Hazardous Climate Change Effects in a Conservative IPCC Report

Hazardous Climate Change Effects in a Conservative IPCC Report

The earth’s mean temperature has risen one degree Centigrade or 1.8 degrees Fahrenheit from the pre-industrial age in 1750.  The European and Paris Agreement goal has been only a total 1.5 degrees C rise, or only 0.5 degrees C more than at present, which is only 0.9 degrees F more.  The IPCC was charged to investigate how to get there, and what the climate consequences would be.  Since that is very hard to achieve, the IPCC also investigated another 1 degree C or 1.8 degree F rise.  Analyses have improved since the last IPCC report, and most older analyses had focused on 2100, when a total 4 degree C or so rise was predicted if there was no action.  Even meeting the current Paris commitments by countries will lead to a total 3 degree C rise by 2100.

The major news sources have all described some aspects of the 751 page report, but we will later try to add more in depth aspects from it, over some articles.  We start with a collage of the news reports.

The damage of not reaching the Paris goals according to the IPCC would cost $54 trillion at 1.5 degrees C, and $69 trillion at 2 degrees C.  At 1.5 degrees C, the US economy will decrease 4% in GDP.  At 2.0 degrees C, the decrease will be 4.5% in GDP.

According to a an earlier Stanford Report, the damages would be less at $30 trillion in worldwide damage at 2 degrees C, and $6 trillion in US economic damage. 

As we have described in other articles, Climate Action cities and businesses representing $6 trillion of the US economy are working toward the Paris goals.

In order to stop at the 1.5 degree C goal, there has to be a 45% reduction in CO2 emissions from 2010 by 2030.  After that, there has to be an almost 100% drop by 2050.  The US has dropped 14% in CO2 emissions from 2005.  Coal use, which currently provides 40% of world electricity, will have to drop to 1-7% by 2050.  Wind and solar, which create 20% of electricity today, will have to increase to as much as 67%.

The advantage of the 1.5 degree over the 2.0 degree C goals is that 420 million fewer people will be exposed to extreme heat waves, and 65 million fewer people will be exposed to exceptional heat waves.  In India and Pakistan, with the larger temperature increase, deadly heat waves will strike almost yearly.  With 1.5 degrees C, half as many people will suffer from lack of water.  There will also be fewer downpours and droughts.  Fewer people will suffer from lack of food.  Eventually, coral loss will go from 70-90% to >99% between the scenarios. 

By 2100, sea level rise with 1.5 degrees C will be about a foot to two and a half feet, but with 2.0 degree C rise, will be 4 inches more.  That extra rise could expose 10 million more people to sea level rise.  Sea level rise will continue beyond 2100 in either scenario.  The rise to 1.5 degrees C may occur by 2040, and 50 million people will be exposed to increased coastal flooding.  This will occur in the United States, Bangladesh, China, Egypt, India, Indonesia, Japan, the Philippines, and Vietnam.

The sea level rise to 2100 will be 10% from Antarctica, 17% from Greenland, 25% from glaciers, and 40% from thermal expansion.  A tipping point in marine ice sheet melting in Antarctica, or Greenland Ice melting may occur between the two temperature increase scenarios.  That could result in meters of sea level rise over hundreds to thousands of years.  West Antarctica marine ice sheets rest on underwater land, so their melting increases sea level, and allows the glaciers behind them to flow faster to the sea.

All bad ocean effects of warming will increase with 2 degrees C over 1.5 degrees C, including ocean acidification, temperature increases, and effects on biodiversity, fisheries, and ecosystems.  More permafrost melting will occur.  An ice-free Arctic summer will increase from once per century to once per decade with the higher temperature scenario.

People subjected to risk and poverty could increase by several hundred million between the two scenarios.

While the temperature rise stated is always the global sea level average, that is determined by 71% of surface being over the ocean.  The warming over land is always higher.  In the Central North-America, the peak warming for the 1.5 degree C case is 2.65 degrees C for 2055-2066, dropping to 2.31 degrees C by 2100.  For the 2 degrees C case, the peak is about 2082-2090, when the Central North-America temperature is 3.18 degrees C, falling to 3.12 degrees C at 2100.  The 2.65 degrees C is an increase of 1.65 degrees C or 3.0 degrees F above today.  The 3.18 degrees C is an increase of 2.18 degrees C or 3.9 degrees F above today.

The IPCC has a short press report.  Then there is a 33 page Summary for Policy Makers, which includes, with every statement, added likelihood ratings, and references to the full report.  Finally, the full report of 751 pages is in five chapters with supplemental material.  Out of all of that, they only make five multiple graph figures available for posting into blogs.  The report was written and edited by 91 scientists from 40 countries, based on 6,000 studies. 

About Dennis SILVERMAN

I am a retired Professor of Physics and Astronomy at U C Irvine. For a decade I have been active in learning about energy and the environment, and in lecturing and attending classes at the Osher Lifelong Learning Institute (OLLI) at UC Irvine.
This entry was posted in Clean Energy, Climate Change, Climate Science, Coal, Coastal Flooding, Fossil Fuel Energy, Global Climate Action Summit, Greenhouse Gas Emissions, Laguna Beach Flood Levels, Mayor's Climate Action Plan, Ocean Acidification, Paris Climate Accord, Paris Climate Agreement, US Climate Mayors. Bookmark the permalink.

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