This page explains the main terms and ideas behind the CADI maps. For a full technical description of our methodology, see the Methods page.
Attainable yield is the realistic upper limit of what a crop can produce in a given location, considering climate, soil, and terrain. It comes from the FAO/IIASA Global Agro-Ecological Zones (GAEZ) model and is the key building block for our maps.
Attainable yield accounts for: temperature and rainfall patterns, solar radiation and growing season length, soil quality (nutrients, texture, depth, drainage), and terrain constraints (slope, elevation).
What attainable yield is not: It is not an observation of what farmers actually harvest. It does not capture market conditions, farmer decisions, conflict, policy, or any socioeconomic factor. It represents what could be grown under a given climate and soil, assuming a consistent level of farm management. This makes it ideal for isolating the climate signal—but it should not be confused with actual production data.
Different crops produce different amounts of food energy per hectare. To compare productivity across crops and regions, we convert crop-specific attainable yields (e.g., tonnes of wheat per hectare) into a common unit: kilocalories per hectare per year (kcal/ha/year). This caloric yield allows us to aggregate the output from multiple crops within a single grid cell into a single measure of caloric production potential.
People Fed Yearly is a way to express how much food a grid cell can produce in terms of how many people it could feed for a whole year. It converts the total caloric production potential into a simple, intuitive number:
$$\text{PFY} = \frac{\text{Total calories that can be produced per year}}{2{,}000 \;\text{kcal/day} \times 365 \;\text{days}}$$
We use 2,000 kcal per person per day as the reference—a widely used adult guideline in both EU and US nutrition labelling.
Important: The number of people that could be fed is a simplified, energy-only metric. It does not account for diet composition, animal feeding, food waste, market access, or trade. It tells you how much caloric energy a place could produce, not how many people it actually feeds.
We report changes in PFY in two complementary ways:
Both metrics matter. A 50% loss in a low-productivity region may be catastrophic for local food security even if the absolute numbers are small. Conversely, a 5% loss in a breadbasket region can affect millions of people.
Our maps display how much agricultural productivity changes—or is projected to change—in each 10 km grid cell around the world. Two views are available:
In all cases, cropping patterns—which crops are grown and how much area each occupies—are held fixed at their observed year-2020 distribution. Only climate conditions vary across time periods, so any differences represent the pure climate-driven change in production potential.
The Shared Socioeconomic Pathways (SSPs) are a set of scenarios developed for the IPCC Sixth Assessment Report. They describe plausible futures for global development and greenhouse gas emissions, spanning different challenges to mitigation and adaptation.
Scenario labels such as SSP1-2.6, SSP3-7.0, and SSP5-8.5 combine a socioeconomic storyline with a forcing pathway targeting an approximate radiative forcing level in 2100 (2.6, 7.0, or 8.5 W/m²). Key scenarios include:
For future projections, we use a single climate scenario: the IPCC’s SSP5-8.5. The reason is empirical. The GAEZ model generates its projections using the 1981–2000 period as a baseline. However, we can already observe what actually happened in the following period, 2001–2020. When we compare the GAEZ projections to those observed changes, only SSP5-8.5 produces near-term changes consistent with the deterioration in agricultural productivity that has already taken place.
Lower-emissions scenarios project smaller changes from the 1981–2000 baseline. Because the actual deterioration observed by 2001–2020 has already exceeded what those scenarios anticipate, using them would paradoxically show an improvement going forward—not because conditions are expected to get better, but simply because the damage already observed has outpaced their projections.
This does not mean we endorse or predict this emissions path. It means that SSP5-8.5 currently provides the most empirically grounded basis for projecting forward from recent observed trends.
The sections below provide additional technical detail on the terms used in the maps and indicators.
People Fed Yearly (PFY) translates annual caloric production potential into an approximate number of "people-fed equivalents" per year:
$$\text{PFY}=\frac{C_{\text{year}}}{c_{\min}\cdot 365},$$
where \(C_{\text{year}}\) is total kilocalories that can be produced per year in a grid cell and \(c_{\min}\) is a reference daily calorie requirement (kcal/person/day).
In practice we use \(c_{\min}=2000\) kcal/person/day, a widely used adult reference intake in nutrition labelling (EU: 8,400 kJ / 2,000 kcal; US FDA: 2,000 calories/day as general guidance).
PFY is an energy-only normalisation: it does not account for diet composition, food waste, access, or trade.
Caloric yield expresses crop attainable yields in a common unit of dietary energy, typically kilocalories per hectare per year (kcal/ha/year). It converts crop-specific attainable yields (e.g., tonnes/ha) into kilocalories using crop energy content tables, which allows comparison across crops and regions.
In this project, caloric yield is computed from GAEZ attainable yields under a given climate and management scenario, converted to kilocalories, and (when needed) aggregated across crops using the observed crop mix within each grid cell.
GAEZ distinguishes different yield levels:
The Shared Socioeconomic Pathways (SSPs) are five socioeconomic storylines (SSP1–SSP5) describing plausible global development trajectories and spanning different challenges to mitigation and adaptation.
In CMIP6 and the IPCC Sixth Assessment Report, scenario labels such as SSP1-2.6, SSP3-7.0, and SSP5-8.5 combine an SSP storyline with a forcing pathway targeting an approximate radiative forcing level in 2100 (2.6, 7.0, or 8.5 W/m²).
SSP1-2.6 combines the "Sustainability" storyline with a low forcing pathway (≈2.6 W/m² in 2100). Assessed end-of-century warming: 1.8°C (very likely 1.3–2.4°C).
SSP3-7.0 combines the "Regional Rivalry" storyline with a high forcing pathway (≈7.0 W/m² in 2100). Assessed end-of-century warming: 3.6°C (very likely 2.8–4.6°C).
SSP5-8.5 combines the "Fossil-fueled Development" storyline with a very high forcing pathway (≈8.5 W/m² in 2100). Assessed end-of-century warming: 4.4°C (very likely 3.3–5.7°C).