A 4°C warmer world “will be catastrophic” for forest biodiversity: expert

Will species be able to survive in 4 degree hotter world? Daniel Tiveau/CIFOR

BOGOR, Indonesia (8 January, 2013)_Global temperatures may be climbing at a rate too fast for our forests and its biodiversity to adapt, a scientist with the Center for International Forestry Research (CIFOR) warned after the World Bank predicted a 4°C warming of the planet if policymakers continue to be apathetic about greenhouse gas emissions.

“The long-term effects will undoubtedly be catastrophic,” said Terry Sunderland, CIFOR principal scientist specialising in biodiversity.

“Everything will become imbalanced and whole ecosystems will be lost.”

The World Bank report, Turn down the heat: Why a 4°C Warmer World Must be Avoided provides an overview of risks and analyses associated with changes in climate. It says large concentrations of carbon dioxide will accelerate geographical shifts, with increased drought in some areas, greater rainfall in others and the continued acidification of oceans.

That will significantly reduce plant and animal species richness and species turnover.

Of 5,197 African plant species, for instance, 25-42 percent could lose all suitable range by 2085, according to the report, and there is a risk of herbivore extinction in regions affected by drought.

“In higher latitudes, a warmer climate will shift ecosystems to those suited to less temperate and more subtropical environments,” Sunderland said.

“The problem with this process, when compared to natural climate change, as we have seen in the past, is the sheer speed of change.”

The Earth’s atmosphere and oceans have been warming since the late 19th century due largely to the burning of fossil fuels, the clearing of forests and other carbon dioxide-releasing activities by humans, scientists have said.

CIFOR research has found that natural forest cover loss is a primary cause of biodiversity loss. Even natural forest in protected areas is at threat, the study shows, advising environmental projects to be mindful of activities that could potentially draw resources away from more critical actions.

The global community has in recent years committed to hold warming below 2°C, which the Cancun agreements codified in 2010, and small island developing states and least developed countries have recognised that even a 1.5°C jump would cause severe harm to their development and, in some cases, survival.

Even now, direct anthropogenic activities are having a devastating impact on the world’s remaining wild places and wild lands.

“Factor in climate change and we have a perfect storm of biodiversity loss and extinctions,” Sunderland said.

“We must also remember that extinctions don’t happen to isolated species, but have major cascade effects across the entire system.”

It is becoming increasingly likely that invasive species that are more opportunistic and adaptive will become common, he added, and we may witness a homogenisation of nature, with a few highly fecund pioneer species dominating global ecosystems.

“Size will provide some resilience to change, but as we are diminishing most ecosystems to isolated pockets or islands, these will be the first to become affected and likely disappear.”

Sunderland says the larger contiguous regions in the tropics such as Congo Basin, Amazonia and Borneo will be more resilient, but will still experience mass extinctions as the climatic regime shifts, probably to a drier climate than we have seen in the past.

“The remaining forest, if we are lucky, will be isolated to ‘refugia’,” he said, “where rainfall patterns are sufficient to maintain humid tropical forests.”

Likewise, the vast temperate Boreal forests may be lost in the name of agricultural expansion.

This will start happening with greater frequency “as prevailing climate in higher latitudes becomes more suitable to large-scale crop production – especially as other regions become too dry to support commercial agriculture, such as continental US and Australia,” Sunderland said.

Mangroves, which provide vital ecosystem services, are also under great threat of a fast changing climate, he said.

“Sea level change will basically wipe out the majority of the mangrove ecosystems.”

This will affect the fisheries industry as mangroves are the nurseries for many fish species and thus also livelihoods. Mangroves also purify the water of silt, waste and nutrients, to provide clean water that coral reefs – which provide the habitat for around one third of our marine species and hold organisms with many medicinal properties – need. Mangroves further act as a buffer between the sea and the land in times of extreme weather events.

“Without biodiversity, we lose the ecosystem services it provides, direct provisioning services, dietary diversity, nutrition, medicines, crop relatives – the lot,” Sunderland said.

“And once it is gone, there is no going back.”