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The Global Obstacle Course · The Climate Translation

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  You might have heard the comforting talking point, don't worry, the climate has changed
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  before in the past, and plants and animals have survived, they adapt.
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  At first glance, it sounds reasonable, life is mostly resilient.
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  For millions of years, yes, species have gone extinct, but the some have learned
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  to adjust, migrate or evolve, as the planet slowly changed around them.
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  But there's a critical piece missing from that argument, speed.
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  Right now, species are disappearing at a rate of 100 to 1000 times faster than the natural
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  background rate we see in Earth history.
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  This isn't adaptation, playing out over a millennia.
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  It's change happening faster than biology can keep up.
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  Today we're going to look at what I call the global obstacle course, and why modern climate
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  change is forcing plants and animals into a brutal choice, adapt, move or die.
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  Welcome to the podcast on Dr. Mac, and this is The Climate Translation.
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  In my classroom, I often start this topic with a simple analogy I call the moving target.
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  Imagine a species is like a professional athlete, they're strong, they're skilled, they
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  can handle a lot.
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  If the climate changes slowly, over tens of thousands of years, like the transition out
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  of an ice age, that target moves slowly.
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  Some species have time to respond.
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  Plants can shift where they drop their seeds, animals can slowly migrate north a few miles
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  at a time.
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  Over many generations, evolution has time to work.
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  That's how adaptation is supposed to happen.
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  But today the target isn't moving slowly anymore.
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  Modern climate warming is happening 20 to 60 times faster than those natural changes.
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  It's like asking the same athlete to hit a target that's now mounted on a supersonic
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  jet, no matter how strong or talented they are, the rules of the game have changed.
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  That brings us to what I call the speed trap.
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  One of the most common things I hear from both students and in public conversations is
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  the idea that life is mostly resilient, and that species have adapted in the past.
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  On the surface, that's true.
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  While the vast majority of species have got extinct since the Earth has formed, species
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  do adapt and change.
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  Life as a whole is resilient, we wouldn't be here if that wasn't the case.
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  But adaptation isn't a superpower.
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  It's a biological process, and it depends on one thing we're rapidly running out of.
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  Time.
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  To see why speed matters, let's look at the numbers.
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  When the Earth came out of the last ice age, the planet warmed by about 5 degrees Celsius.
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  But that change took 5 to 10,000 years.
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  Forest didn't pick up and move overnight.
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  They migrated slowly, generation by generation.
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  Animals had thousands of generations to adjust their bodies, behaviors, and breeding patterns.
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  Now compare that to today.
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  One track to see a similar amount of warming, not in thousands of years, but in a hundred.
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  That's a magnitude greater than the natural climate shifts.
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  This creates something scientists call an evolutionary mismatch.
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  Evolution works like a long conversation between species and the environment.
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  Trades that work get passed on.
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  Trades that don't, slowly fade away.
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  But right now we're changing the environment so fast that many species don't even have
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  a chance to respond.
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  The conversation gets cut off mid-sentence.
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  And there are some hard limits that make this speed trap especially dangerous.
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  First, it's the generation gap.
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  For a species to adapt genetically, it has to reproduce a lot.
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  If you're a fruit fly, with a lifespan of a few weeks, you might have a dozen generations
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  and a short time.
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  But if you're a rhinoceros or an elephant, animals that take years to mature and have
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  very few offspring, you simply can't evolve fast enough to keep up with the rapidly warming
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  planet.
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  Second, there are fixed limits when it comes to heat.
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  Nature shows that while many animals can adapt to colder temperatures, they hit a biological
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  wall when it comes to heat.
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  Their cells, proteins, and organs just stop functioning after a certain point.
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  No amount of trying harder can push past that limit.
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  And third, there's something called phenotypic plasticity.
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  It's a fancy way of saying flexibility.
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  Some species can change their behavior.
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  Birds may nest earlier in the year.
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  Some insects become lighter in color to reflect heat.
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  But flexibility only works up to a point.
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  When warming becomes a tidal wave, instead of a gentle rise, that flexibility snaps and
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  populations collapse.
