Tropical forests may be getting too hot for photosynthesis

Subject: Environment

Section: Ecosystem

Context:

A small percentage of leaves on trees in tropical forests may be approaching the maximum temperature threshold for photosynthesis to work, suggests a study.

Study findings:

The study indicated a resilience of tropical forests to how warming impacts carbon uptake and long-term drought.
Tropical forests serve as critical carbon stores and host most of the world’s biodiversity and may be particularly sensitive to increasing temperatures.
The critical temperature acts as an absolute upper limit.
The critical temperature beyond which photosynthetic machinery in tropical trees begins to fail averages at about 46.7 degrees C.
Modeling suggests that tropical forests can withstand up to a 3.9 degree C increase over current air temperatures before a potential tipping point.
An estimated 0.01% of all leaves currently surpass this critical temperature but there are uncertainties in the range of potentially critical temperatures in tropical trees.
In addition to temperature increase caused by global warming, deforestation and fragmentation can amplify local temperature changes.
The combination of ambitious climate change mitigation goals and reduced deforestation can ensure that these important realms of carbon, water and biodiversity stay below thermally critical thresholds.

Tropical rainforests:

Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as lowland equatorial evergreen rainforest.
True rainforests are typically found between 10 degrees north and south of the equator.
They are a subset of the tropical forest biome that occurs roughly within the 28-degree latitudes (in the equatorial zone between the Tropic of Cancer and Tropic of Capricorn). Within the World Wildlife Fund’s biome classification, tropical rainforests are a type of tropical moist broadleaf forest (or tropical wet forest) that also includes the more extensive seasonal tropical forests.