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Our cities are sinking

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A new study by the Columbia University Climate School has found that all of the 28 most populous cities in the United States are sinking to some extent.  This phenomenon of subsidence is not just taking place in cities on the coast, where relative sea level is an issue, but also in cities in the interior.

The primary cause of subsidence is large-scale groundwater extraction for human use.  When water is withdrawn from aquifers made up of fine-grained sediments, the pore spaces formerly occupied by water can eventually collapse, leading to compaction below and sinkage at the surface.

The fastest sinking city in the US is Houston, with more than 40% of its area subsiding more than 5 millimeters a year and 12% sinking at twice that rate.  Some local spots are going down as much as 5 centimeters a year.   These seem like very small numbers but the fact that the subsidence is often not uniform across an urban area means that there are stresses to building foundations and other infrastructure.  Parts of Las Vegas, Washington D.C., and San Francisco have particularly fast sinking zones.

There are other causes of subsidence.  In Texas, pumping of oil and gas adds to the phenomenon.  A 2023 study found that New York City’s more than one million buildings are pressing down on the Earth so hard that they may be contributing to the city’s ongoing subsidence.  About 1% of the total area of the country’s 28 largest cities faces some danger from uneven subsidence.

Overall, some 34 million Americans live in cities affected by subsidence.  Global cities facing especially rapid subsidence include Jakarta, Venice, and here in the U.S., New Orleans.

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All of the Biggest U.S. Cities Are Sinking

Photo, posted December 27, 2012, courtesy of Katie Haugland Bowen via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Too hot for people

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The effort to mitigate the effects of climate change has a goal of keeping the global temperature increase below 1.5 degrees Celsius above preindustrial levels.  To date, the average global temperature has increased by more than 1 degree.  We hear about rising sea levels, powerful storms, and various other alterations in climate and weather patterns.  A new interdisciplinary study by three institutions looked at the impact of surpassing the 1.5-degree level upon people being able to withstand heat and humidity.

Humans can only withstand certain combinations of heat and humidity before their bodies begin to experience heat-related health problems such as heat stroke and heart attacks. 

In human history, temperatures and humidity that exceed human limits have been recorded only a limited number of times and only for a few hours at a time, in the Middle East and Southeast Asia.

According to the new study, if global temperatures increase by 2 degrees Celsius above preindustrial levels, the 2.2 billion residents of Pakistan and India’s Indus River Valley, the one billion people living in eastern China, and the 800 million residents of sub-Saharan Africa will annually experience many hours of heat surpassing human tolerance.

If the warming continues further to 3 degrees, heat and humidity levels that surpass human tolerance would affect the Eastern Seaboard and the middle of the US from Florida to New York and from Houston to Chicago.

The worst heat stress will occur in regions that are not wealthy and that are experiencing rapid population growth.  But even wealthy nations will not escape from the expansion of conditions that are too hot for people.

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Climate-driven extreme heat may make parts of Earth too hot for humans

Photo, posted June 28, 2018, courtesy of Ivan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Carbon From 25 Cities | Earth Wise

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There are roughly 10,000 cities in the world, defined as places with at least 50,000 inhabitants with a sufficient population density.  Roughly half the world’s population lives in cities.

Urban carbon emissions are one of the world’s biggest problems with respect to the climate.  A new study has determined that just 25 cities globally are responsible for 52% of urban greenhouse gas emissions.

The study gathered data on greenhouse gas emissions in 167 cities in 53 countries.  The results were that megacities in Asia, such as Shanghai and Tokyo, were among the biggest total emitters, and that major cities in Europe, the US, and Australia tended to have larger per capita emissions.  Several Chinese cities, however, matched levels seen in developed countries.  Researchers tracked emissions over time in 42 of the cities studied.  Some cities saw declining emissions in the period between 2005 and 2016.  These included Oslo, Houston, Seattle, and Bogota.  Others saw large increases, including Rio de Janeiro, Johannesburg, and Venice.

The largest sources of emissions are power generation, industry, and transportation.  In a third of the cities, road transportation alone accounted for over 30% of emissions.  (Railways, waterways, and aviation combined only accounted for less than 15% of total emissions).

Half of the world’s population lives in cities, but cities are responsible for more than 70% of greenhouse gas emissions.  Thus, cities have a big responsibility for the decarbonization of the global economy.  Of the 167 cities in the study, 113 have set emission-reduction targets.  But as the study shows, cities have much more work to do to meet the goals of the Paris Climate Agreement.

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Two Dozen Large Cities Produce 52 Percent of Urban Carbon Emissions

Photo, posted December 1, 2017, courtesy of Hector Galbis via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Cost Of Rising Seas

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Coastal cities in the United States are grappling with the need for extensive infrastructure projects to protect against rising seas and worsening storms.  The cost of these projects will be enormous, and it is unclear how to pay to them.

Boston has many neighborhoods in low-lying areas, and it is estimated that $2.4 billion will be needed to protect the city from flooding.  The city abandoned plans to build a harbor barrier that would have cost $6 to $12 billion because it was economically unfeasible.

