The Technosphere is Melting the Cryosphere

Iceberg in Lilliehöökfjord, Svalbard.  Image credit: Hannes Grobe, CC BY-SA 4.0

David P. Turner / February 1, 2021

Earth system scientists think of planet Earth as composed of multiple interacting spheres.  The cryosphere is a term given to the totality of frozen water on Earth – including snow, ice, glaciers, polar ice caps, sea ice, and permafrost.

The cryosphere has a significant effect on the global climate because snow and ice largely reflect solar radiation, hence cooling the planet.

Unfortunately, the cryosphere is melting.  That loss of snow and ice is providing a significant positive (amplifying) feedback to anthropogenically induced global warming.

Over the course of Earth’s geological history, the cryosphere has existed as everything from nearly 100% coverage of the planetary surface around 700 Mya (million years ago) i.e. snowball Earth (Figure 1) to virtually disappearing during the Hothouse Earth period (about 50 Mya).

Figure 1. Snowball Earth.  The planet was nearly covered in snow and ice around 700 million years ago.  Image Credit: NASA.

The multiple glacial-interglacial cycles over the last several million years were initiated by changes in sun/earth geometry (the Milankovitch cycles), but strengthened by changes in snow/ice reflectance along with changes in greenhouse gas concentrations.

Figure 2.  Ice cover (black) shifted markedly between the glacial and interglacial periods over the last 3 million years.  Image credit:  Hannes Grobe CC Attribution 3.0

The culprit in the current melting of the cryosphere is something new to the Earth system – the technosphere.  This recently evolved sphere consists of the totality of the human enterprise on Earth, including its myriad physical objects and material flows.

By way of fossil fuel combustion, the technosphere is driving up the concentrations of greenhouse gases in the atmosphere and correspondingly, warming the global climate.  That new heat is causing reduced snow cover, receding glaciers, melting of ice caps, and loss of sea iceBy various anthropogenically driven mechanisms, the cryosphere is also said to be “darkening” and hence melting quicker because more solar radiation is absorbed.

Projections by Earth system models of cryosphere condition over the next decades, centuries, and millennia suggest it will significantly wane if not disappear.

Besides the positive feedback to climate change by way of reflectance effects (and release of greenhouse gases from permafrost melting), the diminishment of the cryosphere will have profound impacts on the technosphere.

  1.  The circulation of water through the hydrosphere on land is regulated in many cases by accumulation of snow and ice on mountains.  That water is subsequently released throughout the year, thus providing stable stream flows for downstream irrigated agriculture and urban use. 
  2. The melting of glaciers and the polar ice caps will drive up sea level.  If all such ice is melted (over the course of hundreds to thousands of years), sea level is projected to rise 68 m.  The magnitude of sea level rise projected over the next 100 years for intermediate emissions scenarios is on the order of one meter.
  3. It remains controversial, but reduction of snow and ice cover may alter the behavior of the jet stream and could induce more extreme weather events in mid- to high latitudes of the northern hemisphere.

Efforts to reduce greenhouse gas emissions will certainly slow the erosion of the cryosphere and should be made.  The precautionary principle suggests we avoid passing tipping points associated with melting of the Greenland ice cap and the Antarctic ice cap.  However, the momentum of environmental change is strongly in that direction.

Once these ice caps are gone, there is a hysteresis effect such that the ice does not return with a simple reversion to the current climate (e.g. by an engineered drawdown of the CO2 concentration).

The planet is headed towards a warmer, largely ice free, condition.  The biosphere has been there before.  The technosphere has not.  Humanity will be challenged to develop adequate adaptive strategies.

Recommended Video: What is the Cryosphere │How it Affects Climate Change

Peak Carbon Dioxide Emissions and Peak Carbon Dioxide Concentration

David P. Turner / December 2, 2020

A remarkable speculation is now circulating in the cybersphere to the effect that global emissions of carbon dioxide (CO2) from fossil fuel combustion may have peaked in 2019.  Considering that recent formal projections generally indicate increasing emissions through 2030 or longer, this assertion is striking.  It matters because CO2 emissions determine the growth in the atmospheric CO2 concentration, which in turn influences the magnitude of global warming.

