Tropical Rainforest Index

https://www.udel.edu/udaily/2021/july/rodrigo-vargas-tropical-rainforest-index-national-geographic/

by infodocket • 5 years ago

34 6 5 years ago

The short version of this paper (https://www.cell.com/one-earth/fulltext/S2590-3322(21)00344-...) describes this new index as follows:

Here, we built a spatially explicit tropical forest vulnerability index (TFVI) based on observations of forest cover, carbon, and water fluxes to identify areas where rainforests are losing resilience to disturbance and are changing toward an irreversible state, a “tipping point.”

The extended version of the paper (https://www.cell.com/one-earth/pdfExtended/S2590-3322(21)003...) has a lot more detail and math, and the underlying model is described on page 999 (13 in the PDF) under Equation 8. The model is implemented using the rlm function in R (https://www.rdocumentation.org/packages/MASS/versions/7.3-54...), which fits a linear regression model using iterated re-weighted least squares (IWLS). The input and output variables can be seen on page 1022 (35 in the PDF) in Table S1.

As an aside, I really dislike the increasing use of "tipping points" in discussions around climate change. It seems so vague and imprecise, and the claim of irreversibility seems hard to establish. In the context of this paper, if you read the extended version, it seems tipping point here is essentially long-term loss of biomass (not necessarily a climate-related outcome). Additionally, rather than irreversibility, the model they use predicts losses as a 1-month or 1-year lagged outcome based on various input stressor variables. The magnitude of the output index will need to be interpreted to determine how significant the negative outcome is (that is, the model does not actually determine an irreversible 'tipping point'). Here's the relevant text:

The absolute magnitude of TFVI represents the risk of critical transitions that would result in abrupt decreases (negative values) or increases (positive values) of the response variable given long-term trends in the stressors. The larger the absolute value of TFVI, the greater the risk of a critical transition to either higher or lower value of the ecosystem response.

pacifist• 5 years ago

As an aside, I really dislike the increasing use of "tipping points"

Tipping points have been part of the conversation all along. They are a reality we have to deal with. Sounds to me like you need to come to terms with that reality: that we have a huge problem barreling towards us and we need to respond urgently, immediately and dramatically.

throwawaysea3• 5 years ago

Your final sentence seems like an alarmist take to me, although since it isn’t specific in its suggestions, I cannot really say. I feel we need to respond but not to extremes. For example I don’t think banning gas cars or banning gas stoves or moving away from capitalism, all of which have been variously suggested, are necessary. However I feel subsidizing wind, solar, and nuclear energy and instituting carbon trade structures connected to net carbon reductions (like direct capture) would make sense.

As for tipping points - scientific matters require evidence and precision, not hyperbole that has come to occupy our news and social media. This paper uses the phrase “tipping points” in highlights and introductory blurbs but doesn’t actually provide proof for those tipping points. It feels like a sensationalized headline to me if the model cannot actually prove irreversibility, which is what the phrase “tipping point” implies. That’s not to say we can’t speculate about that possibility, but if we are to speculate, we should make it clear that this is what we’re doing - not wrap speculation with a scientific paper.

pstuart2• 5 years ago

We should be collectively investing in ways of making people there make a better living rather than cutting down the forest to raise cattle and crops.

This is a tragedy of the commons on a global level.

throwawaysea3• 5 years ago

I wonder if the global community should just pay countries with carbon sinks for the opportunity cost of using those lands and resources. Those countries can then spend that money to their citizens’ benefit and agree to enforce protection of the land. This can all be monitored by satellite, with carbon sink nations risking sanctions if they violate that agreement.

pstuart2• 5 years ago

Aid needs to go directly to those impacted, rather than get intercepted and siphoned off.

Tropical Rainforest Index

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