Every year, thousands of tourists flock to our nation's capital for the Cherry Blossom Festival. This year was even billed as a 'once in a lifetime celebration' -- the 100th anniversary of Japan's gift of 3,000 cherry trees to the United States. The festival is now taking place -- but without the spectacular blooms. The cherry blossoms came and went weeks ahead of schedule, because of record-breaking high winter temperatures.
A freak weather anomaly? No, it's consistent with an undeniable trend. The cherries' early flowering and demise are just the latest signs that climate change is upon us. Thanks to a rise in the planet's temperature, caused by heat-trapping gases in the atmosphere, we've experienced an increase in such extreme weather events as searing drought in Texas, a devastating heat wave in Russia, and unprecedented floods everywhere from Iowa and Vermont to Pakistan and Australia. Meanwhile, Arctic sea ice and Antarctic ice shelves are disappearing. Streams are becoming too warm for trout. An epidemic of pine beetles, unleashed by warmer temperatures, has devastated millions of acres of forests, while ocean waters are becoming more acidic, threatening the marine food web.
The sobering reality is that climate change is no longer abstract or theoretical, a threat to distant polar bears or tiny low-lying Pacific Islands. Instead, it means flooded Nashville basements
and Iowa cities, withered crops in Oklahoma and new cases of Lyme disease from the northward spread of disease-bearing ticks.
More worrisome, the Earth's past tells us that little nudges on the climate system can change the planet dramatically and rapidly, causing ice sheets to advance or retreat and sea levels to rise or fall. That's because the nudges are amplified by planetary responses that cause more warming. A little extra heat can shrink ice caps, so poles become 'darker' and absorb more heat from the sun. That, in turn, melts permafrost, releasing large amounts of previously frozen carbon into the atmosphere. The result of these so-called feedbacks is accelerating warming.
Now, humans aren't nudging the climate, we're giving it a mighty push. Because of fossil fuel burning and deforestation, levels of carbon dioxide in the atmosphere are increasing at a rate much faster than the rate associated with the development of a hothouse Earth 55 million years ago, when the Arctic regions contained vast tropical swamps -- and the tropics were too hot for most life. The stark lesson from geologic history is that the Earth's climate has experienced numerous tipping points, when runaway feedbacks led to climates far hotter or colder than today's. We may be near such a tipping point -- the first to be caused by humanity.
Signs of such feedbacks already exist. The loss of Arctic sea ice, for instance, has helped warm the Arctic region. That, in turn, has changed the strength and pattern of the jet stream -- enough to cause both the U.S. 'year without a winter' and the European deep freeze. Meanwhile, the permafrost is melting. Without rapid, concerted action to reduce emissions, the risks of climate disasters are growing.
Yet even with changes already staring us in the face, Congress has abandoned any effort to confront the threat. Four years ago, Presidential candidates John McCain, Hillary Clinton and Barack Obama all vowed to take action. The Obama administration has moved forward with emissions curbs on cars and new power plants, along with support for clean energy. But leading Republicans question whether humans are causing a problem at all (though both Mitt Romney and Newt Gingrich were for caps on emissions before they were against them).
The climate deniers argue that the science isn't fully certain, a time-honored tactic for sowing doubt and delaying action. But as with the link between smoking and cancer, the fundamental science of climate change is certain. The rising concentrations of greenhouse gases are certain. The simple physics of how the greenhouse blanket warms the planet is certain. The global temperature rise since the start of the Industrial Revolution is certain. And the fact that small amounts of warming can beget more warming is certain. We may not know the exact details of what will happen. But the planet has already surprised scientists by changing faster than expected, such as in the loss of polar ice. It's certain that more surprises -- many of them nasty -- lie ahead.
But we do know how to cope with risk. We take precautions and buy home insurance to protect against theft and fire. We drive cautiously and buy cars with air bags and crumple zones in case we get hit by drunk drivers. Now, faced with the risks of a disrupted climate, it's only prudent to take precautions. The exact policy could take many forms, from emissions caps to fees (which can be returned as dividends to citizens or used to reduce taxes), while also striving to make communities more resilient. Many of these approaches offer other benefits as well, such as cleaner air and less dependence on imported oil. The debate Washington should be having now is over what policies to enact -- not whether or not climate change exists.
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