Agricultural Land Exposed to Prolonged Droughts

import os
import pandas as pd
import matplotlib.pyplot as plt
import matplotlib.patches as mpatches
from matplotlib.lines import Line2D
import numpy as np
from pathlib import Path
from scipy import stats

plt.rcParams['figure.figsize'] = (12, 6)
plt.rcParams['font.size'] = 11

# Configuration
admin_id = 'EL64'

# Reference period (WMO standard: 1991-2020)
baseline_start = 1991
baseline_end   = 2020

# Paths (relative to the tutorials/ folder)
data_dir           = Path('../data') / admin_id
drought_reanalysis = data_dir / 'drought_hazard' / f'drought_duration_reanalysis_{admin_id}.csv'
drought_proj_path  = data_dir / 'drought_hazard' / f'drought_duration_projections_{admin_id}.csv'
corine_agri_csv    = data_dir / 'corine_land_cover' / 'land_cover_categories.csv'
satellite_agri_csv = data_dir / 'satellite_land_cover' / f'agricultural_land_fraction_{admin_id}.csv'

print(f'Region: {admin_id} (Central Greece)')
print('\nData files:')
for f in [drought_reanalysis, drought_proj_path, corine_agri_csv, satellite_agri_csv]:
    print(f'  {f}')

# Drought reanalysis
drought_hist_df = pd.read_csv(drought_reanalysis)
drought_hist_df['time'] = pd.to_datetime(drought_hist_df['time'])
drought_hist_df['year'] = drought_hist_df['time'].dt.year

# Drought projections
drought_proj_df = pd.read_csv(drought_proj_path)
drought_proj_df['time'] = pd.to_datetime(drought_proj_df['time'])
drought_proj_df['year'] = drought_proj_df['time'].dt.year

print(f'Drought reanalysis : {drought_hist_df["year"].min()}-{drought_hist_df["year"].max()}')
print(f'Drought projections: {drought_proj_df["year"].min()}-{drought_proj_df["year"].max()}')
print(f'Climate models     : {drought_proj_df["model"].nunique()}')
print(f'Scenarios          : {sorted(drought_proj_df["scenario"].unique())}')

# CORINE land cover (5 snapshot years; 'agricultural' column in %)
df_corine = pd.read_csv(corine_agri_csv)
df_corine['ag_fraction'] = df_corine['agricultural'] / 100.0

# Satellite land cover (annual 1992-2022; ag_fraction already in 0-1)
df_satellite = pd.read_csv(satellite_agri_csv)

print('CORINE land cover (snapshot years):')
print(df_corine[['year', 'agricultural', 'ag_fraction']].to_string(index=False))
print(f'\nSatellite land cover: {int(df_satellite["year"].min())}-{int(df_satellite["year"].max())} '
      f'({len(df_satellite)} years)')
print(f'  Latest ag_fraction: {df_satellite["ag_fraction"].iloc[-1]:.4f}')

# Build a full annual CORINE series by forward-filling the 5 snapshot values
all_hist_years = pd.DataFrame({'year': range(drought_hist_df['year'].min(),
                                             drought_hist_df['year'].max() + 1)})
corine_annual = all_hist_years.merge(df_corine[['year', 'ag_fraction']], on='year', how='left')
corine_annual['ag_fraction'] = corine_annual['ag_fraction'].ffill()

# Merge with drought reanalysis
hist_corine = drought_hist_df[['year', 'dmd']].merge(corine_annual, on='year', how='inner')
hist_corine['exposure'] = hist_corine['dmd'] * hist_corine['ag_fraction']

hist_satellite = drought_hist_df[['year', 'dmd']].merge(
    df_satellite[['year', 'ag_fraction']], on='year', how='inner')
hist_satellite['exposure'] = hist_satellite['dmd'] * hist_satellite['ag_fraction']

bl_corine    = hist_corine[hist_corine['year'].between(baseline_start, baseline_end)]
bl_satellite = hist_satellite[hist_satellite['year'].between(baseline_start, baseline_end)]

print(f'Historical CORINE exposure   : {hist_corine["year"].min()}-{hist_corine["year"].max()}')
print(f'Historical satellite exposure: {hist_satellite["year"].min()}-{hist_satellite["year"].max()}')
print(f'\nBaseline ({baseline_start}-{baseline_end}) mean exposure:')
print(f'  CORINE   : {bl_corine["exposure"].mean():.4f} months/yr\u00b7fraction')
print(f'  Satellite: {bl_satellite["exposure"].mean():.4f} months/yr\u00b7fraction')

fig, axes = plt.subplots(3, 1, figsize=(14, 11), sharex=True)

