<h1 class="title article-title">From: <i>Popular Science</i><br>
</h1><h1 class="title article-title"><a href="http://www.popsci.com/science/article/2012-06/climate-change-here-its-time-get-ready">Strategies for a Changing Planet: Awareness</a> </h1>
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We're on a collision course with extreme weather. It's time to acknowledge that, and to prepare </div>
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<span class="author">By David Roberts</span>
<span class="posted">Posted 07.09.2012 at 10:12 am</span>
<span class="comment_bubble"></span><span class="comments"><a href="http://www.popsci.com/science/article/2012-06/climate-change-here-its-time-get-ready?page=#comments" rel="comments" class="active">29 Comments</a></span>
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<span class="img-title">Already Happening</span>
<span class="pic-credit">Nick Jacques</span>
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<p><i><a href="http://www.popsci.com/category/tags/climate-preparation">Climate
change is already happening, and it's time to get ready. Here's how we
could adjust our most basic needs--food, water, shelter--to survive. </a></i></p>
<p>There is no longer any question of preventing climate change. Some 98
percent of working climate scientists agree that the atmosphere is
already warming in response to human greenhouse-gas emissions, and the
most recent research suggests that we are on a path toward what were
once considered “worst case” scenarios. </p>
<p>How much warmer must it get before things really go to hell? “Climate
sensitivity” remains a subject of intense investigation, and what
counts as hellish is a matter of judgment, but United Nations climate
negotiators have settled on a goal to limit atmospheric carbon dioxide
to 450 parts per million, which would cause the global mean temperature
to peak no more than 3.6°F above preindustrial levels. If it gets much
hotter than that, we will most likely be confronted by levels of drought
and severe storms for which humanity has no precedent. That sounds bad
enough—and indeed, postindustrial temperatures have already risen by as
much as 1.6°—but there’s increasing reason to believe, as James Hansen
and many other climate scientists do, that severe effects will arrive
well below 450 ppm, and possibly below today’s level of 396 ppm. Danger
is much closer than we thought.</p>
<p>We will almost certainly blow past 3.6° in any case. One recent study
found that the average global temperature would rise another 3.2° by
the end of the century even if human carbon emissions dropped to zero
tomorrow, a scenario that is, of course, extremely unlikely. Simply
limiting the temperature rise to twice the “safe” level would require
heroic, sustained global effort, a level of ambition that appears
nowhere in evidence. And if humanity does nothing to restrain climate
pollution, the trajectory it’s on right now could carry the rise to as
much as 10° within the century.</p>
<p>We no longer have a choice about whether to confront <a href="http://www.popsci.com/science/article/2012-02/could-climate-change-make-mount-everest-unclimbable">major changes</a>
already in the works. By the end of this century, sea levels will rise,
drought will spread, and millions of animals, human and otherwise, will
be driven from their homes. Scientists call the process of preparing
for these changes “adaptation,” but a more apt term can be found in the
tech world: ruggedizing. Greater extremes require tougher, more
resilient societies.</p>
<center><strong>* * *</strong></center>
<p>In 2009, researchers from the University of Oxford, the Tyndall
Center for Climate Change Research and the U.K. Met Office Hadley Center
organized a conference on what a change of 7.2° or greater might look
like—oddly, one of the first concerted scientific examinations of the
impacts of temperatures that high. Here are some of the results: 7.2°,
which could conceivably arrive as early as 2060, would mean a planet
that was hotter than at any time in the past 10 million years. By 2100,
sea levels would rise by as much as six feet, leaving hundreds of
millions of the world’s coast-dwellers homeless, even as huge swaths of
the ocean itself became “dead zones.” Glaciers and coral reefs would
largely vanish from the planet. </p>
<p>It may be possible to weather this onslaught if we begin preparing
now, by building low-carbon, high-density cities away from the coasts,
radically improving the efficiency of water and energy systems, boosting
local and global emergency-response capacities, and adjusting to a less
consumption- and waste-oriented lifestyle. But although humans are an
ingenious species, some changes simply exceed any realistic capacity for
adaptation. The real threat, the existential threat, is that climate
change will gain so much momentum that humanity loses what remaining
power it has to slow or stop it, even by reducing carbon emissions to
zero. If change becomes self-sustaining, our children and grandchildren
will inherit an atmosphere irreversibly out of control, with inexorably
rising temperatures that could, according to one recent study, render
half of Earth’s currently occupied land uninhabitable—literally too hot
to bear—by 2300.</p>
<p><span style="border-top:5px solid black;margin:5px 0.5em 0.25em;float:right;font-weight:bold;color:rgb(153,153,153);padding-top:0.25em;text-align:left;width:40%;line-height:1;font-size:16pt;padding-left:0.2em">Given the risks humans pose to the planet, we might someday leave Earth simply to conserve it.</span>These
are only scenarios spit out by climate models; there’s no way to
predict exactly what will happen. It might be tempting to seize on
uncertainty as reason to wait and see. Why prepare if we don’t know
exactly what we’re preparing for? But the uncertainties in the science
of climate impacts—and they are legion—make the future more perilous,
not less. Things look bad, and if there’s a chance they could turn out
better than expected, there’s also a chance they could turn out worse.
Out on the “long tail” of the probability curve, there are small but not
insignificant chances for damages that are, for all practical purposes,
unlimited. For instance, if several of the world’s major land-based ice
sheets melt, we could see a 40-foot rise in sea levels within
centuries.</p>
<p>These are stark and discomfiting findings. Above all, they suggest
that global temperature should be held as low as is still possible, at
virtually any cost. But they also make clear that some changes are
inevitable. We no longer have a choice between mitigating climate change
and adapting to climate change. We must do both.</p>
<center><strong>* * *</strong></center>
<p>When we talk about adaptation, we often imagine accommodating a
specific new set of conditions; a temperate place gets too hot, a cold
place gets temperate, so we move our farms around and get on with it.
But we simply do not know, and most likely will not for some time, what
particular temperature we are bound for, or whether there will ever
again be a stable temperature. It is not a specific set of conditions
but uncertainty itself to which <a href="http://www.popsci.com/science/article/2012-06/how-urban-planners-will-accommodate-climate-refugees">we must adapt</a>.</p>
<p>Even as we remain flexible, we will have to think and work on a very
large scale. Major infrastructure projects—highways, dams, levies,
electrical transmission lines, trains and subways—represent investments
meant to pay off over generations. The New York City subway system is
more than 100 years old. Today there’s a nontrivial chance that much of
Manhattan will be under water in 100 years. How do we invest in the
future when it has become so cloudy and threatening? As the stories in <a href="http://www.popsci.com/category/tags/climate-preparation">this series report</a>,
scientists and engineers already have many excellent (and some less
than excellent) answers. It can be done. But the time to do it is now.</p>
<p><i>David Roberts is a senior staff writer for</i> <a href="http://grist.org/">Grist.org</a>. <i>He lives in Seattle.</i></p>
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