New Study Links CO2 Increase to Rainfall Changes, Impacts on Biodiversity Hotspots

Sub: Environment

Sec: Climate Change

Context:

Research by scientists from the Birbal Sahni Institute of Palaeosciences (BSIP) suggests that evergreen forests in the Western Ghats, northeast India, and the Andaman Islands may be replaced by deciduous forests due to these climate shifts.

Details:

Rising greenhouse gas levels could significantly alter rainfall patterns in equatorial regions, potentially transforming India’s biodiversity hotspots.
The study examined fossil pollen and carbon isotope data from the Eocene Thermal Maximum 2 (ETM-2), a period of global warming that occurred approximately 54 million years ago.
This era serves as a potential analogue for future climate scenarios, offering valuable insights into the effects of increased atmospheric carbon dioxide on tropical ecosystems.

Research Focus and Findings:

Researchers focused on the Panandhro Lignite Mine in Gujarat, which provided a unique opportunity to study vegetation-climate relationships near the equator during the ETM-2.
Analysis of fossil pollen revealed that when atmospheric CO2 concentrations exceeded 1000 ppmv near the paleo-equator, rainfall decreased significantly, leading to an expansion of deciduous forests.
The study raises important questions about the survival of equatorial/tropical rainforests and biodiversity hotspots under increased carbon emissions.
It helps understand the relationship between CO2 and the hydrological cycle and aids in the future conservation of biodiversity hotspots.

Deep-Time Hyperthermal Events as Climate Analogs:

Deep-time hyperthermal events are considered potential analogues for future climate predictions. However, data on these hyperthermal events are mainly known from the mid- and high-latitude regions.
There is a lack of quantitative data from the equatorial or tropical regions.
Researchers from BSIP, an autonomous institute of the Department of Science and Technology, used fossil pollen and carbon isotope data from the ETM-2 to quantify the terrestrial hydrological cycle during that period.
During the ETM-2, the Indian plate lingered near the equator during its journey from the southern to the northern hemisphere, making it a perfect natural laboratory to understand the vegetation-climate relationship near the equator.

Biodiversity Hotspots:

There are currently 36 recognized biodiversity hotspots. These are Earth’s most biologically rich—yet threatened—terrestrial regions.
To qualify as a biodiversity hotspot, a region must meet two strict criteria:

It must have at least 1,500 vascular plants as endemics — which is to say, it must have a high percentage of plant life found nowhere else on the planet. A hotspot, in other words, is irreplaceable.
It must have 30% or less of its original natural vegetation. In other words, it must be threatened.

Source: PIB