Art is made of natural materials. Stone. Pigment. Wood. Clay. Fibers.

And metals. Even water, fog, and ice. And it's also made of stuff that is seemingly less natural but still made from things we derive from the earth.

Art is also notoriously difficult to preserve. We devote considerable resources to keeping a selection of it secure, at the perfect temperature and humidity, so that it has a fighting chance of outliving us mortals. And we fail at these efforts all the time.

Some works can't be put in a museum, or shouldn't be. Great wonders of the world crumble, masterpieces fade, and the paths of glory lead but to the grave. But art is also the stoic residue of humankind's unstoppable urge to create, to--forgive another poetry reference--rage against the dying of the light.

The things humans make come from the earth and are also highly susceptible to it. Art can help reveal the world around us, frame it, amplify it, and also highlight our precarious relationship to it. This is the fourth of five videos focusing on a much-discussed aspect of life today, and looking back to see how people from the past have made artworks and objects that speak to it in some way.

This time, we look at art and climate. First we're going to look at some very special maps that bear little resemblance to the digital kind I'm completely reliant upon and can't get anywhere without. The objects we're going to look at come from the Marshall Islands, which consist of more than twelve hundred islands in eastern Micronesia and span more than 700,000 nautical square miles.

As you'll notice, what joins them is the sea. And it was an exceptional ability to navigate that sea that first brought humans to these islands thousands of years ago, and it's what has linked them together to this day. Called “meddo” or “rebbelib”, these are navigational charts made from bamboo or palm leaf sticks and tied together with twine.

Shells are tied on to indicate islands. But this isn't a map of land, it's a map of water, an ingenious way of charting ocean currents and the interaction of swell patterns in the waters that link the islands together. Each chart is unique, showing the way an individual seafarer understood the bodies of water they were familiar with.

They're mental maps to help navigators memorize the sea, constructed and consulted on land, and left on shore when their journeys began. The charts were used to plot and communicate routes, and pass along knowledge gleaned over generations. Understanding the sea has always been critical to life on the Marshall Islands, and these charts encompass a vast amount of information necessary for survival.

Some of these were collected by visitors to the islands and made their way into museums and public collections, where they are appreciated for their formal beauty and elegant synthesis of complex information. But for the Marshallese these charts are much more than that, not only illustrating the relationship between land and sea so integral to life, but also coming to represent identity for people who have faced considerable hardship and acute threats their ways of life. After occupation by a number of foreign powers over centuries, the Marshall Islands were seized from Japan by US Forces in 1944, and then famously became the site for nuclear testing on Bikini Atoll from 1946 to 1958.

Today the Republic of the Marshall Islands' most urgent threat, along with continued contamination from testing, is climate change, with global warming and rising sea levels imperiling their very existence. Art has long captured the tremendous beauty of earth and its climate, as well as its variability and our powerlessness to it. You can think about the Katsushika Hokusai's Under the Wave off Kanagawa, part of his polychrome woodblock series of prints titled “Thirty-six views of Mount Fuji.” Each image gives us at least a glimpse of the mountain, and in this particular print we see it in the distance as a giant wave occupies much of the foreground, about to crash down upon three fishing boats and their occupants.

While scientists think it was not a depiction of a tidal wave and instead just a rogue wave caused by high winds in an area notorious for its rough seas, the image has nonetheless been called upon to represent a host of natural disasters. But in its essence, The Great Wave, as it's come to be called, embodies our struggle both to harness the natural forces of earth, and protect ourselves from their ravages. Artists have well documented the extremes of our climate, as well as average temps and beautiful vistas.

And yes, I know that weather is weather, and climate is the weather conditions that happen over a long period or in general. But artists have done a tremendous job of recording our climate--and our effects on it. Dorothea Lange's unforgettable photographs of the Dust Bowl in the 1930s, when dust storms wreaked havoc through much of the United States due to misguided farming methods and nearly decade-long drought.

Pieter Bruegel the Elder's paintings do a good job of showing us the climate shift that occurred between the 16th and 19th Centuries that we now refer to as the “Little Ice. Age.” His painting Hunters in the Snow from 1565 offers us a scene of regular people going about winter life in a rural village. Bruegel was Flemish but the scene isn't terribly faithful to the landscape of the.

