We Can No Longer Delay Minimizing Global Warming/Climate Change

Summary: The Intergovernmental Panel on Climate Change has issued six Assessment Reports over the past three decades.  This blog has presented three posts recently tabulating the effects of warming and the scientific need for reducing greenhouse gas (GHG) emissions that the Reports presented.  The posts focus on the unabated increase in man-made carbon dioxide emissions, the consequent increase in global average temperature, and the inexorable increase in sea level.  For each of these topics, from the beginning the Reports have declared the necessity of minimizing GHG emissions in order to avoid the worst harms and damages from continued warming.  Their warnings have become more urgent, and have been expressed with increasingly unambiguous certainty, as the series of Reports has been issued.

Harms and damages that were only hypothetical in the early Reports have now become commonplace, as sea levels have continued rising; droughts, famine and wildfires have ensued; and more intense, violent climate and weather events have unfolded with freakish intensity.  Even so, policymakers and commercial interests in the private realm have largely ignored these warnings throughout the three decades.  Now is the time energetically to combat further warming globally to make up for three decades of inaction, and to mitigate worsening climate change.  We have no alternative.

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Introduction – The Urgent Need to Minimize Greenhouse Gas (GHG) Emissions.  In three recent posts this blog has summarized aspects of the work of climate scientists over the last 30 years.  The first post is titled “What,Again? Greenhouse Gases Accumulate in the Atmosphere”, the second is “What, Again? Global Warming Continues Unabated”, and the third is “What, Again? Sea Level Will Continue Rising for Centuries”.

Each post summarizes the aspect of climate science reflected in its title, as presented by the U. N.’s Intergovernmental Panel on Climate Change (IPCC) in its series of six Assessment Reports (ARs) issued over the past 31 years up to the (first of three volumes of) the Sixth AR, which appeared in August 2021. Each post included a tabulation of the significant findings, and the suggested future policies, related to the title of the post, as found in each AR.  Significantly, the need to reduce GHG emissions was already expressed in the first AR in 1990 and has been reinforced in each report up to the present time in the Sixth AR.  What has changed is that the strength of the climate science underpinning those conclusions has increased dramatically over time.  The capabilities of gathering data and using more powerful computers to analyze them, and to develop more refined, detailed climate models, have all increased remarkably.

Sadly, the world’s policymakers and industries have not heeded these warnings, but have continued policies and practices leading to unabated, indeed increasing, GHGs emissions throughout these three decades, as shown in the graphic below.

 

 

Direct measurements of atmospheric carbon dioxide (smoothed over the 12 months of a year) taken atop the Mauna Loa volcano in Hawaii beginning in 1958.  The base level prior to the Industrial Revolution is 280 ppm.  Ppm, parts of carbon dioxide in 1 million parts of air. The vertical lines represent the dates of issue of the respective Assessment Reports, and the date of the U. N. Paris Climate Agreement (2015).    Adapted from the carbon dioxide data referenced in the URL at the bottom of the image.

 

In spite of the persistent urgings of the six teams of climate scientists writing the six ARs over three decades, and the agreement reached in Paris among virtually all GHG-emitting nations to begin reducing their emissions, the data in the graphic show no indication of slowing emission rates up to the present time.

Accumulated GHGs are directly responsible for increasing global temperatures.  Many man-made GHGs, including the extra carbon dioxide emitted by burning fossil fuels, are “long-lived” GHGs.  Once emitted into the atmosphere they remain there for hundreds or thousands of years without being destroyed or taken up by the earth system, so that they accumulate to ever higher levels with each passing year.  (A minor fraction of carbon dioxide is absorbed by photosynthesis and by dissolving into oceans and lakes.)  That is why the image above shows that carbon dioxide levels in the atmosphere keep increasing.  The increase from one year to the next represents the net amount added to the atmosphere during that year.  Indeed, the carbon dioxide level increased from about 353 ppm at the time of the First AR to about 416 ppm at the Sixth AR, the present.

Greenhouse gases are called that because they retain a portion of the sun’s energy reaching the earth as heat energy, instead of having that heat be radiated from earth back into outer space.  This leads the temperature of the earth system to increase. The earth system mimics glass greenhouses in retaining heat.  Their glass enclosure captures outgoing heat energy, so that excess heat accumulates inside the greenhouse.  The interiors of cars in the summer sun heat up for the same reason.  Climate modeling of future warming, summarized in recent ARs, shows that the extent of incremental heating of the earth system depends on excess GHGs in the atmosphere (including excess carbon dioxide from fossil fuels) in almost a straight-line fashion.

It is critical to reduce the net annual GHG emission rate to near zero by midcentury, and optimally sooner.  The IPCC released “Global warming of 1.5°C [2.7°F]. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels, V. Masson-Delmotte, and coworkers (eds.)” in 2018.

As emphasized above, the world’s policymakers had ample time to implement GHG reduction technologies in orderly fashion had they heeded climate scientists’ warnings beginning with the First AR.  These urgings have been ignored or rejected in the three decades since, with the result that future weather and climate extremes that scientists warned of at the outset have actually come to pass ferociously in recent years.  In addition, the goal of limiting warming to 2.0°C [3.6°F] above pre-industrial levels, proposed in earlier reports, has been replaced in the Special Report by a more stringent limit, 1.5°C.  Climate action has to be undertaken urgently from this time onward, to make up for the lower revised limit and the time lost in past decades. The IPCC Special Report lays out this case in great detail. 

Conclusion.  Climate scientists have been characterizing the harms and damages they expected from continued unabated burning of fossil fuels, and from other GHG sources, for more than three decades.  Throughout that period policymakers have not acted meaningfully on the scientists’ urgings to reduce use of fossil fuels, nor to reduce other GHG sources.  And now, in recent years those harms and damages are coming to pass around the globe with increasing frequency and severity.

This post presents the urgent, critical case that ambitious, aggressive, effective actions need to be taken starting now to reduce annual GHG emission rates toward zero by midcentury or preferably earlier.  Policymakers can no longer ignore the inexorable action of the physical laws governing global warming.  Industries providing fossil fuels and those using that energy seek to preserve their business models indefinitely.  This is now clearly untenable.  They must change the way they do business or get out of the way.  We all must act internationally, at the national level, at the state and provincial level, and locally; global warming originates across our planet and must be addressed by all nations and citizens of the world in concert. As many have said, “There is no Planet B!”

© 2021 Henry E. Auer