News Section
Stories from Climate Central's Science Journalists and Content Partners

Greenhouse Gas Emissions Rate Puts Billion More at Risk

Repost This

By Paul Brown, Climate News Network

London − Allowing the Earth’s temperature to rise by more than 3.6ºF will see dramatic changes in vegetation across the planet and expose a billion more people to severe water scarcity, according to new research.

So vast are the potential changes that the scientists from the Potsdam Institute for Climate Impact Research (PIK) in Germany comment that they doubt if humans have the capacity to manage the impacts it will have.

Allowing the Earth’s temperature to rise by more than 3.6ºF will see dramatic changes in vegetation across the planet and expose 500 million more people to severe water scarcity.
Credit: UNICEF East Asia & Pacific/flickr

A temperature rise of 9°F would cause all ice-free land on the planet to experience dramatic changes in its ecosystems  for example, tundra turning to forests and African grasslands to deserts.

In a paper published today in the international scientific journal Earth System Dynamics, the scientists say they are surprised at how much worse the impacts would become once the 3.6ºF threshold is passed. At the moment, they say, the failure of politicians to make commitments to cut emissions means that the temperature is set to reach and pass the danger zone of 6.3ºF.

While the scientists spell out what will happen to the vegetation and the water availability, they do not venture into predicting what conflict might arise if a billion people or more whose food supply would collapse embarked on mass migration to avoid starvation.

The “green” areas of the world most affected are the grasslands of Eastern India, shrub lands of the Tibetan Plateau, the forests of Northern Canada, and the savannas of Ethiopia and Somalia. The melting permafrost of the Siberian tundra will also be significant, releasing further greenhouse gases.

The changes in vegetation are only part of the story. The report also concentrates on the effect of temperature on water shortages for the human population. Even if global warming is limited to 3.6ºF above pre-industrial levels, another 500 million people could suffer water scarcity, and this will grow substantially as the temperature rises.

Water scarcity

Dr. Dieter Gerten, research expert on water scarcity, and lead author of one of the three studies contained in the PIK paper, said mean global warming of 3.6ºF — the target set by the international community — is projected to expose an additional 8 percent of humankind to new or increased water scarcity.

However, a rise of 6.3°F — likely to occur if national emissions reductions remain at currently pledged levels — would affect 11 percent of the world population, while a rise of 9°F could increase this to 13 percent.

Areas of the Tibetan Plateau, such as the Deosai Plains in Pakistan, could become deserts if the emissions rate isn't cut now.
Credit: Kashiff, Wikimedia Commons via Climate News Network

“If population growth continues, by the end of our century under a business-as-usual scenario these figures would equate to well over one billion lives touched,” Gerten says. “And this is on top of the more than one billion people already living in water-scarce regions today.”

Parts of Asia, North Africa, the Mediterranean and the Middle East are particularly vulnerable to further water scarcity. The eastern side of the United States and northern Mexico, already short of water, will suffer further stress.

Maps published with the paper show the areas most at risk from both water shortages and vegetation changes. One of the worst affected regions is an area that includes Pakistan and the border area of India — which is already suffering from floods, droughts and a subsequent loss of crop production.

Dire consequences

The scientists use their findings to show that the current world leaders have the key to the fate of the planet. If they reduce emissions now, they could prevent the worst of the temperature rises, but if they fail to do so the consequences will be dire.

The paper says a warming of 9ºF — likely to happen in the next century if climate change goes on unabated — would put nearly all terrestrial natural ecosystems at risk of severe change. “So despite the uncertainties, the findings clearly demonstrate that there is a large difference in the risk of global ecosystem change under a scenario of no climate change mitigation, compared to one of ambitious mitigation,” says geo-ecologist Sebastian Ostberg, lead author of the third section of the study.

While the report does not speculate on the actual effects these changes will have on the ability of the human population to survive, the scientists permit themselves the observation that it is hard to see how humans can adapt to such rapid changes.

Much more irrigation would be needed to grow the same amount of food, the scientists suggest, but this would put even more strain on scarce resources.

Paul Brown is a joint editor for Climate News Network. Climate News Network is a news service led by four veteran British environmental reporters and broadcasters. It delivers news and commentary about climate change for free to media outlets worldwide.

