DAILY SCIENCE

As the climate changes, protecting more land will not necessarily preserve more biodiversity
But protecting currently underrepresented types of land might.
June 24, 2020

Imagine you are an American pika, living on a mountain peak in Crater Lake National Park. The park is great: full of tasty grass and wildflowers, and (for now) protected from drilling, hunting and development. But the park is getting warmer, and you don’t like hot weather — if you get too hot for even a few hours, you might die. As the years pass, where will you and your descendants go?

Across the world, protected areas—from national parks to wildlife sanctuaries — keep countless creatures safe from immediate anthropogenic threat. But we can’t bar climate change. In the coming years, as temperatures and precipitation levels shift, many of these places may become uninhabitable for the species they’re meant to safeguard. Writing in Science Advances, a group of researchers lays out the climate conditions currently represented in protected areas, and how those conditions are expected to change over time. They also present some ideas for maintaining a diversity of climate types within these areas, in order to maintain biodiversity in turn.

The researchers focused on two particular climate metrics: annual mean temperature and annual precipitation. The intersection between these metrics tends to define biomes: a space that is both hot and dry is likely preferred by desert creatures, while a warm, wet space may be a rainforest, and so on. They used this schema to quantify currently available climate space — first for countries as a whole, and then for the protected areas within those countries.

In this way, they were able to figure out “the distribution of available climate and its representation within global terrestrial protected areas,” they write — in other words, whether a country’s protected areas are representative, climate-wise, of that country as a whole. (They call this measure “protection evenness.”) They then projected into the future, using climate models to predict how these temperature and precipitation distributions may change over the next decades. 

Globally, the forecast is different for different habitat types. For example, “the amount of protected land occurring in warm and cold climates over a wide range of annual precipitation is expected to decline substantially over the next 50 to 100 years,” they write. This could be bad news for ecosystems that thrive in these conditions, including broadleaf forests, grasslands, shrublands, and tundras. On the other hand, hot and cool climates — which tend to support biomes like deserts and temperate rainforests—will likely gain more ground within protected areas, they write, “highlighting potentially favorable outcomes for species and ecosystems adapted to these portions of climate space.”

More broadly, though, the amount of currently protected climate that will remain protected in the future is quite low. More than half of countries “are expected to fail to protect >90% of their available climate at current levels,” the authors write. This is especially true for smaller countries, and countries whose climates are changing more quickly. But countries with a high protection evenness will have better luck.

As the authors point out, this suggests that simply protecting more land will not necessarily preserve more biodiversity in the future—but protecting currently underrepresented types of land might. Countries looking to create more conservation land and national parks “should consider how newly protected land would act to conserve biodiversity over time, in addition to how it would capture current patterns of biodiversity,” they write.

When choosing what land to protect, we are used to thinking about time: the past and its legacies; the present and its availabilities. We need to think more about the future, too.

Source: Elsen, Paul et. al. “Keeping pace with climate change in global terrestrial protected areas.” Science Advances, 2020.
Image: Frédéric Dulude-de Broin/Wikipedia

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