The tropics are more sensitive to extreme weather than anyone thought

As reported by Stanford University, USA (https://earth.stanford.edu/) in late April, the Amazon’s carbon balance is capable of changing remarkably quickly when faced with heat and drought. It looks like tropical ecosystems are more sensitive to climate change than anyone thought, and it’s worrying news as CO2 and other greenhouse gas emissions continue to increase.

About land systems and CO2

Land ecosystems breathe CO2 when they grow and decay. The amount of gas they take up and release delivers vital insights into the way the systems react to climate change. Tropical forests have a remarkable potential to stash and release carbon, which means tropical regions and ecosystems play a huge role in regulating the planet’s overall climate.

Analysing CO2 and weather data

The team from Stanford analysed data combining information about the weather data with CO2 measurements from air surveys. They were looking at the amount of atmospheric carbon exchange taking place across the Amazon basin, noting the sources of CO2 in the rainforest every month for three years and covering an area measuring several million square kilometres.

The powerful 2010 drought plays a part

During 2010 a nasty drought plus unusually high temperatures hit great swathes of the Amazon basin, but things had returned to normal a year or two later.  The shift was alarmingly quick, revealing that the region changes fast in response to climate changes. As the report said: “Heat anomalies during the wet season are strongly correlated with increased carbon loss in the same month, and lower-than-average rainfall during the wet season is correlated with increased carbon loss in the following month.”

We already knew the 2010 drought caused massive carbon loss in the Amazon. But the new study let scientists analyse the carbon and climate conditions in different areas of the region as the drought spread and evolved. The results revealed how lost carbon might have preceded the drought, when the climate was unusually hot but hadn’t yet become unusually dry.

Climate change set to make things worse

There’s strong evidence that the Amazon is already experiencing dramatic hikes in heat, and experts predict ongoing climate change will make things even worse. It doesn’t matter how much levels of rainfall change, since the region could be even more vulnerable to heat stress than anyone thought. And it means tropical rainforests could take several years to recover from a big drought.

Why does it matter?

The Amazon ecosystem plays a crucial part in the world’s climate and carbon system, as well as being home to a unique level of biodiversity. We still don’t know enough about the interactions between tropical carbon and the climate, but we do know they can have a profound effect on the planet’s climate. Knowing more will help scientists ‘resolve major unknowns’, to everyone’s benefit.

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