Low Countries, what with the topography of this valley and the steep mountain faces in the distance. But what he does capture very effectively is COLD, with three bundled up hunters, heads down, trudging home with their dogs through the snow. In the mid-ground we see skaters on a frozen pond, pulling each other, playing games, and yes also falling.

It's one of a number of winter landscapes painted by Breugel, a genre for which he's well known, and one of six paintings that form a cycle describing the seasons of the year and the various labors associated with it. There had been a long tradition of portraying the months of the year and the activities that go along with them, a chronicling of the succession of seasons that many artists would continue to investigate. Claude Monet painted the haystacks near his home in Giverny, France, numerous times between 1890 and 91, showing the same subject appearing vastly different depending on the shifting light and seasons.

But the climatic shifts that Bruegel gives us a window onto were not merely cyclical. This picture was painted during the coldest winter of the 16th century. The Little Ice Age, which was not extreme enough to be called an actual “ice age,” nonetheless led to food shortages and famine, and we can see increased rates of illness and suicide during this time as well.

But Bruegel's painting shows us the everyday amid this larger shift, the hardships as well as the lighthearted moments of play. But just as climate shapes the kind of art being made, climate also of course shapes art itself--because art is both of the world and in it. And so often, to preserve valued works and structures, communities must frequently rebuild them.

Located in central Mali, the Great Mosque of Djenné, is the largest mud-built structure in the world. Its first iteration is thought to have been constructed in the 13th century, commissioned by Djenne's first Muslim sultan. And the town is located in the Sahel, the transitional grassland between the Sahara desert to the north and the savanna to its south.

Djenne's traditional mud brick architecture requires constant upkeep and re-plastering, with every rainy season washing away plaster and eroding the brick. After considerable deterioration to the first mosque, a second was built between 1834-35, and a third was completed in 1907. Over the centuries the size, layout, and design evolved and adapted, but the basic technique and distinctive style remain linked to the original, with an annual replastering festival still happening to this day.

Every April before the rainy season,  the entire town participates in the work of adding a new layer to the mosque's exterior. Usually the women provide water to make the mud mixture, while the men do the actual mixing and application, using the timber beams that extend from the mosque's exterior to help climb it. All around musicians perform and elders watch and give advice, the entire event a celebration of their faith, community, and cultural heritage.

Investors have offered to modernize the building, remaking it in concrete, but those efforts have been resisted, despite the mosque being under near constant threat not just due to the climate of Mali, but also more frequent flooding of the rivers that surround it, as well as encroaching violence and political unrest. This great mosque has always been fragile, always contingent on perpetual maintenance, and its existence will continue to rest in the hands of its caretakers. The keepers of the Ise Shrine in Japan's Mie Prefecture have taken a different approach to the preservation of their holy site.

Called “Jingu,” it's a complex of 125 Shinto shrines, including one dedicated to. Naiku, the sun goddess. Thousands of rituals unfold here each year, but every twenty years a ritual takes place here called Shikinen Sengu, in which the shrine of Naiku is completely reconstructed directly adjacent to the current one.

And it's been happening for around 1300 years. The process begins with the ritual cutting of the first trees for the new shrine, and takes about 8 years to complete, concluding with the transfer of the Holy Mirror from the old site to the new. Locals take part in transporting the timbers and other ceremonies to mark the relocation.

The tradition keeps the community bonded to the site, shields the shrine from the inevitable effects of aging, preserves the original design, and--perhaps most importantly--keeps the skills of artisans alive, imparting techniques to the next generation each time. Emerging from the Shinto conceptions of death, renewal, and the impermanence of all things, this ritual allows the shrine to survive through continual reframing and rebirth. It's a whole different task to protect an entire city from the eroding effects of our climate.

Venice, Italy's location at the top of the Adriatic Sea makes it vulnerable to natural flooding, when winds push water into the lagoon on top of which the city was built, a process that started around the first century CE. Today, the city's dwindling population of permanent residents is well acquainted with the aqua alta, or the high waters that routinely push into the city and flood its famous and less famous squares, and then recede again. But this flooding has become increasingly frequent and the average water level has risen, due to both the sinking of the land and the rising of sea levels due to climate change.

