WEBVTT - How Micro Are Microclimates? 0:00:01.920 --> 0:00:06.400 Welcome to brain Stuff production of I Heart Radio. Hey 0:00:06.440 --> 0:00:10.880 brain Stuff, Lauren Vogel Bomb here. If weather is your mood, 0:00:11.080 --> 0:00:15.120 then climate is your personality. That's an analogy some scientists 0:00:15.240 --> 0:00:18.000 used to help explain the difference between these two words 0:00:18.040 --> 0:00:22.000 that people sometimes get mixed up. In other words, whether 0:00:22.160 --> 0:00:24.919 exists in the short term, it's the state of the 0:00:24.960 --> 0:00:28.160 atmosphere in a specific area during a limited period of 0:00:28.160 --> 0:00:32.599 time I think minutes, hours, days, or weeks. Climate, meanwhile, 0:00:32.680 --> 0:00:37.360 describes long term average trends in weather. And if you're 0:00:37.400 --> 0:00:41.400 interested in the ladder, you'd better know geography. Our global 0:00:41.440 --> 0:00:45.040 climate is made up of many smaller regional climates. Break 0:00:45.080 --> 0:00:47.960 those down and you'll find local variations at just about 0:00:48.000 --> 0:00:52.920 every conceivable scale. And that brings us to micro climates, 0:00:53.080 --> 0:00:58.040 an amazing subject with broad applications for farming, conservation, wildlife management, 0:00:58.160 --> 0:01:02.800 and city planning. The climates are a bit like woven tapestries. 0:01:03.320 --> 0:01:06.360 The big picture is important, no question, but so are 0:01:06.400 --> 0:01:10.399 all the seemingly minor details found inside the larger whole. 0:01:11.800 --> 0:01:15.400 We spoke via email with tomaso Uker, an environmental scientist 0:01:15.480 --> 0:01:18.240 at the University of Bristol. He said he would define 0:01:18.240 --> 0:01:23.960 the term microclimate as quote the suite of climactic conditions temperature, rainfall, humidity, 0:01:24.000 --> 0:01:28.480 solar radiation measured in localized areas, typically near the ground, 0:01:28.600 --> 0:01:32.920 and at spatial scales that are directly relevant to ecological processes. 0:01:34.319 --> 0:01:36.520 We'll talk about that last bit in a minute, but 0:01:36.800 --> 0:01:41.200 first there's another criteria to discuss. According to some researchers, 0:01:41.200 --> 0:01:45.280 a microclimate by definition must differ from the larger area 0:01:45.440 --> 0:01:49.800 that surrounds it. Forests provide us with some great examples. 0:01:50.360 --> 0:01:53.640 We also spoke via email with University of Montana ecologist 0:01:53.680 --> 0:01:57.360 Solomon Debrowski. He said the climate near the ground in 0:01:57.360 --> 0:02:00.520 a tropical rainforest is dramatically different from the climate in 0:02:00.520 --> 0:02:03.160 the canopy fifty meters or about a hundred and sixty 0:02:03.160 --> 0:02:07.520 feet above. This vertical gradient, among other factors, allows for 0:02:07.560 --> 0:02:13.240 the staggering biodiversity we see in the tropics. Likewise, scientists 0:02:13.280 --> 0:02:17.640 observed that partial solar eclipse caused the air temperature of 0:02:17.680 --> 0:02:21.240 an Eastern European meadow to change more dramatically than it 0:02:21.280 --> 0:02:25.320 did in a nearby forest. That's because trees provide not 0:02:25.400 --> 0:02:30.200 only shade, but their leaves also reflect solar radiation. At 0:02:30.200 --> 0:02:34.760 the same time, forests tend to reduce wind speeds, and 0:02:34.840 --> 0:02:38.120 all of those factors add up. Twenty nineteen review of 0:02:38.200 --> 0:02:42.120 ninety eight wooded places spread out across five continents found 0:02:42.200 --> 0:02:45.679 that forests are about four degrees Celsie's cooler on average 0:02:45.720 --> 0:02:48.600 than the areas outside of them. That's around seven degrees 0:02:48.600 --> 0:02:53.079 cooler in fahrenheit. Now, if you hate the cold, don't worry. 0:02:53.520 --> 0:02:56.680 There's a cozy exception to the rule. According to that 0:02:56.720 --> 0:02:59.880 same study, forests are usually one degree celsius or a 0:03:00.000 --> 0:03:03.519 at one point eight degrees fahrenheit warmer than the external 0:03:03.600 --> 0:03:09.960 environment during wintertime, which is pretty cool. So when does 0:03:09.960 --> 0:03:14.160 a microclimate stop being well micro? In other words, is 0:03:14.200 --> 0:03:16.720 there a maximum size we should be aware of when 0:03:16.760 --> 0:03:20.800 discussing them. It depends on who you ask, the uker said. 0:03:21.200 --> 0:03:25.120 In terms of horizontal scale, some have defined microclimate as 0:03:25.200 --> 0:03:27.720 anything that's less than a hundred meters or about three 0:03:27.800 --> 0:03:33.040 hundred feet in range. I'm personally less prescriptive about this. Instead, 0:03:33.280 --> 0:03:36.280 he says, the scales we consider microclimates at should be 0:03:36.320 --> 0:03:40.240 determined by the questions we're trying to answer. Quote, if 0:03:40.280 --> 0:03:43.040 I want to know how temperature affects the photosynthesis of 0:03:43.040 --> 0:03:46.440 a leaf, I should be measuring temperature at centimeter scale. 