Postcards from Earth’s climate futures

Our world is undergoing a radical transformation.

This is the unmistakable message of the latest report on Monday from the United Nations Intergovernmental Panel on Climate Change (IPCC). Unchecked greenhouse gas emissions, mostly from burning fossil fuels, are warming the planet and altering the environment at a pace unmatched in recorded history.

But the report carries another message: Humanity can still determine how exactly our home is changed. We can continue along our current path, hurtling toward a world that is at least 2.5 degrees Celsius (4.5 degrees Fahrenheit) warmer than the one in which our civilization took shape, a world of chronic food shortages, escalating disasters and conditions too hot to survive.

Or humans can change course. It remains possible to eliminate planet-warming pollution in the next three decades and keep warming to roughly 1.5 degrees Celsius (2.7 degrees Fahrenheit) above preindustrial levels. This would avert the worst consequences of climate change and preserve a chance for people to adapt to the impacts we can’t avoid.

Drawing on the IPCC findings and analysis from outside experts, The Washington Post envisioned how three locations around the globe could be transformed depending on humanity’s emissions trajectory over the next 80 years. These postcards from Earth’s possible futures show what the world stands to lose as temperatures tick upward. They also reveal how much can still be saved.

Today, Yosemite is a sanctuary of cool conifer forests and sparkling streams. Glaciers cling to granite cliffs, and wildflower-strewn meadows flourish in places too high for trees to grow. Roughly 400 vertebrate species and more than a thousand different plants are found within the park.

But climate change is already taking a toll on this bastion of biodiversity. If humanity does not curb its carbon emissions, Yosemite’s prized landscapes will look quite different in 2100.

High emissions scenario

In the worst-case warming scenarios, snow would fall less and melt earlier from mountain slopes. The park’s plunging waterfalls and many streams would dwindle. Water levels in the Hetch Hetchy reservoir, which supplies San Francisco, would plummet.

The hotter and drier conditions could increase tree death in the Sierra Nevada as much as 50 percent. Endangered bighorn sheep, frogs and fishers, which are small carnivorous tree dwellers, could vanish from within the park’s boundaries. Bird flocks would shift northward, to be replaced by species usually found further south.

Fires would triple burned area in the region, challenging the ability of even adapted ecosystems to recover. Some conifer forests may be replaced by more drought-tolerant oak woodland.

Low emissions scenario

Warming of 1.5 degrees Celsius will still present challenges for Yosemite, but the changes will be much less drastic. In this scenario, droughts are only slightly more frequent. Fires are not as severe.

This gives park inhabitants a chance to adapt and survive. Tree mortality rates are projected to increase 20 to 30 percent rather than 50 percent. Animals can adjust their migration patterns to suit their habitat needs.

Park scientists and visitors also have a role to play, by limiting pollution, rehabilitating ecosystems and restoring natural forces that have been disrupted by human activities.

Depending on how much humans continue to emit, climate change is projected to put between 9 and 13 percent of species worldwide at high risk of extinction. Wildfire frequency could increase in up to two-thirds of Earth’s land area. And more than 30 percent of terrestrial ecosystems could undergo major climatic shifts.

To Sarah Stock, a National Park Service wildlife ecologist, confronting this crisis means embracing change. “Biologists used to manage species and their habitats by mimicking past conditions, and that strategy just isn’t an option any more,” she said.

Counterintuitively, fire is one of her greatest tools for protecting the park’s imperiled ecosystems. Like much of the American West, Yosemite’s forests evolved to endure periodic blazes, which cleared clutter from the understory and opened up space for new trees to grow. Misguided federal policies suppressed natural fires for a century, meaning the hotter and drier West also has more fuel to burn.

But by setting controlled low-intensity fires within the park, Stock and her colleagues are recreating the natural “fire regime” by enhancing the overall resilience of the landscape. The strategy has already borne fruit, lessening the destruction from a wildfire that burned through an important owl habitat in 2013. The following year, the owls returned, making their nests in the patchwork of forest that survived.

“We can’t just set aside these places and expect them to be insulated from global changes,” Stock said. “But we can buffer our habitats, our forests, our meadows, from the effects.” When it is given the chance, she added, “I’ve gotten some glimpses of how resilient nature can be.”

Lagos embodies the perils and possibilities that cities face as the planet warms. A booming economy and bustling lifestyle make it a magnet for the ambitious, the artistic and the aspiring.

But the surging Atlantic is eroding beloved beaches, and rising heat threatens to suffocate vibrant neighborhoods. This city, projected to become the world's biggest by the end of the century, will be shaped by the degree of global temperature rise and Nigeria’s capacity to respond.

High emissions scenario

The worst-case scenario would spell enormous suffering for people in Lagos and across West Africa. Exposure to extreme heat would increase more than 100-fold.

Monsoon rains would be delayed but more intense, threatening farmers first with drought and then with catastrophic floods. Yields of staple foods such as maize would decline, putting millions of people at risk of starvation.

These crises could drive migration into the city, exacerbating housing shortages and pollution problems. Worsening floods would continue to batter neighborhoods, displacing residents and creating opportunities for diseases to spread.