# Panel 1: drought duration
axes[0].plot(hist_corine['year'], hist_corine['dmd'],
             color='#D62828', linewidth=1.5, alpha=0.8, label='ERA5 reanalysis')
axes[0].set_ylabel('Drought duration\n(months/year)', fontsize=11)
axes[0].set_title('Historical Agricultural Drought Exposure \u2014 Central Greece (EL64)',
                  fontsize=14, fontweight='bold', pad=15)
axes[0].legend(fontsize=10)
axes[0].grid(True, alpha=0.3, linestyle='--', linewidth=0.5)
axes[0].spines['top'].set_visible(False)
axes[0].spines['right'].set_visible(False)

# Panel 2: agricultural fraction
axes[1].step(hist_corine['year'], hist_corine['ag_fraction'],
             color='#8B4513', linewidth=2, where='post', label='CORINE (forward-filled)')
axes[1].plot(hist_satellite['year'], hist_satellite['ag_fraction'],
             color='#228B22', linewidth=1.5, label='Satellite (annual)')
axes[1].scatter(df_corine['year'], df_corine['ag_fraction'],
                color='#8B4513', s=60, zorder=5, label='CORINE snapshots')
axes[1].set_ylabel('Agricultural fraction\n(0\u20131)', fontsize=11)
axes[1].legend(fontsize=10)
axes[1].grid(True, alpha=0.3, linestyle='--', linewidth=0.5)
axes[1].spines['top'].set_visible(False)
axes[1].spines['right'].set_visible(False)

# Panel 3: exposure index
axes[2].fill_between(hist_corine['year'], 0, hist_corine['exposure'],
                     color='#8B4513', alpha=0.3)
axes[2].plot(hist_corine['year'], hist_corine['exposure'],
             color='#8B4513', linewidth=2, label='CORINE')
axes[2].fill_between(hist_satellite['year'], 0, hist_satellite['exposure'],
                     color='#228B22', alpha=0.2)
axes[2].plot(hist_satellite['year'], hist_satellite['exposure'],
             color='#228B22', linewidth=2, label='Satellite')
axes[2].axvspan(baseline_start, baseline_end, color='gray', alpha=0.1,
                label=f'Baseline ({baseline_start}\u2013{baseline_end})')
axes[2].set_ylabel('Agricultural drought\nexposure (months/yr\u00b7fraction)', fontsize=11)
axes[2].set_xlabel('Year', fontsize=12)
axes[2].legend(fontsize=10)
axes[2].grid(True, alpha=0.3, linestyle='--', linewidth=0.5)
axes[2].spines['top'].set_visible(False)
axes[2].spines['right'].set_visible(False)

plt.tight_layout()
plt.show()

overlap = hist_corine.merge(hist_satellite[['year', 'ag_fraction', 'exposure']],
                            on='year', suffixes=('_corine', '_sat'))

print('Comparison over overlapping years:')
print(f'  Mean CORINE ag fraction   : {overlap["ag_fraction_corine"].mean():.4f}')
print(f'  Mean satellite ag fraction: {overlap["ag_fraction_sat"].mean():.4f}')
diff_pp = (overlap['ag_fraction_corine'] - overlap['ag_fraction_sat']) * 100
print(f'  Mean offset (CORINE - satellite): {diff_pp.mean():+.2f} pp')
print(f'\nBaseline ({baseline_start}-{baseline_end}) mean exposure:')
print(f'  CORINE   : {bl_corine["exposure"].mean():.4f} months/yr\u00b7fraction')
print(f'  Satellite: {bl_satellite["exposure"].mean():.4f} months/yr\u00b7fraction')
ratio = bl_corine['exposure'].mean() / bl_satellite['exposure'].mean()
print(f'  Ratio (CORINE / Satellite): {ratio:.2f}')

