Climate Catastrophes: Worst-Case Scenarios

Climate change is already under way. But what's the worst that could happen in the future?

Climate change is a global reality. Extreme weather events are taking a toll on the daily lives of people around the world. If climate change is already fueling powerful storms, long-lasting droughts and more frequent floods, what will the future look like?

James Hansen, the former NASA scientist who helped first raise awareness of the issue of climate change in his testimonies before Congress in 1988, sounded the alarm this week in a grim and controversial report that predicts catastrophic from a warmer world and rising tides, up to 16 feet by 2100, four times the level predicted by the United Nations Intergovernmental Panel on Climate Change (IPCC).

The magnitude of climate effects in Hansen's predictions are beyond what most climatologists are comfortable with. But even if Hansen is an outlier, what exactly does the worst-case scenario look like for human beings and other life on Earth?

Why Doesn't Anybody Care About Climate Change?

If you wanted a preview of how climate change might affect the water supply, look no further than the four-year, extreme drought California has endured. 

While the National Oceanic and Atmospheric Administration (NOAA) released a study in late 2014 suggesting that the drought can be tied to natural variability, other research, including two separatestudies released by Stanford University scientists, finds that human-caused climate change helped fuel or at the very least worsened the drought.

The American West isn't the only corner of the world suffering from extreme drought either. Drought has touched almost every continent and many large countries, including parts of Brazil, China and Australia.

 Scientists also predict that climate change will make extended dry spells and even megadroughts, a drought spanning at least two decades, more common in the future.

California Drought by the Numbers

Water scarcity means more than shorter showers, dirty cars and brown lawns. It can also lead to crop failures that could potentially jeopardize food security.

 According to the United States Food and Agriculture Organization (FAO) , climate change threatens food availability and destabilizes the way we get our food. In fact, climate change is already affecting the food supply, the IPCC finds, fueling famine and instability.

When food security is at risk, everyone feels the effects. "Impacts will be felt in both rural and urban locations where supply chains are disrupted, market prices increase, assets and livelihood opportunities are lost, purchasing power falls, human health is endangered, and affected people are unable to cope," the FAO report grimly asserts.

How Global Warming Will Change Your Life

City landscapes can change remarkably within just a decade as new buildings and neighborhoods rise up and others are torn down. In about a century, however, residents of New York, Los Angeles, Seattle, New Orleans and more than 1,400 cities and towns across the United States are unlikely to recognize their hometowns given that parts of them will be underwater.

Some cities are already taking steps to deal with climate change, even as state and federal governments dither.

Miami, frequently described as ground zero in the United States for the effects of rising tides, sits no more than 4 feet above sea level. Residents face a dual threat of the ocean flooding their homes and saltwater contaminating their water supply. This city also happens to be in the same state whose governor banned the use of the terms "climate change" and "global warming" from government communications, e-mail and reports, according to the Miami Herald.

South Florida officials have devised their own plans to prepare for encroaching oceans as a result of human-caused climate change. Investments in roads, sea walls and drainage systems are being made to cope with increased flooding. But the efforts simply aren't enough for a low-lying state that will needs multi-billion dollar infrastructure projects if it doesn't want to sink beneath the waves.

Underwater Houses for a Flooded Future

Rising tides resulting from melting sea ice won't just swallow cities; entire countries could sink beneath the waves.

The Maldives, Solomon Islands, Seychelles and other island nation have all seen waves steadily encroaching on their territory. Residents and policymakers alike fear a future in which these lands are uninhabitable, turning potentially millions of people into climate refugees. It's worth noting that none of these islands nations are major contributors to climate change; they're just suffering the effects.

Some governments are already taking steps to ensure their people have a home even when they no longer have a land to call their own. The president of Kiribati, a Pacific republic made up of 32 atolls and one island (seen here), has engaged in talks with authorities in Fiji's military government to buy up to 5,000 acres of land. When Kiribati is overtaken by the ocean, its 102,697 people would have place to relocate.

Other countries that won't sink entirely won't necessarily fair much better. in 2014 found that around 3.1 percent of the world's population will be exposed to regular flooding, around once every three years, by 2100 under the worst climate scenarios.