The atmospheric CO2 concentration is currently 415 ppm (up from a preindustrial value of around 280 ppm) and is rising at a rate of 2-3 ppm per year.  The consensus among climate scientists is that rapid greenhouse-gas-driven climate change will be harmful to the human enterprise on Earth.  It would be good news indeed if CO2 emissions were on the way down.

Estimates for annual global CO2 emissions are produced by assembling data on consumption of coal, oil, and natural gas, as well as data on production of cement, which also releases CO2 (the sum is termed Fossil Fuel & Industry emissions).  Deforestation is another significant anthropogenic source of CO2, but it is not considered in this blog post except to say that reducing deforestation will further reduce total CO2 emissions.

The suggestion that we are passing peak fossil fuel emissions is based on several observations.

1.  The rate of increase in global emissions has been low in recent years, averaging less than 1% per year for 2010-2018.  CO2 emissions are falling in the US and the EU, and the annual rate of increase in emissions is declining in India

Covid-19 related reductions in global fossil fuel consumption for 2020 will be 7% or more.  Emissions will likely rebound to some degree as the pandemic recedes but perhaps not fully.

2.  Peak global coal use likely occurred in 2013.  Aging coal powered electricity plants in the U.S. are often replaced with plants powered by natural gas (more efficient that coal) or renewable energy.  Some coal plants are being prematurely retired.  A gradual phase out in global coal consumption will be driven by the price advantage of renewable energy, impacts of coal emissions on human health, and the reluctance of insurance companies to cover new coal power plant construction.

3.  Peak oil use may have occurred in 2019.  Global demand in 2020 will fall about 10% because of Covid-19.  Structural changes such as reduced commuting and business-related flying mean that some of the demand reductions will be persistent.  Vehicles powered by electricity and hydrogen rather than gasoline are on the ascendancy, sparked in part by governmental mandates to phase in zero emissions vehicles.

4.  Even a near term peak in natural gas consumption is being discussed.  Again, the price advantage of renewable sources will increasingly weigh against fossil-fuel-based power plants.  Ramped up production of renewable natural gas could substitute for fossil natural gas in some applications.

Surprisingly, it appears likely that a long-term decline in total fossil fuel use will be driven more by lack of demand than lack of supply.

Emissions from cement manufacturing are still climbing and amount to about 4% of total fossil fuel emissions.  However, a recent study suggests that the CO2 uptake from slow weathering of aging cement around the world is providing a large offset (more than half) to current cement manufacturing emissions.  Innovative uses of wood and geopolymers can potentially replace cement in many construction applications.

The election of Biden to the U.S. presidency is also relevant.  Biden’s leadership will return the U.S. (largest cumulative CO2 emissions on the planet) to the international fold with respect to climate change mitigation.  President Xi Jinping of China (largest CO2 emitter on the planet) has also displayed leadership (in words if not deeds) on the climate change issue.  A revitalized collaboration between the U.S. and China on climate change mitigation could push the needle on global emissions reduction.

Currently about half of fossil fuel CO2 emissions remain in the atmosphere, with the remainder sequestered on the land (e.g. in vegetation and soil) and in the ocean.  Once fossil fuel emissions begin decreasing and fall by half − and assuming the net effect of increasing CO2 and climate warming is still substantial carbon uptake by the land and ocean − the atmospheric CO2 concentration will peak and begin to decrease.  The year of peak CO2 concentration could be as early as 2040 (see carbon cycle projection tool below).

There is of course plenty that might go wrong.  The net effect on the land and ocean sequestration just referred to could be a decline in carbon uptake.  On land, carbon sources such as permafrost melting and forest fires will be stimulated by climate warming.  In the ocean, warming will intensify stratification, thereby reducing carbon removal to the ocean interior. 