# Latest observed agricultural fraction for each dataset
ag_frac_corine    = df_corine['ag_fraction'].iloc[-1]
ag_frac_satellite = df_satellite['ag_fraction'].iloc[-1]
last_corine_year    = int(df_corine['year'].iloc[-1])
last_satellite_year = int(df_satellite['year'].iloc[-1])

print('Persistence values:')
print(f'  CORINE    ({last_corine_year}): {ag_frac_corine:.4f}  ({ag_frac_corine*100:.2f}%)')
print(f'  Satellite ({last_satellite_year}): {ag_frac_satellite:.4f}  ({ag_frac_satellite*100:.2f}%)')

def make_exposure_stats(drought_df, ag_frac_const, scenario, smooth_window=30):
    """Return per-year exposure statistics for a fixed ag fraction and one RCP scenario.
    Applies a centred rolling mean to each model's drought series before aggregation."""
    df = drought_df[drought_df['scenario'] == scenario].copy()
    df['dmd_smooth'] = df.groupby('model')['dmd'].transform(
        lambda x: x.rolling(window=smooth_window, center=True, min_periods=1).mean()
    )
    df['exposure'] = df['dmd_smooth'] * ag_frac_const
    stats_out = df.groupby('year').agg(
        exposure_median=('exposure', 'median'),
        exposure_p17=('exposure', lambda x: np.percentile(x, 17)),
        exposure_p83=('exposure', lambda x: np.percentile(x, 83)),
        dmd_median=('dmd_smooth', 'median'),
        dmd_p17=('dmd_smooth', lambda x: np.percentile(x, 17)),
        dmd_p83=('dmd_smooth', lambda x: np.percentile(x, 83)),
    ).reset_index()
    return df, stats_out

# CORINE persistence
rcp45_raw_corine, rcp45_stats_corine = make_exposure_stats(drought_proj_df, ag_frac_corine, 'RCP4_5')
rcp85_raw_corine, rcp85_stats_corine = make_exposure_stats(drought_proj_df, ag_frac_corine, 'RCP8_5')

# Satellite persistence
rcp45_raw_sat, rcp45_stats_sat = make_exposure_stats(drought_proj_df, ag_frac_satellite, 'RCP4_5')
rcp85_raw_sat, rcp85_stats_sat = make_exposure_stats(drought_proj_df, ag_frac_satellite, 'RCP8_5')

print('Exposure statistics computed (30-year rolling mean applied to drought series).')
print(f'Projection range: {rcp45_stats_corine["year"].min()}-{rcp45_stats_corine["year"].max()}')

fig, axes = plt.subplots(2, 1, figsize=(14, 10), sharex=True)

# Smooth historical drought for visual consistency with 30-yr rolling mean projections
hist_smooth = drought_hist_df[['year', 'dmd']].copy()
hist_smooth['dmd'] = hist_smooth['dmd'].rolling(window=10, center=True, min_periods=1).mean()

def add_panel(ax, hist_df, stats45, stats85, hist_label, frac_val, frac_year, frac_color, title):
    ax.plot(hist_df['year'], hist_df['exposure'],
            color='black', linewidth=2.5, label=hist_label, zorder=5)
    for color, stats_df, label in [
        ('#F77F00', stats45, 'RCP4.5 (multi-model median)'),
        ('#D62828', stats85, 'RCP8.5 (multi-model median)'),
    ]:
        ax.plot(stats_df['year'], stats_df['exposure_median'],
                color=color, linewidth=2.5, label=label)
        ax.fill_between(stats_df['year'],
                        stats_df['exposure_p17'], stats_df['exposure_p83'],
                        color=color, alpha=0.15)
    ax.axvspan(baseline_start, baseline_end, color='gray', alpha=0.1,
               label=f'Baseline ({baseline_start}\u2013{baseline_end})')
    ax.axvline(frac_year, color=frac_color, linestyle=':', linewidth=1.5,
               label=f'Last observation ({frac_year})')
    ax.set_ylabel('Agricultural drought\nexposure (months/yr\u00b7fraction)', fontsize=11)
    ax.set_title(title, fontsize=12, fontweight='bold')
    ax.legend(fontsize=9, loc='upper left')
    ax.grid(True, alpha=0.3, linestyle='--', linewidth=0.5)
    ax.spines['top'].set_visible(False)
    ax.spines['right'].set_visible(False)

hist_corine_smooth = hist_smooth.merge(corine_annual, on='year')
hist_corine_smooth['exposure'] = hist_corine_smooth['dmd'] * hist_corine_smooth['ag_fraction']

hist_sat_smooth = hist_smooth.merge(df_satellite[['year', 'ag_fraction']], on='year', how='inner')
hist_sat_smooth['exposure'] = hist_sat_smooth['dmd'] * hist_sat_smooth['ag_fraction']

add_panel(axes[0], hist_corine_smooth, rcp45_stats_corine, rcp85_stats_corine,
          'Historical (reanalysis)', ag_frac_corine, last_corine_year, '#8B4513',
          f'CORINE persistence (ag fraction = {ag_frac_corine*100:.1f}%)')

