15 September 2021: While evidence mounts of potential uncertainties and flaws within modern climate models, arguably the largest controversy is found within future temperatures themselves on Earth. This is have everything to do with ocean circulation and melting ice at the poles - punctuated by a process deemed the name arctic amplification. Through a deep inquiry into this problem, studies suggest that accelerating ice loss could actually lead to a significant drop in temperature, especially felt in the northern hemisphere.
Arctic Amplification Explained
As the climate of the planet continues to shift, warming is disproportionately more extreme at both the north & south poles. Due to this more intense warming, ice loss at the poles has exceeded original estimates dramatically. This is the process called arctic amplification. In fact, warming is estimated to be over three times that of the global average for temperature increase (1,2). The reasons for why this is happening is still widely controversial.
While many studies suggest that arctic amplification is indeed a factor of anthropogenic warming, i.e. human induced warming (3), contradicting studies suggest that current climate models are oversensitive to the surface albedo feedback loop because models without direct changes to snow or ice cover can also demonstrate the same process of arctic amplification (4). Even in models which agree that anthropogenic warming is the main contributor to the phenomena suggest more inquiry is required to better adjust the models (3). What is agreed upon is the fact that arctic amplification is indeed occurring. The implications of such could actually lead to an outcome much of climate advocates have been missing.
Ocean Circulation & Temperate Northern Climates
Every ecosystem on Earth is effected by ocean circulation. Ocean currents, large bodies within the oceans that flow together, are a vital part of the temperature regulation on the planet, and also transport nutrients, life, gases, and other entities throughout the world (5,6). The movement of ocean circulation is determined by a complex set of climatic factors including atmospheric circulation, solar absorption, and water cycles of the planet (5).
An important piece in terms of the Earth's climate shift is found within thermohaline circulation. While winds drive ocean currents near the surface, temperature and salinity drive currents far below the ocean's surface (7). This creates a "conveyor belt" of sorts within the oceans.
As currents flow within the oceans, the circulation brings cold subsurface flows southward which rises into warm surface flows that head back north. This is the process that brings warm, temperate climates to both western Europe and to North America. Cross-equitorial ocean flow brings that heat directly northward and is fundamentally critical for the continued temperate climates of these northern regions (8,9).
When visualizing this concept, one must consider the latitude of northwestern Europe and North America, including that of the northeastern US and British Isles. For areas that are closer to the northern arctic than the equator, without the warm waters brought into the region by ocean circulation, these areas of the world would be much colder than they are now. In fact, during Earth's previous glacial cycles, these areas of land were covered largely with massive ice sheets and glaciers (10,11,12).
Currently, the Earth is in the Holocene period, a period of interglacial climatic conditions which humanity has enjoyed for the past 12,000 years or so (12). A graphic below shows the ice sheets that existed during the previous glacial period, per Ehlers et al., 2011:
How Global Warming Can Lead to a Cold Climate
It is widely accepted that ocean circulation contributes and regulates the global climate system by redistributing solar heating from the equatorial regions to the poles (13). Thus, a slowdown or shutdown of this process can have very detrimental consequences to northern latitudes, such as North America & Europe. It has been observed through multiple peer-reviewed studies that ocean circulation is indeed slowing down dramatically (14,15,16,17).
In fact, dramatic climatic shifts due to probable changes in ocean circulation have been observed in Earth's geological past - most recently during the Younger Dryas (19), a period in which warming leading out of the previous glacial period suddenly reversed dramatically and plunged temperatures rapidly. This evidence is visible in the Greenland ice core samples that have been extracted (14,18). Even more intriguing, the ice core samples from the Younger Dryas after the cooling event show an even more rapid warming event just 1,200 years after - leading directly into the Holocene period of today (14,18). It is estimated that temperatures abruptly increased by as much as 10 degrees Celsius within only10 years in Greenland - an unprecendented level of global warming (18) that absolutely dwarfs any warming the Earth is showcasing today.
Inquires into current modern climate change have led to multiple publications suggesting that due to arctic amplification causing ice sheets to melt, the observable slowdowns in ocean circulation may also result in rapid temperature decrease (20,21,22,23,24).
In the geologic record, we find substantial evidence that shutdowns of key ocean circulation have cooled Europe by 5 - 10 degrees Celsius (23). This is due to how the ocean circulation occurrs, as discussed in the above section Ocean Circulation & Temperate Northern Climates. As sea ice continues to melt due to arctic amplification, this dumps cold, freshwater into the oceans. As more of this freshwater finds its way into the oceans, this directly effects the density and salinity of the water which can cause major disruptions as the process continues. Once a critical threshold is surpassed, the circulation of the entire system may shut down, leading to warmed oceans waters never reaching the northern hemisphere - most notably that of North America & Europe (23,24).
Should this occurr, without the circulation of warm ocean water around the planet, temperatures could actually fall dramatically as they did during the Younger Dryas period possibly due to similar circumstances as some studies suggest (19). Thus, there is legitimate evidence to suggest that because of the implications of global warming, regardless of the underlying cause, the trends seen today in global temperatures could actually be in for a dramatic reversal in the coming decades if ocean circulation does shut down.
There is still continous, ongoing debate about the legitamcy & accuracy of current climate models, known uncertaintities, and how all these processes may fit together. Previous instances of abrupt climate change, most notably seen during the Younger Dryas period, suggest that the planet has seen much more dramatic change in the past.
Additionally, evidence that counteracts present modelling suggests that ocean circulation, and the subsequent shutdown of this circulation, could have a much more dramatic effect on cooling the planet than previously understood. While many factors associated with modern climate change seem controversial or contradictory, it should be noted that the Earth's climate is one of the most immensely complex systems in which we study and should be treated as such.
Modelling of such a system can in no way be fully accurate as there are numerous factors in which humanity simply does not understand well enough or cannot account for within closed-system experimentation. As climate science continues to improve and more studies are released, it is imperative that all findings are considered and models are continuously changed to demonstrate the most complete understanding of the climate possible - even if the evidence found is contradictory to current beliefs.
This article was originally posted here: https://zlorance.wixsite.com/futurehumanity
Article Citation: Lorance, Z. (2021). Why the Future on Our Planet Could be Dramatically Colder, Not Hotter. Future Humanity Library. September 15, 2021.
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