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You probably don't need a calculator to figure out that adapting to a warming world, when food and water are less scarce and many people's homes are literally underwater, is a costly proposition.

A report (PDF) released in 2012 by the Madrid-based humanitarian group DARA and the Climate Vulnerable Forum found that climate change is already cutting global gross domestic product (GDP) by $1.2 trillion, or 1.2 percent, every year. By 2030, that number could double. 

If government policies don't adapt and climate change goes unchecked, the cost of dealing with global warming will rise with each passing year. Determining what the costs entail exactly vary widely from study to study.

A paper published in the journal 
Technological Forecasting and Social Change in February found that a combination of uncertainty about future technological advances and unpredictability in production and consumption patterns make it impossible to pin down a reasonable cost estimate, which in turn limits the ability to do any kind of cost benefit analysis.

The study's authors, however, insist that such analysis is unnecessary given the quantitative and qualitative impacts climate change is already having.

What 11 Billion People Mean for Climate Change

Even in the most dire climate models, the human race endures, even if a large number of our cities do not. Many animal species, however, aren't so lucky.

According to a study published in May in Science, as many as one in six animals faces the threat of extinction as a result of climate change. This number assumes global temperatures will rise 4.3 degrees Celsius compared to preindustrial periods. If Earth's climate warms 2 degrees instead, that ratio falls to about one in 20 species.

Animals who will almost certainly fall victim to a warming world include penguins-140630.htm">emperor penguins, penguins, sea turtles, polar bears and more.

Animals Benefiting from Climate Change: Photos

Climate change won't just have a devastating impact on species across the planet. It poses a threat to human health as well. In fact, according to the 2015 Lancet Commission on Health and Climate Change, climate change could wipe out a half century of advancements in global health.

Thanks to improved nutrition and a reduction in the number of people coping with extreme poverty, humans have enjoyed increased longevity and are less likely to suffer chronic condition. Climate change could reverse that by creating food and water scarcity, compelling population migrations and changing infectious disease patterns.

Climate change is unlikely to create new diseases, but it will make existing ones worse. Take malaria for example. According to a study published in 2008 in the British Medical Journal, between 20 million and 70 million more people could dwell in malarial regions by 2080 as disease-carrying mosquitoes expand their territory. Climate change already kills 150,000 people annually, the World Health Organization (WHO) finds.

In the case of Lyme disease, to provide another example, a warmer world means more severe infections, found a study published in Applied and Environmental Microbiology. Ticks have three life cycle stages -- larval, nymphal and adult -- and have one blood meal during each stage. If the host is infected with the bacteria that causes Lyme, the tick passes the disease on at the next stage. Those stages are largely determined by seasonal weather patterns, and researchers found that the longer a tick spends in each stage, the more severe the infection when the tick moves on to the next host.

Another study published in 2005 also concluded that a warmer world means a larger habitable area for ticks. In fact, given how ticks encroaching on new territory has led to a general increase in Lyme diagnoses since the early 1980s, and the EPA lists the disease as a climate change indicator.

11 Health Threats from Climate Change

Given the environmental, economic and even geographic consequences of climate change, resource conflicts that lead to violent outbreaks is certainly a possibility, according to an article published in 2013 in the journal Science.

In fact, Democratic presidential candidate and former Maryland governor Michael O'Malley in a recent interview suggested that the civil war in Syria and rise of ISIS was partly the result of climate change, as The Atlantic reports. Although his comments were mocked by the Republican National Committee, a paper published in the Proceedings of the National Academy of Sciences explained how a megadrought in the region between 2006 and 2011 destroyed farms and overwhelmed cities, sparking a humanitarian crisis that contributed to civil war.

The outcome certainly isn't one of direct cause-and-effect, and the link to ISIS is a shaky one, given that the group existed as the Islamic State of Iraq, which preceded the drought. Climate change certainly similarly isn't responsible for the scenes in devastation in Syria similar to the one in this photo. But climate conditions could certainly be identified as one of several antagonists that sparked regional instability that led to protest, violence then war.

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