Charleston, South Caroline needs $2 billion to reduce flooding that occurs regularly during high tides.  The Houston, Texas area needs $30 billion to provide protection against a 100-year flood.  Hurricane Harvey caused $125 billion in damages in Texas in 2017.  New York City is considering a $10 billion storm surge barrier and floodgates to shield parts of the city from rising waters.

Florida faces the greatest exposure to flooding with an estimated $76 billion in costs to address some of its problems.

At the federal level, multiple agencies represent potential funding sources, but none offer the kind of money required to address the need.  This places a heavy burden on state and local governments.  Various states have passed legislation related to shoreline resiliency and flood abatement, but relatively little funding has been approved.  Some bond measures have passed, but the totals are small compared with what is needed.

Educating people about the costs of not doing anything or not doing enough soon enough is essential.  As Hurricane Katrina demonstrated, not spending a large amount of money on resilience can result in having to spend a colossal amount of money on recovery.

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Who Will Pay for the Huge Costs of Holding Back Rising Seas?

Photo, posted December 26, 2013, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Off-The-Charts Heat

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There have been some blistering heatwaves this summer – in Europe, in the Middle East, and here in the United States.  A new report by the Union of Concerned Scientists projects that within the next 20 years, millions of people in the United States could be exposed to dangerous “off-the-charts” heat index conditions of 127 degrees Fahrenheit or more.  Within 60 years, over one-third of the population could be exposed to such conditions.

Extreme heat kills hundreds of people every year across the U.S.  Our bodies’ natural cooling process is affected by humidity and the combined heat index measures the impact of high temperature and high humidity.  When the combined heat index reaches 90 degrees, it is considered to be a “dangerous day”, when many groups of people are at serious risk.

Because of the warming climate, the number of dangerous days has been increasing in many parts of the country.  Unless there is success in limiting the effects of climate change, by 2050, even relatively temperate cities like Detroit, Minneapolis, New York, and Chicago will have 50 or more dangerous days a year.  Places like Dallas, Houston, Phoenix and Miami will experience dangerous days for half of the year.

The National Weather Service’s heat index goes up to 127 degrees Fahrenheit.  But in as soon as 20 years, the Southeast, Southern Great Plains, and Midwest will begin to experience days that are so hot that they are “off the charts.”

These extreme conditions could still be avoided with steep, rapid carbon emission reductions.  But however successful we are going forward, the US will still be significantly warmer than today with 85 urban areas exposed to 30 or more days with a heat index above 105 degrees, compared with just three urban areas historically.

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‘Off-the-charts’ heat to affect millions in U.S. in coming decades

Photo, posted August 8, 2008, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Dangerous Cities For Migrating Birds

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Billions of birds migrate north in the spring and south in the fall.  The majority of them fly at night. But as they pass over large cities, the birds can become disoriented by bright artificial light – so-called light pollution, causing them to crash into buildings or windows.

Researchers estimate that 600 million birds die from building collisions in the United States every year.  Now, a new paper from researchers at Cornell University reveals which metropolitan areas are most dangerous for birds and why.

The researchers ranked cities where, as a result of geography and exposure to light pollution, birds are at the greatest risk of becoming attracted to and disoriented by lights and crashing into buildings. They combined light pollution levels with bird density data in order to make their calculations.  Their paper was recently published in the journal Frontiers in Ecology and the Environment.    

Chicago, Houston, and Dallas finished as the three most dangerous cities for migrating birds.  While migration routes vary depending on the season, these three cities still topped all others during both the spring and fall migrations due to their size and geographic positioning in the heart of North America’s most trafficked aerial corridors.  

Audubon’s Lights Out program is one of several national efforts encouraging cities to reduce light pollution, particularly on heavy migration nights, in order to reduce bird mortality. 

But homeowners need to do their part as well since an estimated quarter-million birds die from collisions with residential houses every year.  The suggestion to cities and homeowners alike is the same:  If you don’t need the lights, turn them off. 

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Chicago tops list of most dangerous cities for migrating birds

Photo, posted May 18, 2017, courtesy of Pedro Szekely via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A New Catalyst For Splitting Water

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Hydrogen is widely considered to be a desirable source of clean energy.  It can be used in fuel cells to power electric motors in cars or can be burned directly in internal combustion engines.   If it is compressed or converted to liquid, it can be efficiently stored and transported.  Most of all, when it is used as an energy source, the only emission it produces is water.

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Hurricanes Are Slowing Down

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According to a new study recently published in the scientific journal Nature, some hurricanes are moving slower and spending more time over land, which is leading to catastrophic rainfall and flooding. The speed at which hurricanes track along their paths – known as translational speed – can play a major role in a storm’s damage and devastation.  17

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Can We Stop A Hurricane?

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This has been a particularly terrible hurricane season.   Harvey, Irma, Jose, Maria, and Nate all formed in the Atlantic and headed for North America. People in Houston, Florida, all over the Caribbean, and especially Puerto Rico are trying to recover from the effects of these powerful storms.

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Clean Coal For Real

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We have heard the term “clean coal” for years, mostly from politicians and in coal company advertising.  The concept sounds good:  burn coal but don’t produce carbon dioxide emissions.  While there have been various small-scale tests of technologies to accomplish this, it has not actually been a viable option for the power industry.

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