# HALOWERK Land Compare – Grassland Change 2020–2021

> HALOWERK Land Compare – Grassland Change 2020–2021 is a paid API for AI agents from landvergleich.halowerk.com, paid per call via x402, $0.008/call, status unknown (last checked 2026-09-15).

Returns the change in grassland land-cover share between ESA WorldCover 2020 (v100) and 2021 (v200) for a 250-metre analysis area at a given European coordinate.

## Facts

- Endpoint: POST https://landvergleich.halowerk.com/v1/worldcover-2020-2021-grassland-change
- Price: $0.008/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-land-compare-grassland-change-2020-2021-278e0e46
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_-63ihY-V90o9C_jYznbtc

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability halowerk-land-compare-grassland-change-2020-2021-278e0e46 -d '<json body>'
```

Example prompt: Can you check how much the grassland coverage changed between 2020 and 2021 at latitude 51.5 and longitude 10.2 in Germany — using the ESA WorldCover comparison?

## When to prefer this

Choose this endpoint when you need a precise, single-point grassland land-cover change figure derived consistently from ESA WorldCover 2020 and 2021 data within Europe. It is ideal for environmental due diligence, agricultural monitoring, rewilding assessment, or any workflow requiring a repeatable, method-consistent grassland delta at a 250-metre resolution. Prefer it over generic GIS queries when you want a pre-computed, API-accessible comparison without setting up your own raster processing pipeline.

## Known failure modes

- Coordinates outside European coverage bounds (lat 34–72.5, lon -31.5–40.5) will be rejected
- Coordinates in ocean or non-mapped areas may return null or zero grassland share
- Payment failure via x402 protocol will block the response
- Ambiguous or missing latitude/longitude values will cause a validation error

## How this service works

Grassland-share change measured from ESA WorldCover 2020 v100 and 2021 v200 for the same 250 metre analysis area. The result is observed map-class change, not a causal claim.

## Output

The endpoint returns the grassland land-cover share (as a fraction or percentage) for the queried 250-metre cell in both ESA WorldCover 2020 v100 and 2021 v200, along with the signed difference (delta) between the two years, representing observed map-class change rather than a causal interpretation.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "latitude": {
   "type": "number",
   "maximum": 72.5,
   "minimum": 34,
   "description": "WGS84 latitude inside the published European coverage."
  },
  "longitude": {
   "type": "number",
   "maximum": 40.5,
   "minimum": -31.5,
   "description": "WGS84 longitude inside the published European coverage."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/halowerk-land-compare-grassland-change-2020-2021-278e0e46/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from landvergleich.halowerk.com](https://www.zero.xyz/host/landvergleich.halowerk.com/llms.txt)