or weaken the overwhelming scientific evidence that human activities are warming the Earth to dangerous levels. Some evidence even suggests that human-induced global warming may be a driving force behind some winter cold snaps, and that Arctic warming in particular may ultimately increase the frequency and persistence of U.S. winter cold snaps.

 

There is a clear scientific consensus that human activities—primarily the burning of fossil fuels—are causing the Earth to warm, and that the Arctic is warming two to three times as fast as the globe as a whole.

 

This overarching warming trend has been punctuated periodically by episodes of unusually cold winter weather (“cold snaps”)ⁱ in northern temperate regions, including the United States and Eurasia.

 

The vast majority of these cold snaps are not setting new records for coldness. In fact, almost all the temperature records that have been broken in recent decades have involved record-breaking heat. Nonetheless, these cold snaps bring temperatures that are significantly colder than average for the time of year, and they can have serious effects on human health, transportation systems, and energy consumption.

 

Scientists do not know for certain which factors contribute most to periodic cold snaps. Some science suggests that changes in the tropics could be an important factor. Other research has suggested that climate-change-related Arctic warming may be key.

 

Two lines of evidence support the possibility of an Arctic warming connection: direct observations and computer simulations.

Direct Observations:

Scientists have observed that unusually warm temperatures in the northern polar region can destabilize the jet stream—a high-altitude current of wind that circles the polar region and generally carries weather systems from west to east.

 

A destabilized jet stream tends to “wobble” northward and southward as it moves eastward, allowing pools of cold, polar air to penetrate far southward in some regions of the globe (and at the same time bringing warmer air north).

A wobbly jet stream in some parts of the globe can also weaken the polar vortex, a persistent swirl of cold air in the northern polar stratosphere. That in turn can amplify jet stream wobbles, adding to the southward flow of cold air into temperate regions.

In general, when the jet stream meanders, it also travels east more slowly, which can make these cold plunges and (and concomitant northward warm surges into polar regions) more persistent.

Computer Simulations:

When scientists collect meteorological data at relatively high spatial resolution (“high resolution” in this context means pockets of air about a cubic kilometer in volume, or about 400 times the volume of the great pyramid of Giza) and combine this information with the latest understanding of how such volumes of atmosphere interact with each other, the resulting computational simulations predict that as the Arctic warms, we can expect an increase in the frequency and persistence of cold spells in northern temperate regions for some years ahead, albeit fewer broken cold records as global warming continues.”

It is important, when chatting about the weather, to clarify that cold snaps do not undermine the clear evidence of human-caused global warming—or that any single weather event is representative of what is happening with the climate. In the United States, long-term records show that heat waves are increasingly outnumbering cold snaps⁵ and the same is true globally. Between January and early November 2019, for example, 20 nations or territories set all-time heat records and recorded 107 instances of a hottest all-time temperatures for a given month. During the same period there was not a single all-time national cold record set for any month. 2019 was the second warmest in recorded history and 2019 ocean temperatures were warmest ever recorded.

The earth is changing fast and we are ones destroying our climate. We can also fix it. Vote for climate friendly politicians this November. Do not let a cold snap fool you!

Questions? E-mail me at climatelynx@earthlink.net

The American Association of Science (AAAS) was founded in 1848 and is the largest general science organization in the world. It promotes science and, in the recent anti-science years, has focused on defending scientists. Its world-renowned “Science” magazine is published by the AAAS and distributed to its 120,000 members.