Low emissions scenario

Cities such as Lagos are safer and healthier in a world only 1.5 degrees warmer. The avoided air pollution alone would save some 300,000 lives annually and cut global extreme heat exposure by 85 percent.

Local farmers could withstand wild weather by diversifying the crops they cultivate. Agroforestry, or the practice of growing food amid a natural ecosystem, would protect biodiversity and promote carbon storage in trees while helping to feed a growing population.

Lagos’ climate action plan calls for planting trees, installing solar panels and curbing the use of polluting generators. A public transit system would ease traffic and reduce planet-warming fumes, while upgrades to the city’s wastewater systems could lessen flood damage and prevent disease outbreaks.

Nigerian activist Philip Jakpor doesn’t need to read the IPCC report to know that climate change will be catastrophic for his home. As director of programs for the social justice nonprofit Corporate Accountability and Public Participation Africa, he has borne witness as coastlines disappear and farmland turns to desert. He has seen floodwaters displace millions of his countrymen and watched rotting fish wash up by the thousands along polluted coasts.

“People live in fear, real fear,” said Jakpor, who is also a volunteer with the advocacy group Environmental Rights Action. “There is going to be a lot of conflict. There is going to be hunger. You will have millions of people scrambling over a few areas of arable land.”

Curbing carbon pollution would preserve a vital chance for vulnerable people to cope. Africa will need to spend five to 20 times as much money adapting to 4 degrees Celsius of warming, compared to the cost of coping with warming of 1.5 degrees Celsius.

Yet African nations contribute no more than 3 percent of the world’s annual warming emissions. Even Nigeria, a major oil and gas producer, doesn’t have the economic clout to shift Earth’s warming course or adapt to change on its own. The future of Lagos depends in part on wealthy countries and large corporations shifting away from fossil fuels and providing financial support to help low-income countries become safe and sustainable, Jakpor said.

Despite a flurry of pledges to reduce emissions to “net zero” by the middle of the century, research shows that the world’s biggest emitters have not taken the near-term steps needed to secure a livable planet. The IPCC report makes clear that achieving the Paris climate agreement goals will require a major transformation of the global economy, not over the course of decades, but in the next few years.

“We are not waiting for the year 2100. We are not waiting for the year 2050,” Jakpor said. “We believe the time for action should be now.”

The Republic of the Marshall Islands is a sprawling collection of coral atolls and islands in the middle of the Pacific Ocean, home to roughly 60,000 citizens. Its inhabitants have lived on the low-lying islands for thousands of years, separated from the rest of the world by vast ocean.

In few places does climate change pose such an existential threat. Rising seas, worsening heat and other impacts threaten to inundate communities, upend livelihoods in farming and fishing and force residents to consider migrating.

High emissions scenario

If the world continues on its current emissions trajectory, many islands could eventually experience flooding driven by waves across their entire surface every year. Saltwater will intrude into aquifers, threatening fresh water supplies throughout the Marshall Islands.

If sea levels rise one meter, a World Bank study found, nearly 40 percent of buildings in the capital of Majuro could face “permanent inundation” without efforts to adapt. At two meters, that number spikes to 94 percent, said Artessa Saldivar-Sali, a World Bank senior municipal engineer. Adaptation measures may become inadequate, forcing expensive and painful relocations.

Warming oceans could translate to a decline in the fisheries. A combination of heat, rising seas and extreme weather could shrink yields for sweet potato, taro and other crops.

Low emissions scenario

At 1.5 degrees of warming, significant changes will still happen. Even a half meter of sea level rise could cause about 10 percent of buildings in Majuro to flood, Saldivar-Sali said, but the future is more livable for many small island states.

Some coral reefs would still vanish. Fishermen will still see a decline in their catches. Yet hunger wouldn’t be as widespread, and far fewer islanders would experience severe water resource stress.

But the nation is actively working to prepare for what lies ahead. Adaptation measures under consideration include everything from developing warning systems and investing in ecosystem restoration to building sea walls, elevating buildings and reclaiming land.

Some approaches are more extensive and expensive than others. Some are meant to protect vulnerable coastlines from rising seas, while others are meant to move key infrastructure out of harm’s way. Leaders in the Marshall Islands are looking at a broad range of measures as part of a national adaptation plan. “We call it our ‘national survival plan,’” said Tina Stege, the Marshall Islands climate envoy.

In addition to rising seas, which are the most urgent threat facing her nation, Stege said intensifying rainstorms, as well as extended drought, have wreaked havoc for farmers in the island nation. Saltwater intrusion threatens drinking water sources. The warming climate has brought the threat of increased disease outbreaks such as dengue.

“That’s the thing about climate change. It’s not just one thing. It’s everything together,” she said. “It’s an onslaught of different things.”

Like other island nations that have insisted warming beyond 1.5 Celsius threatens their very existence, the Marshall Islands faces potentially agonizing changes ahead.

“We’re talking about how we are going to survive. We are accepting that what we look like in 50 years is different than what we look like now, under any scenario,” Stege said. “We will have to transform. That’s a really tough conversation.”

But standing on the front lines of climate change, she insisted, the Marshallese people have never wavered in their resilience.

“What we’ve said as a community and a nation is we are committed to being there. We are not accepting a future in which we don’t exist.”