Comments

By Eric Peterson (Front Royal, VA 22630)
on October 14th, 2013

“The eastern side of the United States and northern Mexico, already short of water, will suffer further stress.”

Has Dr. Dieter Gerten been to the eastern side of the United States?  Is he aware of the Gulf of Mexico?  Essentially there has been and will be little chance of increased water stress in the eastern US.  The SE US drought of 2007 was a 100 year event, not unprecedented and caused by natural weather patterns.  It was exacerbated by very poor water management.

OTOH, climate models show drought increases in the southwestern US, but that means mostly expansion of the existing desert to areas that are currently slightly less arid.

Reply to this comment

By Thomas Radecki (Clarion/PA/16214)
on October 17th, 2013

Clearly, being close of a large body of water doesn’t prevent drought. North Africa is a great example and the SE US is on the same latitude as the northern part of the Sahara Desert.  Already, the rainfall in most countries bordering the Mediterranean have fallen dramatically and progressively in the last 100 years.  Indeed, the current civil war in Syria was largely triggered by severe drought forcing huge numbers of farmers into the cities in a desperate effort to survive and the Assad regime ignoring their problem.

The U.S. National Center on Atmospheric Research has long projected based on the findings of 22 climate models that most of the U.S. is in for severe and extended drought increasing over the next several decades.  Already, the recurring Texan droughts early this century are turning into a drought that just doesn’t want to quit.  Right now, California is having a severe drought and the Colorado River Basin hasn’t pulled out of their prolonged drought. Just like in the Mediterranean area and Texas, the expected pattern is for droughts which used to occur every hundred years to start returning more and more often.  The U.S. Gulf Coast is projected to suffer from extended to semi-permanent moderate to severe drought, not as bad as some parts of the West and Midwest but a still a severe stress on agriculture.

It is fairly certain that the Hadley cell airflow patterns associated with subtropical deserts which dry up the water and take it further north will expand with southern Europe and the U.S. Gulf Coast getting less and less precipitation. Continuing to generate massive amounts of global warming gases will seriously hurt U.S. agriculture as it did last year. It will be very hard to feed our country.  Other countries may will not be willing to export to us as happened when the Asian rice crop failed in 2008 and many Asian countries banned rice exports.

China is smarter than us.  They just bought 5% of the country of the Ukraine to grow crops to export back to China along with the pork products from Smithfield Foods, which they also just bought.  It appears very unlikely that the Earth will be able to grow enough food for 9 to 11 billion people. It is very likely billions will die from starvation and some are likely to be Americans.

Reply to this comment

By Carol Pobst (southbridge/massachusetts/01550)
on October 20th, 2013

The social changes linked to climate change in the tropical and subtropical regions (october 9th report by the UHawaii) will also impinge upon the US and NE Europe.  ‘mass migration; is a doomsday scenario, while established models in the SOCIAL SCIENCES need to be used which can coordinate with new scientific modelling of changes.  Who is out there who can make real changes in the developed countries planning perspectives?

Reply to this comment

By Eric Peterson (Front Royal, VA 22630)
on October 22nd, 2013

“It is fairly certain that the Hadley cell airflow patterns associated with subtropical deserts which dry up the water and take it further north will expand with southern Europe and the U.S. Gulf Coast getting less and less precipitation”

The Hadley cell expansion is seasonal (summer only) and may not affect land areas due to geography changing the flow patterns.  What can be said is a slight expansion has been noted over the ocean.  The Texas drought is a La Nina phenomenon and not unprecedented according to the tree ring records.  California drought has mostly the same cause, a cooler eastern Pacific means less precipitation.

“Continuing to generate massive amounts of global warming gases will seriously hurt U.S. agriculture as it did last year.”

Agricultural yields have generally increased with added CO2.  Extra CO2 makes many plants more drought tolerant.

Reply to this comment

Name (required):
Email (required):
City/State/Zip:
Enter the word "climate" in the box below:

[+] View our comment guidelines.

Please note: Comment moderation is enabled. Your comment will not appear until reviewed by Climate Central staff. Thank you for your patience.