add_panel(axes[1], hist_sat_smooth, rcp45_stats_sat, rcp85_stats_sat,
          'Historical (reanalysis)', ag_frac_satellite, last_satellite_year, '#228B22',
          f'Satellite persistence (ag fraction = {ag_frac_satellite*100:.1f}%)')

axes[1].set_xlabel('Year', fontsize=12)
fig.suptitle('Future Agricultural Drought Exposure \u2014 Central Greece (EL64)',
             fontsize=14, fontweight='bold', y=1.01)
plt.tight_layout()
plt.show()

factor_periods = {
    'Near-term':  (2021, 2050),
    'Mid-term':   (2041, 2070),
    'Long-term':  (2071, 2100),
}
period_order = ['Near-term', 'Mid-term', 'Long-term']

# Per-model baseline dmd (average across both scenarios)
baseline_dmd_models = (
    drought_proj_df[drought_proj_df['year'].between(baseline_start, baseline_end)]
    .groupby(['model', 'scenario'])['dmd'].mean()
    .reset_index()
    .groupby('model')['dmd'].mean()
    .reset_index()
    .rename(columns={'dmd': 'baseline_dmd'})
)

period_results = {}
for period_name, (start, end) in factor_periods.items():
    hazard_rcp45, hazard_rcp85 = [], []
    for scenario, h_list in [('RCP4_5', hazard_rcp45), ('RCP8_5', hazard_rcp85)]:
        period_dmd = (
            drought_proj_df[
                drought_proj_df['year'].between(start, end) &
                (drought_proj_df['scenario'] == scenario)
            ]
            .groupby('model')['dmd'].mean().reset_index()
            .rename(columns={'dmd': 'period_dmd'})
        )
        m = period_dmd.merge(baseline_dmd_models, on='model')
        m['hazard_factor'] = m['period_dmd'] / m['baseline_dmd']
        h_list.extend(m['hazard_factor'].values)
    period_results[period_name] = {
        'hazard_rcp45': np.array(hazard_rcp45),
        'hazard_rcp85': np.array(hazard_rcp85),
    }

print('Hazard (= exposure) change factors relative to 1991-2020 baseline:')
for period, res in period_results.items():
    print(f'  {period}:')
    print(f'    RCP4.5 median: {np.median(res["hazard_rcp45"]):.3f}  '
          f'[{np.percentile(res["hazard_rcp45"],17):.3f} - '
          f'{np.percentile(res["hazard_rcp45"],83):.3f}]')
    print(f'    RCP8.5 median: {np.median(res["hazard_rcp85"]):.3f}  '
          f'[{np.percentile(res["hazard_rcp85"],17):.3f} - '
          f'{np.percentile(res["hazard_rcp85"],83):.3f}]')

fig, ax = plt.subplots(figsize=(12, 6))

data_to_plot, box_colors, x_positions = [], [], []
x = 1.0
for period_name in period_order:
    res = period_results[period_name]
    data_to_plot.extend([res['hazard_rcp45'], res['hazard_rcp85']])
    box_colors.extend(['#F77F00', '#D62828'])
    x_positions.extend([x, x + 0.14])
    x += 1.0

bp = ax.boxplot(
    data_to_plot, patch_artist=True, widths=0.09, showfliers=False,
    medianprops=dict(color='black', linewidth=1.5), positions=x_positions,
)
for patch, color in zip(bp['boxes'], box_colors):
    patch.set_facecolor(color)
    patch.set_alpha(0.75)
    patch.set_edgecolor(color)

ax.axhline(1.0, color='gray', linestyle='--', linewidth=1.5, alpha=0.7, label='No change')
y_min, y_max = ax.get_ylim()
ax.set_xlim(0.75, 3.45)
ax.set_xticks([])
for i, period_name in enumerate(period_order):
    start, end = factor_periods[period_name]
    ax.text(1.07 + i, y_min - 0.06 * (y_max - y_min),
            f'{period_name}\n({start}\u2013{end})', ha='center', va='top', fontsize=10)

legend_handles = [
    mpatches.Patch(facecolor='#F77F00', alpha=0.75, label='RCP4.5'),
    mpatches.Patch(facecolor='#D62828', alpha=0.75, label='RCP8.5'),
    Line2D([0], [0], color='gray', linestyle='--', linewidth=1.5, label='No change'),
]
ax.legend(handles=legend_handles, loc='upper left', fontsize=10)
ax.set_ylabel('Hazard (= exposure) change factor\nrelative to 1991\u20132020 baseline', fontsize=11)
ax.set_title(
    'Projected change in agricultural drought exposure\n'
    'Central Greece (EL64) \u2014 persistence land use assumption',
    fontsize=13, fontweight='bold'
)
ax.grid(True, axis='y', alpha=0.3, linestyle='--', linewidth=0.5)
ax.spines['top'].set_visible(False)
ax.spines['right'].set_visible(False)
plt.tight_layout()
plt.show()

print('Under the persistence assumption, the exposure change factor equals the hazard change factor.')
print('Boxplot spread shows multi-model uncertainty.')

