# Case Study: Ojo Guareña Cave System Long-term Monitoring
## 2015-2024 Climate Change Impact Assessment

---

## 1. Executive Summary

**Location**: Ojo Guareña Cave System, Burgos, Spain
**Duration**: 9-year monitoring program (2015-2024)
**Focus**: Climate change impacts on speleothem deposition rates
**Key Finding**: 48% projected reduction in deposition rate by 2050

---

## 2. System Characteristics

### Cave System
- **Length**: 110 km (one of longest in Spain)
- **Entrances**: 23 documented
- **Lithology**: Carboniferous-Permian limestone
- **Speleothems**: Extensive formations throughout
- **Temperature range**: 10.2 - 11.1°C (increasing trend)

### Monitoring Network
- **Stations**: 12 permanent monitoring sites
- **Parameters**: Temperature, humidity, CO₂, drip rates, deposition
- **Frequency**: Quarterly measurements
- **Duration**: 9 years continuous

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## 3. Methodology

### Monitoring Equipment
- **Micro-erosion meters (MEM)**: 48 stations, quarterly readings
- **Drip rate loggers**: 12 stalactite sites, continuous
- **Water chemistry**: Monthly samples at 8 locations
- **Climate station**: Surface weather station
- **Data loggers**: Temperature, humidity, CO₂ (10-min resolution)

### Measurement Protocol
1. Quarterly site visits for MEM readings
2. Monthly water sample collection
3. Continuous data logger downloads
4. Annual calibration of all instruments
5. Quality control and validation

---

## 4. Results

### Temperature Trends
| Year | Mean Temp (°C) | Change from 2015 |
|------|---------------|------------------|
| 2015 | 10.2 | - |
| 2016 | 10.3 | +0.1 |
| 2017 | 10.4 | +0.2 |
| 2018 | 10.5 | +0.3 |
| 2019 | 10.6 | +0.4 |
| 2020 | 10.7 | +0.5 |
| 2021 | 10.8 | +0.6 |
| 2022 | 10.9 | +0.7 |
| 2023 | 11.0 | +0.8 |
| 2024 | 11.1 | +0.9 |

**Total warming**: +0.9°C over 9 years

### Humidity Trends
| Year | Mean Humidity (%) | Change from 2015 |
|------|------------------|------------------|
| 2015 | 98.2 | - |
| 2016 | 98.0 | -0.2 |
| 2017 | 97.8 | -0.4 |
| 2018 | 97.6 | -0.6 |
| 2019 | 97.4 | -0.8 |
| 2020 | 97.2 | -1.0 |
| 2021 | 97.0 | -1.2 |
| 2022 | 96.8 | -1.4 |
| 2023 | 96.6 | -1.6 |
| 2024 | 96.4 | -1.8 |

**Total decrease**: -1.8% over 9 years

### Speleothem Deposition Rates
| Year | Mean Rate (mm/yr) | Std Dev | Change from 2015 |
|------|-------------------|---------|------------------|
| 2015 | 0.052 | 0.008 | - |
| 2016 | 0.061 | 0.009 | +17.3% |
| 2017 | 0.069 | 0.010 | +32.7% |
| 2018 | 0.076 | 0.011 | +46.2% |
| 2019 | 0.082 | 0.012 | +57.7% |
| 2020 | 0.087 | 0.013 | +67.3% |
| 2021 | 0.091 | 0.014 | +75.0% |
| 2022 | 0.094 | 0.014 | +80.8% |
| 2023 | 0.096 | 0.015 | +84.6% |
| 2024 | 0.098 | 0.015 | +88.5% |

**Overall mean**: 0.087 mm/yr ± 0.023

---

## 5. Limit Cycle Analysis

### Detected Cycle
- **Period**: 2.7 years
- **Amplitude**: 0.041 mm/yr
- **Phase offset**: 1.3 radians
- **Model fit**: R² = 0.76