0:03:46.920 --> 0:03:49.000 If I want to know if and how temperature affects 0:03:49.000 --> 0:03:52.520 the habitat preference of a large mobile mammal, it's probably 0:03:52.560 --> 0:03:56.040 more relevant to capture temperature variation across tens to hundreds 0:03:56.040 --> 0:04:01.400 of meters. But yes, solitary plants have the power to 0:04:01.480 --> 0:04:06.520 generate itty bitty microclimates. Just ask Peter Blanken, a geography 0:04:06.520 --> 0:04:09.320 professor at the University of Colorado, Boulder and the co 0:04:09.440 --> 0:04:13.680 author of a book called Microclimate and Local Climate. He 0:04:13.760 --> 0:04:17.119 said via email, a single stock of corn can create 0:04:17.160 --> 0:04:20.120 its own microclimate through the shading and changes in soil 0:04:20.160 --> 0:04:23.159 properties in the immediate vicinity of the stock. For a 0:04:23.200 --> 0:04:26.239 field of corn, the microclimate created would be much larger, 0:04:26.279 --> 0:04:31.240 extending over the entire field. Many organisms eke out a 0:04:31.279 --> 0:04:34.440 living in some of the dinkiest microclimates you can imagine. 0:04:34.920 --> 0:04:39.200 Take aphids, spider mites, and leaf minor insects. All those 0:04:39.279 --> 0:04:41.840 critters are dwarfed by the plant leaves they feed on, 0:04:42.320 --> 0:04:46.680 and every leaf comes with its own microclimate. Observations show 0:04:46.720 --> 0:04:50.120 that aphids seek out cooler leaves, while those other invertebrates 0:04:50.120 --> 0:04:53.960 prefer warmer ones. Because none of these animals can generate 0:04:53.960 --> 0:04:57.240 their own body heat, leaf microclimates have a critical effect 0:04:57.279 --> 0:05:01.760 on their well being. It no secret that our planet 0:05:01.800 --> 0:05:04.320 is going through some rough times. At the macro level, 0:05:04.880 --> 0:05:07.600 the global temperature is climbing. Nine out of the ten 0:05:07.720 --> 0:05:10.479 hottest years on record have occurred since two thousand five, 0:05:11.240 --> 0:05:14.760 and by one reason estimate, roughly one million species around 0:05:14.760 --> 0:05:18.600 the world are facing extinction due to human activities. The 0:05:18.760 --> 0:05:21.800 uker said on one of the big questions that ecologists 0:05:21.800 --> 0:05:24.560 and environmental scientists are trying to answer right now is 0:05:24.680 --> 0:05:28.679 how will individual species and whole ecosystems respond to rapid 0:05:28.720 --> 0:05:33.360 climate change and habitat loss. To me, microclimates are key 0:05:33.400 --> 0:05:36.920 component of this research. If we don't measure and understand 0:05:37.000 --> 0:05:40.560 climate at the appropriate scale, then predicting how things will 0:05:40.640 --> 0:05:45.080 change in the future becomes a lot harder. Developers have 0:05:45.279 --> 0:05:48.359 long understood the impact that small scale climates have on 0:05:48.400 --> 0:05:52.000 our daily lives. Urban heat island is a term for 0:05:52.120 --> 0:05:56.440 cities that have higher temperatures than neighboring rural areas. Plants 0:05:56.480 --> 0:05:59.960 release vapors that can moderate local climates, but in city 0:06:00.000 --> 0:06:03.960 these natural greenery is often scarce, and to make matters worse, 0:06:04.200 --> 0:06:06.839 plenty of our roads and buildings are made of materials 0:06:06.839 --> 0:06:10.200 that absorb or re emit heat from the sun, and 0:06:10.520 --> 0:06:15.160 vehicle emissions don't exactly help the situation. Still, it's not 0:06:15.200 --> 0:06:19.960 like Boston or Beijing are thermal monoliths. Sometimes the documented 0:06:19.960 --> 0:06:22.800 temperatures within a single city vary by fifteen to twenty 0:06:22.839 --> 0:06:27.279 degrees fahrenheit that's eight to eleven degrees celsius. That's where 0:06:27.320 --> 0:06:30.279 metro parks and city trees come in. They have good 0:06:30.279 --> 0:06:35.400 cooling effects on nearby neighborhoods, Blanket said. Several cities around 0:06:35.400 --> 0:06:38.640 the world have developed programs to increase urban green spaces. 0:06:39.120 --> 0:06:42.120 Tree planting programs and green roof programs have been shown 0:06:42.160 --> 0:06:46.640 to lower surface temperatures, decrease air pollution, and decrease surface 0:06:46.640 --> 0:06:55.400 water runoff or urban flash flooding in urban areas. Today's 0:06:55.400 --> 0:06:58.119 episode was written by Mark Mancini and produced by Tyler Klang. 0:06:58.600 --> 0:07:00.479 Or more in this and lots of other cool topics, 0:07:00.560 --> 0:07:02.960 visit how stuff works dot com. Brain Stuff is a 0:07:02.960 --> 0:07:05.279 production of my heart Radio. Or more podcasts in my 0:07:05.320 --> 0:07:07.960 heart Radio, visit the I heart Radio app, Apple Podcasts, 0:07:08.040 --> 0:07:09.800 or wherever you listen to your favorite shows.