all_proj_years = np.array(sorted(drought_proj_df['year'].unique()))
frac_2018 = ag_frac_corine
year_ref  = last_corine_year   # 2018
year_end  = 2100

# Scenario 1: Persistence
frac_persistence = {yr: frac_2018 for yr in all_proj_years}

# Scenario 2: Linear trend extrapolated from CORINE 1990-2018
slope, intercept, *_ = stats.linregress(df_corine['year'].values, df_corine['ag_fraction'].values)
frac_trend = {yr: max(0.0, slope * yr + intercept) for yr in all_proj_years}

# Scenario 3: +10% relative change by 2100
# Scenario 4: -10% relative change by 2100
frac_plus10, frac_minus10 = {}, {}
for yr in all_proj_years:
    if yr <= year_ref:
        frac_plus10[yr]  = frac_2018
        frac_minus10[yr] = frac_2018
    else:
        t = (yr - year_ref) / (year_end - year_ref)    # linear ramp 0 -> 1
        frac_plus10[yr]  = frac_2018 * (1 + 0.10 * t)
        frac_minus10[yr] = frac_2018 * (1 - 0.10 * t)

scenarios_land = {
    'Persistence':    frac_persistence,
    'Trend':          frac_trend,
    '+10% by 2100':   frac_plus10,
    '-10% by 2100': frac_minus10,
}

print(f'CORINE linear trend: {slope*10:.4f} fraction-points / decade')
print(f'  At 2018: {(slope*2018+intercept)*100:.2f}%  (CORINE actual: {frac_2018*100:.2f}%)')
print(f'\nLand use fractions at year 2100:')
for name, frac_dict in scenarios_land.items():
    print(f'  {name}: {frac_dict[2100]*100:.2f}%')

fig, ax = plt.subplots(figsize=(12, 4))

ax.scatter(df_corine['year'], df_corine['ag_fraction'] * 100,
           color='#8B4513', s=70, zorder=10, label='CORINE snapshots', marker='o')

ls_map = {'Persistence': '-', 'Trend': '--', '+10% by 2100': ':', '-10% by 2100': '-.'}
future_mask = all_proj_years >= year_ref
for name, frac_dict in scenarios_land.items():
    ys = np.array([frac_dict[yr] * 100 for yr in all_proj_years])
    ax.plot(all_proj_years[future_mask], ys[future_mask],
            linestyle=ls_map[name], color='#333333', linewidth=2, label=name)

ax.axvline(year_ref, color='gray', linestyle=':', linewidth=1.2, alpha=0.7)
ax.set_ylabel('Agricultural fraction (%)', fontsize=11)
ax.set_xlabel('Year', fontsize=11)
ax.set_title('Agricultural land fraction (CORINE-based scenarios)', fontsize=12, fontweight='bold')
ax.legend(fontsize=10)
ax.grid(True, alpha=0.3, linestyle='--')
ax.spines['top'].set_visible(False)
ax.spines['right'].set_visible(False)
plt.tight_layout()
plt.show()

def exposure_timeseries(drought_df, scenario_rcp, ag_frac_dict, smooth_window=30):
    """Annual exposure statistics for a time-varying ag fraction and one RCP."""
    df = drought_df[drought_df['scenario'] == scenario_rcp].copy()
    df['dmd_smooth'] = df.groupby('model')['dmd'].transform(
        lambda x: x.rolling(window=smooth_window, center=True, min_periods=1).mean()
    )
    df['ag_frac'] = df['year'].map(ag_frac_dict)
    df['exposure'] = df['dmd_smooth'] * df['ag_frac']
    return df.groupby('year').agg(
        exposure_median=('exposure', 'median'),
        exposure_p17=('exposure', lambda x: np.percentile(x, 17)),
        exposure_p83=('exposure', lambda x: np.percentile(x, 83)),
    ).reset_index()

results_all = {}
for land_name, frac_dict in scenarios_land.items():
    for rcp in ['RCP4_5', 'RCP8_5']:
        results_all[(land_name, rcp)] = exposure_timeseries(drought_proj_df, rcp, frac_dict)

print('Exposure timeseries computed for all 4 land scenarios x 2 RCPs.')

