Some of the world's biggest challenges, including climate change and political violence, extend far beyond any one nation's borders.
Global catastrophes can occur for a number of reasons, and the Global Challenges Foundation's 2018 report highlights some of the main risks to humanity today. The foundation, created in 2012, works with researchers to publish annual reports on threats that could devastate at least 10% of the world's population. This year's report contributors include astrophysicist Martin Rees and multiple experts focused on disarmament affairs at the United Nations.
According to the foundation, the next 50 years will set the pace for humanity's survival in the next 10,000 years.
"Why care now? Because so much is at stake, too little is done, and if we wait until later, caring may no longer matter," the report's authors said.
Take a look at the 10 greatest challenges facing humans right now.
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A nuclear explosion could trigger a "nuclear winter," with widespread famines to follow.
Nuclear weapons can kill thousands of people upon impact, and their lingering effects create even more harm.
Kennette Benedict, a Bulletin of Atomic Scientists senior adviser, and Nobuyasu Abe, the commissioner of Japan's Atomic Energy Commission, wrote in the report that nuclear explosions could trigger a "nuclear winter," where a massive amount of dust and sulfates could conceal the Sun and cool the Earth for years.
One model suggests the use of 4,000 nuclear weapons would release 150 teragrams of smoke, which is enough to lower global temperatures by 8 degrees for four or five years. The world's largest nuclear arsenals, located in the United States and Russia, each have about 7,000 warheads.
Benedict and Abe wrote that it would be very difficult to grow food during this time, and chaos would follow amid a widespread famine.
Technological progress in synthetic biology and genetic engineering is making it easier and cheaper to weaponize pathogens.
Nuclear weapons are complicated and made of rare materials, but biological and chemical weapons can be made for much less money.
Angela Kane, a senior fellow at the Vienna Center for Disarmament and Non-Proliferation, wrote in the report that biological weapons could cause global catastrophes if a pathogen leads to a pandemic. Toxic chemicals may be less deadly, but they can still contaminate a large area if they are put into water supplies.
Kane added it is possible that a worldwide consensus on banning countries from using toxic chemicals will unravel. She noted that biological and chemical weapons — despite being banned — have been used at least four times in the past 40 years.
Climate change will have devastating consequences.
Leena Srivastava, the vice chancellor of TERI University in India, wrote that despite the Paris climate deal, there is a 90% chance that global temperature increases will exceed 2 degrees Celsius this century.
There is also a 33% chance that the rise will go beyond 3 degrees in the 21st century, and the world is not on track to preventing this from happening, Srivastava said.
Most of Florida and Bangladesh will be underwater if the change exceeds 3 degrees, and major coastal areas like Shanghai and Mumbai will be swamped. Srivastava wrote that large numbers of refugees will leave those regions, which would suffer from extreme weather and low food production.
At least three past civilizations have fallen apart due to climate change — Norse Viking settlers, the Khmer Empire, and the Indus Valley Civilization. All three were affected by climate change that was local and not caused by humans, Srivastava wrote.
The climate change we face now is global, and there is nowhere for us to run.
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