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  When we put this all together, the picture becomes clear.
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  The problem isn't that life can't adapt.
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  The problem is we're changing the climate faster than that adaptation can happen.
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  We're outrunning the very process that allows life to survive change in the first place.
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  And that's the challenge plants and animals are facing right now.
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  At this point, a fair question usually comes up.
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  If the world is getting warmer, why can't plants and animals just move north?
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  In paper, it sounds reasonable, and in fact, many species are already trying.
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  On average, plants and animals are shifting toward the poles at about 6 kilometers per decade.
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  But here's the problem.
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  We haven't given them a clear path.
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  We've turned the planet into a massive, high stakes, obstacle course.
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  To understand why this matters, we need to look at how migration used to work.
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  In past climate shifts, animals moved across wide, unbroken landscapes, forests connected
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  to grasslands, wetlands flowing into rivers, and elk or turtle could slowly follow suitable
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  conditions over generations.
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  Today, that continuity is gone.
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  The first barrier is physical fragmentation.
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  We've carved the planet into pieces with millions and miles of highways, rail lines, fences,
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  and pipelines.
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  For a small animal, a six-lane interstate isn't just a road, it's a deadly barrier.
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  For larger animals, traffic and fencing turn migration routes into traps.
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  Cities create an even bigger problem.
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  Urban and industrial areas form vast islands of concrete and heat that many species simply
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  can't cross.
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  If an animal is trapped on a shrinking patch of forest surrounded by development, it's
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  not trying to migrate, it's stuck.
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  The second barrier is timing.
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  Migrating isn't just about getting to a cooler place, it's about arriving at the right
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  time.
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  This is where scientists talk about phenological mismatch, which just means things are out
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  of sync.
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  Take birds, for instance.
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  Many species rely on an internal biological clock to know when to fly north, but as
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  spring arrives earlier, insects may peak weeks before the birds arrive.
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  The birds show up on schedule only to find the pantry already empty.
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  The same problem shows up with insects and plants.
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  A butterfly might successfully move north, but if the specific plant its caterpillars
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  depend on hasn't moved or can't survive the new conditions, that butterfly has migrated
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  into a food desert.
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  The third barrier is probably the most brutal, it has nowhere to run.
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  Mountain species.
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  For small rodents and alpine plants that need cold conditions, moving north often means
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  moving uphill.
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  As temperatures rise, they climb higher and higher to stay cool.
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  When mountains end, scientists sometimes call this the extinction elevator.
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  You keep moving up, step by step, until there's no more mountain left.
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  Even before reaching the peak, the usable habitat shrinks to a smaller and smaller circle,
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  squeezing populations into decline.
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  This is why migration by itself is no longer a reliable escape plan.
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  We've built walls around landscapes, we've scrambled the timing of food and seasons,
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  and in some places we've simply taken away every possible direction to move.
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  So when we hear that nature will adapt, or species will relocate, it's important to
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  understand what we've changed.
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  The challenge isn't willing this, it's feasibility.
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  For many species, the path north just isn't open anymore.
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  So far we've talked about movement, why plants and animals can't simply pack up and head
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  north, but adaptation isn't just about geography, it's also about biology.
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  And this is where things get even more constrained.
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  Every species has a hard limit, a physical boundary written into their bodies.
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  No matter how resilient life is, no organism can negotiate with basic biology.
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  Let me give you a few examples.
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  Take rhinospheres.
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  Rhinos are massive animals built for warm climates, but they have a serious limitation, they
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  can't sweat.
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  Humans cool themselves by evaporating sweat off their skin, rhinos don't have that option.
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  When temperatures rise, their main tools are shade, mud wallows, and slowing down.
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  That can work up to a point, but once air temperatures and humidity cross certain thresholds
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  the strategy stop working.
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  Heat builds up faster than the body can release it.
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  At that point, even resting in the shade isn't enough.
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  Overheating becomes a life threatening problem, not because the rhino is weak, but because
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  its physiology has reached a ceiling.
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  Now let's shrink things down.
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  In Australia there's a small marsupial called a numbat.