On the other hand, land sequestration is increasing now and could continue to do so in response to CO2 enhancement of photosynthesis and plant water use efficiency.  Policy driven increases in the land carbon sink (e.g. more reforestation and afforestation) are also possible.  The ocean carbon sink is likewise increasing now, continuing an upward trend over the last 20 years.

Whatever specific years do turn out to be peak CO2 emissions and peak CO2 concentration, they will be remembered as historic hallmarks in humanity’s effort to address an existential threat of its own making.

Recommended:  Interactive CO2 Emissions and Concentration Projection Tool.

Earth Day 2020

Earth Day 2020 and Global Solidarity

David P. Turner / April 19, 2020

Earth Day in 2020 is the 50th Anniversary for this annual gathering of our global tribe.  Historically, it has been an opportunity to note declines in environmental quality and to envision a sustainable relationship of humanity to the rest of the Earth system.

This year, in addition to the usual concerns about issues like climate change and ocean acidification, Earth Day is accompanied by concern about the specter of the COVID-19 pandemic.  A glance at the geographic distribution of this virus is the latest reminder that interactions with the biosphere, in this case the microbial component, can link all humans in powerful ways. 

Environmental issues that were on the front burner when Senator Gaylord Nelson initiated Earth Day in 1970 were mostly local − polluted rivers, polluted air, and degraded land cover.  These issues were addressed to a significant degree in the U.S. by passage of the Clean Water Act (1972), the Clean Air Act (1970), and the Endangered Species Act (1973).  These were national level successes inspired by environmental activism.

Awareness of global environmental change in 1970 was only dimly informed by geophysical observations such as the slow rise in the atmospheric CO2 concentration.  But by the 1980s, climate scientists began a drumbeat of testimony to governments and the media that the environmental pollution issue extended to the global scale and might eventually threaten all of humanity. 

The United Nations has functioned as a forum for international deliberations about global environmental change issues, and the signing of the Montreal Protocol on Substances that Deplete the Ozone Layer in 1987 hinted at the possibilities for global solidarity with respect to the environment.

To help matters, economic globalization in the 1990s began uniting the world in new ways.  Huge flows in goods and services across borders fueled a truly global economy.  The level of communication required to support the global economy was based on the rapidly evolving Internet.  It provided the foundation for a global transportation/telecommunications infrastructure that now envelops the planet.

A political backlash to economic and cultural globalization has recently brought to power leaders like Donald Trump (U.S.) and Jair Bolsonaro (Brazil).  Their inclination is much more towards nationalism than towards global solidarity on environmental issues.

However, humanity is indeed united – in fear of climate change and coronavirus pandemics if nothing else.

Each year, the growing incidence of extreme weather events associated with anthropogenic climate change negatively impinges on the quality of life of a vast number of people around the planet.  This year, billions of us are locked down in one form or another to slow the spread of a virus that likely emerged from trafficking in wild animals.  In a mythopoetic sense, it is as if Earth was responding to the depredations imposed upon it by our species.

Philosopher Isabelle Stengers refers to the “intrusion” of Gaia (the Earth system) upon human history.  The message from Gaia is that she is no longer just a background for the infinite expansion of the human enterprise (the technosphere). 

Humanity can reply to Gaia with ad hoc measures like building sea walls for protection from sea level rise.  Or we can get organized and develop a framework for global environmental governance.

There are many impediments to becoming a global “we” that will work collectively on global environmental change issues.  Nevertheless, the incentives for doing so are arriving hard and fast.  The diminishment of the wild animal trade in China in response to COVID-19, and the unintended reduction of greenhouse gas emissions globally associated with efforts to slow the spread of COVID-19, signal that radical change is possible. 

Fitting testaments to an emerging global solidarity about environmental issues would be eradication of commercial exploitation of wild land animals everywhere in the world, and stronger national commitments to reduce greenhouse gas emissions relative to current obligations under the Paris Climate Agreement. 

Both initiatives of course face strong cultural and political headwinds.  But Earth Day, as one of the largest recurring secular celebrations in the world, is an opportunity to think anew.

Recommended audio/video:
One World (Not Three), The Police