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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".

Friday, July 12, 2019

We All Feel the Increasing Impacts of Global Warming

Summary: All over the world unprecedented weather extremes are occurring, with profound effects on human activities and health.  This post reports some recent climate events.  These instances are consistent with the forecasts that climate scientists have been making for several decades.  The IPCC issued a new, more urgent report in October 2018 specifying that we have to keep the world temperature increase below 1.5°C above pre-industrial levels, primarily by eliminating all emissions worldwide in about two decades.


Tidal flooding, Eastern U. S.  Many cities along the Eastern seacoast of the U. S. already suffer fair-weather tidal flooding due to rising sea levels.  According to the U. S. National Oceanic and Atmospheric Administration (NOAA) as reported by National Public Radio (NPR), tidal flooding is worsening in more than 40 U. S. coastal cities.  Most of these flood days are not related to storm activity, but rather to rising sea level.  Tides are worst, i.e., highest, when the moon is full or new.  This image

Source: NPR All Things Considered

shows downtown Annapolis, MD, founded three centuries ago on the shores of Chesapeake Bay, flooded during a high tide in 2017.  As NPR reports, NOAA finds that tidal flooding events in Annapolis have increased by 925% over the last 50 years.  The city is planning a Flood Mitigation Project in conjunction with many agencies including the U. S. Naval Academy, which is located in Annapolis.

Charleston, SC is also suffering from worsening ocean flooding (NPR).  The city is built on a low-lying peninsula, exposed to the sea.  In addition, in recent years flooding has been aggravated by extreme rainfall.  Both of these factors result from worsening global warming.  The city issues flood warnings as frequently as weekly during the summer.  Its officials now understand they must plan for 2-3 feet (0.6-0.9 m) of flooding over the next 50 years.

Temperatures for January-May 2019 for most regions around the globe are warmer than average or set warmest records, whereas only a very few regions were cooler than average (see the following image).

Source: NOAA National Centers for Environmental Information, State of the Climate: Global Climate Report for May 2019, published online June 2019, retrieved on July 10, 2019; .

The average is for the 30-year reference period from 1981-2010.  It is seen that for the vast majority of global surface pixels the 5-month averages were mildly or much warmer than the 30-year reference period.  In an accompanying graphic NOAA shows land and ocean temperature departures from the 30 year reference period for the January-May interval annually from 1880 to the present (not shown).  Starting about 1976 the departures are all only positive, trending up to 0.8-1.1°C (1.4-2.1°F) above the average between 2015 and 2019.  The full 139-year record shows clearly that, although there are year-to-year variations, the long-term trend in the 5-month global average temperature has been gradually increasing by about 1.3°C (2.3°F) starting at about 1910.

Global warming has been determined to have caused two current climate extremes.  First, a severe heat wave blanketed much of western Europe during the end of June 2019.  It broke heat records across much of the area.  A group of experts in the field of climate attribution examined the temperature data in two ways, as described in a commentary in the journal Nature. 

Attribution science has made great strides in recent years.  In this case, the scientists examined the heat wave in two ways.  First, they compared the actual temperature record with results from climate models for the European region, running cases that included or excluded a man-made greenhouse effect.  They found that the record heat was five times more likely with extra greenhouse gases than without.  Second, they assessed whether historical records going back 100 years are consistent with the actual heat wave data when climate models are used to “hindcast” the data.  They found that global warming and air pollution made the current heat wave 100 times more likely than without those factors. 

More generally, the commentary summarizes that about two-thirds of the 200 attribution inquiries reported to date have positively identified global warming as making the particular event being studied more likely or more severe than without warming.

Second, a report from India describes “Zero Day, the day when a city’s taps dry out and people have to stand in line to collect a daily quota of water.”  This is currently happening in many Indian states because aquifers are being over-drawn and this year’s monsoon rains were 30% less abundant than usual.  The image below exemplifies the disaster:

Zero Day has already occurred in the city of Chennai, and is predicted to happen next year in many cities, including the capital, Delhi.  In all 600 million people may be impacted.  Groundwater is the source for most of India’s rural inhabitants and for its agriculture.  The Ministry of Drinking Water and Sanitation states that global warming is one factor contributing to this crisis.
The Paris Agreement of December 2015 pledged 193 members of the United Nations voluntarily to reduce greenhouse gas emission rates sufficiently to keep the planet below a 2°C rise above pre-industrial levels by 2100.  But the Agreement is failing; the rate of emissions is still increasing, raising the total accumulated greenhouse gas burden of the atmosphere.  As a result, the IPCC issued a new, more drastic report in October 2018 specifying that we have to keep that temperature increase below 1.5°C, and to reach a worldwide reduction of emission rates to zero by about 2040, or 21 years from now. 

Failing to achieve this goal will lead to more intense warming, and will contribute to more rapid sea level rise, impacting coastal cities around the world, as discussed above.  It will also contribute to the more intense extremes of heat, such as Europe has experienced, as well as more extreme heat and aridity such as India is experiencing.

The economic harm alone is problematic, since in general our political structures don’t budget for funds to revive the losses, and insurance may be inadequate or nonexistent.  All people of the world have to mobilize individually and politically to eliminate fossil fuel use and develop a renewable energy economy to achieve the goal of zero emissions.

© 2019 Henry Auer