fig, ax = plt.subplots(figsize=(15, 7))

# Historical reference (smoothed, CORINE forward-fill)
hist_ref = hist_corine.copy()
hist_ref['exposure'] = (
    hist_ref['dmd'].rolling(window=10, center=True, min_periods=1).mean()
    * hist_ref['ag_fraction']
)
ax.plot(hist_ref['year'], hist_ref['exposure'],
        color='black', linewidth=2.5, label='Historical (reanalysis, CORINE)', zorder=10)

rcp_colors = {'RCP4_5': '#F77F00', 'RCP8_5': '#D62828'}
rcp_labels = {'RCP4_5': 'RCP4.5', 'RCP8_5': 'RCP8.5'}
ls_map = {'Persistence': '-', 'Trend': '--', '+10% by 2100': ':', '-10% by 2100': '-.'}

years_proj = results_all[('Persistence', 'RCP4_5')]['year'].values

for rcp in ['RCP4_5', 'RCP8_5']:
    color = rcp_colors[rcp]

    # Envelope spanning all land scenarios (multi-model median range)
    all_medians = np.vstack(
        [results_all[(ls, rcp)].set_index('year')['exposure_median'].reindex(years_proj).values
         for ls in scenarios_land]
    )
    ax.fill_between(years_proj, all_medians.min(axis=0), all_medians.max(axis=0),
                    color=color, alpha=0.12)

    # Climate model spread (P17-P83) for persistence scenario
    ts_pers = results_all[('Persistence', rcp)]
    ax.fill_between(ts_pers['year'], ts_pers['exposure_p17'], ts_pers['exposure_p83'],
                    color=color, alpha=0.07, hatch='//')

    # Individual land scenario lines
    for land_name, ls in ls_map.items():
        ts = results_all[(land_name, rcp)]
        ax.plot(ts['year'], ts['exposure_median'],
                color=color, linewidth=1.6, linestyle=ls, alpha=0.9)

ax.axvspan(baseline_start, baseline_end, color='gray', alpha=0.08)
ax.axvline(year_ref, color='gray', linestyle=':', linewidth=1.2, alpha=0.7)

ax.set_xlabel('Year', fontsize=12)
ax.set_ylabel('Agricultural drought exposure (months/yr\u00b7fraction)', fontsize=11)
ax.set_title(
    'Agricultural drought exposure |  RCP & land use scenario uncertainty\n'
    '(Central Greece (EL64),  CORINE-based land use scenarios,  30-year rolling mean)',
    fontsize=13, fontweight='bold'
)

legend_handles = [
    Line2D([0], [0], color='black', linewidth=2.5, label='Historical'),
    mpatches.Patch(facecolor='#F77F00', alpha=0.4, label='RCP4.5 (land scenario range)'),
    mpatches.Patch(facecolor='#D62828', alpha=0.4, label='RCP8.5 (land scenario range)'),
    mpatches.Patch(facecolor='gray', alpha=0.12, hatch='//', label='Climate model spread P17\u2013P83 (persistence)'),
    Line2D([0], [0], color='gray', linewidth=1.6, linestyle='-',  label='Persistence'),
    Line2D([0], [0], color='gray', linewidth=1.6, linestyle='--', label='Trend (extrapolated)'),
    Line2D([0], [0], color='gray', linewidth=1.6, linestyle=':',  label='+10% by 2100'),
    Line2D([0], [0], color='gray', linewidth=1.6, linestyle='-.', label='\u221210% by 2100'),
    mpatches.Patch(facecolor='gray', alpha=0.08, label=f'Baseline ({baseline_start}\u2013{baseline_end})'),
]
ax.legend(handles=legend_handles, loc='upper left', fontsize=9, frameon=True,
          framealpha=0.92, ncol=2)
ax.grid(True, alpha=0.3, linestyle='--', linewidth=0.5)
ax.spines['top'].set_visible(False)
ax.spines['right'].set_visible(False)
plt.tight_layout()
plt.show()

print('\nInterpretation:')
print('  Solid / dashed / dotted / dash-dot lines : four land use scenarios.')
print('  Orange vs. red colour family             : RCP4.5 vs. RCP8.5.')
print('  Coloured band (light fill)               : median exposure range across land scenarios for each RCP.')
print('  Hatched band                             : climate model spread (P17-P83) for the persistence scenario.')