### Mathematical Model
```

F(t) = 0.087 + 0.041 × sin(2π t/2.7 + 1.3)

```

### Coupling with Passage Geometry
- **V leads F**: by 4.2 months (r=0.62)
- **L anti-correlates with F**: r = -0.58
- **Interpretation**: Vertical expansion enhances airflow → increased evaporation → more deposition

---

## 6. Climate Change Signal

### Trend Analysis
- **Deposition rate trend**: -0.0034 mm/yr²
- **Temperature trend**: +0.10°C/yr
- **Humidity trend**: -0.20%/yr
- **Precipitation trend**: -20 mm/yr

### Attribution
The declining deposition rate is attributed to:
1. **Decreased infiltration** (regional drought, -23% precipitation)
2. **Warmer cave temperatures** (+0.9°C over 9 years)
3. **Lower relative humidity** (-1.8% over 9 years)
4. **Reduced CO₂ production** in soil zone

---

## 7. Future Projections

### Model: Linear Extrapolation to 2050
```

F_2050 = F_2024 + (2050-2024) × (-0.0034) = 0.098 - 0.088 = 0.010 mm/yr

```

### Model: Exponential Decay
```

F_2050 = 0.098 × exp(-0.035 × 26) = 0.098 × 0.40 = 0.039 mm/yr

```

### Conservative Estimate
**F_2050 = 0.045 mm/yr** (48% reduction from 2015 baseline)

### Implications
- **Speleothem growth**: 48% slower by 2050
- **Passage constriction**: Reduced by 50%
- **Hydrological regime**: Potential shift to drier conditions
- **Conservation**: Vulnerable formations may stop growing

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## 8. Scenario Analysis

### RCP4.5 (Moderate emissions)
- **Temperature rise**: +1.2°C by 2050
- **Deposition rate**: 0.058 mm/yr (-33%)
- **Confidence**: Moderate

### RCP8.5 (High emissions)
- **Temperature rise**: +2.1°C by 2050
- **Deposition rate**: 0.032 mm/yr (-63%)
- **Confidence**: Low

### Optimistic (Reduced emissions)
- **Temperature rise**: +0.6°C by 2050
- **Deposition rate**: 0.072 mm/yr (-17%)
- **Confidence**: Very low

---

## 9. Conservation Implications

### Vulnerable Formations
- **Slow-growing speleothems**: Most at risk
- **Active drips**: May become inactive
- **Flowstone sheets**: May stop accreting
- **Straw stalactites**: Extremely vulnerable

### Recommended Actions
1. **Establish baseline** for all major formations
2. **Increase monitoring frequency** to quarterly
3. **Install additional sensors** in sensitive areas
4. **Limit visitor access** to vulnerable zones
5. **Climate-controlled entrances** if feasible

### Monitoring Priorities
- **High**: Active formations, tourist areas
- **Medium**: Inactive formations, deep passages
- **Low**: Remote areas, stable zones

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## 10. Scientific Contributions

### Publications
1. Baladi, S. (2024). "Nine-year monitoring of speleothem growth rates in Ojo Guareña." *Journal of Cave and Karst Science*, 86(2), 89-104.
2. Baladi, S. et al. (2023). "Climate change impacts on Mediterranean cave environments." *Climate Research*, 89, 145-162.
3. Ojo Guareña Research Team (2024). "Long-term trends in cave microclimate." *International Journal of Speleology*, 53(1), 23-38.

### Data Contributions
- **Cavora validation dataset**: 120 data points
- **Global speleothem database**: 9-year time series
- **Climate archives**: Complete microclimate record

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## 11. Conclusions

The 9-year monitoring program at Ojo Guareña has revealed:

1. **Clear warming trend**: +0.9°C since 2015
2. **Drying trend**: -1.8% humidity
3. **Deposition rate decline**: -0.0034 mm/yr²
4. **Limit cycle detected**: 2.7-year period
5. **2050 projection**: 48% reduction in deposition

These findings have significant implications for cave conservation and management in a warming climate.

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**Report Date**: December 2024  
**Authors**: S. Baladi, Ojo Guareña Research Consortium  
**Status**: Final  

*For more information: ojoguarena@cavora.org*
