Where have all the species gone? Understanding climate change’s toll on nature » Yale Climate Connections

A tiny flying fox, cheery yellow warbler, and freshwater mosquitofish recently lost protection under the U.S. Endangered Species Act, and not for good reason. They’d been declared extinct.

They are among the 21 species to lose federal protection as the result of nationwide extinction, a harbinger of more loss to come amid the increasing destruction of climate change.

Among the delisted species were Guam’s Little Mariana fruit bat and the endemic San Marcos gambusia fish of Texas. Eight species on the list were Hawaiʻian birds.

Hawaiʻi has been called ground zero for the loss of biodiversity – or a healthy mix of species, genetic heritage, and ecosystems. Of the nearly 1,300 species protected under the U.S. Endangered Species Act, which includes plants and animals, an outsize number live on the Hawaiʻian Islands.

In the 20th century alone, the rate of species extinction has been on par with previous mass extinction events. Animals have disappeared at a rate of 30 to 120 times that of any other point in the last 66 million years.

The main driver of biodiversity loss is land conversion, mostly from forest or prairie or wetland to agriculture – humans have already altered 70% of land on Earth not covered by ice. Humans have also polluted and allowed invasive species to spread in ways otherwise impossible. Recognizing this driver means we already know one solution: Protect land in a range of ways, from creating nature preserves to establishing policies to stop deforestation.

But now climate change is amplifying an already precarious situation. And that complicates the solution, too.

The compounding effects of climate change on biodiversity loss

A study published in the journal Global Change Biology in 2024 estimated that an additional 17% of Earth’s species will be lost as a direct result of climate change.

Earth has already warmed by about 2°F since the Industrial Revolution. What does that have to do with plant and animal life? Everything.

Forty percent of Arctic sea ice has melted since the late 1970s, and nearly 60% of the world’s ocean surface endured at least one marine heat wave in 2021 alone. If the current rate of ocean warming continues, the United Nations predicts that all coral reefs – the most biologically diverse ecosystems on the planet – could bleach by the end of this century, devastating marine life of all kinds.

On land, forests are weakened by periods of intense drought. Climate change is worsening the spread of invasive species, and native species are forced to move to higher latitudes or higher altitudes to escape increasingly warm temperatures. A shifting climate is altering the weather patterns that have kept ecosystems functioning for millions of years. The speed of climate change is already making it harder for many species to adapt to and thrive.

And this is only the beginning of climate impacts to come. In the 2023 Global Tipping Points report, scientists warned that as Earth heats, the planet is becoming dangerously close to passing important natural thresholds that would cause irreparable damage to ecosystems and human life. These include melting ice sheets and permafrost in the Arctic, the destruction of coral reefs, and the collapse of the Atlantic Meridional Overturning Circulation, powerful currents that circulate water between the Atlantic Ocean and the Arctic.

Read: Atlantic circulation collapse? New clues on the fate of a crucial conveyor belt

To learn what it may take to help avert the worst-case climate impacts on animal and plant life, researchers are diving deeper into the links between climate change and biodiversity. For example, a team of conservation biologists recently analyzed climate and biodiversity models from 1900 to 2050. Published in Science, their paper compared how land use change affected biodiversity in the past and how such scenarios may play out in the future depending on factors like land protection policy and greenhouse gas emissions reductions.

The results offer reason for both optimism and alarm.

In models where climate change was not considered, existing and prospective land protection efforts were shown to help slow or even reverse biodiversity loss in the next few decades. That’s a powerful case for continuing to implement practical land protection policy.

But when climate change is accounted for, their research found that curbing biodiversity loss becomes far more challenging, with higher emissions leading to greater damage across species and ecosystems alike.

This will have a profound impact on human life, too. One reason? As climate change continues, many scientists think communities will need to lean more heavily on healthy ecosystems to stay resilient amid the escalating impacts. For example, in coastal areas, people may depend on saltwater marshes to act as buffers against sea level rise.

What can the world do to reduce biodiversity loss and climate change?

There are real things humans can do to soften the blows of climate change and biodiversity loss. In a paper published in BioScience, Brazilian scientists suggest a few key ways forward:

• Conserve carbon stocks and sinks by protecting land and ocean, both systems that have historically stored over half of humans’ historical emissions, naturally. In particular, the researchers pointed to the Amazon, Congo Basin, and Southeast Asia as incredibly biodiverse ecosystems that are also some of the largest natural carbon storage areas on Earth.
• Stop expanding agricultural land. Almost 40% of Earth’s land is used for agriculture, a major source of land conversion that has decimated nearly 20% of the Amazon rain forest. Creating policies that confine agriculture to land that has already been converted to farmland would preserve biologically rich places that often double as sites of natural carbon storage.
• Incorporate biodiversity into business models. Companies regularly promote themselves as holding values and goals related to protecting nature, and corporations are increasingly attaching themselves to science-based targets for climate action. But these plans often lack specific goals tied to biodiversity.

The power of willpower in fostering biodiversity

The situation is urgent, but all is not lost. In a recent perspective piece in Philosophical Transactions of the Royal Society B, ecologist Erle Ellis argues that humans underestimate the power of aspirations, specifically those related to changing how people interact with nature. In other words: We can devise solutions to the problems we humans have created.

“When these transformative capabilities to shape environments are coupled with sociocultural adaptations enabling societies to more effectively shape and live in transformed environments, the social-ecological scales and intensities of these transformations can accelerate,” Ellis writes.

Right now, for example, researchers from across Canada, the United States, and Mexico are working on the Biodiversity and Climate Change Assessment, a project that will help identify meaningful ways forward.

The next big step will be to merge the power of aspiration with the science to help map the land- and climate-based solutions it will take to protect as many species as possible – including the human one.

James Arnott is Executive Director of the Aspen Global Change Institute. Kaitlin Sullivan is a freelance journalist. She covers health, science, and the environment. This article was produced in partnership with Energy Innovation and the Aspen Global Change Institute. Both organizations are Yale Climate Connections content-sharing partners.