Here’s what the threat of increasing, widespread, prolonged droughts on a global scale means / leads to / why it matters:
Hard to grow food; fresh water scarcity; would cost trillions in losses; hard for economies to thrive, let alone subsist / not collapse; mass job losses, hardship, poverty, unrest, hunger, disease, desperation, dissent, oppression; human and animal rights abuses and injustices; resource wars; mass migrations; biodiversity loss; mass extinctions; multiple threats to security, quality of life, duration of life, ability to survive.
The percentage of Earth’s land area stricken by serious drought has more than doubled from the 1970s to the early 2000s. Thousands of species and millions of people are already suffering — and often dying(!) — from these kinds of impacts RIGHT NOW.
Read this brief excerpt from an article about the study, Drought could hit world’s populous areas, Deborah Zabarenko, Reuters:
Increasing drought has long been forecast as a consequence of climate change, but a new study from the U.S. National Center for Atmospheric Research projects serious impact by the 2030s. Impacts by century’s end could go beyond anything in the historical record, the study suggests.
To get an idea of how severe the drought might get, scientists use a measure called the Palmer Drought Severity Index, or PDSI. A positive score is wet, a negative score is dry and a score of zero is neither overly wet nor dry.
As an example, the most severe drought in recent history, in the Sahel region of western Africa in the 1970s, had a PDSI of -3 or -4. By contrast, the new study indicates some areas with high populations could see drought in the -15 or -20 range by the end of the century.
…”Decadal mean values of PDSI have not reached -15 to -20 levels in the past in any records over the world.”
Read the excerpts below from Climate change: Drought may threaten much of globe within decades, a press release summary of an essential study by UCAR (University Center for Atmospheric Research), Drough Under Global Warming: A Review.
* * * * *
The United States and many other heavily populated countries face a growing threat of severe and prolonged drought in coming decades, according to a new study by National Center for Atmospheric Research (NCAR) scientist Aiguo Dai. The detailed analysis concludes that warming temperatures associated with climate change will likely create increasingly dry conditions across much of the globe in the next 30 years, possibly reaching a scale in some regions by the end of the century that has rarely, if ever, been observed in modern times.
…the paper finds most of the Western Hemisphere, along with large parts of Eurasia, Africa, and Australia, may be at threat of extreme drought this century.
In contrast, higher-latitude regions from Alaska to Scandinavia are likely to become more moist…
…”We are facing the possibility of widespread drought in the coming decades, but this has yet to be fully recognized by both the public and the climate change research community,” Dai says. “If the projections in this study come even close to being realized, the consequences for society worldwide will be enormous.”
While regional climate projections are less certain than those for the globe as a whole, Dai’s study indicates that most of the western two-thirds of the United States will be significantly drier by the 2030s. Large parts of the nation may face an increasing risk of extreme drought during the century.
Other countries and continents that could face significant drying include:
* Much of Latin America, including large sections of Mexico and Brazil
* Regions bordering the Mediterranean Sea, which could become especially dry
* Large parts of Southwest Asia
* Most of Africa and Australia, with particularly dry conditions in regions of Africa
* Southeast Asia, including parts of China and neighboring countries
The study also finds that drought risk can be expected to decrease this century across much of Northern Europe, Russia, Canada, and Alaska, as well as some areas in the Southern Hemisphere. However, the globe’s land areas should be drier overall.
“The increased wetness over the northern, sparsely populated high latitudes can’t match the drying over the more densely populated temperate and tropical areas,” Dai says.
A climate change expert not associated with the study, Richard Seager of Columbia University’s Lamont Doherty Earth Observatory, adds:
“As Dai emphasizes here, vast swaths of the subtropics and the midlatitude continents face a future with drier soils and less surface water as a result of reducing rainfall and increasing evaporation driven by a warming atmosphere. The term ‘global warming’ does not do justice to the climatic changes the world will experience in coming decades. Some of the worst disruptions we face will involve water, not just temperature.”
…In addition, previous studies by Dai have indicated that climate change may already be having a drying effect on parts of the world. In a much-cited 2004 study, he and colleagues found that the percentage of Earth’s land area stricken by serious drought more than doubled from the 1970s to the early 2000s…
…By the 2030s, the results indicated that some regions in the United States and overseas could experience particularly severe conditions, with average decadal readings potentially dropping to -4 to -6 in much of the central and western United States as well as several regions overseas, and -8 or lower in parts of the Mediterranean. By the end of the century, many populated areas, including parts of the United States, could face readings in the range of -8 to -10, and much of the Mediterranean could fall to -15 to -20. Such readings would be almost unprecedented.
Future drought. These four maps illustrate the potential for future drought worldwide over the decades indicated, based on current projections of future greenhouse gas emissions. These maps are not intended as forecasts, since the actual course of projected greenhouse gas emissions as well as natural climate variations could alter the drought patterns.
The maps use a common measure, the Palmer Drought Severity Index, which assigns positive numbers when conditions are unusually wet for a particular region, and negative numbers when conditions are unusually dry. A reading of -4 or below is considered extreme drought. Regions that are blue or green will likely be at lower risk of drought, while those in the red and purple spectrum could face more unusually extreme drought conditions. (Courtesy Wiley Interdisciplinary Reviews, redrawn by UCAR)
More: The study
- Report summary – Drought may threaten much of globe within decades, UCAR
- Blog – Risk of multiple, devastating global droughts, Climate Progress
- Article – Drought could hit world’s populous areas, Reuters
- Article – Much of planet could see extreme drought in 30 years, AFP
- Website – University Center for Atmospheric Research (UCAR)
- Blog – Ponzi Redux: Could food shortages bring down civilization? CP
- Article – Could food shortages bring down civilization? Lester Brown, SA
- Podcast – Lester Brown on rising temperatures & rising food prices, CP
- Article – Only months, not years, to save civilization from climate change, Brown
- Book – Plan B 4.0: Mobilizing to Save Civilization, Lester Brown
- Worldwatch Institute
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