Project Drawdown seeks to determine how and when we can reach drawdown—the point in time when levels of greenhouse gases in the atmosphere stop climbing and start to steadily decline—using technologies and practices that reduce sources of greenhouse gases, remove greenhouse gases from the atmosphere, or catalyze societal changes that lead to reduced sources or enhanced sinks. To be included in the solution set, technologies and practices must meet the following criteria: be currently available, growing in scale, financially viable, and able to reduce greenhouse gas concentrations in Earth’s atmosphere. They also must have a net positive impact, and there must be sufficient data available to assess their potential.
To assess a proposed solution, Project Drawdown research fellows with extensive subject area expertise review existing scientific literature to characterize the solution’s potential with respect to these criteria. The fellow then uses the information gathered to identify a “business as usual” adoption scenario and scenarios for three levels of enhanced adoption that are all feasible but with different degrees of ambition.
Scenario 1: Solutions are adopted at a realistically vigorous rate, adjusting for estimated economic and population growth. It roughly corresponds to limiting warming to 2°C.
Scenario 2: Solutions are adopted at a more ambitious rate. It roughly corresponds to limiting warming to 1.5°C.
Maximum: Solutions fully replace conventional technologies and practices within a limited competitive market and/or enhance sinks.
The fellows use Project Drawdown simulation models to calculate for each of the scenarios for the period 2020–2050:
the amount of greenhouse gas that would be reduced, avoided, or stored
the cost of implementation
the operating cost or savings relative to the reference scenario.
Estimates are deliberately conservative, with costs estimated on the high end and benefits on the low end.
Once the preliminary analysis is complete, the methods and findings are reviewed by external experts in the field and refined as indicated. If the proposed solution still meets criteria for inclusion, it becomes part of the solution set.
Because the various solutions are interdependent (for example, demand for pasture is influenced by the degree to which plant-rich diets are adopted), we adjust the numbers derived for each solution set for interaction effects by running them through a series of integration models. This accounts for resource constraints (e.g., total amount of land) and avoids double counting. The results of the integration are the numbers you see presented for each solution.
Finally, we add up the projections within and across sectors to paint a picture of how we can best allocate resources to reach drawdown and what the total cost of implementing and operating would be.