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  Humans are insect eaters and they're active during the day, but they have an incredibly
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  narrow thermal window.
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  On hot days, a numbat can only spend about 10 minutes in direct sunlight before it risks
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  fatal heat gain.
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  Climate change forces them into a brutal choice.
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  If they hunt less to avoid the heat, they starve.
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  If they shift their activity to cooler times like dusk or night, they become easy target
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  for predators they didn't evolve to deal with.
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  There's no good option.
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  It's not a failure to adapt, it's a trap created by their physiology.
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  Then there's coral reefs.
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  Corals don't get to move at all.
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  They're fixed in place.
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  They already live very close to the upper temperature limit.
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  Inside coral tissue live tiny algae called zooxanthellae.
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  They provide most of the coral's energy.
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  When ocean temperatures rise by just one or two degrees Celsius, that partnership breaks
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  down.
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  The corals expel their zooxanthellae algae.
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  This is what we call coral bleaching.
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  Leached coral is not dead immediately, but it's starving.
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  If temperatures don't drop quickly, the reef dies.
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  No migration.
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  No behavioral workaround.
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  Most hard biological boundaries that have been crossed.
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  When I explain this to students I emphasize something important.
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  Climate change doesn't usually kill species by dramatic catastrophe.
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  It kills them by pushing them past what their bodies can tolerate.
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  Adaptation works when conditions shift slowly and stay within biological limits.
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  But when warming is fast and relentless, those limits become walls.
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  This is why we can't rely on resilience alone.
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  Some species can move.
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  Some can adjust their behavior.
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  But many are already living at the edge of what their physiology allows.
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  And when they push past that edge, there's nowhere left to go.
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  That brings us to the part of the show where we step away from the graphs and data and
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  look at the real life situations.
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  Because climate conversations don't happen in classrooms or labs.
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  They happen at barbecues, at family dinners, and at work lunches.
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  So if you hear someone say, why should we be worried, plants and animals adapt?
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  Try translating the science and the pictures they can see.
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  Here's some simple ways to do that.
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  You can say, you're right, nature is really good at adapting.
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  But adaptation runs on a biological clock, and the clock only ticks so fast.
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  Right now we're changing the climate up to 50 times faster than that clock is designed
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  to handle.
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  It's not that nature is weak, it's that we've changed the speed of the race.
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  We're not asking a tortoise to run faster, we're asking it to beat a Ferrari.
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  If someone says, well, can't animals just move north?
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  Try this, and the past they could.
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  But today, the doors are locked.
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  Our landscapes are filled with highways, cities, fences and farms.
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  What used to be a wide open path is now a maze of dead ends.
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  You could say, try picking up your house and moving it to a cooler neighborhood, but finding
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  every road is blocked by brick wall.
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  That's what migration looks like for a lot of wildlife today.
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  They aren't refusing to move.
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  They're trapped.
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  Sometimes people point out that rats, pigeons and weeds are doing fine, and that's true,
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  but they're generalists.
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  They can eat almost anything.
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  Most of nature isn't like that.
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  Would you be okay if the only food left was plain crackers?
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  Some species can't survive on almost anything.
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  Most can't.
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  Many animals and insects depend on one specific plant, or one specific timing of food.
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  If that food disappears, they don't adapt.
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  They starve.
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  A world made only of survivors is a fragile world for everybody.
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  And here's the most important translation of the mall.
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  When we talk this way, we're not denying nature's resilience, we're respecting it.
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  We're acknowledging that even the strongest systems have limits, especially when we're
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  changing the rules of the road this fast, and we need to seriously consider what we're
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  doing.
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  The natural world has always changed, but it's never had to change this fast.
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  It's never had to do it alone.
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  What happens next depends on the choices we make.
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  How do we use energy?
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  How do we protect land and water?
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  And how well do we listen to one another?
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  I'm Dr. Mac, and this has been the climate translation.
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  If you have a question about the climate that you've been too afraid to ask, or if you
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  have a differing opinion, please let me hear from you.
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  I can use you viewpoints and future episodes.
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  You can reach me at theclimatetranslation at gmail.com.
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  I'll see you next time.