The 2 ° C warming in Puerto Rico caused a crash 60 times higher than the population of insects

Since the mid-1970s, the biomass of arthropods in Puerto Rico's tropical forests has increased by a factor of 60. Arthropods include insects, but also other invertebrates such as centipedes and bedbugs.

"Our findings suggest that the effects of global warming in tropical forests could be even greater than expected," said Brad Lister, lead author of the study and faculty member of the department's biological sciences department. Polytechnic Institute of Rensselaer. "Insect populations in the Luquillo Forest are collapsing and, once this has started, the animals that eat them lack food, resulting in reduced reproduction and survival, and therefore, a decrease in abundance. "

Not enough climate action

Under the Paris Agreement, more than 190 countries committed to reducing their greenhouse gas emissions to avoid a warming of 2 ° C from mid-19th century levels. Although the increase may seem moderate, the United Nations Intergovernmental Panel on Climate Change warns of serious consequences. To get an idea, even the difference between 1.5 ° C and 2 ° C warming is to produce an overall rise in sea level of 10 cm, which would be devastating for many coastal areas. In addition, the probability of an ice-free Arctic Ocean in summer is also multiplied by 10, from 1.5 ° C to 2 ° C. Most striking is that coral reefs would decrease by 70 to 90% with global warming of 1.5 ° C, while almost all (> 99%) would be lost at 2 ° C, according to IPCC authors. Special report on global warming 1.5 ° C recently concluded.

The world is already 1 ° C warmer than pre-industrial levels, with devastating hurricanes in the United States, record droughts in Cape Town and forest fires in the Arctic – if we want to act, we need to do it urgently.

But global warming is not uniform, with some parts of the world being much warmer than others. For example, the Arctic is warming faster than any other region of the Earth and is rapidly becoming a warmer, wetter and more variable environment. Over the last 50 years, the temperature of the Arctic has increased more than twice compared to the global average.

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The tropical forests of Puerto Rico are also very vulnerable, becoming 2 ° C warmer than 40 years ago. To evaluate the effects of such dramatic temperature rise, researchers at the Rensselaer Polytechnic Institute studied data on the abundance of arthropods collected between 1976 and 2013 in three mid-altitude habitats in the tropical rainforest. Luquillo, protected from Puerto Rico.

On the basis of arthropod samples taken from sticky traps on the ground and in the forest cover, biomass catch rates were multiplied by 60 between 1976 and 2013. The biomass collected at ground level at The help of a net has also decreased up to 8 times. during the same period. Cold-blooded creatures living in the tropics are particularly vulnerable to climate change because they have adapted to stable temperatures all year round.

Arthropods are at the bottom of the food chain for many ecosystems. Not surprisingly, their decline coincided with the lizards, frogs and insectivorous birds of Luquillo.

Scientists estimate that the world's tropical forests are home to two-thirds of all species. Given the dramatic collapse of Puerto Rican arthropods under a warming of only 2 ° C, the study published in the Proceedings of the National Academy of Sciences Stresses how vulnerable tropical ecosystems can be.

"Limiting global warming to 1.5 ° C, compared to 2 ° C, would reduce adverse impacts on ecosystems, human health and well-being, thereby facilitating the achievement of the United Nations Sustainable Development Goals", said Priyardarshi Shukla, co-chair of the IPCC working group. Group III.

It is still possible to keep global warming below 1.5 ° C. However, this will require unprecedented change by all stakeholders – and all of us. Another IPCC report released last week concluded that the objectives of the Paris Agreement, while a big step in the right direction, are not ambitious enough – according to current projections we will reach 1.5 ° C by 2030.

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