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This blog is expressly directed to readers who do not have strong training or backgrounds in science, with the intent of helping them grasp the underpinnings of this important issue. I'm going to present an ongoing series of posts that will develop various aspects of the science of global warming, its causes and possible methods for minimizing its advance and overcoming at least partially its detrimental effects.

Each post will begin with a capsule summary. It will then proceed with captioned sections to amplify and justify the statements and conclusions of the summary. I'll present images and tables where helpful to develop a point, since "a picture is worth a thousand words".

Tuesday, October 9, 2018

IPCC Report on Global Warming Warns of Need for Immediate Action

Limiting Greenhouse Gas Emission Rates and Global Temperature Increases.  A new report on the state of the global climate (see Notes) finds that the world has not made enough progress in minimizing the increase in the long-term global average temperature (referenced to the temperature in pre-industrial times).  Restraining the temperature increase to the necessary extent demands rapid, widespread technological and socioeconomic changes to the world’s energy economy, leading to elimination of greenhouse gas emissions, that are unknown in human history. 

The temperature increase depends, in almost a straight-line fashion, on the accumulated burden of added carbon dioxide (CO2) and other greenhouse gases (GHGs) in the atmosphere: the more GHGs, the higher the global average temperature becomes.  In other words, the world has made insufficient progress in recent years in reducing the use of coal, petroleum and natural gas (fossil fuels, which produce CO2 when burned), so that the atmospheric burden of GHGs continues to increase without meaningful restraint.

The Earth has already warmed by about 1.0°C (1.8°F) above preindustrial levels, causing many harms around the world.  Even without further GHG emissions, the man-made GHG already added will remain in the atmosphere for thousands of years, causing continued long-term climate effects. 

Comparing A Stringent Emission Goal to an Earlier, More Relaxed Goal.  To avoid worse consequences, the countries of the world have to work toward limiting the total increase to 1.5°C (2.7°F) by 2050, which is lower and sooner than the 2.0°C (3.6°
F) originally set as the goal for 2100 in the Paris Agreement.  Some comparisons of differences in projected changes between the two global average temperature increases, given in the report, are summarized here: 
·        Global sea level increases by 2100 would be 10 cm (4 in) less at 1.5°C than at 2.0°C warming.  This is significant because shorelines are most vulnerable not just to increased sea levels in calm weather, but to flooding from higher and stronger storm surges in extreme weather. Regardless, sea levels will continue rising beyond 2100;

·        Global coral reefs would be destroyed because of warmer water temperatures and a more acidic ocean composition, to the extent of 70-90% at 1.5°C, but essentially completely lost at 2.0°C.  This is important because reefs are complete ecosystems that support marine life, ultimately providing much of the seafood that humans consume;

·        Climate-associated effects to human livelihoods and health, food availability, water supplies, and economic growth will be less at 1.5°C than at 2.0°C; and

·        Extremes of climate and weather on land that we are already experiencing around the world (such as more intense rainfall, worse flooding, more intense heat and drought, and worse forest wildfires) would be worse at 2.0°C than at 1.5°C.

Rapid reductions in annual rates of GHG emissions must be undertaken immediately to keep the increase in global average temperature below 1.5°C.  CO2 emission rates must fall by about 45% below 2010 rates by 2030, and reach zero by around 2050.  In contrast, less stringent reductions, about 20% by 2030, not reaching a zero rate until about 2070, would result in an average temperature increase of 2.0°C.

The 1.5°C trajectory requires “rapid and far-reaching transitions in energy, land, urban and infrastructure (including transport and buildings), and industrial systems”.  It also necessitates development of new technologies not yet industrialized to ensure success.

The Greenhouse Effect Was Identified in the 1800s.  The scientific understandings of the greenhouse effect, that CO2 was a greenhouse gas, and that CO2 emissions threatened a worsening greenhouse effect, were identified initially in the nineteenth century.  Charles Keeling was the first to measure the increase in atmospheric CO2 directly, beginning in 1958.   

More recently climate scientists have understood the threats posed by increased GHG emissions and global warming.  For example, Rafe Pomerance began warning as early as 1979, of the impending harm from continued burning of fossil fuels, but his urgings and those of colleagues were ignored (Nathaniel Rich, New York Times Magazine, August 5, 2018). 

IPCC Assessment Reports. The Intergovernmental Panel on Climate Change (IPCC), created under the United Nations (UN) Environment Program and the World Meteorological Organization, has been issuing Assessment Reports presenting scientific data and discussing mitigation and adaptation methodologies beginning in 1990, at intervals of 5-7 years.  The most recent one, the fifth, appeared in three parts over 2013-4. 

The basic conclusions throughout this series have not wavered from those presented in the first Report; the difference over this 24-year period has been rather that a) the number of climate scientists at work, and our understanding of climate science based on their results, have grown dramatically; and b) technologies that permit more extensive and more accurate gathering of data, as well as the power to analyze large bodies of data, has likewise grown significantly.  This has permitted the conclusions and recommendations made in the Fifth Assessment Report to be offered with the highest levels of certainty and confidence, compared to those in the previous versions.  Even so, over this interval the world has not embraced these recommendations as energetically and as early as would have been needed to respond to the climate crisis.


The IPCC Report on Global Warming of 1.5°C summons the world to take extensive, radical and immediate actions to keep the rise in global average temperature below about 1.5°C.  Because of earlier inaction it now foresees the need to reduce global GHG emission rates to zero by 2050.  This will require committed technological development and deployment, and the exercise of political will that reflects scientific necessity and moral responsibility across the globe. 

This transformation must account for three factors in future global energy demand.  First, all power generation, transportation, and heating and cooling of the built environment must be furnished from renewable sources.  Second, raising the living standards of less developed nations imposes additional demands for renewable energy.  And third, the anticipated increase in the world’s population likewise is a major source of increased energy demand.   
Failure to act decisively is likely to result in worsening climatic consequences as time passes whose effects will continue indefinitely.


The IPCC issued this report at the direction of the UN conference that led to the Paris Agreement on the climate in 2015. 

Press Release and Headline Statements of the Intergovernmental Panel on Climate Change for the Summary for Policymakers of the full Report on Global Warming of 1.5°C and

© 2018 Henry Auer