Many factors contribute to Venice's fragile state, including the hoards of tourists dropped off here daily from cruise ships whose traffic and wakes erode the city's foundations. Project Mose is a massive civil engineering effort underway to construct a sea wall designed to lift on command to 10 feet above the water and protect the lagoon from high tides. The project is not yet complete and must balance numerous aims, including the preservation of salt marshes, mud flats, marine life, and the entire lagoon ecosystem.

And yet there aren't any other good options, not really, with the Mediterranean Sea projected to rise up to five feet before the year 2100. The architectural marvel that is Venice, full of cultural treasures spanning centuries, has depended on engineering ingenuity since its founding, and will continue to for as long as it exists. Sometimes, nothing can be done to protect our cultural heritage except completely closing off access to them.

The magnificent cave paintings in Lascaux, France, were created approximately 15,000 years ago, and only rediscovered in 1940. The survival of these depictions of prehistoric wildlife, human like figures, and abstract designs, was made possible by the uniquely dry surface of white calcite rock, upon which our unknown artists applied charcoal and ochre. The Lascaux caves were open to the public from their discovery until 1963, and many understandably flocked to experience this astounding immersive work of art.

But the delicate environment of the cave was thrown off by the number of visitors, whose exhaled breath changed the cave's chemistry. Mold and lichens began to grow, putting the paintings at risk. While the cave has indeed been closed to the public, you can still visit replicas close to the original site.

To experience their beauty and appreciate all that we don't know about these paintings, we must look at photographs and footage, and accept the replicas, with the assurance of knowing that these remarkable creations are safeguarded from the damage we humans cause even when we try hard not to. And then there are the artworks created to reveal and highlight the fluctuations of our climate, like Robert Smithson's Spiral Jetty. Extending off of Rozel Point peninsula on the northeastern shore of the Great Salt Lake in Utah, Spiral Jetty was constructed over the course of a week in April of 1970.

Smithson hired a construction crew to move over 6000 tons of earth and black basalt rocks from the shoreline to form a coil 15 feet wide and 1500 feet long. At the time, the water level of the lake met the edge of the coil, but it became submerged only a couple of years later. It remained mostly underwater until 2002 when drought caused it to reemerge.

It's been visible since then, often with water far off in the distance, and it's appearance shifts dramatically depending not only on water level, but also the microbes and algae that can turn the lake a reddish color, as well as the salt from the lake that encrusts the jetty. It's here than you can contemplate geologic time, when the pocked surfaces of the jetty's basalt rocks were formed by gases trapped in erupting lava. And also the origin of the lake itself, a shallow remnant of Lake Bonneville, which during the Pleistocene Epoch covered the entire western half of Utah and beyond.

Spiral Jetty emerged from Smithson's preoccupation with the idea of entropy, and he understood that the work would exist in a state of constant transformation, it's form never fixed and susceptible to decay from the moment it was created. Earth's climate has changed throughout its existence, with numerous cycles of glacial advance and retreat. But we know for sure that our planet is getting warmer, and at an alarming rate.

Most of our warming has occurred in the last 35 years, with the five warmest years on record taking place since 2010. The rate of Antarctica ice mass loss has tripled in the last decade, and glaciers are retreating almost everywhere around the world. And we also know this warming is  largely driven by increased carbon dioxide and other human-made emissions into the atmosphere.

A number of artists working today make art that speaks to our changing world. Zaria Forman paints retreating glaciers, inspired by flights she took with NASA's operation. IceBridge.

Olafur Eliasson transported 30 icebergs from Greenland to London and presented them in front of Tate Modern, where visitors could touch and interact with ice blocks that had detached from the Greenland ice sheet, from which a thousand similar blocks of ice detach every second. Mel Chin's Unmoored offered us views through a mixed-reality app exploring a potential future of rising oceans filling Times Square. The world we live in and the objects we make to put into it are fragile.

Art can help us appreciate our planet and its climate, reveal to us its workings, and visualize imminent futures. What are the works of art and architecture and objects that help you better understand our planet and its shifting climate? Let's talk about them in the comments.